ELAVL1, or Elav-like RBP 1, is an RNA-binding protein that recognizes AU-rich elements in target messenger RNAs and can influence RNA stability and translation. The study was motivated by evidence that ELAVL1 is frequently overexpressed in human malignancies and has previously been associated with aggressive features of cervical cancer. Its expression in cervical tumors has also been linked in earlier work to stabilization of messenger RNAs encoding proteins such as cyclin B1, TPD52 and HOXC6. The new experiments focused on whether ACVRL1 and CASP14 participate in a previously uncharacterized route through which ELAVL1 influences cervical cancer cells.

Expression analysis showed that ELAVL1 messenger RNA and protein levels were higher in the cervical cancer cell lines SiHa and HeLa than in the non-tumorigenic cervical epithelial cell line HCerEpiC. These comparisons used RT-qPCR and western blot analysis, with three technical replicates from three biological replicates for each cell line. ELAVL1 levels were also higher in cervical cancer tissues than in patient-matched adjacent non-tumor samples. The researchers additionally examined a public gene-expression dataset through TNMplot. In that independent analysis of 14 uterine tumor tissues and 14 paired adjacent normal tissues, ELAVL1 expression was significantly higher in tumor samples, with a reported p value of 0.00695. The experimental and public-dataset results therefore converged on ELAVL1 overexpression in cervical and uterine tumor tissue, although the clinical comparison was limited by its small sample size and did not establish patient outcomes.

Functional experiments in SiHa and HeLa cells indicated that ELAVL1 supports several malignant characteristics. Researchers reduced ELAVL1 expression with small interfering RNA and measured cell growth, migration, invasion and apoptosis. CCK-8 assays showed lower proliferation after knockdown, while wound-healing and Transwell assays showed reduced migration and invasion. For the wound-healing experiments, cells were pretreated with 2 μg/mL mitomycin C to reduce interference from proliferation, and migration was evaluated 48 hours after transfection. Cells with silenced ELAVL1 also had a higher proportion of apoptotic cells in flow-cytometry measurements and increased levels of cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase, or PARP, proteins. In the reciprocal experiment, overexpressing ELAVL1 in SiHa cells increased proliferation, wound closure and invasion. Fluorescence imaging further associated ELAVL1 knockdown with reduced formation of F-actin-rich migratory and invasive protrusions. Together, these observations establish a functional association between ELAVL1 expression and aggressive cell behavior in the two cell-line models, without demonstrating that ELAVL1 alone initiates cervical cancer.

The investigators then used the ENCORI/starBase RNA-binding-protein prediction tool to search for a possible connection between ELAVL1 and ACVRL1. The analysis predicted an ELAVL1-binding site in the ACVRL1 messenger RNA 3′ untranslated region at chromosome 12 position 51922109. An RNA immunoprecipitation followed by quantitative PCR supported physical association between ELAVL1 protein and ACVRL1 RNA: ACVRL1 RNA was enriched in the ELAVL1 immunoprecipitate, while the immunoglobulin G control produced only faint nonspecific signal. In dual-luciferase reporter assays, ELAVL1 knockdown reduced activity from a reporter carrying the wild-type ACVRL1 3′ untranslated region. Altering the predicted binding sequence removed this response, suggesting that the candidate region participates in ELAVL1-dependent regulation. These experiments support a post-transcriptional interaction, although they do not establish the precise biochemical mechanism or whether ACVRL1 messenger RNA stabilization is the only consequence of the binding.

ACVRL1 and CASP14 were also investigated as potential interacting proteins. The study cited previous liquid chromatography–mass spectrometry screening that had identified CASP14 among 11 candidate ACVRL1-interacting proteins, then used AlphaFold3 to predict a possible structural interface between the two proteins. Immunofluorescence imaging showed that ACVRL1 and CASP14 colocalized in the nuclei of SiHa and HeLa cells, with CASP14 stained green and ACVRL1 stained red. These findings offer a structural and cellular basis for examining the pathway, but a predicted interface and spatial overlap alone do not demonstrate direct protein binding or a causal intracellular signaling sequence. The authors therefore tested the proposed regulatory relationships with gene-silencing experiments rather than relying on the imaging results alone.

When ELAVL1 was knocked down in SiHa and HeLa cells, both messenger RNA and protein levels of ACVRL1 and CASP14 decreased. Silencing ACVRL1 reduced CASP14 messenger RNA and protein levels without producing a significant change in ELAVL1 expression. In contrast, reducing CASP14 did not noticeably alter ELAVL1 or ACVRL1 expression. This ordering was consistent with an indirect model in which ELAVL1 acts upstream of ACVRL1, which in turn influences CASP14 abundance. The results do not, however, exclude feedback, intermediary regulators or other target RNAs, and knockdown experiments cannot by themselves establish direct causation for every step of the proposed pathway. The observations were measured in cell cultures, not in patients.

Co-transfection experiments provided functional evidence that ACVRL1 and CASP14 contribute to the phenotypes associated with ELAVL1. In SiHa cells overexpressing ELAVL1, simultaneous knockdown of ACVRL1 partially reversed the increases in proliferation, migration and invasion. Knocking down CASP14 produced similar partial reversals of all three behaviors. Additional flow-cytometry analysis showed that CASP14 depletion increased the proportion of apoptotic cells in SiHa and HeLa cultures relative to their negative controls. Because the downstream interventions only partially offset the ELAVL1 phenotype, the findings also suggest that ELAVL1 influences other targets or regulatory modules. The experiments nevertheless support a measurable contribution from the ACVRL1/CASP14 axis to the cellular effects of ELAVL1 in cervical cancer cells. The study used multiple independent biological replicates for the functional assays, with technical replicates used for selected molecular measurements.

The study extended its findings to an in vivo model using SiHa cells implanted subcutaneously in female nude mice. Ten mice were used for the xenograft experiment, with five assigned to the control condition and five to the ELAVL1-silencing condition. Once tumors had formed, researchers administered either an in vivo control or ELAVL1-targeting small interfering RNA at multiple tumor sites. RT-qPCR analysis showed that ELAVL1 messenger RNA was reduced in treated tumors. Tumor volume was significantly smaller in the ELAVL1-silencing group than in the control group, tumor weight was also significantly lower, and the messenger RNA level of the proliferation marker Ki-67 was reduced. The xenograft result indicates that local ELAVL1 silencing can suppress tumor growth in this particular mouse model. It does not demonstrate that a clinically deliverable ELAVL1 inhibitor would be safe or effective in people, and the subcutaneous xenograft reproduces only part of human cervical cancer biology.

Overall, the experiments support ELAVL1 as a cancer-promoting regulator in HPV-associated cervical cancer cell models and nominate ACVRL1 and CASP14 as components of a possible downstream pathway. SiHa cells are HPV16-positive, while HeLa cells are HPV18-positive, linking the cell models to the high-risk HPV types emphasized in the study. The research connects ELAVL1 binding to the ACVRL1 3′ untranslated region with changes in pathway expression, malignant cell behaviors and reduced tumor growth after knockdown. Important limitations include the small clinical sample, reliance on two cell lines and a mouse xenograft, possible influence from other ELAVL1 targets, and the absence of patient outcomes or clinical intervention data. The findings therefore identify a testable regulatory network and a potential target for further research, but they do not yet establish that manipulating this pathway is a safe or effective cervical cancer treatment in humans.

Subject of Research: Mechanistic study of ELAVL1 regulation and cervical cancer progression through the ACVRL1/CASP14 pathway.

Article Title: ELAVL1 overexpression potentiates cervical cancer malignancy via regulating the ACVRL1/CASP14 pathway

Article References: Liu, J., Wang, J., Gao, Y., Cui, X., Wang, W., Ma, H., Jiao, Y., Xu, J., Hao, J., Xu, Z., Li, L., & Hao, M. (2026). ELAVL1 overexpression potentiates cervical cancer malignancy via regulating the ACVRL1/CASP14 pathway. iScience, 29(11), Article 117956. https://doi.org/10.1016/j.isci.2026.117956

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117956

Keywords: ELAVL1, cervical cancer, ACVRL1, CASP14, RNA-binding protein, HPV16, HPV18, cancer cell models, molecular regulation, xenograft tumors, overexpression, potentiates

The story begins with exon 10 of the MAPT gene. Tau exists in the human brain as six isoforms, distinguished by whether they contain three or four microtubule-binding repeats, the so-called 3R and 4R forms. The inclusion or skipping of exon 10 determines which repeat is present, and the normal adult brain maintains a roughly balanced ratio of the two. When that ratio slips, the consequences can be devastating: mutations and splicing dysregulation around exon 10 are linked to a family of disorders including progressive supranuclear palsy, corticobasal degeneration, Pick’s disease, and frontotemporal dementia with parkinsonism linked to chromosome 17, as well as Alzheimer’s disease itself, where neurofibrillary tangles of tau accumulate inside dying neurons.

Scientists have known for years that exon 10 is governed by an intricate web of cis-acting sequence elements and trans-acting proteins. Previous work had implicated factors such as TDP-43, hnRNP A1, Rbfox3, and hnRNP C in controlling this splicing decision. The new study, led by Yaqiong Yu and colleagues with senior authors Tao Jiang and Deng Xiao, adds HuR, also known as ELAVL1, to that roster, and does so with a mechanistic depth that distinguishes it from a simple correlation. Using a combination of reporter assays, binding studies, and transcriptome-wide analyses, the team demonstrated that HuR does not merely associate with the MAPT pre-messenger RNA; it actively suppresses the inclusion of exon 10.

The mechanistic core of the finding lies in a specific structural domain of the HuR protein. HuR belongs to the embryonic lethal abnormal vision family of RNA-binding proteins and carries three RNA recognition motifs, or RRMs. Through systematic domain analysis, the researchers showed that the first of these motifs, RRM1, is critical for HuR’s splicing-inhibitory effect on exon 10. When this domain’s function was disrupted, the repressive effect was lost. This level of resolution matters because it converts a broad observation, that HuR touches tau RNA, into a testable molecular model in which a defined protein surface contacts a defined RNA target to alter a splicing outcome relevant to human disease.

Where exactly does HuR bind? The answer, according to the study, is a uridine-rich stretch of sequence located downstream of intron 9 in the MAPT pre-mRNA, immediately adjacent to the exon 10 region whose inclusion it represses. U-rich elements are a classic signature of ELAV-family protein binding, and genome-wide surveys have previously revealed that a large proportion of AU-rich elements across the human transcriptome sit within introns, where they can influence splicing as well as mRNA stability. The intronic location of the HuR binding site in MAPT fits this pattern neatly and provides a plausible physical mechanism: by occupying the downstream intron, HuR may interfere with the spliceosome’s recognition of the exon, tipping the balance toward skipping.

Perhaps the most intriguing aspect of the study is its demonstration that HuR does not work alone. The researchers found that HuR binds the U-rich region in MAPT together with a cohort of cooperating RNA-binding proteins: FUBP1, KHSRP, hnRNPD, hnRNPAB, hnRNPDL, and TIAL1. Splicing decisions in mammalian cells are rarely made by a single factor; instead, regulatory complexes assemble cooperatively on pre-mRNA, and the combined occupancy of activators and repressors determines the final output. The identification of this multi-protein assembly at the tau exon 10 locus suggests that the ratio of 3R to 4R tau is set by a network rather than a switch, with HuR functioning as one node whose influence depends on its partners.

Adding another layer of complexity, the team observed that HuR expression shows a negative relationship with the expression of several of these partners, including FUBP1, KHSRP, hnRNPD, and TIAL1. Such inverse expression patterns hint at cross-regulatory circuits among RNA-binding proteins, a phenomenon documented before in the hnRNP family, where auto- and cross-regulation help maintain proteostasis of the splicing machinery. If HuR and its co-factors restrain one another’s abundance, then perturbations that shift one factor, whether through aging, stress signaling, or disease processes, could ripple through the entire complex and reshape tau splicing in neurons. This systems-level view reframes tauopathies not as failures of a single gene but as failures of a regulatory network.

The implications extend well beyond MAPT. When the researchers examined the broader consequences of altering HuR levels, they found that the protein regulates both the expression and the alternative splicing of genes involved in autophagy and apoptosis, the cellular self-cleaning and self-destruction pathways that are famously dysregulated in Alzheimer’s disease. Defective autophagy is thought to contribute to the accumulation of amyloid-beta and phosphorylated tau, while inappropriate apoptosis drives neuronal loss. The idea that a single RNA-binding protein sits upstream of splicing programs in both pathways positions HuR as a potential coordinator of several AD-relevant transcriptomic networks simultaneously, a convergence point where multiple disease processes might intersect.

This broader role is consistent with a growing literature on the ELAV family in the nervous system. HuR has been shown to control the RNA metabolism of glutaminase, to regulate age-related hearing loss in mice, and to interact with amyloid precursor protein in ways that promote apoptosis under amyloid-beta stress. Its cousin ELAVL4 has been implicated in splicing changes and glutamatergic dysfunction that precede neuron loss in cerebral organoids carrying MAPT mutations, and ELAVL2-family biology has been linked to neuroprotection in retinal ganglion cells. The new study slots neatly into this picture while adding something genuinely new: a direct, mechanistically resolved connection between HuR and the splicing event most tightly associated with tauopathy.

Therapeutically, the timing is notable. Antisense oligonucleotides targeting tau are already in clinical trials, with a phase 1b study of the MAPT-targeting agent MAPTRx in mild Alzheimer’s disease demonstrating that tau-directed RNA therapies can reach the nervous system safely. A splicing-factor approach would represent a different strategy: rather than reducing total tau, it would aim to restore the correct 3R-to-4R ratio by modulating the proteins that decide exon 10’s fate. The identification of RRM1 as the critical functional domain of HuR provides a concrete target for such efforts, whether through small molecules that disrupt the HuR-RNA interaction or through oligonucleotides that mask the U-rich binding site in intron 9. Similar splicing-correction approaches have already rescued mis-splicing in other genetic diseases, including sensorineural hearing loss and spinal muscular atrophy, proving the concept is feasible.

Caution is warranted, as it always is in this field. HuR is a multifunctional protein with hundreds of documented RNA targets, and global manipulation of its activity could produce unintended effects in cells throughout the body. The negative correlations between HuR and its co-factor expression, while suggestive, raise questions about cause and effect that will require longitudinal and cell-type-specific studies to resolve. Moreover, the study was conducted without human participants or animal subjects, so translating these molecular findings into living brains remains a substantial journey. Even so, the work delivers something Alzheimer’s research badly needs: a new, mechanistically grounded entry point into the splicing decisions that shape tau biology, and a reminder that the answers to neurodegeneration may lie not only in the proteins that misfold, but in the RNA editors that decide which versions of those proteins are made in the first place.

Subject of Research: The role of the RNA-binding protein HuR in regulating alternative splicing of MAPT and other Alzheimer's disease-related genes

Article Title: HuR modulates disease-relevant alternative splicing of MAPT and other Alzheimer's disease-related genes

Article References: Yu, Y., Liu, S., Ma, C., Tan, M., Min, L., Jiang, T., & Xiao, D. (2026). HuR modulates disease-relevant alternative splicing of MAPT and other Alzheimer's disease-related genes. Molecular Genetics and Genomics, 301(1), Article 202. https://doi.org/10.1007/s00438-026-02527-8

Image Credits: AI Generated

DOI: 10.1007/s00438-026-02527-8

Keywords: HuR, ELAVL1, MAPT, tau, alternative splicing, Alzheimer's disease, tauopathies, exon 10, RNA-binding proteins, autophagy, apoptosis, neurodegeneration

The technique, developed by Iwona Nowak, Ahsan H. Polash, Hang T. Huynh, Mahekdeep Kaur and colleagues in the laboratories of Aishe A. Sarshad, Markus Hafner, and Daniel Benhalevy, fuses two powerful approaches that had never been married at this scale. The first is APEX2-based proximity labeling, an enzymatic tagging system that marks proteins and nucleic acids within a narrow radius of a genetically targeted protein. The second is 4-thiouridine-enhanced ultraviolet crosslinking, which covalently locks RNA-binding proteins onto their RNA targets and allows precise identification of crosslinked nucleotides. By combining these with sequential affinity purifications, first for the RNA-binding protein of interest and then for the biotin tag, the researchers built a pipeline that isolates only those protein-RNA contacts that occurred in the marked compartment.

The logic of the method is elegant in its layering. A protein of interest, such as the RNA-binding factor being studied, is expressed as a fusion with APEX2, a peroxidase that in the presence of biotin-phenol and hydrogen peroxide converts nearby molecules into biotin-tagged derivatives. Cells are first treated with 4-thiouridine, which is incorporated into newly synthesized RNA and dramatically strengthens ultraviolet-induced crosslinking between RNA and any protein touching it, a strategy borrowed from fPAR-CLIP protocols. When ultraviolet light fires, RNA-binding proteins are frozen onto their targets with nucleotide precision. APEX2 then labels everything in its immediate vicinity with biotin, creating a spatial signature.

What follows is a double selection. The researchers purify the RNA-binding protein and its crosslinked RNA fragments through an initial affinity step, recovering crosslinked RNA with mutations that reveal the exact binding sites, the hallmark of enhanced crosslinking-and-immunoprecipitation approaches. They then recover only those complexes that also carry the APEX2-deposited biotin tag in a second purification. A transcript must pass both filters to be counted: it must have been physically touched by the protein and must have been within the proximity-labeling radius, effectively bracketing the interaction in space and time. The result is a map of protein-RNA contacts that is simultaneously compartment-specific and nucleotide-resolved.

Control experiments were central to validating the approach. The team confirmed that APEX2 fusion proteins localized correctly to their intended compartments and that proximity-dependent biotinylation was restricted to the expected neighborhoods, presenting this evidence across multiple supplementary figures alongside imaging and immunoblot analyses. Without accurate spatial confinement, any apparent compartment specificity could simply reflect leakage or overexpression artifacts, so establishing the fidelity of the labeling step was essential before biological conclusions could be drawn.

With the method proven, the researchers turned it loose on three of the most intensively studied RNA-binding proteins: AGO2, the central effector of the microRNA silencing machinery; YBX1, a multifunctional nucleic acid-binding protein involved in mRNA stability and translation; and ELAVL1, better known in some circles as HuR, a regulator of mRNA stability and stress responses. All three proteins are known to operate in multiple cellular compartments, making them ideal test cases for a technology designed to disentangle location-dependent behavior.

The findings were striking. Each of the three proteins displayed distinct, compartment-specific RNA-binding patterns, targeting different sets of transcripts and even different sequence contexts depending on where in the cell it was acting. Importantly, the researchers found that these spatial differences arose through canonical motif recognition: the same proteins continued to recognize their characteristic sequence motifs in each compartment, but the repertoire of available targets, and thus the functional consequences of binding, shifted dramatically with location. In other words, the proteins did not change their binding preferences so much as their access to substrates changed, partitioning the accessible RNA targets and reshaping each protein’s regulome across the cell.

This partitioning concept has broad implications. For AGO2, compartment-specific mapping opens a window onto how microRNA targeting might differ between the cytoplasm, where canonical silencing occurs, and other locales where AGO2 has been implicated in less conventional roles. For YBX1 and ELAVL1, both implicated in cancer biology and stress physiology, knowing which transcripts are bound in which compartments could clarify how these proteins execute distinct functions from seemingly identical biochemical activities. The method essentially converts a single flat binding profile into a set of spatially annotated maps, revealing that what looked like one interactome is actually several overlapping ones.

Technically, RBProximity-CLIP also demonstrates the value of the 4-thiouridine enhancement inherited from fPAR-CLIP. Enhanced crosslinking increases crosslinking efficiency and yields the characteristic signature of crosslink-induced mutations, allowing binding sites to be pinpointed to individual nucleotides. Combined with proximity tagging, this delivers a rare combination of spatial and sequence resolution in a single experiment, something neither classical CLIP nor proximity labeling alone can provide. The authors provide detailed reagent lists, including antibodies, detection reagents for imaging and immunoblotting, and oligonucleotide sequences for library preparation, alongside full-length uncropped gel and blot images, underscoring the reproducibility infrastructure that accompanies methodological advances of this kind.

The work was a genuinely international effort, jointly led from the University of Gothenburg’s Wallenberg Centre for Molecular and Translational Medicine, the RNA Molecular Biology Laboratory at the National Institute of Arthritis and Musculoskeletal and Skin Diseases in Bethesda, and Tel Aviv University, with support from the Swedish Research Council, the Knut and Alice Wallenberg Foundation, the Swedish Society for Medical Research, the National Institutes of Health Intramural Research Program, the Israel Science Foundation, and the Hellenic Foundation for Research and Innovation. Published as an open-access article in Genome Biology, the study arrives at a moment when the field is increasingly aware that spatial context is not a luxury but a fundamental dimension of gene regulation. As RBProximity-CLIP is adopted and extended, it promises to turn the cell from a featureless bag of molecules into a mapped territory, where every protein-RNA encounter has an address, and where the grammar of gene expression can finally be read with both sequence and location in view.

Subject of Research: A subcellular-resolution RNA-binding protein mapping method combining proximity labeling and enhanced crosslinking

Article Title: RBProximity-CLIP enables subcellular mapping of RNA-binding protein interactions at nucleotide resolution

Article References: Nowak, I., Polash, A. H., Huynh, H. T., Kaur, M., Lobo, V., Scutenaire, J., Fong, M., Alluhaibi, G., Anastasakis, D. G., Hafner, M., Benhalevy, D., & Sarshad, A. A. (2026). RBProximity-CLIP enables subcellular mapping of RNA-binding protein interactions at nucleotide resolution. Genome Biology. https://doi.org/10.1186/s13059-026-04278-6

Image Credits: AI Generated

DOI: 10.1186/s13059-026-04278-6

Keywords: RNA-binding proteins, RBProximity-CLIP, proximity labeling, APEX2, CLIP-seq, AGO2, YBX1, ELAVL1, 4-thiouridine, subcellular resolution, protein-RNA interactions, Genome Biology