ITPR3 encodes the type 3 inositol 1,4,5-trisphosphate receptor, an endoplasmic-reticulum channel that releases stored calcium when activated by IP3. The receptor participates in calcium-dependent processes including transcription, cell migration, proliferation, apoptosis and homeostasis. Its large cytoplasmic regulatory region contains sites for post-translational modification and interactions with other proteins, making the mapping of individual phosphosites potentially useful for understanding how calcium signaling is coordinated with other cellular systems. Earlier experimental work has suggested that S916, S934 and S1832 do not directly change ITPR3-mediated calcium release, leaving open the possibility that they influence regulatory complexes or downstream signaling instead.

For the study, published by Rai and colleagues in Frontiers in Bioinformatics in October 2026, researchers searched PubMed for human phosphoproteomics studies through May 2024. Their screening yielded 160 relevant publications containing 789 qualitative profiling datasets and 187 quantitative differential datasets. The curated material included label-free, tandem mass tag and SILAC measurements produced with different mass-spectrometry platforms and phosphopeptide-enrichment methods. To retain high-confidence assignments, the team required a localization probability of at least 75% or an A-score above 13, and it filtered differential datasets using p values below 0.05, fold changes of at least 1.3 for increases and no more than 0.76 for decreases.

That harmonized collection contained 24 ITPR3 phosphosites in qualitative profiles and 18 in differential datasets. S1832 was detected most often, appearing in 655 profiling datasets and 99 differential datasets, followed by S2670 with 644 and 69 appearances, S934 with 561 and 74, and S916 with 215 and 24. These four sites were designated as predominant because of their recurrence across independent studies rather than because their biological effects had been demonstrated. S916 and S934 lie between the receptor’s two RYDR domains, S1832 falls between the second RYDR and RIH domains, and S2670 is near the C terminus. All four are outside the IP3-binding and transmembrane channel domains. Sequence comparisons also showed that the positions were not conserved across the three mammalian IP3 receptor isoforms, although they were highly conserved in ITPR3 orthologues from humans, mice, rats and cattle.

The four sites also showed evidence of coordinated phosphorylation. S1832 was positively co-regulated with S2670 in 27 datasets, with S934 in 19 and with S916 in 15; S934 and S916 were positively co-regulated in 11 datasets. More extensive computational comparisons found that S1832 was positively and negatively co-regulated with 165 and 88 phosphosites in other proteins, respectively. The corresponding counts were 241 positive and 108 negative for S934, 412 positive and 61 negative for S2670, and 339 positive and 581 negative for S916. These relationships were not interpreted as direct physical interactions. Instead, they indicate that phosphorylation of ITPR3 at one position often changes alongside phosphorylation elsewhere in the cell under the experimental conditions represented in the datasets.

Functional enrichment separated the four sites into partly overlapping but distinguishable regulatory landscapes. Proteins positively associated with S1832 were enriched for chromatin organization, heterochromatin formation and regulation of DNA-templated and RNA polymerase II transcription. The S2670 network was associated with chromatin remodeling, transcriptional regulation and control of the G2-to-M transition, while proteins positively co-regulated with S916 were enriched for RNA processing and spliceosome-mediated mRNA splicing. The S934 network was associated more prominently with protein localization, small-GTPase signaling, lamellipodium organization, DNA-break localization and cortical microtubules. Negatively co-regulated proteins likewise showed site-specific patterns involving transcription, translation, alternative splicing, organelle organization, the cytoskeleton and anoikis. Hub-protein analysis supported these divisions, with highly connected nodes aligned to the enriched processes.

The analysis also nominated candidate upstream kinases, but did not demonstrate that they phosphorylate the sites in cells. CAMK2D was positively co-regulated with S1832, whereas MELK, RPS6KB2 and PAK4 were negatively associated with it. For S934, RPS6KA4, MARK2 and CAMK2D appeared in the positive network, and PAK4 was identified by both co-regulation analysis and NetworKIN/AKID prediction. PRKCD and PRKCE were predicted as possible upstream kinases for S2670. The S916 network included WNK1, RPS6KA3, MAP3K20, TRPM7, STK10 and PAK2 among negatively associated kinases, with PAK4 and PAK2 also highlighted by sequence-based prediction. These kinase labels therefore combine co-occurrence patterns with computational inference, leaving direct kinase activity and site modification to be tested experimentally.

Mapping co-regulated proteins onto established signaling resources placed the ITPR3 sites within a network extending beyond the receptor’s immediate calcium-release function. S1832 was positively associated with calcium/calmodulin-dependent protein kinase II delta and epidermal growth factor receptor, while S934 was positively associated with histamine receptor H1, VDAC1, PHKB, PHKA2 and CAMK2D. PLCD3, a component of IP3 generation, appeared in the positive S2670 network, while STIM2, involved in store-operated calcium entry, appeared in the negative S916 network. Other associated proteins included the receptors EGFR and MET and the calcium-responsive kinase PTK2B. Complex-interaction networks were enriched for pathways including calcium signaling, Rap1 signaling, focal adhesion, adherens and tight junctions, endocytosis, axon guidance, neurotrophin signaling and proteoglycans in cancer. These pathway associations connect ITPR3 phosphorylation with receptor signaling, endoplasmic-reticulum calcium release, store-operated entry and potentially mitochondrial calcium transfer, but do not establish the direction or mechanism of those effects.

Restricting the curated differential data to cancer-derived cell lines showed that each predominant site was repeatedly observed, though at different frequencies. S1832 appeared in 82 of 98 cancer-cell-line datasets, S934 in 65 of 76, S2670 in 55 of 63 and S916 in 17 of 24. In the broader collection, S1832 was generally increased in skin, blood and cervical cancer datasets but decreased in lung cancer datasets. S934 showed different directions among cancer types, including decreases in lung and liver and increases in skin, colon, breast, cervical and blood cancers. A separate cProSite analysis provided tumor-level log2 fold changes and found particularly strong differences for individual sites: S1832 was upregulated in pancreatic ductal adenocarcinoma at log2 fold change 1.2909 with p below 0.0001; S2670 in breast cancer at 1.4838 with p equal to 0.0004; and S934 in ovarian cancer at 2.4224 with p below 0.0001. S916 was downregulated in kidney cancer at −0.8818 with p equal to 0.0013.

The results generate a site-specific map for future experiments, but the evidence is exploratory. The underlying studies used different cell types, treatments, mass-spectrometry platforms, quantification methods and data-processing pipelines. The researchers could not uniformly normalize or correct batch effects because raw data were not available for every study and a common reprocessing workflow was lacking. Even though fold-change thresholds were applied within individual datasets, differences in dynamic range among quantification strategies could influence the compiled patterns. Functional enrichment, interaction networks, pathway assignments and kinase relationships are computational associations, and the cancer findings do not show that ITPR3 phosphorylation causes tumor growth, changes calcium flux or predicts clinical outcomes. The authors accordingly call for phosphosite-directed mutagenesis, kinase assays and cellular functional studies. Until those tests are performed, the strongest conclusion is that four conserved ITPR3 phosphosites recur in cancer datasets and occupy distinct, testable regulatory networks associated with calcium handling, transcription, RNA processing, cytoskeletal organization and receptor signaling.

Subject of Research: Computational mapping of recurrent ITPR3 phosphosites, calcium-signaling associations and cancer-cell-line phosphorylation patterns

Article Title: Decoding the phosphorylation landscape of ITPR3 across calcium signaling and regulatory networks in cancer

Article References: Rai, S. B., Sujina, A., Kammarambath, S. R., Mahin, A., Subair, S., Sambreena, A., Pavithra, S., Raju, R., & Palollathil, A. (2026). Decoding the phosphorylation landscape of ITPR3 across calcium signaling and regulatory networks in cancer. Frontiers in Bioinformatics, 6, Article 1972498. https://doi.org/10.3389/fbinf.2026.1972498

Image Credits: AI Generated

DOI: 10.3389/fbinf.2026.1972498

Keywords: ITPR3, phosphoproteomics, protein phosphorylation, co-regulation, calcium signaling, cancer cell lines, kinase prediction, endoplasmic reticulum, bioinformatics, interaction networks, Decoding, phosphorylation

CYLD belongs to a family of enzymes known as deubiquitinases, or DUBs. To understand what these enzymes do, it helps to think of ubiquitin as a small molecular tag that cells attach to proteins. Depending on how the tags are chained together, they can signal that a protein should be destroyed, that it should change location, or that it should participate in a signaling cascade. DUBs are the scissors that snip these tags off, reversing the process. CYLD is a member of the ubiquitin-specific protease subfamily, the largest class of DUBs, and it specializes in removing two particular types of ubiquitin chains: those linked through lysine 63 and those linked head-to-tail through methionine 1, known as linear chains. Both chain types are heavily used in inflammatory signaling, which explains why CYLD sits at the heart of so many cellular decisions.

Structurally, CYLD is unusual among its relatives. It carries three CAP-Gly domains at its N-terminus, which anchor it to microtubules and to signaling partners, and a large catalytic USP domain at its C-terminus. Crystallographic and biochemical work has revealed that CYLD lacks a subdomain called the Fingers region that most other USPs use to grip the end of a ubiquitin chain. This absence is not a defect but an adaptation: it allows CYLD to cut in the middle of lysine 63 and linear chains rather than only at their tips, giving it a kinetic advantage over enzymes that must nibble from the outside in. Subtle differences in its active site, particularly an extended loop between two beta strands, explain why CYLD strongly prefers lysine 63 chains and is essentially inactive against lysine 48 chains, the type that usually marks proteins for destruction by the proteasome.

Embedded within the catalytic domain is another oddity: a small zinc-binding module resembling a B box, a structure more commonly found in E3 ligases, the enzymes that attach ubiquitin rather than remove it. Experiments with recombinant CYLD lacking this region showed that the B box is dispensable for catalytic activity and does not bind ubiquitin itself. Instead, it appears to serve two other purposes: it mediates dimerization of CYLD molecules and helps retain the enzyme in the cytoplasm. Mutants lacking the B box partially drift into the nucleus, suggesting that this small module acts as a kind of cytosolic anchor. Meanwhile, the CAP-Gly domains do double duty. The first two bind microtubules, while the third interacts with NEMO, a regulatory subunit of the IKK complex that sits at the center of the NF-κB pathway, and is essential for full enzymatic activity in vitro.

CYLD’s most famous role is as a brake on NF-κB, a transcription factor that drives inflammation, cell survival, and immune responses. When tumor necrosis factor (TNF) binds its receptor on the cell surface, a signaling complex assembles that includes RIPK1, TRAF2, and the LUBAC complex, which decorates the assembly with linear ubiquitin chains. CYLD is recruited to this complex through its partner SPATA2 and begins trimming the ubiquitin tags. If NF-κB remains active, the cell survives and divides. But if NF-κB is repressed, a secondary complex forms containing caspase-8, which triggers apoptosis, the orderly form of cell death. If caspase-8 is absent or inhibited, RIPK1 instead pairs with RIPK3 to activate MLKL, a pore-forming protein that causes necroptosis, an inflammatory type of cell death. By removing ubiquitin from RIPK1, CYLD tips the balance toward these death pathways, acting as a kind of molecular referee between life and death.

But CYLD’s influence extends well beyond apoptosis and necroptosis. Recent work has shown that it also restrains pyroptosis, a lytic and highly inflammatory form of cell death triggered by infection and cellular stress. In macrophages, CYLD deubiquitinates PLK4 to limit the activity of the NLRP3 inflammasome, a molecular machine that ignites pyroptosis. In breast cancer cells, hypoxia drives the RNF213-mediated ubiquitination and degradation of CYLD, which in turn permits NF-κB-driven expression of NLRP3 and, together with endoplasmic reticulum stress, triggers pyroptotic death. CYLD has also been implicated in ferroptosis, an iron-dependent form of cell death, through its effects on the YAP protein in prostate cancer cells. The enzyme’s dual role in either promoting or restraining different death modalities depends on its interactions, its modifications, its location within the cell, and the specific signal it receives.

Central to all of this is SPATA2, a partner protein identified in 2016 by four independent groups using mass spectrometry. SPATA2 binds CYLD through complementary domains and simultaneously connects it to the LUBAC complex via an interaction with HOIP. This bridging function recruits CYLD to the TNF receptor signaling complex and to other immune signaling platforms. In vitro, SPATA2 enhances CYLD’s enzymatic activity against both linear and lysine 63 chains, and cells lacking SPATA2 show increased ubiquitination of CYLD’s substrates. SPATA2 also competes with another DUB called OTULIN for binding to HOIP, balancing the overall activity of the LUBAC. Mice lacking both SPATA2 and CYLD develop uncontrolled inflammation and die perinatally, underscoring how tightly these two proteins cooperate to keep immune signaling in check.

Perhaps the most fascinating layer of regulation comes from post-translational modifications, chemical tags that alter CYLD’s behavior without changing its genetic sequence. Phosphorylation, the addition of phosphate groups to serine or threonine residues, is the best studied. CYLD carries a cluster of phosphorylation sites between its second and third CAP-Gly domains, with serine 418 being a particularly important target. This residue is phosphorylated in response to a wide range of stimuli, including TNF, bacterial products, antigen receptor engagement, and constitutively in some aggressive blood cancers. The kinases responsible include the canonical IKKβ and the noncanonical TBK1 and IKKε. Intriguingly, the consequences of phosphorylation are disputed: some studies report that it dampens CYLD’s activity, promoting cell survival in T-cell leukemia, while others find that it enhances the enzyme’s ability to trim lysine 63 chains. A recent mass spectrometry analysis identified six phosphorylation sites in TNF-stimulated cells, five of which fall within the phospho-patch, suggesting that multiple modifications may act in concert rather than in isolation.

CYLD is also itself a target of ubiquitination, a poetic irony for an enzyme that spends its life removing ubiquitin from others. The E3 ligase SCFβ-TRCP ubiquitinates CYLD and reduces its abundance, a process that requires prior phosphorylation and plays a role in osteoclast differentiation. Another E3 ligase, MIB2, decorates CYLD with lysine 48 chains at two specific lysines, driving its proteasomal degradation and thereby amplifying NF-κB signaling in response to TNF. In hypoxic tumors, RNF213 ubiquitinates both CYLD and SPATA2, targeting them for lysosomal degradation and initiating pyroptotic cell death. Beyond ubiquitin, CYLD is modified by SUMOylation, the attachment of small ubiquitin-like modifiers. In neuroblastoma cells and glioblastoma stem-like cells, SUMOylation at lysine 40 impairs CYLD’s catalytic activity, leading to hyperactivation of NF-κB and, in the case of glioblastoma, promoting an aggressive phenotypic transition of the tumor cells.

Finally, CYLD can be irreversibly cut by proteases, a modification that permanently alters its function. Caspase-8 cleaves CYLD at aspartic acid 215 following TNF stimulation, inactivating the enzyme and blocking necroptosis in fibroblasts and macrophages. During influenza A virus infection, caspase-8-mediated cleavage of CYLD enhances innate antiviral immunity by preventing the deubiquitination of signaling proteins. The paracaspase MALT1, a caspase-like enzyme central to lymphocyte activation, cuts CYLD at arginine 324 in T cells, in aggressive B-cell lymphomas, and in glioblastoma stem cells, generally silencing the enzyme and promoting cell survival. Remarkably, recent work suggests that the N-terminal fragment released by caspase-8 cleavage is secreted into the bloodstream and may serve as a biomarker of septic shock. As the Nantes authors emphasize, mapping the complete landscape of CYLD’s modifications, understanding how they interact hierarchically, and exploring their interplay with SPATA2 represent the next great challenges for researchers hoping to exploit this remarkable enzyme therapeutically.

Subject of Research: Post-translational modifications regulating the deubiquitinating enzyme CYLD in cell death and inflammation

Article Title: The good, the bad, and the modified: CYLD’s post-translational tale

Article References: Macé, Y. M., Bidère, N., & Douanne, T. (2025). The good, the bad, and the modified: CYLD’s post-translational tale. Frontiers in Cell Death, 4, Article 1583221. https://doi.org/10.3389/fceld.2025.1583221

Image Credits: AI Generated

DOI: 10.3389/fceld.2025.1583221

Keywords: CYLD, deubiquitinase, post-translational modifications, NF-κB signaling, cell death, apoptosis, necroptosis, pyroptosis, SPATA2, phosphorylation, ubiquitination, tumor suppressor

Post-translational modifications, or PTMs, are biochemical edits applied to proteins after translation. Phosphorylation, ubiquitination, acetylation, methylation, SUMOylation, O-GlcNAcylation, and poly-ADP-ribosylation each alter a protein’s behavior in distinct ways. A phosphate group can switch an enzyme on or off. A ubiquitin chain can mark a transcription factor for destruction. An acetyl group can change where a protein sits inside the cell or whom it binds to. The review’s central claim is that these modifications do not merely fine-tune bone biology; they act as a networked control system that gates, amplifies, and dampens the signals flowing through pathways such as Wnt, BMP, RANKL, Notch, and Hedgehog, which orchestrate the activity of osteoblasts, osteoclasts, and osteocytes.

The authors organize the evidence around three conceptual pillars. The first is bidirectionality: PTMs and classical signaling pathways do not operate in a one-way hierarchy but feed back into each other. Signaling cascades recruit enzymes that modify target proteins, while those modified proteins in turn alter the intensity, duration, and spatial distribution of the signals themselves. The second pillar concerns functional modes. Some PTM events act as gates, holding a pathway silent until a specific cue arrives. Others amplify a weak signal into a robust cellular response, or dampen an overactive pathway to prevent runaway bone resorption. The third pillar is spatiotemporal regulation: the same modification can have different consequences depending on which cell type carries it, in which subcellular compartment it occurs, and at which stage of development, aging, or disease it appears.

Osteoblasts, the bone-forming cells derived from mesenchymal stem cells, illustrate the stakes. Their differentiation depends on transcription factors such as RUNX2 and Osterix, whose activity and stability are controlled by phosphorylation and ubiquitination. Glycogen synthase kinase 3 beta, a well-known kinase, phosphorylates beta-catenin in the Wnt pathway and tags it for degradation, thereby suppressing osteoblast differentiation. When GSK3β itself is phosphorylated at an inhibitory site, beta-catenin accumulates and drives bone formation. The review emphasizes that such regulatory loops are not isolated curiosities but recurring motifs: the same kinase or ligase can be repurposed by different PTM events to produce opposite outcomes depending on context.

Osteoclasts, the bone-resorbing cells, are governed by an equally dense PTM web. The RANKL signaling cascade, which drives osteoclast differentiation and activation, depends on phosphorylation events that propagate signals from the cell surface to the transcription factor NFATc1, the master regulator of osteoclast identity. Ubiquitination and deubiquitination of signaling intermediates determine whether the response is sustained or extinguished. Cathepsin K, the protease that dissolves bone matrix, is itself subject to regulatory processing. The review highlights that dysregulated PTM events in osteoclasts contribute directly to pathological bone loss in osteoporosis and inflammatory conditions such as rheumatoid arthritis, where tumor necrosis factor alpha and interleukin-6 reshape the modification landscape of signaling proteins.

Osteocytes, the embedded mechanosensory cells that make up the vast majority of bone cells, add another layer of complexity. These cells sense mechanical loading and orchestrate remodeling by secreting molecules such as sclerostin and RANKL. The review notes that PTMs regulate osteocyte function through modifications of proteins involved in mechanotransduction, the process by which physical force is converted into biochemical signals. O-GlcNAcylation, the attachment of N-acetylglucosamine sugars to proteins by the enzyme OGT and their removal by OGA, emerges as a nutrient-sensitive modification that links cellular metabolism to bone cell behavior. Histone acetylation and methylation, mediated by histone acetyltransferases and deacetylases, control the accessibility of genes required for osteocyte survival and communication within the bone matrix.

The pathological implications are substantial. The review connects dysregulated PTMs to osteoporosis, osteoarthritis, metabolic bone diseases, inflammatory bone loss, and impaired fracture repair. In osteoarthritis, modifications of cartilage and subchondral bone proteins alter the balance between matrix degradation and synthesis. In senescence-associated conditions, PTMs influence the secretory phenotype of aging skeletal cells, which promotes local inflammation and tissue degeneration. Poly-ADP-ribosylation, a modification involved in DNA damage responses, appears in the context of oxidative stress and cell death in bone cells. Peptidylarginine deiminase enzymes, which convert arginine residues to citrulline, are implicated in inflammatory joint disease and may influence bone erosion. Each of these connections points to PTM enzymes as potential therapeutic targets, though the review is careful to note that causality remains unproven for many site-specific events.

That caution is one of the review’s most valuable contributions. The authors acknowledge that evidence is uneven across PTM types and skeletal cell populations. Phosphorylation is well characterized in osteoblast and osteoclast signaling, but less-studied modifications such as SUMOylation, neddylation, and lactylation remain poorly mapped in bone. Many reported PTM events are correlational rather than causal; showing that a modification is present in a disease state does not prove it drives the pathology. Distinguishing which of the thousands of possible modification events actually control bone homeostasis requires targeted mutagenesis of specific modification sites, cell-type-specific deletion of modifying enzymes, and quantitative proteomics that can track modification dynamics over time and across compartments.

Emerging technologies are beginning to close these gaps. Quantitative PTM proteomics now allows researchers to measure thousands of modification events simultaneously and compare their abundance between healthy and diseased bone. Single-cell RNA sequencing and spatial transcriptomics reveal which cell populations carry which modification machinery, resolving the heterogeneity that bulk assays obscure. Multi-omics integration, combining proteomics, transcriptomics, epigenomics, and metabolomics, offers a systems-level view of how PTM networks interact with metabolic state and gene expression. The review argues that these tools, combined with classical genetics and pharmacology, will be essential for identifying which PTM events are true regulatory nodes rather than passive consequences of cellular state.

The broader significance of the review lies in its reframing of bone biology as a networked control problem rather than a linear cascade of pathways. Just as engineers design control systems with sensors, actuators, and feedback loops, skeletal cells deploy PTMs as molecular switches that sense context and adjust signal flow accordingly. Understanding this architecture could transform how researchers approach bone diseases, shifting attention from individual pathways to the modification events that tune them. For patients with osteoporosis or non-healing fractures, the promise is that targeting the right PTM node could restore balance to the remodeling cycle with greater precision than current therapies, which broadly suppress bone resorption or stimulate formation without addressing the underlying regulatory logic. The review does not claim to have found those targets yet, but it provides a roadmap for where to look and a framework for evaluating what is found.

Subject of Research: Post-translational modifications regulating osteoblast, osteoclast, and osteocyte signaling in bone homeostasis and disease

Article Title: Networked control of bone homeostasis: interfacing post-translational modifications with cellular signaling

Article References: Zou, Y., Kang, J., Li, Z., Niu, J., Wang, Z., Wang, S., Han, X., Ning, B., & Liu, R. (2026). Networked control of bone homeostasis: interfacing post-translational modifications with cellular signaling. BMC Medicine. https://doi.org/10.1186/s12916-026-05308-7

Image Credits: AI Generated

DOI: 10.1186/s12916-026-05308-7

Keywords: bone homeostasis, post-translational modifications, osteoblasts, osteoclasts, osteocytes, bone remodeling, osteoporosis, osteoarthritis, phosphorylation, ubiquitination, O-GlcNAcylation, cellular signaling

LAMB1, short for laminin subunit beta 1, is a principal component of laminins, a family of large cross-shaped molecules that form a core part of the basement membrane, the specialized extracellular matrix layer that underlies and supports epithelial tissues. In healthy organs, laminins provide structural scaffolding, anchor cells in place, and transmit signals that regulate differentiation, adhesion, and migration. But over the past decade, cancer biologists have increasingly recognized that this same scaffold can be hijacked. Elevated LAMB1 levels have been linked to poor outcomes in gastric cancer, hepatocellular carcinoma, and nasopharyngeal carcinoma, and a 2025 comprehensive review in the Journal of Translational Medicine catalogued the growing evidence that laminins actively shape cancer pathobiology rather than merely serving as passive architectural supports.

What remained unclear until now was LAMB1’s role in esophageal squamous cell carcinoma, a tumor type that arises from the flat epithelial cells lining the esophagus and that accounts for the majority of esophageal cancer cases worldwide. According to GLOBOCAN 2020 estimates cited by the researchers, the global burden of esophageal squamous cell carcinoma and esophageal adenocarcinoma remains substantial, with projections to 2040 indicating continued pressure on health systems, particularly in regions where the squamous form dominates. Despite advances in surgery, chemoradiotherapy, and, more recently, perioperative immunotherapy, five-year survival for many patients diagnosed with this disease remains discouraging, motivating a search for molecular markers that could guide earlier detection and more precise treatment.

To find such markers, the team began with bioinformatic screening of datasets from The Cancer Genome Atlas, cross-referencing tumor expression data with curated gene sets related to the extracellular matrix. Their computational sweep identified LAMB1 as a candidate gene associated with prognosis in esophageal squamous cell carcinoma. That prediction was then tested experimentally. Using quantitative polymerase chain reaction to measure messenger RNA, Western blotting to quantify protein, and immunohistochemistry to visualize where LAMB1 accumulates within tissue sections, the researchers demonstrated that LAMB1 expression was consistently elevated in esophageal squamous cell carcinoma tissues and in cell lines derived from the disease, compared with normal counterparts.

Expression, however, is only half the story; the critical question is whether LAMB1 actively drives malignancy or merely accompanies it. To answer this, the team performed gain- and loss-of-function experiments. When they forced LAMB1 overexpression in esophageal cancer cells, the cells became more aggressive: they proliferated faster, migrated more readily across experimental surfaces, and invaded more deeply through matrix-coated membranes in the laboratory assays. Conversely, when the researchers silenced LAMB1 using knockdown techniques, these malignant phenotypes were suppressed, with proliferation, migration, and invasion all dropping. The symmetry of the results, directionally consistent whether LAMB1 was added or removed, strengthens the causal interpretation that this matrix protein is not a bystander but an active promoter of tumor behavior.

The mechanistic heart of the study lies in the JAK2/STAT3 signaling cascade, a canonical communication channel inside cells. Janus kinases, or JAKs, are enzymes that attach phosphate groups to proteins, and when the JAK2 kinase is activated, it phosphorylates the STAT3 transcription factor. Phosphorylated STAT3 then travels to the nucleus, where it switches on genes that promote cell survival, cell-cycle progression, angiogenesis, metastasis, and resistance to chemotherapy. In esophageal squamous cell carcinoma specifically, prior research has shown that activated STAT3 can reduce patient survival by upregulating vascular endothelial growth factor and cyclin D1, and other studies have linked pathway activation to epithelial-mesenchymal transition, the process by which epithelial cancer cells acquire the motile, invasive characteristics needed to metastasize.

The new experiments connected LAMB1 to this cascade with unusual clarity. The researchers found that LAMB1 activates JAK2/STAT3 signaling by enhancing protein phosphorylation, effectively turning up the volume on the pathway. The proof of causation came from two independent interventions. First, the team treated the cells with ruxolitinib, a JAK1/2 inhibitor already approved for clinical use in certain blood disorders, and the drug efficiently abrogated the malignant phenotypes that LAMB1 had driven. Second, they silenced STAT3 directly with knockdown technology and observed the same reversal. In both cases, blocking the pathway erased the proliferative, migratory, and invasive advantages conferred by LAMB1, establishing that LAMB1 acts upstream and depends on JAK2/STAT3 to exert its tumor-promoting effects.

To confirm that the mechanism operates in living organisms and not only in culture dishes, the researchers turned to xenograft experiments, in which human cancer cells are implanted into laboratory animals under institutional ethical oversight. Tumors engineered with LAMB1 knockdown grew significantly less than controls, and molecular analysis of the resulting tumor tissue showed reduced activation of the JAK2/STAT3 pathway, mirroring the in vitro findings. The study was approved by the Ethics Committee of the Fourth Hospital of Hebei Medical University and the institution’s animal care committee, and informed consent was obtained from all human participants, providing the governance framework that lends the results their clinical credibility.

The translational implications are twofold. As a biomarker, LAMB1’s elevated expression and its association with prognosis suggest that measuring it in tumor biopsies could help stratify patients, potentially identifying those with more aggressive disease who might benefit from intensified treatment or closer surveillance. As a therapeutic target, the ruxolitinib result is particularly intriguing because JAK inhibitors are already in clinical use, and the broader JAK2/STAT3 axis has attracted substantial pharmaceutical attention, with structural analysis and structure-activity relationship investigations fueling the development of pathway-targeting compounds. The study hints that esophageal cancer patients whose tumors are driven by LAMB1 might, in principle, respond to agents that interrupt this signaling route, although the researchers caution that much work remains before such a strategy could be tested in patients with this solid tumor.

There are also important caveats and open questions. The study did not receive external funding, and the authors declare no competing interests, but single-pathway mechanisms rarely explain a cancer’s full behavior, and LAMB1 has been implicated in other signaling routes, including the Hippo-YAP1 pathway in hepatocellular carcinoma and ERK/c-Jun signaling in gastric cancer, raising the possibility of parallel or interacting mechanisms in the esophagus as well. Moreover, how LAMB1 physically engages JAK2, whether through integrin receptors at the cell surface, mechanotransduction from matrix stiffness, or another route, remains to be dissected. Data supporting the study are available from the corresponding author upon reasonable request, and the corresponding author, Ziqiang Tian, led the supervision of the project. Still, by tracing a line from an extracellular scaffold protein through a druggable kinase cascade to the malignant behavior of one of the world’s most lethal cancers, the study adds a compelling new link in the chain that connects tumor architecture to tumor aggression, and it hands researchers a concrete new lead in a disease that badly needs one.

Subject of Research: The role of the extracellular matrix protein LAMB1 and the JAK2/STAT3 signaling pathway in the progression of esophageal squamous cell carcinoma

Article Title: LAMB1 accelerates esophageal squamous cell carcinoma by triggering JAK2/STAT3 signaling

Article References: Zhang, M., Liu, Z., Lv, H., Li, Z., Zhao, L., & Tian, Z. (2026). LAMB1 accelerates esophageal squamous cell carcinoma by triggering JAK2/STAT3 signaling. Molecular Biology Reports, 53(1), Article 1721. https://doi.org/10.1007/s11033-026-12853-0

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12853-0

Keywords: LAMB1, esophageal squamous cell carcinoma, JAK2/STAT3 signaling, extracellular matrix, laminin, ruxolitinib, STAT3 phosphorylation, xenograft, biomarker, cancer progression, phosphorylation, Molecular Biology Reports

Long non-coding RNAs, or lncRNAs, are RNA molecules longer than roughly two hundred nucleotides that are transcribed from the genome but are not translated into proteins. For decades they were dismissed as transcriptional noise, yet it is now clear that many of them perform sophisticated regulatory duties inside cells. Some act as molecular scaffolds, bringing proteins together into functional complexes; others serve as guides, escorting proteins to specific DNA regions; still others function as sponges that soak up microRNAs. In cancer biology, lncRNAs have emerged as master regulators that can tilt the balance between cell growth and cell death, and between tissue stability and invasive spread. The Suzhou-led team set out to determine whether ATP6V1B1-AS1, an lncRNA named for its genomic neighbor in the ATP6V1B1 gene region, plays such a role in ovarian cancer.

To establish the clinical relevance of the molecule, the researchers first examined its expression pattern using data from The Cancer Genome Atlas, a large public repository of tumor genomic profiles, and then confirmed their observations in patient samples using reverse transcription quantitative polymerase chain reaction, a sensitive technique for measuring RNA abundance. The results were consistent: ATP6V1B1-AS1 was upregulated in ovarian cancer compared with normal tissue, and higher levels of the RNA were associated with worse prognosis in patients. This kind of correlation does not by itself prove causation, but it provided the essential starting hypothesis that the molecule might be doing something more than merely marking the presence of aggressive disease.

The team then moved from correlation to function. Using laboratory-grown ovarian cancer cells, they silenced ATP6V1B1-AS1 and measured the consequences with a battery of standard assays. Cell counting kit 8 assays, which quantify metabolic activity as a proxy for the number of living cells, showed that silencing the RNA slowed proliferation. Colony formation assays, which test whether single cells can divide repeatedly to form visible colonies, revealed a reduced capacity for sustained growth. Migration assays demonstrated that the cells also lost much of their ability to move, a property that is central to cancer’s ability to invade surrounding tissue and seed distant organs. Together, these in vitro experiments suggested that ATP6V1B1-AS1 is not a passive bystander but an active contributor to the malignant behavior of ovarian cancer cells.

To verify that these effects hold true in living organisms rather than only in culture dishes, the researchers turned to animal models. They used xenograft models, in which human ovarian cancer cells are implanted into immunodeficient nude mice, allowing human tumors to grow in a living host. They also established lung metastasis models to track the spread of cancer cells to secondary sites. When ATP6V1B1-AS1 was silenced, the mice developed smaller tumors and showed reduced metastatic colonization of the lungs. This in vivo confirmation is a critical step, because the three-dimensional architecture, nutrient gradients, and immune-free but otherwise complex environment of a living animal can expose dependencies that simple cell culture misses. The results indicated that the RNA’s influence on tumorigenesis and metastasis is robust enough to manifest in a whole organism.

With the functional role established, the central question became mechanistic: how does a non-coding RNA accomplish all of this? The team’s answer came from an unbiased search for binding partners. They performed an RNA pull-down experiment, in which the ATP6V1B1-AS1 molecule is used as bait to capture proteins that physically associate with it inside cells. The captured proteins were then identified by liquid chromatography coupled with tandem mass spectrometry, a technique that reads out the molecular weights and sequences of peptides to determine which proteins are present. Among the hits was MAP3K3, also known as MEK kinase 3, a mitogen-activated protein kinase kinase kinase that sits near the top of a signaling cascade controlling the p38 MAPK pathway, a route well known for transmitting stress and inflammatory signals into the cell nucleus.

The interaction between ATP6V1B1-AS1 and MAP3K3 was further validated by co-immunostaining and Western blotting, which confirmed that the RNA and the protein occupy overlapping cellular compartments and that their association has measurable biochemical consequences. Specifically, the binding of ATP6V1B1-AS1 to MAP3K3 facilitated the phosphorylation of p38 MAPK, the chemical modification that activates this pathway. Phosphorylation acts like a molecular switch: when p38 MAPK is phosphorylated, it relays signals that can promote cell survival, proliferation, and motility. Rescue experiments, in which the researchers restored pathway activity after silencing the RNA, demonstrated that the effects of ATP6V1B1-AS1 loss could be traced back through MAP3K3 to p38 MAPK, establishing a coherent signaling axis: ATP6V1B1-AS1 binds MAP3K3, MAP3K3 drives p38 MAPK phosphorylation, and the activated pathway propels ovarian cancer progression.

The significance of this work lies partly in its conceptual contribution to the growing recognition that lncRNAs can regulate cancer not only through gene expression but through direct protein interactions that modulate signaling cascades. Rather than changing how much MAP3K3 is produced, ATP6V1B1-AS1 appears to change what MAP3K3 does, enhancing its ability to activate p38 MAPK. This mode of action is attractive from a therapeutic standpoint because it suggests that disrupting the RNA-protein interaction, rather than blocking the kinase itself, might achieve a similar effect with potentially fewer off-target consequences. It also adds ATP6V1B1-AS1 to a short list of lncRNAs implicated in ovarian cancer, a disease that urgently needs new molecular targets given the limited treatment options available once platinum-based chemotherapy fails.

The research was supported by the Basic Research Medical Applied Basic Research Project in Suzhou City and the Suzhou Applied Basic Research Healthcare Science and Technology Innovation Guiding Project, and it received ethics approval from the Research Ethics Committee of Suzhou Municipal Hospital and the Animal Ethics and Welfare Committee of Nanjing Medical University. The authors, led by Yan Zhang, Ting Chen, and Meng Liu as co-first authors, with Shunyu Hou and Ting Fu as corresponding authors, declare no competing interests. As with any preclinical study, the path from these findings to the clinic will require further validation in larger patient cohorts and the development of strategies to safely interfere with the ATP6V1B1-AS1/MAP3K3/p38 MAPK axis in humans. Nevertheless, the study offers a clear mechanistic blueprint for how a single non-coding RNA can orchestrate tumor growth and metastasis, and it may provide a potential therapeutic target for ovarian cancer at a time when such targets are sorely needed.

Subject of Research: The role of the long non-coding RNA ATP6V1B1-AS1 in promoting ovarian cancer progression via the MAP3K3/p38 MAPK signaling pathway

Article Title: Long non-coding RNA ATP6V1B1-AS1 promotes ovarian cancer progression through targeting MAP3K3/p38 MAPK pathway

Article References: Zhang, Y., Chen, T., Liu, M., Zhang, Y., Zhou, L., Xi, X., Yu, L., Hou, S., & Fu, T. (2026). Long non-coding RNA ATP6V1B1-AS1 promotes ovarian cancer progression through targeting MAP3K3/p38 MAPK pathway. Journal of Ovarian Research. https://doi.org/10.1186/s13048-026-02310-8

Image Credits: AI Generated

DOI: 10.1186/s13048-026-02310-8

Keywords: ovarian cancer, long non-coding RNA, ATP6V1B1-AS1, MAP3K3, p38 MAPK, phosphorylation, metastasis, tumor progression, signal transduction, cancer biology, RNA-protein interaction, therapeutic target

Post-translational modification, or PTM, represents the terminal regulatory layer of gene expression. Rather than altering DNA or RNA, PTMs chemically modify proteins after they are synthesized, changing their activity, localization, stability or interaction partners within seconds to minutes. This speed is precisely what makes PTMs indispensable for cells confronting sudden internal and external stimuli, from bacterial products breaching the epithelial lining to cytokines flooding the lamina propria. Among the many chemical marks cells can deploy, phosphorylation stands out for its reversibility and ubiquity, and the review positions the phosphorylation-dephosphorylation equilibrium as the terminal arbiter of whether an inflammatory program stays restrained or runs amok.

At the heart of the authors’ argument sits a single enzyme: the catalytic subunit alpha of protein phosphatase 2A, known as PP2Acα and encoded by the PPP2CA gene. Protein phosphatase 2A is the predominant serine/threonine phosphatase in mammalian tissues, accounting for more than 70 percent of total serine/threonine phosphatase activity. In practical terms, whenever a kinase attaches a phosphate to a serine or threonine residue, PP2A is the workhorse most likely to remove it. That sheer volume of activity means PP2A does not merely clean up after kinases; it actively shapes the amplitude, duration and outcome of signaling pathways, including several that are central to intestinal inflammation.

The review emphasizes that PP2A is not a single entity but a family of holoenzymes assembled around the catalytic subunit. A scaffolding A subunit and one of many regulatory B subunits join PP2Ac to determine substrate specificity, subcellular localization and pathway preference. The C-terminus of the catalytic subunit mediates the selection of regulatory subunits, effectively deciding which signaling circuit the phosphatase will engage. This modularity transforms PP2A from a blunt dephosphorylating instrument into a precision targeting system, and it explains why the same catalytic core can restrain inflammatory signaling in one cellular context while supporting cell survival in another.

Where does PP2A intersect the inflammatory machinery that drives colitis? The review assembles evidence from several canonical pathways. In the NF-κB system, distinct B subunits of PP2A regulate the pathway through dephosphorylation of IKKβ, IκBα and RelA, the transcriptionally active subunit of NF-κB. Because phosphorylation of these components is what propels NF-κB into the nucleus to switch on genes encoding tumor necrosis factor, interleukins and chemokines, PP2A acts as a built-in brake on the master regulator of innate immunity. Similarly, in Toll-like receptor signaling, phosphatases including PP2A counterbalance kinases such as IKKβ and glycogen synthase kinase 3β, ensuring that responses to bacterial lipopolysaccharide are proportionate rather than explosive.

The inflammasome provides another vivid example. The NLRP3 inflammasome, a multiprotein complex whose activation in intestinal macrophages and epithelial cells fuels the cytokine storm characteristic of colitis, is itself controlled by phosphorylation. Studies cited in the review show that NLRP3 phosphorylation is an essential priming event for inflammasome activation, that phosphorylation of its pyrin domain regulates assembly of the complex, and that glycolytic enzyme PGK1 can phosphorylate NLRP3 to trigger activation independently of its metabolic role. Dephosphorylation events, in turn, can disarm the complex. The same logic extends to cell death pathways: RIPK1 autophosphorylation at serine 166 drives necroptosis and inflammation, while phosphatases such as PPM1B dephosphorylate RIPK3 to restrain necroptotic death of epithelial cells, a process increasingly implicated in barrier erosion during IBD.

Beyond immune signaling, the review highlights how phosphorylation governs the physical integrity of the intestinal barrier itself. Tight junctions, the protein seals between epithelial cells, are exquisitely sensitive to phosphorylation. Phosphorylation of occludin at tyrosine residues 398 and 402 prevents its interaction with the scaffold protein ZO-1 and destabilizes tight junction assembly, opening paracellular gaps that permit luminal antigens to seep into the tissue. Myosin light chain kinase and Rho kinases tighten or loosen these junctions through phosphorylation cascades, and recent work shows that PEAK1 maintains tight junctions and resists colitis by inhibiting autophagy-mediated degradation of ZO-1. A phosphatase capable of reversing these modifications would therefore protect barrier function directly, a therapeutic goal distinct from simply suppressing immune cells.

Why focus on PPP2CA specifically rather than phosphatases in general? The authors point to converging lines of evidence. PP2Acα has already been shown to play a key role in inflammatory diseases such as rheumatoid arthritis, and it is critically required for CD8-positive T-cell homeostasis and antibacterial responses, indicating a broad immunological footprint. In the gut, PP2A participates in Wnt/β-catenin signaling, which sustains epithelial renewal and is disrupted in intestinal inflammation; Wnt signaling inhibits casein kinase 1α activity by modulating its interaction with PP2A, and Hsp105 recruits PP2A to dephosphorylate β-catenin. PP2A also sits within the mTORC1-ULK1 regulatory triangle that controls autophagy, a process genetically linked to Crohn’s disease, and lysosomal PP2A dephosphorylates TSC2 in an amino acid-dependent manner to regulate mTORC1. Metabolic reprogramming of macrophages, the mechanism underlying interleukin-10’s anti-inflammatory effect, likewise flows through phosphatase-sensitive nodes. Intriguingly, earlier work has connected colonic inflammation to methylation-mediated inhibition of PP2A under hyperosmotic stress, suggesting that environmental factors may directly impair this phosphatase in the intestine.

The therapeutic implications are considerable but tempered by biology. Existing IBD drugs already exploit the phosphorylation network indirectly: tofacitinib, a JAK inhibitor approved for ulcerative colitis, blocks phosphorylation-dependent STAT signaling, and gut-restricted RIPK1 inhibitors that modulate phosphorylation-driven necroptosis have ameliorated colitis in mouse models. Targeting PP2Acα would represent a different strategy, namely restoring dephosphorylation rather than blocking kinases. The challenge is specificity. Because PP2A touches cell cycle control, apoptosis and tumor suppression, indiscriminate activation or inhibition carries risks; PPP2CA dysregulation is documented in colorectal and hepatocellular cancers, and PP2A is a recognized target in oncology drug development. The review argues that the way forward lies in exploiting holoenzyme biology, using regulatory subunit interactions, protein-protein interfaces and emerging bifunctional phosphorylation-targeting modalities to modulate specific PP2A complexes in specific cell types rather than the catalytic subunit globally.

The authors close by framing the field’s core unanswered questions: which PP2A holoenzymes operate in intestinal epithelial cells versus immune populations, which substrates dominate in colitis, and how disease-associated modifications of the catalytic subunit alter its targeting. Answering them will require cell-type-resolved phosphoproteomics and conditional genetic models, tools that recent advances in spatial omics of chronic IBD tissue are beginning to make feasible. What is already clear is that the phosphorylation-dephosphorylation balance is not background noise in IBD but a central control layer, and that PP2Acα, the most abundant serine/threonine phosphatase in mammalian tissues, may be the most consequential and least exploited lever within it. For patients whose disease persists despite current biologics and small molecules, a therapeutic strategy built on re-engaging the body’s own phosphatase machinery offers a genuinely new direction.

Subject of Research: The role of protein phosphorylation and the phosphatase PP2Acα in regulating colitis and inflammatory bowel disease

Article Title: Mechanisms of phosphorylation in colitis regulation: PP2Acα as an emerging therapeutic target for inflammatory bowel disease

Article References: Wu, G., Wang, C., Fang, C., & Li, J. (2026). Mechanisms of phosphorylation in colitis regulation: PP2Acα as an emerging therapeutic target for inflammatory bowel disease. Molecular Biology Reports, 53(1), Article 1715. https://doi.org/10.1007/s11033-026-12847-y

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12847-y

Keywords: inflammatory bowel disease, colitis, phosphorylation, dephosphorylation, PP2Acα, PPP2CA, post-translational modification, NF-κB, NLRP3 inflammasome, intestinal barrier, tight junctions, protein phosphatase 2A

The scale of the undertaking is considerable. The researchers assembled a panel of cell lines representing the major organs, tissues and cancers of the body: epithelial, mesenchymal, endothelial and fibroblast morphologies; cancerous and noncancerous phenotypes; primary and immortalized cells; suspension and adherent cultures; and even embryonal cells and induced pluripotent stem cells to capture early developmental signaling. Each line was profiled under two conditions, serum-starved and serum-stimulated, to sweep in both basal and dynamically regulated phosphorylation events. To boost coverage of the notoriously elusive phosphotyrosine sites, the team also treated colorectal cancer DLD-1 cells with pervanadate, a broad-spectrum inhibitor of tyrosine phosphatases that traps tyrosine phosphorylation at detectable levels. The result is a deliberately broad sampling of the signaling states a human cell can occupy.

Technically, the atlas was built on state-of-the-art mass spectrometry. Both unenriched peptide mixtures, representing each cell’s proteome, and phosphopeptide-enriched samples were analyzed on an Evosep One liquid chromatography system coupled to an Orbitrap Astral mass spectrometer operated in narrow-window data-independent acquisition, or nDIA, mode. Using a 30-samples-per-day gradient with a 200-hertz acquisition method, the team quantified an average of 9,681 protein groups per file. Collectively, the proteome library comprises 543,301 peptide precursors mapping to 16,454 protein groups, roughly 80 percent of the canonical human proteome, with a median protein sequence coverage of 50 percent. Crucially, more than 90 percent of protein kinases, phosphatases, transcription factors, oncogenes and tumor suppressors were identified, and nearly the entire human kinome, around 500 kinases, was covered without detectable bias across kinase families.

The phosphoproteome side of the atlas is even more striking. From the enriched samples, the researchers identified a mean of 30,446 class I phosphosites per file, and the combined phosphopeptide spectral library contains over 500,000 phosphopeptide precursors spanning 225,832 distinct phosphorylation sites. Almost two-thirds of these sites were assigned a localization probability of 0.99 or higher, meaning the exact position of the phosphate on the protein sequence could be pinned down with high confidence. The detected sites comprised 66 percent phosphoserine, 25 percent phosphothreonine and 9 percent phosphotyrosine, the latter proportion inflated by the pervanadate-treated cells; within individual cell lines, tyrosine phosphorylation settled back to the expected few percent. Benchmarking against public databases showed that over 60 percent of the detected sites overlapped with mass-spectrometry-derived resources such as PhosphoSitePlus, and that many sites previously catalogued without direct MS evidence could now be reproduced in a single unified experiment.

One of the most consequential outputs is the empirical spectral library itself, and the team put it through a rigorous stress test. They profiled a heterogeneous pool of differentiating stem cells, deliberately absent from the atlas, across four chromatographic gradients, and searched the data both with the empirical library and with library-free approaches in two widely used software packages, Spectronaut and DIA-NN. The library-based searches increased phosphoproteome depth under every condition tested, delivering a 60 percent gain in quantified phosphosites under high-flow conditions and 40 percent under low-flow conditions in Spectronaut when completeness filtering was applied. The gains came primarily through better-localized sites: library-based searches at a stringent localization cutoff of 0.98 matched the site counts of library-free searches at a much looser 0.75, indicating that high-quality reference spectra resolve the single biggest weakness of library-free phosphoproteomics, confident site localization.

The computational savings were equally dramatic. In DIA-NN, replacing a theoretical in silico phosphopeptide library of nearly 47 million precursors with the empirical library of roughly 540,000 slashed processing time for six files from 9 hours and 55 minutes to just 22 minutes, an average 30-fold speedup across gradients. For a field increasingly drowning in data from automated sample preparation and ultrafast instruments, that difference could reshape how large phosphoproteomics studies are designed. The library also proved its worth in low-input experiments: when the team analyzed EGF-stimulated HeLa cells with peptide inputs ranging from 1 to 20 micrograms, library-based searches yielded an average 18 percent increase in quantified phosphosites and, tellingly, more consistent detection of canonical EGFR activation sites such as the autophosphorylation site Y1110, which appeared in all stimulated replicates and none of the controls when the library was used.

Beyond cataloguing sites, the atlas ventures into one of the hardest quantitative questions in signaling biology: what fraction of a given protein is actually phosphorylated at a given moment, the so-called site stoichiometry. By pairing phosphoproteome measurements with matched proteome data under serum-stimulated and control conditions, the team calculated absolute occupancy for 19,378 phosphosites across 31 cell lines. Occupancies were generally low, below 20 percent, and rose upon serum stimulation. Motif analysis of the sites that gained phosphate revealed basophilic sequences characteristic of AGC-family kinases such as PKA, PKB and S6K, while dephosphorylated sites were enriched for proline-directed motifs targeted by MAPKs and CDKs, indicating phosphatase-mediated shutdown of those pathways. Three independent kinase inference algorithms agreed on the most serum-activated kinases, including ribosomal protein kinases, AKT and MAPK family members, while MARK kinases and cell-cycle CDKs emerged as the most strongly deactivated.

The stoichiometry data also delivered a sobering insight about tyrosine signaling: regulatory phosphotyrosine sites showed the lowest baseline occupancy despite displaying the largest fold changes upon stimulation. Only a small fraction of a tyrosine site needs to be phosphorylated to drive crucial downstream signaling, which explains why global profiling of tyrosine phosphorylation has historically required antibody-based enrichment. The atlas now provides baseline occupancy values for 182 known activation sites and 1,202 regulatory sites, a resource the authors say can help define the occupancy thresholds at which signaling events actually fire.

The culmination of the study is a new metric called the combined kinase activity score, or Cscore, designed to fix a persistent problem in the field: closely related kinases, especially tyrosine kinases, share so many substrates that existing inference tools frequently produce false positives. The team showed that three popular tools assigned EGFR activity to blood cancer cell lines that express no EGFR at all, and failed to flag the constitutively active FLT3 mutant in specific leukemia lines. The Cscore instead integrates five independent lines of evidence: kinase abundance at the proteome and phosphoproteome levels, substrate phosphorylation based on in vitro kinase-reaction relationships, sequence motif enrichment, and quantification of activation-loop sites on the kinase itself, with weights correcting for redundancy among components. Applied across the panel, it produced activity scores for 385 kinases in 31 cell lines and correctly scored directionality, assigning zero activity to EGFR and ERBB2 in suspension cells and high activity to ERBB2 in the BT-474 breast cancer line.

The translational payoff came when the researchers cross-referenced Cscore-predicted vulnerabilities with drug-sensitivity data from the Genomics of Drug Sensitivity in Cancer project. Of 210 kinase-cell line associations identified, several matched known dependencies: the neuroblastoma line NB1 with high ALK activity was sensitive to ALK inhibitors, FLT3-active MOLM-13 and MV-4-11 cells responded to FLT3 inhibitors, and BT-474 cells were sensitive to the ERBB-family inhibitors afatinib and CI-1033. Some predictions, such as NTRK1 activity in OCI-M1 cells, did not validate, a reminder that drug off-target effects and incomplete inhibitor specificity profiles complicate such comparisons. Yet DepMap genetic dependency data independently confirmed vulnerabilities including ALK in NB1, FLT3 in the leukemia lines, ERBB2 in BT-474 and SYK in SU-DHL-4. The authors also flag unvalidated but tantalizing targets, such as the ephrin kinases EPHA3 and EPHA4 in pancreatic cancer cells and ERN1 in HepG2 liver cancer cells. With the full dataset, spectral libraries, stoichiometry tables and Cscore scores deposited in public repositories and browsable through a web interface, the atlas is positioned to become a community standard, one that could turn the noisy landscape of cellular phosphorylation into a navigable map for drug discovery.

Subject of Research: A mass spectrometry-based phosphoproteome atlas of human cell lines mapping kinase activity and signaling vulnerabilities

Article Title: A phosphoproteome atlas of human cell lines reveals the landscape of kinase activity

Article References: Koenig, C., Cho, H., Emdal, K. B., Piga, I., Sabatier, P., Lozano-Juárez, S., Martinez-Val, A., & Olsen, J. V. (2026). A phosphoproteome atlas of human cell lines reveals the landscape of kinase activity. Nature Structural & Molecular Biology. https://doi.org/10.1038/s41594-026-01877-6

Image Credits: AI Generated

DOI: 10.1038/s41594-026-01877-6

Keywords: phosphoproteomics, kinase activity, mass spectrometry, cell signaling, cancer, spectral library, DIA, phosphorylation, precision oncology, proteomics, drug sensitivity, cell lines

That channel is called AKT5, and it was first identified in Arabidopsis thaliana, the small flowering plant that serves as the standard laboratory model for plant biologists around the world. Despite more than thirty years of study, the actual function of AKT5 remained a mystery. Researchers knew the gene existed and could observe its sequence, but they could not demonstrate that the protein it encodes truly transports potassium, nor could they say what role it plays in the living plant. Now a research team at Tohoku University, led by Nobuyuki Uozumi, has finally cracked the problem. In work published in the journal Science Advances, the group reports the first direct demonstration of AKT5 potassium channel activity, reveals the structural mechanism that switches the channel on, and shows that the protein promotes the growth of leaf stalks, the slender structures that connect leaves to the stem.

The significance of the discovery becomes clear when one considers what leaf stalks actually are. In many popular vegetables, including celery and Swiss chard, the leaf stalk, or petiole, is the part that ends up on the dinner plate. A channel protein that influences how long and thick these stalks grow is therefore not an abstract piece of basic science but a potential lever for agricultural improvement. As Uozumi explained, by regulating AKT5 activity in crop plants it may be possible to tailor the size and texture of edible stalks to meet consumer needs. That prospect has generated genuine excitement, because it suggests a route to breeding or engineering vegetables whose harvested portions can be made larger than what conventional cultivation currently achieves.

The path to the discovery was anything but straightforward. The team first attempted to detect potassium transport activity of AKT5 using animal cell expression systems, a standard technique in which a plant gene is introduced into cultured cells so that the resulting protein can be studied with electrophysiological methods. When potassium ions move through an open channel into a cell, their electric charge produces a tiny measurable current, so the presence or absence of such a current reveals whether the channel is functioning. In the initial experiments, no activity was detected at all. AKT5 appeared silent, which may explain why so many earlier attempts over the decades had failed to characterize it as a genuine potassium channel.

The breakthrough came when the researchers introduced a specific enzyme that adds phosphate groups to proteins, a chemical modification known as phosphorylation. With this enzyme present alongside AKT5, potassium transport activity was detected for the first time. The conclusion was elegant: AKT5 is switched on when a phosphate group attaches to a specific amino acid within the protein. Without that modification, the channel remains locked in an inactive state, which is why simply supplying potassium in the earlier experiments had produced no measurable current. Phosphorylation is a common regulatory strategy in biology, used by cells to toggle proteins between active and inactive forms in response to signals, and AKT5 turns out to be a textbook example of this principle applied to a plant nutrient channel.

To understand the activation process at the level of molecular architecture, the team turned to cryo-electron microscopy, a technique that flash-freezes proteins and images them with electron beams to determine three-dimensional structures at near-atomic resolution. Using this method, the researchers captured AKT5 in two states: a closed conformation and a pre-open conformation. The structures showed that AKT5 adopts a shape very similar to other well-characterized potassium channels, yet it possesses a distinctive capacity for transformation. In a striking experiment, the scientists changed a single amino acid in the protein, replacing the aspartate normally found at position 403 with an alanine. This one substitution altered the structure of the molecule dramatically and, remarkably, gave AKT5 potassium transport activity even without phosphorylation.

These structural findings allowed the researchers to assemble a coherent mechanistic model. In its normal state, AKT5 sits in an inactive shape that blocks the passage of potassium ions. When phosphorylation occurs at the key amino acid, the protein undergoes a structural rearrangement centered around position 403, switching into an active conformation that permits potassium to flow through the membrane pore. The single amino acid swap performed in the laboratory essentially mimicked the effect of the phosphate group, bypassing the natural activation step and forcing the channel open. This level of detail matters because it identifies a precise molecular switch that could, in principle, be targeted in future crop improvement efforts, whether through conventional breeding for variants of the channel or through biotechnological approaches that alter its regulation.

With the channel’s biochemical behavior established, the next question was what AKT5 actually does inside a living plant. The researchers examined where the protein is located and found that it is concentrated in leaf stalks, the slender structures that connect leaves to the stem and hold the leaf blade up toward the light. When the team analyzed plants that lacked AKT5 entirely, those plants produced leaf stalks that were shorter than normal. The importance of this phenotype becomes apparent when one remembers the role petioles play in plant architecture: by extending and adjusting their length, leaf stalks position leaf blades to capture sunlight efficiently, a task that becomes especially critical when plants grow crowded together and must compete with neighbors for light.

To test this competitive dimension directly, the researchers grew AKT5-deficient plants under crowded conditions. The result was clear: deprived of the channel, the plants showed reduced growth and became smaller than normal plants subjected to the same density. Taken together with the localization data, the findings indicate that AKT5 promotes cell elongation in leaf stalks by taking up potassium ions. As potassium accumulates inside cells, it raises the internal osmotic pressure, drawing in water and generating turgor pressure that physically stretches the cells. Elongated cells mean elongated stalks, and elongated stalks mean leaves held in better positions for photosynthesis. In this way, a single potassium channel links nutrient uptake, cell physics, and whole-plant competitive strategy.

The broader implications reach well beyond the model plant Arabidopsis. AKT5 is a key molecule that helps plants compete in high-density growing environments, and learning how to control its activity could enable farmers to grow crops at high density without sacrificing productivity. That capability would be a meaningful tool against two of the most pressing global challenges: a growing human population and a shrinking supply of arable farmland. If the AKT5 pathway operates similarly in crops such as celery and Swiss chard, breeders might one day select for channel variants that produce longer, thicker, or more tender edible stalks, while high-density planting systems could exploit the same biology to squeeze more yield from every hectare. The Tohoku University team has thus transformed a thirty-year-old puzzle into a concrete molecular target, providing what the researchers describe as an important foundation for the next generation of agricultural innovation. The study, titled AKT5 is a bona fide potassium channel and controls petiole growth in Arabidopsis, appeared in Science Advances on September 3, 2026.

Subject of Research: Potassium channel AKT5 activation and its role in leaf stalk growth in Arabidopsis thaliana

Article Title: Researchers identify "green thumb" molecule that drives leaf stalk growth in plants

Article References: Researchers identify "green thumb" molecule that drives leaf stalk growth in plants. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: AKT5, potassium channel, Arabidopsis thaliana, leaf stalk growth, phosphorylation, cryo-electron microscopy, plant nutrition, cell elongation, high-density cropping, agriculture, Science Advances, Tohoku University

At the center of the new study is a protein called SPICE1, short for spindle and centriole associated protein 1. SPICE1 has been implicated in tumor biology before, but its role in prostate cancer metastasis and, crucially, the way its abundance is controlled inside cells remained largely unknown. The researchers began by measuring SPICE1 levels in prostate cancer tissues and in bone metastatic lesions taken from patients. The results were striking: SPICE1 was markedly upregulated in prostate cancer tissue compared with normal tissue, and it was increased even further in lesions that had spread to bone. When the team analyzed clinicopathological data, they found that high SPICE1 expression was associated with aggressive disease features and poor prognosis, marking the protein as a potential red flag for the most dangerous forms of the illness.

To determine whether SPICE1 was merely a bystander or an active driver of metastasis, the researchers turned to laboratory experiments using two prostate cancer cell lines, PC3 and C42B. When they silenced SPICE1, the cells lost much of their malignant vigor. Proliferation slowed, migration and invasion were suppressed, and the cells were less able to undergo epithelial–mesenchymal transition, or EMT, the process by which cancer cells shed their rigid epithelial identity and become mobile, invasive, and resistant to therapy. These in vitro findings suggested that SPICE1 is not just correlated with aggressive disease but functionally required for it.

The team then moved from the dish to living systems, using two complementary animal models: subcutaneous xenografts, in which tumor cells are implanted under the skin, and an intra-arterial bone metastasis model that more faithfully reproduces how prostate cancer cells travel through the bloodstream and colonize bone. In both settings, silencing SPICE1 attenuated tumor growth and reduced bone metastasis. Together with the tissue data, the experiments establish SPICE1 as a pro-metastatic effector in prostate cancer, a molecule that tumor cells appear to depend on when they are establishing themselves in the skeleton.

Having shown what SPICE1 does, the researchers next asked how cancer cells keep it from being destroyed. Proteins inside cells are constantly being tagged for degradation by ubiquitin, a small molecular marker that condemns them to the cellular waste disposal system. The team used a battery of biochemical techniques, including co-immunoprecipitation, proximity ligation assays, site-directed mutagenesis, cycloheximide chase experiments, and dedicated ubiquitination and SUMOylation assays, to trace the fate of SPICE1. What emerged was an elegant two-step protection mechanism involving two other proteins: AURKA, a well-known cancer-associated enzyme, and TRIM28, a member of a family of proteins that attach SUMO, a tag that can shield proteins from ubiquitin-mediated destruction.

The first step of the mechanism involves phosphorylation, the attachment of a phosphate group to a protein. The researchers found that AURKA directly interacts with SPICE1 and phosphorylates it at a specific location, the amino acid serine 811. This single chemical modification proved to be the key that unlocks the rest of the pathway. Once SPICE1 is phosphorylated at serine 811, it becomes competent to recruit TRIM28, which functions as a SUMO E3 ligase, an enzyme that catalyzes the attachment of SUMO tags to target proteins. TRIM28 then SUMOylates SPICE1 at a second precise location, lysine 838. The SUMO tag at that site antagonizes ubiquitination, preventing SPICE1 from being marked for degradation. In effect, phosphorylation licenses SUMOylation, and SUMOylation stabilizes SPICE1, allowing the protein to accumulate to levels that support metastatic behavior.

The precision of this mechanism is what makes it scientifically compelling. Both modifications occur at defined amino acid positions, and the researchers demonstrated that disrupting either one collapses the protective chain. Without AURKA-mediated phosphorylation, SPICE1 cannot recruit TRIM28 efficiently. Without TRIM28-dependent SUMOylation at lysine 838, ubiquitination proceeds unchecked and SPICE1 is degraded. The team also performed rescue experiments: when they restored AURKA or TRIM28 in cells where SPICE1 had been silenced, the inhibitory effects on cell proliferation, migration, and invasion were partially reversed. This confirms that the AURKA/TRIM28/SPICE1 axis is not a side observation but a central regulatory circuit that drives the malignant phenotype.

Downstream of SPICE1 stabilization, the researchers identified changes that likely explain how the protein promotes cancer progression. Stabilized SPICE1 was accompanied by increased expression of FASN, the enzyme fatty acid synthase, which allows cancer cells to manufacture their own lipids and supports rapid growth. The team also observed activation of PI3K/AKT signaling, one of the most frequently hijacked growth pathways in human cancer, known for promoting cell survival, proliferation, and metabolic reprogramming. The authors note that these downstream changes likely contribute to the malignant phenotype but are secondary to the core AURKA/TRIM28/SPICE1 regulatory axis, which sits at the top of the cascade.

The clinical implications of the work are considerable. Because each node in the pathway is a defined molecular interaction, the axis offers multiple potential points of intervention. AURKA inhibitors already exist and are being evaluated in various cancers, and the new findings suggest that blocking AURKA could destabilize SPICE1 in prostate cancer cells, undermining their ability to survive and spread in bone. Alternatively, disrupting the SPICE1–TRIM28 interaction or the SUMOylation event itself could achieve a similar effect. The strong association between high SPICE1 expression and poor prognosis also raises the possibility that SPICE1 could serve as a biomarker, helping clinicians identify patients whose disease is most likely to metastasize to bone and who might benefit from more aggressive surveillance or targeted therapy.

As with any laboratory study, the path from mechanism to medicine will require further validation, including studies in larger patient cohorts and the development of strategies that can safely target the pathway in humans. The human tissue collection and animal experiments in the study were approved by the relevant ethics committees of the First Affiliated Hospital of Nanchang University, and the work was partially funded by a grant from the National Natural Science Foundation of China. Still, by revealing how phosphorylation, SUMOylation, and ubiquitination converge to keep a single metastasis-promoting protein alive, the study adds an important piece to the puzzle of why prostate cancer so relentlessly seeks out bone, and it hands researchers a detailed molecular map of where the next generation of therapies might strike.

Subject of Research: Post-translational regulation of SPICE1 by AURKA and TRIM28 in prostate cancer bone metastasis

Article Title: AURKA phosphorylation licenses TRIM28-dependent SUMOylation to stabilize SPICE1 in prostate cancer bone metastasis

Article References: Jiang, H., Tong, W., Wang, S., Xiong, X., Yao, G., Yang, F., Xu, Y., Liu, J., Xie, X., & Liu, Z. (2026). AURKA phosphorylation licenses TRIM28-dependent SUMOylation to stabilize SPICE1 in prostate cancer bone metastasis. Cellular and Molecular Life Sciences. https://doi.org/10.1007/s00018-026-06396-7

Image Credits: AI Generated

DOI: 10.1007/s00018-026-06396-7

Keywords: prostate cancer, bone metastasis, SPICE1, AURKA, TRIM28, SUMOylation, phosphorylation, ubiquitination, PI3K/AKT signaling, FASN, EMT, biomarker

The scale of the machinery involved is worth pausing to appreciate. Dyneins are among the largest motor proteins known in nature, with complete assemblies approaching two megadaltons in mass. Each motor is built around one or more heavy chains, which contain the ATP-hydrolyzing engine and the microtubule-binding stalk, and these cores are decorated with a constellation of intermediate chains, light chains, and associated regulatory proteins. In the ciliary axoneme, the cylindrical scaffold of microtubule doublets that gives the organelle its structure, hundreds of these motors are arrayed in precise, repeating patterns along the length of each doublet. When motors on one side of the axoneme activate, they slide the adjacent doublet toward the cilium tip, and because the doublets are cross-linked by elastic connectors, this sliding is converted into bending. The alternating activity of motors on opposite sides of the axoneme produces the characteristic back-and-forth beat.

What the review by Kondo and King makes clear is that this mechanical cycle is only the beginning of the story. The parameters of the ciliary beat, including its frequency, its amplitude, and the precise shape of the waveform it traces through space, are not fixed properties of the machine. Instead, they are subject to a remarkable diversity of signaling inputs that allow cells to adjust ciliary output in real time in response to changing environmental conditions. This plasticity is not a curiosity; it is essential to physiology. Airway cilia must increase their beat frequency when faced with irritants or pathogens. Sperm must modulate their swimming pattern as they navigate the female reproductive tract and respond to chemical gradients. In simple organisms such as the green alga Chlamydomonas, cilia, called flagella in that context, must react within milliseconds to changes in light and mechanical load to steer the cell toward favorable conditions.

One of the central themes the authors develop is that dynein regulation operates at multiple levels simultaneously, and that understanding ciliary behavior requires understanding how these levels are integrated. The first level involves interactions within individual dynein molecules. The heavy chain motor domain is itself allosterically regulated: the position of its linker arm, the state of its ATPase cycle, and the engagement of its microtubule-binding stalk are all coordinated through long-range conformational communication within the protein. Adjacent to these intrinsic mechanisms, the non-catalytic domains of the heavy chain and the associated intermediate and light chains provide docking sites for regulatory factors that can alter motor activity. Some light chains, for example, have been shown to modulate the motor’s response to calcium or to participate in redox-sensitive pathways, meaning that even the smallest components of the assembly can have outsized effects on function.

The second level of regulation involves interactions between neighboring dyneins along the axoneme. Ciliary beating is not simply the sum of independent motors firing on their own schedules. Instead, regions of dynein activity travel along the cilium in organized waves, a phenomenon that requires communication between motors at different positions. Mechanical feedback plays a crucial role here: the curvature and sliding velocity of the axoneme at any given point influence which motors are active at that moment, creating a self-organizing system in which the mechanical state of the organelle shapes its own chemical activity. This coupling between mechanics and motor chemistry is what allows the traveling waves of bending to emerge from what would otherwise be a chaotic collection of independent enzymes. The review emphasizes that this mechanochemical feedback is a fundamental organizing principle of ciliary motility, one that theoretical models have increasingly captured but that experimental dissection continues to reveal in greater detail.

External signaling inputs add yet another layer of control. Calcium ions are among the best-characterized regulators of ciliary waveform. Changes in intraciliary calcium concentration, whether arising from mechanosensitive channels or from voltage-gated channels responding to membrane potential, can dramatically alter the shape of the beat, converting a symmetric beat into an asymmetric one that steers the cell. The molecular targets of calcium within the axoneme include calcium-binding proteins associated with the dynein arms as well as components of the central apparatus, and the review discusses how these targets translate a simple ionic signal into a complex change in motor coordination. Viscous load represents a complementary input: the resistance the cilium encounters as it moves through fluid feeds back onto the motors, and dyneins respond to this load in ways that help maintain productive beating across a range of external conditions.

Perhaps the most striking examples of environmental coupling come from organisms in which cilia respond directly to light. In Chlamydomonas, a dedicated blue light sensor has been found associated with the flagellar apparatus, allowing the photosensitive alga to modulate its motility in direct response to illumination. This photoreceptor-based pathway represents an extreme case of a general principle: cilia are not autonomous oscillators sealed off from the cell, but rather integrators of information arriving from multiple sensory modalities. The redox state of the cilium provides another such channel. Oxidative conditions can modify specific cysteine residues and alter the activity of redox-sensitive proteins within the axoneme, and the review highlights evidence that ciliary redox state functions as a genuine regulatory axis rather than a passive consequence of cellular metabolism.

Beyond these reversible signaling mechanisms, dynein motors are subject to an extensive repertoire of post-translational modifications. Phosphorylation is the most extensively studied, with kinases both inside and outside the cilium capable of altering motor assembly, activity, and beat parameters. But the review also draws attention to less widely appreciated modifications, including methylation and N-terminal acetylation, which often occur at sub-stoichiometric levels, meaning that only a fraction of the target molecules carry the mark at any given time. This partial modification raises intriguing questions about how such sparse chemical changes can produce coherent functional effects. The authors suggest that sub-stoichiometric modifications may act on specific subsets of dyneins within the axoneme, or that they may tune the probability of certain motor states rather than switching them deterministically, providing a fine-grained layer of control that complements the more dramatic effects of calcium and mechanical feedback.

The concept that emerges from synthesizing all of these mechanisms is that of integrated regulatory axes. No single input acts in isolation. Calcium signaling interacts with phosphorylation pathways. Mechanical load influences the accessibility of regulatory sites. Redox state modulates the sensitivity of motors to other signals. The result is a control network in which the final beat parameters reflect the weighted integration of many concurrent inputs, each of which can be adjusted independently by the cell. This architecture confers both robustness and flexibility: the cilium can maintain productive motility even when one regulatory channel is disrupted, yet it can also execute rapid, precise changes in behavior when conditions demand it. For organisms ranging from algae to humans, this integrative capacity is what makes motile cilia such versatile and successful biological machines.

The clinical significance of this regulatory complexity is difficult to overstate. Defects in dynein assembly or regulation underlie a family of inherited disorders known as primary ciliary dyskinesia, characterized by chronic respiratory infections, situs abnormalities, and infertility. Understanding how the many regulatory axes converge on dynein function may eventually illuminate why certain mutations produce such variable clinical presentations, and may point toward therapeutic strategies that target regulatory pathways rather than the motor core itself. As Kondo and King’s review demonstrates, the era of viewing dynein as a simple sliding engine has given way to a far richer picture, one in which a two-megadalton molecular machine listens simultaneously to calcium, light, mechanical force, redox chemistry, and a chorus of covalent modifications, and translates that cacophony of signals into the elegant, life-sustaining rhythm of the ciliary beat.

Subject of Research: Regulatory mechanisms controlling dynein motor protein activity in the motile ciliary axoneme

Article Title: Integrated regulatory axes controlling dynein motors in the ciliary axoneme

Article References: Kondo, Y., & King, S. M. (2026). Integrated regulatory axes controlling dynein motors in the ciliary axoneme. Cellular and Molecular Life Sciences. https://doi.org/10.1007/s00018-026-06397-6

Image Credits: AI Generated

DOI: 10.1007/s00018-026-06397-6

Keywords: dynein, cilia, flagella, axoneme, motor proteins, calcium signaling, redox regulation, phosphorylation, mechanochemistry, post-translational modification, ciliary beating, primary ciliary dyskinesia