The review, led by Yinyu Wang and Zhidan Bao of Jiangyin People’s Hospital together with colleagues at Jiangyin Clinical College of Xuzhou Medical University and Wuxi Taihu University, focuses on neonatal hypoxic-ischemic encephalopathy, or HIE, a devastating condition caused by perinatal asphyxia and one of the leading causes of neonatal death and disability worldwide. Therapeutic hypothermia remains the standard of care, but its benefits are most reliable in mild cases, its treatment window is narrow, and eligibility criteria exclude many infants who might benefit. The authors argue that the persistence of severe sequelae in cooled infants demands adjunctive therapies aimed at mechanisms that cooling does not address, and they identify the gut-brain axis as a promising frontier.

Short-chain fatty acids, chiefly acetate, propionate, and butyrate, are saturated fatty acids of one to six carbons that gut bacteria generate by fermenting dietary fiber in the colon. Together these three metabolites account for more than ninety percent of total short-chain fatty acids in the body. Butyrate serves as the primary energy source for colonic epithelial cells, with roughly seventy percent consumed locally, while acetate and propionate enter the portal circulation and travel to the liver, muscle, and brain. Crucially, these molecules can partially cross the blood-brain barrier, and although their concentrations in cerebrospinal fluid are far lower than in the periphery, they appear sufficient to exert regulatory signaling. Their low molecular weight, barrier permeability, and favorable safety profile make them attractive drug candidates.

To understand why these gut metabolites might matter for a brain injury, the review first maps the pathology of HIE at the subcellular level. When oxygen and glucose are cut off, ATP is rapidly depleted, ion pumps fail, and calcium floods into the cytosol while draining from the endoplasmic reticulum. Electron leakage from the impaired electron transport chain triggers a burst of reactive oxygen species, and the resulting triple hit of energy failure, calcium overload, and oxidative stress strikes mitochondria and the endoplasmic reticulum simultaneously. Mitochondria, normally supplying more than ninety percent of neuronal energy, flip from cellular guardians into damage amplifiers: their membrane potential collapses, the permeability transition pore opens, cytochrome c escapes, and the apoptotic cascade begins.

The endoplasmic reticulum fares no better. ATP depletion inactivates luminal chaperones such as GRP78, calcium depletion ruins the protein-folding environment, and reactive oxygen species oxidize ER membranes and suppress the SERCA calcium pump. Neurons respond by activating the unfolded protein response, a signaling network with a double-edged character. In its adaptive mode, the PERK-eIF2alpha-ATF4 axis curtails protein synthesis and boosts antioxidant defenses, while IRE1alpha-mediated XBP1 splicing enhances chaperone production and ER-associated degradation. But when stress is excessive or prolonged, the same PERK pathway drives up the pro-apoptotic transcription factor CHOP, sustained IRE1alpha activates the JNK and p38 kinases, and caspase-12 cleaves caspase-9 to launch a mitochondria-independent death program.

The review’s most compelling conceptual contribution is its emphasis on mitochondria-associated ER membranes, or MAMs, as the physical platform that welds these two organelle failures into a single positive feedback loop. MAMs are contact sites held roughly ten to thirty nanometers apart by tethering proteins including IP3R, Grp75, VDAC1, and PACS-2. In healthy cells they shuttle carefully rationed calcium from the ER to mitochondria, activating TCA cycle enzymes and sustaining oxidative phosphorylation. In HIE, however, stressed ER releases calcium through over-opened IP3R channels, and the upregulated IP3R-Grp75-VDAC1 complexes deliver it straight into the mitochondrial matrix. The resulting calcium overload opens the permeability transition pore, uncouples the electron transport chain, and unleashes a storm of superoxide, hydrogen peroxide, and hydroxyl radicals that diffuse back to the ER, oxidizing its membranes, inactivating its chaperones, and deepening the very stress that started the cycle.

Against this backdrop, the authors propose that short-chain fatty acids act not through a single pathway but through three interrelated mechanisms that strike the vicious cycle at its source, its signaling nodes, and its physical interface. The first is epigenetic. Butyrate is the most potent endogenous inhibitor of class I and class IIa histone deacetylases among the short-chain fatty acids, followed by propionate, with acetate comparatively weak. By inhibiting these enzymes, butyrate raises histone H3 and H4 acetylation, relaxes chromatin, and unlocks protective genes. On the mitochondrial side, this upregulates PGC-1alpha, the master regulator of mitochondrial biogenesis, replenishing the population of functional mitochondria lost after injury. On the ER side, it boosts expression of GRP78, GRP94, and the foldase PDI, restoring folding capacity. Butyrate treatment in HIE models also elevates brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, and antioxidant enzymes such as SOD2 and glutathione peroxidase.

The second mechanism runs through cell-surface receptors. Short-chain fatty acids bind the G protein-coupled receptors GPR41 and GPR43, expressed in brain-resident and neurovascular cells, and thereby suppress two dangerous signaling pathways. They inhibit the nuclear translocation of NF-kappaB, cutting the release of TNF-alpha, IL-1beta, and IL-6 while promoting anti-inflammatory IL-10, which curbs the microglial inflammatory storm that drives secondary injury. More critically, they dampen hyperactivation of the PERK-eIF2alpha-ATF4-CHOP axis, lowering CHOP and cleaved caspase-12 levels and effectively blocking the death signal that the stressed ER transmits to mitochondria. The third mechanism is metabolic: short-chain fatty acids regulate the NAD+/NADH ratio and SIRT1 activity, enhancing respiratory chain complex activity, stabilizing membrane potential, inhibiting the permeability transition pore, and, potentially most importantly, blocking IP3R-mediated ER calcium release to break the calcium handoff at the MAM interface.

The review also situates these cellular effects within a broader physiological narrative. HIE itself disrupts the gut: systemic blood flow is redirected toward the brain and heart, mesenteric perfusion falls, the intestinal barrier is damaged, and SCFA-producing anaerobes are lost, stripping the newborn of a basal neuroprotective reserve. Exogenous supplementation, or boosting endogenous production through human milk feeding, prebiotics, or butyrate-producing bacteria such as Clostridium butyricum and Bifidobacterium infantis, could restore that reserve. Beyond the organelle cycle, short-chain fatty acids protect the blood-brain barrier by upregulating tight junction proteins claudin-5, occludin, and ZO-1 in brain microvascular endothelial cells while inhibiting matrix metalloproteinases, and animal studies show reduced Evans blue extravasation and cerebral edema after oral SCFA or probiotic supplementation. Effects extend across cell types, with the strongest evidence for neuronal protection and microglial modulation, and plausible roles for astrocytes and oligodendrocyte lineage cells in the vulnerable white matter.

The authors are candid about the obstacles between this mechanistic vision and the neonatal intensive care unit. Butyrate’s half-life in vivo is measured in minutes, its odor is strong, and it can irritate tissue, motivating sustained-release formulations such as tributyrin, sodium butyrate inclusion complexes, or nano-encapsulated delivery. The optimal dose, route, and timing remain undefined, and pharmacokinetic studies must establish whether effective brain concentrations are achievable under hypoxic conditions. Safety data in neonates with severe acidosis or hepatic and renal insufficiency are lacking, and individual variability in microbiota composition, feeding pattern, and antibiotic exposure may demand microbiota-typed dosing. The authors propose large-animal studies, randomized controlled trials using aEEG normalization, MR spectroscopy ratios, and eighteen-month neurodevelopmental scores as endpoints, and non-invasive monitoring via fecal SCFA profiling. If those steps succeed, a molecule made by gut bacteria from dietary fiber could become a genuine adjunct to cooling, converting a pathological positive feedback loop into a protective negative one precisely during the six-to-seventy-two-hour window when the newborn brain can still be saved.

Subject of Research: Neuroprotective mechanisms of gut microbiota-derived short-chain fatty acids in neonatal hypoxic-ischemic encephalopathy

Article Title: Mechanisms and therapeutic prospects of short-chain fatty acids in neonatal hypoxic–ischemic encephalopathy via modulation of mitochondrial dysfunction and endoplasmic reticulum stress

Article References: Wang, Y., Gao, L., Xu, Y., Niu, L., Tang, X., Zhou, Y., Deng, X., & Bao, Z. (2026). Mechanisms and therapeutic prospects of short-chain fatty acids in neonatal hypoxic–ischemic encephalopathy via modulation of mitochondrial dysfunction and endoplasmic reticulum stress. Frontiers in Molecular Neuroscience, 19, Article 1875196. https://doi.org/10.3389/fnmol.2026.1875196

Image Credits: AI Generated

DOI: 10.3389/fnmol.2026.1875196

Keywords: neonatal hypoxic-ischemic encephalopathy, short-chain fatty acids, butyrate, gut-brain axis, mitochondrial dysfunction, endoplasmic reticulum stress, mitochondria-associated ER membranes, unfolded protein response, histone deacetylase inhibition, neuroprotection, therapeutic hypothermia, blood-brain barrier

The clinical starting point was a group of patients whose stomachs suffer as a consequence of their livers. The team enrolled 111 patients with hepatitis B-related liver cirrhosis or hepatic failure at the Third Affiliated Hospital of Sun Yat-sen University between January 2022 and August 2024, alongside 118 control subjects. Using the gastrointestinal symptom rating scale, a validated 15-item questionnaire, the researchers found that patients with liver disease scored significantly higher overall than controls, 51.49 versus 42.40, with heartburn, acid reflux, nausea, bloating and diarrhea all markedly more frequent. Endoscopy told a matching story: the diseased mucosa showed more erosion and bleeding, and statistical analysis confirmed that mucosal lesions correlated with higher symptom scores, while normal mucosa tracked with lower scores.

Why would a congested stomach become a hypoxic one? The explanation is vascular. In portal hypertension and hepatic failure, restricted blood flow through the portal vein causes gastric venous congestion, and the oxygen supply to the epithelium falls behind demand. Using Hypoxyprobe-1 staining, the team demonstrated that hypoxia was indeed present in the gastric epithelium of these patients. In parallel, they established a mouse model of portal hypertension by partially ligating the portal vein, and again the hypoxia signal rose in step with a quantified gastric injury index. Crucially, the transcription factor HIF-1α, the master regulator of the cellular response to low oxygen, accumulated in the nuclei of epithelial cells in both human and mouse tissue, poised to reprogram gene expression.

That reprogramming showed up first as a metabolic shift. RNA sequencing of clinical gastric samples revealed enrichment of glycolysis and anaerobic metabolism pathways, and untargeted metabolomics of epithelial cells from the mouse model confirmed the biochemical signature: lactic acid rose while isocitric acid and citric acid, intermediates of the mitochondrial citric acid cycle, fell. This is the classic Warburg-like pattern in which cells, deprived of the oxygen needed for oxidative phosphorylation, burn glucose to lactate instead. In the short term this is a survival strategy, but the study suggests that under sustained hypoxia it becomes pathological, feeding a vicious cycle of metabolic disorder, reactive oxygen species generation and cell death.

The central molecular discovery concerns FUNDC1, an outer mitochondrial membrane protein previously known to help build mitochondria-associated ER membranes, or MAMs. These contact sites are far more than structural curiosities: they regulate calcium transfer from the ER to mitochondria, lipid exchange and mitochondrial dynamics. The researchers found that HIF-1α binds directly to a hypoxia-responsive element in the FUNDC1 promoter, driving its transcription, and that a second, post-transcriptional layer reinforces this. The m6A methyltransferase METTL3 chemically modified FUNDC1 messenger RNA, and the RNA-binding protein IGF2BP3, the most upregulated m6A reader in cirrhotic gastric tissue, recognized and stabilized that modified transcript. In mice carrying a mutant METTL3, FUNDC1 upregulation was blunted, confirming the epitranscriptomic mechanism.

With FUNDC1 elevated, the ER and mitochondria embraced more tightly. Transmission electron microscopy showed expanded contact zones in epithelial cells from portal hypertensive mice and from cirrhotic patients, and a proximity ligation assay for the IP3R2–VDAC1 tethering pair quantified the same increase. Coimmunoprecipitation confirmed that FUNDC1, IP3R2, VDAC1 and GRP75 formed complexes under hypoxic conditions. Truncation experiments pinpointed amino acids 7 to 48 of FUNDC1 as the domain essential for MAMs formation, a detail the authors highlight as a blueprint for designing inhibitors that could block the tethering interface specifically.

The consequences of this hyper-tethering were metabolic and oxidative. Seahorse extracellular flux analysis showed that epithelial cells under hypoxia had reduced maximal respiration, increased proton leak, elevated non-mitochondrial oxygen consumption and heightened basal and compensatory glycolysis, all of which were reversed when FUNDC1 was knocked down. Levels of electron transport chain subunits NDUFA9, SDHA, cytochrome b and ATP5A fell, along with ATP production. Meanwhile, mitochondrial superoxide, lipid peroxidation products such as 4-HNE and malondialdehyde, and oxidized mitochondrial DNA all climbed, while antioxidant defenses, superoxide dismutase activity and the glutathione redox ratio, collapsed. Calcium handling was also disturbed, with both cytosolic and mitochondrial calcium rising and membrane potential falling.

The final executioner in the cascade was NINJ1, a transmembrane protein that has recently emerged as the mediator of plasma membrane rupture during lytic cell death. In its inactive state NINJ1 is scattered across the membrane; when activated it oligomerizes into polymers that lyse the membrane and spill cellular contents. The team found NINJ1 oligomerization increased in gastric tissue from cirrhotic and hepatic failure patients, alongside elevated cleaved caspase-3 and cleaved caspase-1, markers of apoptosis and pyroptosis. Silencing NINJ1 in mice with portal hypertension reduced lactate dehydrogenase release, a readout of membrane permeabilization, restored epithelial viability and lessened mucosal injury. Notably, NINJ1 blockade did not change caspase activation, indicating it acts at the terminal step of membrane rupture rather than upstream of cell death signaling.

Two intervention experiments tied the whole axis together and pointed toward the clinic. Mito-TEMPO, a mitochondria-targeted antioxidant, suppressed NINJ1 oligomerization, reduced LDH release and protected the gastric mucosa in the mouse model, placing mitochondrial reactive oxygen species upstream of NINJ1 activation. The HIF-1α inhibitor PX-478 suppressed FUNDC1 expression and attenuated injury. Confocal imaging also showed that fragmented mitochondrial DNA released under oxidative stress colocalized with NINJ1, hinting at a direct or indirect role for escaping mtDNA in activating the rupture machinery, though the authors acknowledge the precise mechanism remains unresolved.

The authors are candid about limitations. The partial portal vein ligation model mechanically constricts the portal vein without reproducing hepatic parenchymal injury, systemic inflammation or the other comorbidities of clinical cirrhosis, and only knockdown rather than tissue-specific knockout approaches were used. Yet the reversibility of the pathway is encouraging: because MAMs remodeling is dynamic rather than covalent, targeted disruption of excessive ER-mitochondria tethering, inhibition of METTL3 or IGF2BP3 with emerging small molecules, or blockade of NINJ1 oligomerization with monoclonal antibodies could, in principle, interrupt the cycle before irreversible tissue damage sets in. If those strategies survive preclinical and clinical testing, the humble contact points between two organelles may become the address at which doctors finally treat the stomach’s silent suffocation.

Subject of Research: The FUNDC1–MAMs–NINJ1 signaling axis in hypoxia-induced gastric mucosal injury

Article Title: Mitochondria-associated endoplasmic reticulum membranes facilitate gastric epithelial injury in hypoxia-induced gastric mucosal lesions

Article References: Tan, S., Luo, J., Ou, X., Guo, X., Ke, B., & Tan, S. (2026). Mitochondria-associated endoplasmic reticulum membranes facilitate gastric epithelial injury in hypoxia-induced gastric mucosal lesions. Journal of Advanced Research. https://doi.org/10.1016/j.jare.2026.10.007

Image Credits: AI Generated

DOI: 10.1016/j.jare.2026.10.007

Keywords: hypoxia, gastric mucosal injury, mitochondria-associated ER membranes, FUNDC1, HIF-1α, m6A methylation, METTL3, IGF2BP3, NINJ1, portal hypertension, mitochondrial oxidative stress, plasma membrane rupture

Localized scleroderma, also called morphea, remains one of the most stubborn fibrotic skin diseases. It causes induration of the dermal and subcutaneous layers, and in severe cases leads to ulcers, disfiguring lesions, joint deformity, restricted movement, and even elevated fracture risk later in life. Current treatment relies mainly on immunosuppressants and glucocorticoids, with emerging options such as tocilizumab and JAK inhibitors, but no available therapy can reverse established skin fibrosis. That therapeutic gap drove the Sichuan team to look deeper into the molecular machinery that keeps fibroblasts, the collagen-producing cells of the dermis, locked in an activated, scar-forming state.

Their starting point was mitochondria. Previous work has established that mitochondrial dysfunction is a core driver of fibroblast activation in scleroderma, and that oxidative stress, a consequence of damaged mitochondria, plays an important role in the disease. Mitochondria are the main source of reactive oxygen species inside cells, and when their calcium handling goes awry, these reactive molecules accumulate and push cells toward senescence, a state of permanent growth arrest. Senescent cells then secrete a cocktail of inflammatory signals known as the senescence-associated secretory phenotype, which promotes fibroblasts and macrophages to adopt a fibrotic phenotype and fuels the scarring process.

Central to mitochondrial calcium control is a structure called the mitochondria-associated endoplasmic reticulum membrane, or MAM. At these contact sites, a channel complex composed of the proteins IP3R1, GRP75, and VDAC1 ferries calcium ions from the endoplasmic reticulum into mitochondria. When this flux becomes excessive, mitochondrial calcium overload damages the organelles, collapses their membrane potential, and elevates production of mitochondrial reactive oxygen species. Using transmission electron microscopy on skin samples from patients treated at West China Hospital between 2024 and 2025, the researchers found that the spatial proximity between the endoplasmic reticulum and mitochondria was significantly reduced in morphea lesions compared with healthy control tissue, providing the first preliminary evidence that MAM homeostasis is disturbed in this disease.

To find a drug that could restore that balance, the team turned to parthenolide, which has documented anti-inflammatory, antioxidative, and antifibrotic effects in liver, lung, kidney, and peritoneal fibrosis models. In human dermal fibroblasts stimulated with TGF-β, the master cytokine of fibrosis, parthenolide treatment reduced the number of β-galactosidase-positive senescent cells, increased proliferation as measured by EdU incorporation, and downregulated the senescence markers p21 and p16 along with the inflammatory cytokines IL-6, IL-1β, and TNF-α. At the highest concentration tested, 5 micromolar over 48 hours, the compound also lowered mRNA and protein levels of α-smooth muscle actin and type I collagen, the hallmarks of myofibroblast activation. Notably, the effects were concentration-dependent, with anti-aging effects appearing at medium and high doses and antifibrotic effects at high doses. When the researchers cleared senescent cells using the dasatinib and quercetin combination, fibroblast activation also eased, supporting the idea that parthenolide relieves fibrosis at least in part by modulating senescence.

The mechanistic hunt then moved to the MAM itself. Confocal microscopy showed that parthenolide diminished the colocalization between mitochondria and the endoplasmic reticulum and increased the inter-organelle distance in activated fibroblasts, while flow cytometry revealed restored mitochondrial membrane potential and reduced reactive oxygen species. RNA sequencing identified 1,111 genes differentially expressed after TGF-β stimulation and 290 after parthenolide treatment, with 161 genes shared between the two sets. Enrichment analyses pointed to wound healing, collagen-containing extracellular matrix, and endoplasmic reticulum lumen pathways. To narrow the field, the researchers performed inverse virtual screening against roughly 2,600 protein structures from the Protein Data Bank, ranking candidates by binding free energy, and intersected the top 100 hits with their differentially expressed genes. Two genes emerged: PI16 and Ero1L.

Ero1L, an oxidoreductase enzyme that lives predominantly at the MAM and responds to hypoxia and oxidative stress, became the prime suspect. Molecular docking predicted that parthenolide binds Ero1L with a binding energy of −7.3 kilocalories per mole, and surface plasmon resonance on a Biacore instrument confirmed a direct physical interaction. Docking simulations highlighted two key residues, ARG-449 and PHE-62, and site-directed mutagenesis showed that converting ARG-449 to alanine abolished the binding affinity, while the PHE-62 mutation had no significant effect, confirming the specificity of the interaction. Parthenolide also reduced Ero1L mRNA and protein expression in TGF-β-treated cells. Single-cell RNA sequencing of a public dataset covering fourteen localized scleroderma patients and fourteen healthy controls, encompassing 32,154 cells clustered into fifteen cell types, showed that Ero1L is expressed at higher levels in activated fibroblasts than in other cell subtypes, and immunohistochemistry revealed elevated Ero1L in patient skin biopsies that correlated positively with both senescence markers and the modified Localized Scleroderma Skin Severity Index.

Causality tests sealed the case. When the researchers overexpressed Ero1L in fibroblasts, the protective effects of parthenolide were reversed: senescence and fibrosis markers climbed back up, mitochondrial reactive oxygen species rose, membrane potential fell, and the compound’s suppression of ER-mitochondrial colocalization was blunted. Conversely, knocking Ero1L down with siRNA mimicked the drug’s benefits, reducing fibrotic and senescent markers, restoring mitochondrial health, increasing the average ER-mitochondria distance on electron micrographs, and weakening the interactions within the IP3R1-GRP75-VDAC1 calcium channel complex. Parthenolide treatment similarly downregulated the three channel proteins and eased mitochondrial calcium overload, suggesting that Ero1L acts upstream of calcium flux at the MAM. The authors propose that Ero1L may also promote fibrosis indirectly through redox regulation, since the enzyme reoxidizes protein disulfide isomerase to maintain the disulfide bonds needed for type I collagen folding and secretion.

Because parthenolide’s poor water solubility and low bioavailability have hindered clinical use, the team engineered a delivery system combining PLGA nanoparticles loaded with the drug and a thermoresponsive F127 poloxamer hydrogel. Electron microscopy showed spherical nanoparticles, and rheological testing confirmed the hydrogel’s injectability and temperature-dependent gel transition at body temperature. High-performance liquid chromatography demonstrated a slower, sustained release without an initial burst phase, and live-dead staining and CCK-8 assays confirmed good biocompatibility. In a bleomycin-induced mouse model of localized scleroderma, weekly injections of the formulation, designated F127@PLGA@PTL at 70 milligrams per kilogram, significantly attenuated dermal thickness, collagen deposition, and myofibroblast counts, reduced Ero1L protein expression, and showed anti-aging effects, while multiplex immunofluorescence indicated the treatment specifically quieted activated fibroblasts without measurable effects on vascular endothelial cells, keratinocytes, or Th2 lymphocytes.

The study is the first to implicate Ero1L in the pathogenesis of localized scleroderma and to demonstrate an anti-aging effect of parthenolide in skin fibrosis, positioning the ER-mitochondrial interface as a therapeutic target for hardening skin diseases. The authors caution that their findings rest on cell culture and mouse models and require validation in human subjects, and they note that parthenolide can behave differently in other contexts, even inducing mitochondrial dysfunction in cancer cells, so its biological effects appear cell-specific and shaped by metabolic state. Still, by connecting a humble herbal compound, a calcium-handling hub, and an aging program into one mechanistic chain, the work opens a concrete path toward therapies that could do what current medicine cannot: soften fibrotic skin by rejuvenating the cells that build it.

Subject of Research: Parthenolide targeting of Ero1L to regulate mitochondria-associated ER membranes in localized scleroderma fibrosis and cellular senescence

Article Title: Targeting Ero1L by Parthenolide Alleviates Cellular Senescence and Fibrosis of Localized Scleroderma by Regulating Mitochondria‐Associated Endoplasmic Reticulum Membranes Stabilization

Article References: Wang, F., Xing, R., Xie, M., Qin, Y., Zhang, Y., Cao, D., He, G., & Lyu, X. (2026). Targeting Ero1L by Parthenolide Alleviates Cellular Senescence and Fibrosis of Localized Scleroderma by Regulating Mitochondria‐Associated Endoplasmic Reticulum Membranes Stabilization. Aging Cell, 25(10), Article e70738. https://doi.org/10.1111/acel.70738

Image Credits: AI Generated

DOI: 10.1111/acel.70738

Keywords: localized scleroderma, parthenolide, Ero1L, mitochondria-associated ER membranes, cellular senescence, fibrosis, calcium flux, dermal fibroblasts, PLGA nanoparticles, F127 hydrogel, oxidative stress, TGF-beta

TMEM232 is not an arbitrary suspect. It is a known susceptibility gene for atopic dermatitis, meaning genetic variants in or near the gene are statistically linked to the disease in human populations. What has remained murky until now is what the protein actually does inside skin cells and how that activity could translate into the leaky, irritated skin that defines the condition. The research team set out to close that gap by combining patient tissue samples, primary human keratinocytes, laboratory-grown human adult low-calcium cutaneous keratinocytes, and mouse models of the disease.

The first clue came from expression analysis. TMEM232 levels were significantly elevated in lesional skin from atopic dermatitis patients, and the degree of upregulation tracked with the severity of tight junction dysfunction. Tight junctions are protein assemblies — including the claudins, occludin and zonula occludens proteins — that zip adjacent keratinocytes together and seal the paracellular route through which water, allergens and microbes would otherwise pass. When the researchers measured transepithelial electrical resistance, a standard readout of barrier tightness, and ran permeability assays using fluorescent tracers, keratinocytes with excess TMEM232 showed weakened resistance and increased leakage, while reducing the protein restored junctional integrity.

To find the mechanism, the team mapped where TMEM232 resides inside the cell. Immunofluorescence revealed that the protein accumulates in the perinuclear region and is selectively enriched at mitochondria-associated endoplasmic reticulum membranes, or MAMs — the specialized lipid and protein platforms where the reticulum and mitochondria come within nanometers of each other. MAMs are the cells’ principal conduits for calcium transfer: calcium released from the endoplasmic reticulum crosses into mitochondria through a well-characterized channel trio consisting of the inositol 1,4,5-trisphosphate receptor 3 on the reticular side, glucose-regulated protein 75 as the cytosolic linker, and voltage-dependent anion channel 1 on the mitochondrial outer membrane.

Using co-immunoprecipitation, proximity ligation assays and colocalization microscopy, the researchers showed that TMEM232 physically associates with this IP3R3-GRP75-VDAC1 complex and, critically, promotes its assembly. The functional consequence was measured directly with calcium-sensitive fluorescent dyes: Mag-Fluo-4 reported a drop in calcium stored within the endoplasmic reticulum, while Rhod-2 recorded a corresponding surge of calcium accumulating inside mitochondria. In other words, when TMEM232 is abundant, the calcium bridge between the two organelles runs wide open, draining the reticulum and flooding the mitochondria.

That calcium imbalance triggered a damaging cascade. Depletion of reticular calcium is a canonical activator of endoplasmic reticulum stress, and the team documented activation of the classic unfolded protein response sensors, including PERK and its downstream phosphorylation of eukaryotic translation initiation factor 2α, alongside other ER stress markers. Meanwhile, mitochondrial calcium overload stoked the electron transport chain into leaking electrons, which the researchers detected as elevated mitochondrial superoxide and increased total intracellular reactive oxygen species using mitochondrial superoxide indicators and H2DCFDA-based assays. Oxidative stress of this kind is well known to destabilize junctional proteins and disrupt cytoskeletal anchoring, providing a plausible route from organelle stress to broken tight junctions.

The causal chain was tested by interrupting it at multiple points. When the researchers disrupted the IP3R3-GRP75-VDAC1 complex, or when they relieved endoplasmic reticulum stress with the chemical chaperone 4-phenylbutyric acid, the tight junction damage caused by TMEM232 overexpression was effectively rescued. These rescue experiments matter because they show that the calcium-transfer complex and the resulting ER stress are not incidental byproducts but necessary links between TMEM232 and barrier failure. The team also employed tools such as thapsigargin and 2-aminoethoxydiphenyl borate to manipulate calcium handling, reinforcing the picture of a TMEM232-driven calcium leak as the upstream event.

The in vivo evidence strengthened the case further. In a mouse model of atopic dermatitis induced by the contact sensitizer 2,4-dinitrochlorobenzene, animals genetically engineered to lack Tmem232 developed milder dermatitis than wild-type controls. Importantly, a more translationally oriented approach — applying small interfering RNA topically to knock down Tmem232 in the skin — also ameliorated the AD-like disease. Together with the cell-based findings, these results position TMEM232 as a genuine driver of barrier pathology rather than a passive biomarker, and they suggest that silencing it at the skin surface could have therapeutic value.

The study reframes atopic dermatitis barrier dysfunction as an organelle-level disease. Rather than viewing the leaky epidermis purely as a consequence of failed structural proteins or inflammatory damage, the work inserts MAMs — and the calcium flux they regulate — into the causal pathway, connecting a genetic risk factor to ER stress, mitochondrial oxidative damage, and ultimately the disintegration of tight junctions. It also raises questions for future research: whether TMEM232 variants differ in their calcium-regulating activity between individuals, whether MAM-targeted interventions could complement existing biologics and barrier repair therapies, and whether similar mechanisms operate in other barrier tissues such as the gut and airways, where tight junction failure underlies distinct chronic diseases.

For patients, the practical hope is a new class of targets. Current atopic dermatitis treatments broadly suppress inflammation or repair lipids in the stratum corneum, but a therapy aimed at TMEM232 or its calcium-channel partners would intervene at a more fundamental point in the disease mechanism. Topical siRNA delivery, as validated in the mouse model, offers a plausible development route, and small molecules that stabilize ER calcium stores or dampen mitochondrial oxidative stress represent alternative strategies. The researchers conclude that targeting TMEM232 represents a potential therapeutic strategy for atopic dermatitis, and their demonstration that the pathway is rescueable in both cells and living animals provides the proof-of-concept needed to pursue it.

Subject of Research: The role of TMEM232 in ER-mitochondrial calcium transfer and tight junction dysfunction in atopic dermatitis

Article Title: TMEM232 associates with the IP3R3-GRP75-VDAC1 complex to enhance ER-Mitochondrial calcium transfer and impair tight junctions in atopic dermatitis

Article References: Chen, L., Wang, Y., He, Z., Xu, J., Zhang, Y., Wang, Z., Wang, M., Li, C., Cai, X., & Xiao, F. (2026). TMEM232 associates with the IP3R3-GRP75-VDAC1 complex to enhance ER-Mitochondrial calcium transfer and impair tight junctions in atopic dermatitis. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-08932-2

Image Credits: AI Generated

DOI: 10.1186/s12967-026-08932-2

Keywords: atopic dermatitis, TMEM232, tight junctions, mitochondria-associated ER membranes, calcium signaling, endoplasmic reticulum stress, IP3R3-GRP75-VDAC1 complex, skin barrier, keratinocytes, oxidative stress, siRNA, Journal of Translational Medicine