Experimental & Molecular Medicine

Inflammatory bowel disease (IBD) often involves disrupted intestinal epithelial barrier, but therapies specifically targeting this barrier are limited. We found that downregulated AUF1 (HNRNPD) contributes to defective barrier integrity in ulcerative colitis (UC). Compared to controls, its expression level was decreased and inversely correlated with clinical severity. Knocking down AUF1 in human and mouse colonic organoids led to impaired barrier function, with reduced Occludin and upregulated Claudin-2, mimicking characteristic IBD-associated mucosal alterations. Distinct RNA-binding activity of AUF1 protein isoforms contributed to these changes: p37 stabilized Occludin mRNA and blocked microRNA-122/Ago2-mediated repression, whereas p40 promoted Claudin-2 mRNA degradation via ubiquitin-proteasome pathway. Restoring AUF1 expression in organoids enhanced epithelial properties and, when transplanted into mice with established colitis, accelerated mucosal healing and epithelial regeneration in recipient mice and decreased fibrosis. Our study unravelled a post-transcriptional mechanism important for intestinal homeostasis and demonstrated a concept of using engineered organoids for treating IBD.

Introduction: There is an unmet need for effective topical anti-pruritic medications for acute itch, as there are only a few over-the-counter products that have a direct effect on itch. Tripelennamine is a first-generation antihistamine that would be useful in treating histamine-induced pruritus, however, supportive robust clinical data is lacking. Objectives: The efficacy of tripelennamine (TPA) compared to diphenhydramine (DPH) and a vehicle control cream base on histamine-induced pruritus was evaluated as the primary endpoint. Histamine-induced urticaria served as the secondary endpoint. Methods: Thirty-six healthy participants completed this single-center, double-blinded, placebo-controlled crossover clinical study. Following pretreatment with TPA1%, DPH 1% or vehicle control creams, histamine challenge occurred via iontophoresis and a visual analog scale (VAS) for pruritus was used to determine extent of itch (AUC-VAS), peak itch, and duration of itch. Results: Compared to the vehicle control, TPA reduced histamine-induced extent of itch (AUC-VAS), peak itch, and itch duration by 59%, 38% and 43%, respectively (p<0.01 all). DPH did not significantly affect these responses and TPA was superior in reducing extent of itch (48% reduction, p<0.05) and duration (38% shorter, p<0.05). TPA, but not DPH, also reduced histamine induced flare and wheal responses (secondary endpoints) by 53% and 27%, respectively. The reduction in flare responses by TPA was superior to that of DPH (45% reduction, p<0.05). Conclusion: TPA significantly attenuated histamine-induced pruritus and urticaria in a human histamine-challenge model and demonstrated greater efficacy than DPH. These findings provide strong evidence of the antipruritic activity of topical TPA and support further clinical investigation of TPA as a treatment for histaminergic itch and related dermatologic conditions.

Brain development, especially developmental myelination, continues through young adulthood. Concordantly, children may be particularly vulnerable to neural-immune challenges. To investigate the consequences of major childhood immune challenges, juvenile mice were exposed to respiratory influenza (H1N1) infection. White matter-specific microglial reactivity accompanied by oligodendrocyte loss was evident until two months following infection. Mice exhibited hyperlocomotion and impaired attention, but not anxiety-like behavior, at one month following infection. Linking the oligodendroglial and behavioral deficits, genetic disruption of oligodendrocyte development at the same juvenile timepoint recapitulated this behavioral phenotype. Microglial reactivity and oligodendrocyte numbers normalized by young adulthood. However, myelin development was disrupted, with persistently decreased myelinated axon density and reduced myelin sheath thickness. Hyperlocomotion resolved, but anxiety-related behaviors emerged at two months after infection. At 6 months, anxiety resolved but cognitive deficits persisted. Elevated CSF chemokines and microglial chemokine expression prompted testing the role of the multi-chemokine receptor CCR3. CCR3 inhibition rescued these cellular and behavioral aberrations after juvenile H1N1 infection. Together, these findings underscore the potential for disruption of myelin development and lasting cognitive and neuropsychiatric sequelae following major immune challenges during the juvenile period and highlight chemokine signaling as an important therapeutic target.

Background: Pressure ulcers often develop complex three-dimensional morphologies that extend beyond the visible wound surface. Subsurface extensions such as tunneling and undermining create hidden cavities that complicate clinical assessment and wound management. Despite their clinical relevance, the prevalence and spatial characteristics of these subsurface wound morphologies have not been well characterized at scale. Methods: We performed a registry-based analysis using data from the LIFT-OFF Pressure Ulcer Registry, which captures longitudinal clinical documentation of pressure ulcers treated in routine care. The registry included approximately 18,000 patients with 32,000 documented pressure ulcers. Spatial characteristics of tunneling and undermining were analyzed using measurements recorded during routine wound assessments, including tract length, direction, and circumferential extent. Directional and circumferential distributions of subsurface defects were examined to characterize wound geometry. Results: Tunneling was present in 764 of 14,700 full-thickness pressure ulcers (5.2%), whereas undermining occurred in 2,293 wounds (15.6%). Tunneling tracts were typically short and exhibited directional clustering relative to the wound bed. In contrast, undermining demonstrated broader circumferential distributions and frequently involved larger subsurface separations beneath the wound margin. Both morphologies demonstrated distinct spatial patterns across anatomical locations and wound stages. Conclusion: Tunneling and undermining are common subsurface features of pressure ulcers and exhibit distinct spatial geometries. Whereas tunneling manifests as directional tract-like extensions, undermining more frequently produces circumferential tissue separation beneath wound margins. Improved characterization of subsurface wound architecture may enhance assessment of wound complexity and provide information not captured by surface measurements alone. Future studies should evaluate whether these features contribute to wound severity assessment, prognosis, and risk stratification.

Importance: Immune checkpoint inhibitors (ICIs) produce diverse immune toxicities, but whether checkpoint blockade also modifies associations between other drugs and adverse events is poorly understood. Objective: To define ICI-associated toxicity organization and determine whether drug-associated adverse events and onset vary with ICI exposure and checkpoint pathway. Design and Setting: Cross-sectional analysis of deduplicated FAERS reports from 2016 through 2025; analyses performed in 2026. Participants: Among 13,701,106 deduplicated reports, 2,365,269 were cancer associated and 256,940 contained an ICI. Median age among cancer reports with observed age was 66 years (IQR, 56-75 years); 1,031,999 (43.6%) were female and 1,003,154 (42.4%) were male. Exposures: ICI exposure in any reported drug role, individual primary-suspect drugs, and checkpoint-pathway exposure. Main Outcomes and Measures: Reporting odds ratios (ORs), cross-organ adverse-event communities, adjusted primary-suspect drug x ICI interaction ORs for Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalized exanthematous pustulosis (AGEP), interstitial nephritis, drug-induced liver injury (DILI), and vomiting (VOM), and accelerated failure-time model time ratios for documented onset. Results: Of 3001 eligible Preferred Terms in cancer-associated reports, 2091 differed at a false discovery rate (FDR) less than .05. Four cross-organ toxicity communities were identified. Of 138 eligible drug-phenotype pairs, 65 had FDR-significant interactions, including moxifloxacin-SJS/TEN amplification (interaction OR, 101.72; 95% CI, 39.11-264.55), enfortumab vedotin-SJS/TEN attenuation (interaction OR, 0.17; 95% CI, 0.13-0.23), and omeprazole-interstitial nephritis amplification (interaction OR, 10.35; 95% CI, 7.62-14.05). Among 60,324 reports contributing to temporal analyses, ICI exposure was associated with longer adjusted documented time to onset for 5 of 6 phenotypes (time ratios, 1.37-1.59) but not AGEP (time ratio, 0.99; 95% CI, 0.67-1.46). Temporal associations also differed across checkpoint pathways. Conclusions and Relevance: ICIs were associated with a structured cross-organ toxicity landscape, phenotype-specific modification of drug-associated adverse events, and distinct temporal patterns across checkpoint pathways. These findings support checkpoint blockade as a modifier of drug-associated toxicity and motivate longitudinal and mechanistic validation.

Genetic mitochondrial diseases (GMDs) are major challenges to human health accounting for a significant fraction of heritable neurologic diseases, myopathies, and inborn errors of metabolism. Leigh syndrome (LS) is the most common clinical presentation of GMD in pediatric patients. LS is a severe and complex disease for which effective clinical therapies are currently lacking. Preclinical therapies identified in the Ndufs4(-/-) mouse model of LS include immune-targeting interventions and chronic mild hypoxia (11% oxygen). Immune-targeting interventions include rapamycin and high-dose pexidartinib, the latter appearing to fully suppress disease. The mechanisms underlying the benefits of hypoxia remain unclear, and the relationship between hypoxia and immune interventions have not been assessed. Here, we report the immune profile of brainstem of the Ndufs4(-/-) mouse model prior to and after disease onset and the impact of pexidartinib treatment. We provide evidence that macrophages/monocytes drive pathology, consistent with recent genetic studies. We additionally find that pre-disease onset animals lack signs of inflammation, and that the elimination of leukocytes fully suppresses the molecular signature of disease. Finally, using distinct post-developmental periods of treatment, we find pexidartinib and rapamycin provide benefits which persist long beyond treatment cessation, while cessation of hypoxia results in rapid disease onset and an acceleration of disease progression. These findings are consistent with hypoxia acting upstream of immune cell activation and have major implications for the therapeutic translation of both hypoxia and immune targeting interventions. Our findings establish hypoxia-cessation as a novel method for synchronizing inflammatory disease onset in the Ndufs4(-/-) model which will be useful in future mechanistic studies.

Background Monogenic autoinflammatory disorders arise from genetic defects that pathologically activate innate immunity. IRAK4, a serine/threonine kinase in the Myddosome pathway, mediates IL 1 and Toll like receptor signaling, driving proinflammatory cytokine and type I interferon responses. While biallelic loss of function IRAK4 variants cause an immunodeficiency, recent reports implicate biallelic IRAK4 variants in severe neuro and systemic autoinflammation (NASA). We investigated a child with a similar phenotype and screened unsolved autoinflammatory leukoencephalopathies in the Myelin Disorders Biorepository Project (MDBP). Methods Individuals with unexplained autoinflammatory leukoencephalopathy and no unifying molecular diagnosis were identified in the Myelin Disorders Biorepository Project (MDBP), and genome sequencing was reanalyzed to prioritize rare, protein altering and splice affecting variants. Candidate variants and their splicing consequences were interrogated with short read and targeted long read RNA sequencing, benchmarked against control PBMC and normal tissue transcriptomes. Nonsense mediated decay of transcripts was also assessed. Clinical, genetic, and treatment data were extracted by standardized deep phenotyping, and brain MRI was reviewed in consensus by two pediatric neuroradiologists. Results We identified six patients from five unrelated families with biallelic, rare IRAK4 variants presenting with severe, persistent autoinflammation without immunodeficiency. Variants included two homozygous and three compound heterozygous changes. All patients had a concordant clinical and radiologic syndrome: episodic, waxing and waning encephalopathy with refractory seizures; neuroimaging showed transient white matter edema that evolved to gliosis, superimposed on marked calcifications and ensuing cerebral atrophy. Biomarkers indicated neuroinflammation and anemia in all cases. Median age at neurologic symptom onset was 12.96 years (IQR 9.44). Immune suppressive therapies achieved partial benefit, but most patients had ongoing seizures, persistent neuroinflammation, and progressive disease, and without treatment, loss of life. Conclusion In these six patients, a strongly concordant clinical and radiological phenotype emerges of IRAK4-mediated autoinflammation, expanding the phenotypic and mutational spectrum of IRAK4 related disease. Further studies are needed to define mechanisms and optimal treatments.

Although the brain was traditionally considered immune-privileged, recent studies show immune factors play key roles in brain function. Dysfunction of these factors is linked to neurodevelopmental disorders, but mechanisms remain unclear. Using a maternal immune activation (MIA) mouse model, we investigated immune-related genes in neurodevelopmental disorder pathogenesis. MIA mice showed increased locomotor activity and disrupted prepulse inhibition. RNA-seq and qPCR analyses revealed persistent increases in major histocompatibility complex class II (MHCII) expression and persistent decreases in GABAergic synapse-related gene expression, particularly glutamate decarboxylase (Gad) expression, in dopaminergic regions. These expressions were negatively correlated, and immunohistochemistry showed MHCII at postsynaptic GABAergic synapses on dopaminergic neurons. Patch-clamp recordings confirmed reduced mIPSC frequency in MIA mice. MHCII knockout mice showed opposite phenotypes, while MHCII overexpression in dopaminergic neurons decreased Gad expression. These results suggest MIA-induced MHCII upregulation enhances pruning of GABAergic synapses on dopaminergic neurons, leading to behavioral deficits.

Autosomal dominant retinitis pigmentosa (adRP) caused by RHO mutations is a leading form of inherited retinal degeneration. Extensive allelic heterogeneity of RHO pathogenic variants limits the translational applicability of mutation-specific gene therapies. To address this, we developed SNARE (SNP-guided Silencing of Aberrant RHO Expression), a mutation-independent, allele-specific antisense oligonucleotide (ASO) strategy. SNARE selectively suppresses mutant RHO transcripts by targeting the common, benign c.-26A/G single-nucleotide polymorphism (SNP) as an allelic discriminator. Candidate gapmer ASOs were screened in engineered reporter lines and validated in patient-derived retinal organoids, identifying RHOligo-A as the lead c.-26A-targeting candidate. In vitro, RHOligo-A achieved robust, preferential knockdown of the target allele, improving RHO localization in retinal organoids, and demonstrated a favorable safety profile with minimal transcriptomic off-target effects and no detectable immunostimulatory activity. Subsequent validation in a novel, humanized RHOP347L/WT mouse model, achieved sustained c.-26A-linked allele-selective suppression, retinal structure preservation, and significantly restored visual function, upon a single intravitreal administration. These findings establish RHOligo-A and SNARE as a scalable, mutation-independent therapeutic platform with strong translational potential and substantial clinical reach for RHO-associated adRP.

The blood-gonadal barrier protects the germline from parental exposures. A phenomenon known as intergenerational inheritance suggests that, exceptionally, this barrier can be surpassed with consequences for the subsequent generation. Specific diet regimes and early traumatic experiences have been among the chronic stressors shown to be able to lead to intergenerational inheritance in mammals. Less is known about how acute stress can affect the germline. Cardiac damage leads to several alterations in peripheral organs and, overall, affects blood flow, metabolism, and the immune response. Whether cardiac damage can also affect the reproductive system is not known and might offer new insights into the potential inheritance of cardiovascular disease. Here, we used zebrafish and mouse models to explore the intergenerational role of cardiac damage and repair. In the first week after a cardiac cryolesion, male zebrafish gonads and gametes activated responses associated with inflammation. In sperm, chromatin accessibility was found altered in response to cardiac cryolesion. Offspring of cryoinjured zebrafish males revealed changes in cardiac function and cardiac gene expression. Induction of systemic sterile inflammation in the paternal generation mimicked cardiac injury effects in the following generation, while anti-inflammatory treatments in the injured paternal generation partially recovered F1 cardiac features. Similar features were found in mouse testis after a neonatal injury, and in the hearts of their offspring, suggesting a conserved role of sterile inflammation as a vector for intergenerational transmission of cardiac injury.

Autosomal dominant gain-of-function mutations in platelet-derived growth factor receptor beta (PDGFRb) cause overgrowth of the skeleton and other connective tissue in Kosaki overgrowth syndrome. However, the target cell type and signaling pathways underlying PDGFRb-driven overgrowth are unknown. Normal postnatal growth is controlled by pituitary-secreted growth hormone (GH), which activates the STAT5 transcriptional factor to upregulate insulin-like growth factor 1 (IGF1). To investigate the role of the GH-STAT5-IGF1 pathway in PDGFRb-related overgrowth, we generated mice with a PDGFRb gain-of-function mutation in skeletal and fibroblast lineages, which resulted in STAT5 activation and gigantism. Conditional deletion of Stat5ab in connective tissue lineages rescued skeletal overgrowth and keloid-like fibrosis in the skin. Conditional deletion of GH receptor (Ghr) did not rescue overgrowth, indicating the physiological activator of STAT5 is not required for overgrowth. However, deletion of Igf1, the STAT5 target gene, and its receptor, Igf1r, in connective tissue, rescued the overgrowth phenotype. These findings demonstrate a GHR-independent STAT5-IGF1 signaling pathway in mutant connective tissue cells, which mediates PDGFRb-driven overgrowth in mice and potentially in humans with similar PDGFRB mutations.

Migraine is a leading cause of disability, yet preventive treatment remains largely empirical despite the availability of several mechanistically distinct therapies. Genetic data can clarify mechanisms and therapeutic hypotheses when association signals are integrated with molecular and clinical data. We meta-analyzed migraine GWAS data from 12 European ancestry cohorts (206,893 cases and 2,093,175 controls) and four African ancestry cohorts (22,115 cases and 178,626 controls). We identified 311 lead variants in European-ancestry analyses and 316 lead variants in trans-ancestry analysis. Fine-mapping and transcriptome-wide analyses prioritized variants and genes implicated in sensory neuronal signaling, vascular tone, and immune regulation, with convergent evidence at several established loci including TRPM8 and PHACTR1. Drug-repurposing analyses identified therapeutic targets and compounds, including established migraine treatments and candidates requiring experimental validation. Genetic correlations, Mendelian randomization, and a phenome-wide scan linked migraine liability to psychiatric, pain, and gastrointestinal phenotypes. Together, these findings expand the known genetic architecture of migraine across ancestries and provide a genetics-led map connecting association signals with biological pathways, multimorbidity and candidate therapeutic mechanisms, providing a foundation for future functional and translational studies.

Controversy surrounds the lineage potential of cardiac cells, particularly epicardial cells, during heart development, largely due to the non-specific expression of epicardial marker genes and the resulting non-specific labeling in Cre-loxP mouse models. Using DARLIN mice, a CRISPR/Cas9-based lineage-tracing system independent of the Cre-loxP system, we analyzed the lineage development of embryonic cardiac cells in an unbiased manner and identified lineages shared among different cell types, such as epicardial cells and vascular endothelial cells (Vas_ECs). To further confirm the lineage potential of epicardial cells, we identified an epicardial cell-specific marker gene, Lrrn4, through analysis of a multi-staged single-cell mRNA-sequencing (scRNA-seq) dataset, and generated a corresponding Lrrn4-CreER mouse line. We then bred this line with a reporter mouse to confirm its specificity for labeling epicardial cells, and subsequently performed prolonged lineage tracing, which revealed specification of the labeled epicardial cells into Vas_ECs. Finally, Using this mouse line, we investigated epicardial cell function by selectively ablating these cells and by expressing TGF{beta} in epicardial cells to convert their lineage from Vas_ECs to fibroblasts. Both approaches resulted in significant developmental defects in embryonic hearts. Together, these results indicate that epicardial cells can give rise to Vas_ECs, and that the Lrrn4-CreER mouse model is a valuable tool for elucidating the role of the epicardium in heart development.

Spinal muscular atrophy (SMA) is caused by a deficiency in the survival motor neuron (SMN) protein, resulting in degeneration of spinal motor neurons (MNs). However, persistent neurological deficits despite postnatal SMN-restoring therapies suggest that recovery of sensorimotor and supraspinal circuits may be incomplete. The cerebellum has recently emerged as a supraspinal contributor to motor deficits in the severe SMN{Delta}7 mouse model, yet it remains unclear whether cerebellar pathology is a conserved and therapeutically reversible feature across severe SMA mouse models and clinical subtypes. Here, we identify cerebellar pathology in Taiwanese SMA mice, characterized by hypoplasia, disrupted organization and loss of Purkinje cells (PCs), altered synaptic circuitry, and impaired cerebellar cortical output. Unlike the previously described p53-dependent PC degeneration in SMN{Delta}7 mice, cerebellar pathology in Taiwanese SMA mice was associated with developmental disorganization and external granule layer (EGL)-restricted p53 activation. Human cerebellar tissue mirrored this distinction, with p53 activation found in PCs from SMA Type I and in the EGL from SMA Type 0 individuals, indicating that cerebellar pathology arises through distinct mechanisms across severe forms of SMA. Importantly, two SMN-restoring strategies produced divergent therapeutic outcomes. In SMN{Delta}7 mice, AAV9-SMN prevented PC degeneration yet incompletely restored cerebellar circuitry. AAV9-SMN-treated Taiwanese mice developed severe ataxia-like deficits, retained profound cerebellar pathology, and survived to approximately one month of age. In contrast, systemic risdiplam rescued cerebellar pathology, motor behavior, and survival in both models. Together, these findings identify cerebellar pathology as a conserved yet distinct feature across severe forms of SMA and reveal cell type-specific tropism as a critical determinant of therapeutic outcome. More broadly, these findings suggest that successful recovery requires restoration of distributed supraspinal circuit integrity in addition to rescue of spinal motor pathways.

Background: The His-Purkinje network drives rapid ventricular activation and is a major substrate for ventricular arrhythmias, yet it is among the least molecularly characterized cardiac compartments. Markers validated in rodents transfer poorly across species, few are confirmed at the protein level in large mammals or humans, and most lack the stability and surface accessibility that demanding applications require. Methods: We combined histology-guided laser-capture microdissection with low-input, cell-type-resolved RNA-sequencing to profile Purkinje fibers, left-ventricular cardiomyocytes and peri-Purkinje stroma from adult sheep. Differentially expressed genes were ranked by a transparent composite framework weighting expression specificity, cross-individual stability and predicted subcellular accessibility; leading candidates were validated by RT-qPCR and immunolabelling in sheep and by RT-qPCR in human myocardium. Results: RNA-sequencing resolved a Purkinje transcriptome distinct from cardiomyocytes and stroma and defined 331 concordantly enriched genes, which the composite framework ranked into stable, specific candidates spanning intracellular and cell-surface compartments. By RT-qPCR, the canonical conduction markers connexin-40/GJA5, HCN4, NEFM and MYL4 were strongly enriched in Purkinje fibers, whereas the rodent gold-standard contactin-2 was not, underscoring species divergence. Thirteen of sixteen prioritized candidates were confirmed by RT-qPCR, and immunolabelling localized MYL4, CNN1, TAGLN and DKK3 to Purkinje fibers; contactin-5 emerged as a novel transcript- and protein-validated Purkinje marker. In human myocardium, a defined subset - MYL4, connexin-40/GJA5, contactin-5 and TAGLN - was conserved, while several markers proved species-restricted. Conclusions: We provide the first genome-wide, cell-type-resolved molecular portrait of the Purkinje fiber in a large-animal model and a generalizable strategy that selects markers for specificity, stability and accessibility. The resulting resource - including the cross-species marker contactin-5 and compartment-matched candidates - supplies validated tools to identify, isolate and target Purkinje cells and demonstrates the necessity of cross-species validation.

Ulcerative colitis (UC) and radiation enteropathy involve intestinal epithelial injury, barrier dysfunction, and inflammation, but effective treatments remain limited. This study evaluated MXC-017, a novel vimentin-targeting urea compound, in mouse models of dextran sulfate sodium (DSS)-induced colitis and radiation-induced enteropathy. Acute colitis was induced in C57BL/6 mice using 3.5% DSS for seven days, followed by regular water for seven days. Radiation enteropathy was induced by 13 Gy total abdominal irradiation. Mice received MXC-017 (150 mg/kg) or vehicle. Disease activity, intestinal permeability, inflammatory and epithelial markers, and histopathology were assessed. MXC-017's effects on cancer stem cell frequency, sphere formation, and migration were also examined in PC-3 and DU-145 prostate cancer cells. MXC-017 reduced DSS-induced colitis severity, accelerated weight recovery, lowered disease activity, partially preserved colon length, and restored barrier function. It also reduced proinflammatory cytokines, macrophage infiltration, epithelial injury, and goblet cell loss while preserving epithelial proliferation and markers of intestinal stem cell function and tight-junction integrity. Following irradiation, MXC-017 improved weight recovery, reduced intestinal permeability, preserved epithelial architecture, and partially mitigated villus shortening. Importantly, MXC-017 did not protect prostate cancer stem cells from radiation. Instead, it reduced stem cell frequency, sphere-forming capacity, and cancer cell migration. These findings support vimentin targeting with MXC-017 as a potential treatment for UC and radiation-induced intestinal toxicity and as an adjunct to radiotherapy for pelvic and abdominal malignancies.

Bi-allelic variants of RNU4ATAC, transcribed into the minor spliceosome component U4atac snRNA, are associated to variable severity of microcephaly, growth retardation, skeletal dysplasia and immunodeficiency as main features. Previous studies highlighted the dramatic effect of U4atac deficiency on splicing of U12-type introns, which represent less than 1% of all introns in the human genome. More recently, our team evidenced a link between U4atac and the primary cilium/centrosome complex through the identification of patients carrying RNU4ATAC bi-allelic variants and exhibiting an atypical Joubert syndrome, a well-known ciliopathy. Yet, the underlying mechanisms remain elusive. Here, we further explored the link of RNU4ATAC to primary cilium and aimed at identifying ciliary U12-type intron containing genes that contribute to the brain abnormalities seen in patients. For that, we performed a transcriptomic analysis of heads of our morpholino oligonucleotide (MO)-mediated u4atac zebrafish model. Through the combined analysis of the generated dataset with those obtained from RNU4ATAC patient cells, we identified two candidate genes: TMEM107, coding for a structural protein of the cilium transition zone, and RFX7, encoding a transcription factor involved in primary cilium formation. By conducting complementary genetic approaches in zebrafish model, we showed that both gene orthologues, tmem107l and rfx7b, functionally interact with u4atac and are required for correct brain development. Altogether, our findings establish TMEM107 and RFX7 as key components of the molecular pathway linking U4atac dysfunction to ciliary defects and impaired brain development, providing new physiopathological insights and therapeutic perspectives for RNU4ATAC-related disorders.

Hirschsprung disease (HSCR) is a severe birth defect where ganglia of the enteric nervous system (ENS) are missing from distal bowel. The aganglionic segment is also characterized by increased epithelial permeability and pro-inflammatory immune activation. These problems may sequentially lead to translocation of gut microbes into the colon wall and systemic circulation, resulting in enterocolitis and sepsis. Current HSCR treatment via surgical resection of the aganglionic segment is lifesaving but not curative, often leaving patients with persistent gastrointestinal complications including recurrent risk of enterocolitis. As alternative, we are developing a regenerative medicine strategy based on in situ stimulation of tissue-resident ENS progenitors via rectal administration of the neurotrophic factor GDNF. Here, we report that GDNF-based therapy has pleiotropic gastrointestinal effects in a mouse model of short-segment HSCR, beyond its role in ENS regeneration. Interestingly, we found that these protective effects are not restricted to the aganglionic distal colon, also positively impacting the ENS-containing proximal colon. GDNF treatment reduces bacterial translocation both locally and in peripheral organs, and this is associated with recovery of the key epithelial junction proteins CLDN3, ZO1 and DSG2. Furthermore, multiparameter flow cytometry-based analysis of 55 lymphoid and 17 myeloid cell subtypes revealed that GDNF treatment has global anti-inflammatory effects, preferentially affecting innate over adaptive immunity. Overall, these findings highlight a critical role for GDNF treatment in reestablishing proper epithelial and immune cell homeostasis, offering promising therapeutic avenues not only for HSCR but also potentially for other intestinal disorders with overlapping pathophysiology.

Chromaffin cells synthesize and secrete catecholamines to coordinate systemic stress responses and regulate diverse neuroendocrine and metabolic functions. However, the molecular mechanisms governing chromaffin-cell differentiation and their disruption in pheochromocytoma (PC) remain incompletely understood. Here, through integrated analyses of human developmental atlases, patient-derived transcriptomic datasets, genetically engineered mouse models, and chromaffin organoids, we identify TEAD1 signaling as a critical regulator of chromaffin-cell differentiation and function. In vivo studies using a chromaffin cell-specific TEAD1 overexpression mouse model demonstrated that suppression of TEAD signaling markedly compromises chromaffin-cell differentiation and endocrine function. Additionally, compared with other TEAD family members, TEAD1 transcriptional activities are readily affected by sequences near the binding motif. To identify therapeutically actionable regulators of TEAD1 signaling, we established a TEAD activity-based screening platform and identified the serotonin receptor HTR5A antagonist SB699551 as a potent modulator of chromaffin-cell state. SB699551 suppressed PC-cell proliferation in vivo, and remodeled catecholamines synthesis in primary human PC cells. Additionally, application of SB699551 to human PC tumor revealed a subpopulation of primary chromaffin cells sensitive to this compound. Mechanistically, CXXC5 and L1CAM were identified as downstream SB699551-TEAD1 signaling effectors mediating chromaffin-cell proliferation and differentiation. Overall, we demonstrate that TEAD1 signaling is a fundamental mechanism regulating chromaffin cell differentiation and that modulation of TEAD1 signaling via SB699551 offers a new area of investigation in chromaffin cell biology.

We established a human taste bud organoid system derived from circumvallate papillae. This model has been highly anticipated in the field of taste research, where feasible approaches for validating taste biology discovered in rodent models have been limited. Through a stepwise exploratory strategy, we systematically identified and optimized the niche factors required to maintain taste bud organoids and promote their differentiation. This human taste bud organoid system comprises Type I-IV taste receptor cells (TRCs) as well as stem/progenitor cells, and its sensory receptor cells exhibit calcium responses to taste stimuli. Using this system, we identified robust Wnt signaling as a requirement for optimal TRC fate progression, uncovered a human-specific transcriptional program in LGR5 cells, and identified previously unrecognized molecular markers for Type I TRCs. By recapitulating native human taste bud cell diversity and function, this organoid provides a tractable platform for studying human taste biology and dysfunction.