Biology subjects

Sharma, N.

Publications and source records attributed to Sharma, N..

At least 19 recordsLinked to original sources

bioRxiv2026

Development of CYP8B1-specific inhibitors for metabolic diseases

Changes in bile acids (BAs) balance lead to various metabolic diseases, yet current treatment options targeting these changes remain severely limited. CYP8B1 (cytochrome P450, family 8, subfamily B, polypeptide 1) is a liver-exclusive enzyme that controls the synthesis of 12-hydroxylated (12-OH) BAs. Inhibiting CYP8B1 is an attractive therapeutic strategy for attenuating 12-OH BA levels, remodeling the gut microbiota and thereby ameliorating metabolic diseases. CYP8B1-specific inhibitors are currently lacking due to structural similarities between the active site of CYP8B1 and other CYPs, and the lack of suitable high-throughput screening (HTS) assays. Herein, we developed a highly sensitive, and specific enzyme-coupled fluorescence assay to detect CYP8B1 activity, making it ideal for HTS. Employing this assay, structure-based drug design by protein X-ray crystallography, structure-activity relationship (SAR) analyses, and in vitro and in vivo validation, we developed novel CYP8B1-specific small molecule inhibitors. The lead candidate alters BA composition, favorably remodels the gut microbiota, and corrects metabolic disease in a metabolic dysfunction-associated steatotic liver disease (MASLD) mouse model. These findings reveal that pharmacologically inhibiting CYP8B1 is able to reshape the BA and gut microbiota profiles and effectively ameliorates metabolic diseases. Overall, CYP8B1-specific inhibitors represent a first-in-class promising, safe and effective therapeutic strategy against metabolic disorders.

pharmacology and toxicology↗

bioRxiv2026

Sphingosine-1-Phosphate Restrains Foamy Macrophage Formation and Modulates Inflammation in Multidrug-Resistant Tuberculosis

The high abundance of lipid loaded foamy macrophages in the granulomatous lesions is a key hallmark of advanced pulmonary tuberculosis. These macrophages serve as lipid-rich intracellular hiding niches that provides Mycobacterium tuberculosis (M.tb) survival and persistence during prolonged anti-tubercular treatment. Persistent infection and dysregulated inflammatory responses further complicate disease control, particularly in multidrug-resistant tuberculosis (MDR-TB), highlighting the need for host-directed therapeutic strategies. Our previous preclinical study demonstrated the therapeutic potential of the host sphingolipid sphingosine-1-phosphate (S1P) in reducing the mycobacterial burden in M.tb-infected animals, accompanied by enhanced pulmonary macrophage activation. To explore its translational potential, we investigated whether S1P modulates foamy macrophage formation in CD14 monocyte-derived macrophages from healthy donors and patients with MDR-TB. Notably, macrophages derived from patients with MDR-TB exhibited greater intracellular lipid droplet accumulation than those derived from healthy donors. This phenotype was further characterized by increased nitric oxide production and quantitative RT-PCR analysis of genes associated with immune regulation and lipid metabolism, including APOE, LDLR1, CLEC4E, CLEC7A, GP96, IL4, and IL13, which suggested a Th2-associated immunological bias in foamy macrophages. Collectively, these findings highlight the potential role of host sphingolipids in modulating foamy macrophage phenotypes and associated immunometabolic dysregulation, supporting further investigation of S1P as a host-directed therapeutic strategy against MDR-TB.

immunology↗

bioRxiv2026

RNA-dependent association of the pyruvate dehydrogenase complex with mtDNA-containing assemblies supports mitochondrial translation

Mitochondrial DNA (mtDNA) encodes core subunits of the oxidative phosphorylation machinery, and its expression is spatially organized, with the genome packaged into nucleoids around which transcription and mitoribosome assembly are concentrated. How this architecture is built, and how it is linked to the metabolic state of the organelle, remains poorly understood. Here we show that the pyruvate dehydrogenase complex (PDHc), which supplies acetyl-CoA to the tricarboxylic acid cycle, is a component of this machinery in Saccharomyces cerevisiae. PDHc co-purifies with mtDNA and resides in high-molecular-weight assemblies whose integrity requires RNA rather than DNA, and proximity labeling places it selectively adjacent to the mitoribosome. The E1 subunit Pda1 concentrates into discrete foci that depend on mtDNA and disperse reversibly upon inhibition of mitochondrial translation. Loss of Pda1, Pdb1 or Lat1, but not of the E3-binding protein Pdx1, compromises the maintenance of mtDNA; deletion of PDA1, PDB1 or LAT1 also reduces output from a mitochondrially encoded reporter, and PDHc-deficient cells are hypersensitive to translational inhibition. Catalytically inactive Pda1 and Lat1 variants rescue both defects as effectively as the wild-type proteins, demonstrating a function genetically separable from acetyl-CoA synthesis. PDHc therefore acts as a non-catalytic component of the RNA-dependent architecture that supports mitochondrial gene expression.

cell biology↗

bioRxiv2026

Confocal and Transmission electron microscopy imaging of Orientia tsutsugamushi

Scrub typhus, caused by Orientia tsutsugamushi, is an obligate intracellular gram-negative pathogen that remains a cause of acute febrile illness in India. Culture isolation of Orientia tsutsugamushi clinical isolates is infrequent because it is technically more challenging than PCR-based molecular identification. In this report, we describe the culture isolation of Orientia from the whole blood of a 64-year-old farmer with acute febrile illness. Whole blood was inoculated onto an 80% confluent L929 cell line. Real-time PCR targeting the 47-kDa and 56-kDa genes, combined with Sanger sequencing, confirmed the isolate. Transmission electron microscopy of infected L929 cells revealed multiple oval-shaped bacteria within the host cytoplasm. Confocal microscopy demonstrated progressive accumulation of CFSE-labelled bacteria within infected cells over time. These findings support the successful isolation and visualization of a blood-derived O. tsutsugamushi isolate and provide a platform for downstream assays of host-pathogen interactions, antimicrobial susceptibility testing, and vaccine development.

microbiology↗

bioRxiv2026

L-Serine potentiates the efficacy of Isoniazid, and Rifampicin as host-directed adjunctive treatment for Mycobacterium tuberculosis.

Host-directed therapies (HDTs) have acquired paramount importance for management of tuberculosis (TB). L-Serine is an important metabolite and immunomodulatory biomolecule with promising role in managing infections, and autoimmune diseases. However, the role of L-Serine as host directed therapeutic against Mycobacterium tuberculosis (M.tb) remains unexplored. Therefore, we adopted de novo-based approach and employed L-Serine and palmitoyl CoA precursors for enhancing sphingolipid in host and accessed their anti-tubercular potential. In this study, we investigated whether L-Serine could modulate the antibiotics efficacy against M.tb. L-Serine particularly in combination with palmitic acid, rifampicin and isoniazid showed enhanced intracellular bacterial clearance in a dose- and time-dependent manner in murine and human macrophages. This synergistic effect was accompanied by increased nitric oxide production and modulation of the host immune response. We identified elevated levels of pro-inflammatory cytokine TNF- and reduced anti-inflammatory IL-10 expression. Furthermore, L-Serine supplementation demonstrated antimicrobial activity in isolated primary CD14 monocytes from TB patients. Similarly, the metabolic supplementation of L-Serine in combination with isoniazid, rifampicin, and palmitic acid significantly reduced bacterial burden in the lungs and spleen, while improving tissue architecture in murine infection model. Our observations suggest that L-Serine and palmitic acid in combination with isoniazid and rifampicin contributes to the observed therapeutic effects. Collectively, this study concludes that L-Serine and palmitic acid acts as a promising host-directed therapeutic adjunct, which enhances antimicrobial immunity and potentiating antibiotic efficacy, providing a potential strategy for improving tuberculosis treatment outcomes.

microbiology↗

bioRxiv2026

Identification of a new mycobacterial peptide that controls the activity of the iron-dependent regulator, IdeR.

Mycobacterium tuberculosis (Mtb) must regulate intracellular iron to survive in the host and cause disease. IdeR (Iron-dependent Regulator) is an essential Mtb protein that governs intracellular iron levels by regulating the expression of genes involved in iron metabolism. IdeR expression, however, is iron independent, and the mechanisms that regulate IdeRs function are not fully understood. Here, we report the discovery of a previously unrecognized Mtb peptide (PRI) that regulates IdeR activity. PRI is induced under iron limitation; it binds to IdeR and restricts its activity. In addition, we demonstrate that altering the balance between PRI and IdeR impairs iron homeostasis and intracellular replication of Mtb in macrophages. The findings reveal a new paradigm in mycobacterial iron regulation and open new avenues for targeting iron homeostatic mechanisms in Mtb, which are crucial for virulence and antibiotic resistance.

microbiology↗

bioRxiv2026

Single-cell analysis of an adult IBD INCEPTION cohort reveals Galectin-linked disease mechanisms

Background and AimsThe molecular pathogenesis of Inflammatory Bowel Disease (IBD) remains unclear. We aimed to establish a high-resolution immune landscape of treatment-naive IBD to identify central drivers of disease onset and early pathogenic signalling. MethodsWe generated a single-cell atlas using intestinal biopsies from a large adult inception cohort of 137 individuals, including treatment-naive Crohns disease (CD), ulcerative colitis (UC), and symptomatic non-IBD controls. We integrated scRNA-seq (1 million cells) with co-varying neighbourhood analysis (CNA) and unbiased tensor decomposition of cell-cell communication (CCC) networks. Findings were validated in vitro macrophage stimulation model and using serum from patients. ResultsThe inception cohort exhibited significantly more homogenous compartmental diversity compared to benchmark reference studies (p < 0.001). Inflammation in both CD and UC was characterized by a marked expansion of inflammatory monocytes. Unbiased CCC analysis identified a dominant disease-specific signalling module centred on the Galectin family (LGALS1 and LGALS9). Galectin-9 expression was specifically enriched in inflammatory monocytes, which exhibited distinct transcriptional programs linked to antigen presentation and microbial sensing. In vitro, Galectin-9 acted as a potent stimulus, driving macrophages toward a pro-inflammatory phenotype. Clinically, serum Galectin-9 levels were significantly elevated in IBD patients and correlated with systemic inflammatory markers and treatment response. ConclusionsOur data identify a galectin-monocyte signalling axis as a unifying inflammatory hallmark of early IBD. Galectin-9 serves as both a functional driver of mucosal inflammation and a dynamic biomarker, offering new opportunities for therapeutic targeting and disease monitoring from diagnosis.

immunology↗

bioRxiv2026

SERCA2b loss of function drives pigmentation by inducing adaptive ER stress and enhancing mitochondrial calcium uptake: significance in pathological hyperpigmentation associated with Darier’s Disease

Pigmentation is a critical protective mechanism that safeguards the skin against UV-induced damage, whereas dysregulated pigmentation predisposes to pigmentary disorders and skin malignancies. Although calcium signaling has emerged as an important regulator of melanogenesis, the identity of the calcium-handling proteins and the molecular mechanisms linking calcium dynamics to pigmentation remain poorly understood. Here, we identify the ER calcium pump SERCA2b as a negative regulator of pigmentation through modulation of ER stress and mitochondrial calcium uptake. We demonstrate that SERCA2b expression inversely correlates with pigmentation levels, and gain- and loss-of-function studies establish SERCA2b as a suppressor of melanogenesis. Mechanistically, SERCA2b depletion induces adaptive ER stress, enhances ER-mitochondrial proximity, and promotes mitochondrial calcium uptake. Notably, mutations in SERCA2b are associated with Darier disease, a condition characterized by hyperpigmented skin lesions, although the underlying mechanism remains unknown. To address this, we generated SERCA2b mutants corresponding to variants identified in Indian Dariers disease patients and examined their effects on pigmentation, ER stress, and mitochondrial calcium dynamics. The mutant phenotypes closely recapitulated SERCA2b loss-of-function effects, demonstrating that adaptive ER stress and enhanced mitochondrial calcium signaling underlie hyperpigmentation associated with Dariers disease. Importantly, treatment with 4-phenylbutyrate (4-PBA), an FDA-approved ER stress alleviator, rescued mutant-induced hyperpigmentation, reduced ER stress, and normalized mitochondrial calcium uptake. Collectively, our findings uncover a previously unrecognized role of SERCA2b in skin pigmentation, establish a mechanistic link between SERCA2b mutations and hyperpigmentation, and identify adaptive ER stress pathways as potential therapeutic target for pigmentary disorders.

Cell Biology↗

bioRxiv2026

Exploring the Structural and Functional role of α,β-unsaturated Ketoesters as Anti-Staphylococcal Agents Targeting Glutathione Peroxidase

Multiple-drug resistant (MDR) Staphylococcus aureus strains (like methicillin-resistant S. aureus or MRSA) uses an arsenal of antioxidant enzymes to mitigate host-induced oxidative stress. Among them the non-canonical Staphylococcal glutathione peroxidase (SaGpx) plays a crucial role in bacterial redox homeostasis by reducing peroxides via thioredoxin-dependent pathways. Thus, enabling oxidative stress mitigation during host infection. Despite its importance in S. aureus, its role in bacterial pathogenesis remains unexplored. This study aimed to elucidate the possible role of SaGpx in Staphylococcal virulence. First, we determined the high-resolution crystal structure of SaGpx (at 1.65 [A] resolution) using X-ray crystallography. Guided by the catalytic cleft architecture of SaGpx, small-molecule based inhibitors were then rationally designed and synthesized. These inhibitors exhibited good binding affinity to SaGpx and complete enzymatic blockade. These inhibitors exhibited potent anti-S. aureus activity (MICs 6.25-31.25 M) along with no cytotoxicity in L929 fibroblast wound-healing assays. Furthermore, the in vivo antibacterial ability of these inhibitors was evaluated using S. aureus-infected skin wound mouse model, where these compounds show potent antibacterial and wound healing ability supported by subsequent histological as well as immunohistochemical analysis. These findings suggest SaGpx as a possible virulence determinant in S. aureus and position these synthesized inhibitors as promising antivirulence therapeutics. HighlightsO_LIThe high-resolution crystal structure of Staphylococcal glutathione peroxidase is solved. C_LIO_LIBased on the SaGpx catalytic site, ,{beta}-unsaturated ketoesters derivatives are synthesized. C_LIO_LISynthesized ,{beta}-unsaturated ketoesters derivatives inhibit SaGpx activity and binds the protein at M range. C_LIO_LISynthesized ,{beta}-unsaturated ketoesters derivatives show in vitro antibacterial activity against S. aureus at low M range. C_LIO_LISynthesized ,{beta}-unsaturated ketoesters derivatives show in vivo antibacterial and wound healing ability S. aureus-infected skin wound mouse model. C_LI

biophysics↗

bioRxiv2026

CFTR function in nasal airway cells from symptomatic and asymptomatic CF heterozygotes

Structured AbstractO_ST_ABSRationaleC_ST_ABSAn estimated 25 million people worldwide have one deleterious variant in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Chronic respiratory disease symptoms are at an increased prevalence in cystic fibrosis (CF) heterozygotes. ObjectivesDetermine the level of CFTR function in CF heterozygotes compared to individuals without CF-causing variants. Establish whether CFTR function differs between asymptomatic and symptomatic CF heterozygotes. MethodsIndividuals without respiratory symptoms or CF family history were recruited as controls. Heterozygotes were recruited from families with a CF individual harboring null alleles or c.1521_1523del (F508del) in CFTR. CFTR function was measured by short circuit current in primary human nasal epithelial cells (HNEs) from participants. Cell composition was assessed by single cell RNA sequencing. Measurements and Main ResultsCFTR function was variable in cells from control and heterozygous individuals. Mean CFTR function in asymptomatic null (8.8{+/-}0.5{micro}A/cm2 (SEM); n=30) and F508del (8.7{+/-}1.0{micro}A/cm2; n=22) heterozygotes was similar and significantly lower at 54.6% and 53.9% than controls (16.1{+/-}1.1{micro}A/cm2; n=24; p<0.0001). Mean CFTR function in symptomatic heterozygotes (8.4{+/-}1.0{micro}A/cm2; n =15) was 52.1% of controls and did not differ from asymptomatic heterozygotes (p=0.7803). Cell identities and proportions were equivalent between control and heterozygous cultures. HNEs from CF heterozygotes showed variable response to CFTR modulators. ConclusionsCFTR function in primary airway cells exhibits substantial interindividual variability and overlaps between controls and CF heterozygotes. CF heterozygotes exhibit approximately 50% of CFTR function in controls, regardless of symptom status. These findings suggest that respiratory symptoms in CF heterozygotes are influenced by factors beyond CFTR dysfunction. At a Glance CommentaryO_ST_ABSScientific Knowledge on the SubjectC_ST_ABSA growing body of evidence indicates that cystic fibrosis (CF) heterozygotes are at increased risk for a range of common and chronic respiratory diseases. Given that an estimated 10 million individuals in the United States are CF heterozygotes, this population may represent a substantial and underappreciated burden of CFTR-associated disease. However, CFTR function has not been well characterized in CF heterozygotes, and it remains uncertain whether observed clinical phenotypes reflect reduced CFTR activity. Resolving these issues will be essential for clarifying the pathobiology of common respiratory diseases and for evaluating the potential role of CFTR modulator therapy in symptomatic CF heterozygotes. What This Study Adds to the FieldAnalysis of 24 controls and 67 CF heterozygotes revealed substantial interindividual variability in CFTR function, as measured ex vivo in differentiated nasal airway epithelial cells. Mean CFTR function in CF heterozygotes was approximately 50% of that observed in controls. CFTR function did not differ significantly between symptomatic and asymptomatic heterozygotes. These findings suggest that reduced CFTR activity may contribute to symptom susceptibility in CF heterozygotes, but additional factors beyond CFTR dysfunction are likely required for the development of CF-like features. Ethical approval and participant consent statementAll participants provided written consent to the research study under IRB00116966 and/or IRB00235883 and consented to have their anonymized data published. All research was conducted in a fair and ethical manner.

genetics↗

bioRxiv2026

Clinical and primary cell evidence reveals complex CFTR function-phenotype relationships

RationaleThe CFTR function-phenotype relationship remains incompletely understood, with prior work yielding heterogeneous findings suggesting linear and nonlinear associations. ObjectiveDefine the genotype-function-phenotype relationship using data from the Clinical and Functional TRanslation of CFTR (CFTR2) and human nasal epithelial (HNE) studies. MethodsClinical data (sweat chloride, lung function, pancreatic status) from 84,418 individuals in CFTR2 were linked to CFTR functional measures derived from 289 CFTR genotypes. Total genotype function was calculated as the average percent wild-type chloride conductance of both variants in heterologous cell lines. This framework was applied to an HNE cohort including people with CF, CF heterozygotes, and controls. CFTR function was derived from short circuit measurements in HNEs from 153 individuals and correlated with phenotype for 415 individuals. Weighted linear and logarithmic regressions were applied to evaluate the function-phenotype relationship. Measurements and Main ResultsSimple linear regression obscured marked heterogeneity across datasets. Piecewise linear regressions revealed marked attenuation of slope magnitude with increasing function across phenotypes. This pattern was well-described by a logarithmic function, such that modeling function on a log scale rendered the relationship approximately linear. HNE data demonstrated similar attenuation, corroborating this pattern. ConclusionsLarge-scale natural history data integrated with primary cell findings show that the function-phenotype relationship is not sufficiently described by a single linear effect but is a proportional relationship, in which equivalent changes in CFTR function yield different phenotypic outcomes depending on baseline function. This framework provides precision in predicting clinical benefits from CFTR-directed therapies and identifying meaningful thresholds of CFTR rescue. Impact StatementThis work integrates registry and primary cell data to define the relationship amongst CFTR genotype, CFTR protein function, and clinical phenotype. These findings establish reference points for evaluating the degree of phenotypic improvement anticipated from functional restoration from CFTR-targeted treatments. More broadly, this study advances the understanding of CF disease mechanisms by linking molecular function to real-world clinical outcomes across data sources. At a Glance CommentaryO_ST_ABSScientific Knowledge on the SubjectC_ST_ABSThe relationship between CFTR function and clinical phenotype remains incompletely understood. Prior studies have suggested both linear and nonlinear associations between CFTR activity and disease manifestations. Defining this relationship is increasingly important for interpreting functional data and predicting clinical benefit from CFTR-directed therapies. What This Study Adds to the FieldUsing clinical and functional data from more than 84,000 individuals in CFTR2 together with primary human nasal epithelial cell measurements spanning people with cystic fibrosis, carriers, and unaffected controls, we demonstrate that the CFTR function-phenotype relationship is not adequately described by a single linear model. Instead, the relationship is best fitted by piecewise linear regressions of varying slope conforming to a logarithmic pattern, with the greatest phenotypic gains occurring at the lowest levels of baseline CFTR function. These findings provide a quantitative framework for interpreting functional rescue and predicting therapeutic benefit across the CFTR functional spectrum.

genetics↗

bioRxiv2026

Viral Nuclease Inhibitors: Small molecule disruptors of the UL12 alkaline nuclease display broad anti-herpes virus activity

Herpes simplex virus-1 (HSV-1) UL12 gene encodes a well-conserved 5 [->] 3 alkaline exonuclease. UL12 collaborates with the HSV single-strand DNA binding protein ICP8 to mediate recombination-dependent replication of viral DNA and is essential for the production of DNA that can be packaged into infectious virus. The UL12 gene has orthologs in the eight other human herpesviruses, including UL98 in HCMV and SOX in KSHV, which are also essential for virus production. We have developed viral nuclease inhibitors (VNIs) of HSV-1 UL12 that potently block its nuclease activity and display strong antiviral effects in cell culture. These inhibitors are also effective against alkaline nucleases from the {beta}-HHV HCMV (UL98) and the {gamma}-HHV KSHV (SOX), and we have demonstrated antiviral activity against HSV-1 and HCMV in cell culture. In this work, we describe the first crystal structure of an alphaherpesvirus alkaline nuclease (UL12.5), which was used to elucidate structure activity relationships and improve the selectivity of our inhibitors. These VNIs exhibit EC50 and IC50 values in the nanomolar to low micromolar range. Our findings highlight the potential of targeting HHV alkaline nucleases with novel small molecules, paving the way for the development of new therapies that can be broadly antiviral on their own or in combination with nucleoside analogs. Significance StatementHerpesviruses are widespread pathogens that establish lifelong infections and cause serious disease in immunocompromised individuals, neonates and older adults, yet treatment options remain limited. We report the first crystal structure of the HSV-1 alkaline nuclease UL12.5 and use it to design potent small-molecule inhibitors. These inhibitors exhibit antiviral activity against HSV-1 and HCMV, supporting alkaline nuclease as a conserved and druggable target across all herpesvirus subfamilies. The significance is threefold: it confirms alkaline nucleases as having an essential role in viral replication, provides a structural foundation for rational antiviral design and introduces a new class of inhibitors with potential as pan-herpesvirus therapeutics, alone or in combination, to overcome resistance and improve clinical outcomes.

pharmacology and toxicology↗

bioRxiv2026

Pharmacological rescue of mitochondrial dysfunction, neurite degeneration, and premature death of ALS and AD iPSC-derived neurons

Mitochondrial (MT) dysfunction is a key driver of ALS pathology. Without a healthy MT system, motor neurons (MN) function at sub-optimal levels and die. In addition, other effects of ALS, like axon/dendrite degeneration, may occur from a pathophysiological cascade spurred by MT dysfunction. A phenotypic screen identified Dipyridamole (DPM), an FDA-approved and safe drug, as having extraordinary effects on ALS patient induced pluripotent stem cell (iPSC)-derived MNs. The drug prevented MT fragmentation, loss of MT content, impaired MT bioenergetics, axon/dendrite degeneration, and premature MN death, extending neuronal survival by more than fivefold. Importantly, its efficacy extended across iPSC-derived neurons representing two different familial forms of ALS (C9orf72, TDP43) and Alzheimers disease (PSEN1), implying broad neuroprotection across ALS forms and other neurodegenerative diseases. DPM increased MT respiration and pyruvate uptake in a mechanism requiring the Mitochondrial Pyruvate Carrier (MPC), mechanistically explaining its biological activities. Thus, DPM is a promising drug to repurpose or refine for treating neurodegenerative diseases or other diseases that would benefit by augmenting pyruvate uptake into MT. TeaserDipyridamole, an FDA-approved drug, restores mitochondrial function and protects neurons in ALS and Alzheimers disease.

neuroscience↗

bioRxiv2026

Lamellar Normative Modelling of the Hippocampus Across the Human Lifespan

The hippocampus is a central hub of human memory and cognition and is closely associated with brain disorders. Studies have shown that it exhibits complex structural variation across the lifespan, yet the details of hippocampal morphology changes remain poorly understood. Here, we establish norms over the hippocampal geometry that resolve lamellar morphology and map lifespan trajectories across more than 27,000 individuals from 158 scanning sites. Hippocampal geometry shows spatially non-uniform developmental and ageing patterns across the lifespan, with lamellar thickness, width and length following dissociable trajectories. Across multiple brain disorders, this representation reveals localized and heterogeneous alterations beyond conventional subfield-level summaries, and uncovers a dichotomy in disease-associated patterns, with neurodegenerative conditions and schizophrenia showing predominant atrophy, whereas some other disorders exhibit focal or regionally selective hypertrophy. Transfer to a longitudinal Alzheimers Disease Neuroimaging Initiative cohort further supports out-of-sample generalization of our approach and enables individual-level tracking and conversion risk stratification. Overall, this work establishes a population-scale geometric reference for the hippocampus, extends normative brain mapping from coarse regional phenotypes to anatomically organized subcortical structure, and enables anatomically grounded characterization of disease-related alterations and individual-level deviation mapping, providing a principled basis for understanding and stratifying brain disorders across the lifespan in health and disease.

neuroscience↗

bioRxiv2026

Targeting Gi/o-coupled GPCRs to inhibit nociceptors: insights from the serotonin receptor Htr1b and triptans

Pain perception is initiated upon activation of nociceptors of the dorsal root ganglia (DRG) and trigeminal ganglia. We identified G protein-coupled receptors (GPCRs) expressed in CGRP+ mouse and human DRG neurons and found that agonists of several identified Gi/o-coupled and orphan GPCRs attenuated neuronal excitability. Experiments focusing on the Gi/o-coupled serotonin receptor Htr1b, which is expressed in mouse and human CGRP+ DRG neurons, revealed that Htr1b/1d agonists, the triptans sumatriptan and zolmitriptan, attenuated CGRP+ neuron excitability in vitro and exhibited analgesia across several pain models, including neuropathic pain. Conditional genetic deletion experiments showed that triptan-induced analgesia is mediated by Htr1b expressed in A-fiber mechanonociceptors. Also, triptan-associated adverse effects are partially mediated by Htr1b-independent targets. Further testing identified the GPCR Gpr19 as an additional promising target for treating pain. These findings establish a preclinical screening platform for identifying novel analgesics and reveal nociceptor GPCRs that may be targeted to treat pain.

neuroscience↗

bioRxiv2026

Humanization of the rpb9 locus in fission yeast reveals conserved and divergent roles of rpb9 and human POLR2I

Background/ObjectivesRNA polymerase II is a multifunctional complex that is critical for gene regulation and environmental responses. Its POLR2I subunit in human is associated with various pathologies, including cancer chemoresistance. However, much of our understanding of how POLR2I could function indirectly derives from studies of its homologs in yeasts called Rpb9. Here, we endogenously humanized the rpb9 gene of the fission yeast Schizosaccharomyces pombe to examine the functional capabilities of POLR2I. MethodsWe edited the genomic rpb9 locus in S. pombe so that it encodes the human POLR2I protein, and investigated functional and structural conservation. ResultsWith our humanized yeast system, we find widespread functional complementation by human POLR2I of S. pombe rpb9 roles in yeast growth, chronological aging, and stress responses. We also find that POLR2I complements novel roles for yeast rpb9 in facultative heterochromatin assembly, resistance against the chemotherapy 5-fluorouracil, and resistance against the fungicide thiabendazole. In contrast, we find that POLR2I cannot complement the role of rpb9 in resistance against the transcription elongation inhibitor 6-azauracil (6-AU) in our system. Interestingly, POLR2I could complement 6-AU resistance if ectopically expressed. Lastly, we observe extensive structural homology between Rpb9 and POLR2I proteins. ConclusionsOur study establishes an endogenous cross-species gene complementation strategy that uncovers both conserved and rewired functions of fission yeast rpb9 and its human homolog, POLR2I. In addition to validating conserved roles, we also identified conservation of previously unrecognized roles of rpb9 in heterochromatin formation and chemoresistance.

synthetic biology↗

bioRxiv2026

TRPM2 couples cell-autonomous type-I interferon signaling to pigmentation homeostasis

Transient Receptor Potential Melastatin 2 (TRPM2), a Ca{superscript 2}-permeable cation channel, regulates innate and adaptive immunity and has recently been implicated in vitiligo, an autoimmune pigmentary disorder. However, whether TRPM2 exerts cell-autonomous immunoregulatory functions and how such signaling intersects with pigmentation remain unknown. Here, we reveal an unexpected role for TRPM2 as an intrinsic suppressor of pigmentation through type-I interferon (IFN) signaling in melanocytes. Pharmacological inhibition, genetic silencing, and gain-of-function approaches demonstrate that TRPM2 negatively regulates melanogenesis in vitro. Notably, TRPM2-deficient zebrafish and TRPM2-/- mice exhibit enhanced pigmentation in vivo, establishing physiological relevance. Transcriptomic profiling uncovers autonomous activation of the type-I-IFN pathway upon TRPM2 loss, leading to induction of interferon-stimulated gene 15 (ISG15). Mechanistically, ISG15 attenuates global ubiquitination and stabilizes microphthalmia-associated transcription factor (MITF), the master regulator of melanogenesis, thereby promoting pigmentation. Collectively, our findings define a previously unrecognized TRPM2-type-I-IFN-ISG15-MITF signaling axis that functionally integrates cell-autonomous immune surveillance pathways with pigmentary control. Further, it provides a conceptual framework linking type-I interferon signaling to pigmentation homeostasis and pigmentary disorders. Key highlights of the studyO_LITRPM2 negatively regulates pigmentation in vitro (mouse and primary human cells) and in vivo (zebrafish and mice). C_LIO_LIUnbiased RNA-sequencing identifies ISG15 as a positive regulator of melanogenesis downstream of TRPM2 silencing. C_LIO_LITRPM2 knockdown generates a cell autonomous type-I-IFN response in melanocytes that induces ISG15 expression. C_LIO_LIISG15 antagonizes global ubiquitination and regulates stability of MITF, the master regulator of pigmentation. C_LI

cell biology↗

bioRxiv2026

A normative reference for large-scale human brain dynamics across the lifespan

Human brain function emerges from dynamic reconfigurations of large-scale neural networks. While population-level reference charts have transformed the study of static brain structure and connectivity, an equivalent normative framework for intrinsic brain dynamics has been lacking. This gap has limited our ability to characterize individual variability, development, ageing, and mental health conditions at scale. Here, we establish a population-level normative reference for large-scale human brain dynamics using resting-state fMRI data from more than 10,000 individuals spanning the lifespan and 91 scanning sites. We derive a compact set of recurring brain-state configurations that are reproducible across scanners and acquisition paradigms and that generalize to previously unseen cohorts. Anchoring these dynamic states to normative lifespan models enables the quantification of individual deviations relative to population reference distributions. We show that intrinsic brain dynamics undergo systematic reorganization across development and ageing, with pronounced changes before early adulthood and more gradual modulation thereafter. Applying this framework across multiple mental health conditions reveals disorder-specific and highly heterogeneous deviations in brain dynamics that are not captured by static neuroimaging measures. Robust transfer to independent cohorts and longitudinal analyses demonstrate that normative brain dynamics can be reliably assessed out of distribution. These results delineate a population-scale dynamic architecture of the human brain and extend normative brain mapping from static phenotypes to the temporal domain, providing a reference framework for studying brain function across the lifespan in health and disease.

neuroscience↗