Biology subjects

Anand, S.

Publications and source records attributed to Anand, S..

At least 19 recordsLinked to original sources

bioRxiv2026

Lactate Promotes Tunneling Nanotube Formation and Reduces Temozolomide Sensitivity in Glioblastoma Cells

Tunneling nanotubes (TNTs) mediate intercellular communication and contribute to cancer progression. Tumour cells produce excess lactate through increased glycolysis, but whether lactate regulates TNT formation has not been studied. Here, we show that lactate promotes TNT formation in U-87 MG glioblastoma (GBM) cells under both glucose-restricted and glucose-replete conditions, with a similar effect in MDA-MB-231 breast cancer cells. This effect depends on lactate uptake and metabolism rather than receptor-mediated signalling: inhibition of monocarboxylate transporter 1 (MCT1) or lactate dehydrogenase (LDH) reduced TNT formation, while exogenous lactate restored TNT formation during LDH inhibition. 3-chloro-5-hydroxybenzoic acid, an agonist of the plasma membrane-localized lactate receptor (GPR81/HCAR1), did not reproduce the effect of lactate. Lactate also increased intercellular mitochondrial transfer, attenuated temozolomide (TMZ)-induced growth suppression of GBM spheroids, and increased expression of the TNT-associated genes CDC42, MYO10 and FSCN1. Inhibition of p300/CBP-mediated lactylation with A-485 reduced both protein lactylation and TNT formation, implicating lactylation in TNT biogenesis. Lactate increased basal and ATP-linked respiration that persisted during MCT1 inhibition and reduced on LDH inhibition, indicating that the effects of lactate on respiration and on TNT formation are at least partly separable. Together, these findings identify lactate as a regulator of TNT formation and link tumour metabolism to intercellular connectivity and TMZ response, highlighting lactate metabolism and lactylation as potential therapeutic targets.

cell biology↗

bioRxiv2026

Abnormally low expression of tumor necrosis factor stimulated gene 6 (TSG-6) in obese type 2 diabetic mice contributes to altered inflammation and delayed cutaneous wound healing

Type 2 diabetes mellitus (T2DM) is a chronic disorder associated with obesity and hyperglycemia. T2DM is linked to significant clinical complications such as delayed wound healing and diabetic foot ulcers. Tumor necrosis factor-stimulated gene 6 (TSG-6) is a protein with multiple functions including regulation of cytokine binding to glycosaminoglycans in extracellular matrices and on vascular endothelial walls. Loss of TSG-6 in knockout mice increases skin inflammation and delays wound healing. Here, in both a genetic model (db/db mice) and a dietary model that simulates human T2DM (mice treated with a high-fat diet [HFD] and streptozotocin [STZ]), we observed sustained hyperglycemia and a reproducible delay in wound closure. TSG-6 expression was markedly reduced in diabetic skin in these models, both before injury and post wounding. HFD+STZ diabetic mouse wounds showed elevated levels of pro-inflammatory cytokines (IL-6, TNF-, and MIP-1) and lower levels of the anti-inflammatory cytokine IL-10, relative to normoglycemic mice. Re-introduction of TSG-6 protein into the wounds normalized healing rates, corrected abnormal cytokine expression levels, and increased macrophage accumulation in dermal and adipose compartments. Thus, T2DM is associated with reduced levels of TSG-6 in diabetic skin, which contributes to the pro-inflammatory milieu and the delay in wound closure.

physiology↗

bioRxiv2026

NMR assignments and secondary structure analysis of the human 5MP1 C-terminal domain

Eukaryotic translation initiation is tightly regulated by interactions among translation initiation factors (eIFs) that ensure accurate start codon selection. The translation regulator, eIF5 mimic protein 1 (5MP1) contributes to this process by competing with eIF5 for binding to eIF2, thereby increasing the stringency of translation initiation. Despite its important regulatory role and emerging involvement in tumorigenesis, structural information on human 5MP1 remains limited. Here, we report the near-complete backbone and partial side-chain NMR resonance assignments of the C-terminal domain of human 5MP1 (residues 250-419), carrying a W404E substitution that disrupts dimerization. The WT protein forms a dimer at NMR concentrations, which increases the effective size of the protein and also causes disappearance of peaks corresponding to aminoacids at the dimer interface due to conformational exchange. Backbone resonance assignments were completed for 96.4% of the non-proline residues. Secondary structure was analyzed using Chemical Shift Index (CSI) and compared with the AlphaFold structural model. Regions of disagreement between the experimental and computational secondary structure assignments were further examined using 15N-NOESY-HSQC spectra, allowing experimental validation of local structural features. While the AlphaFold model accurately reproduces the overall fold of the 5MP1 C-terminal domain, several localized discrepancies were identified, particularly near the N- and C-terminal regions of the domain, where experimental NMR data support alternative secondary structure assignments. These resonance assignments and experimentally validated structural features provide a foundation for future investigations of the molecular interactions, dynamics, and functions of 5MP1 in translation initiation.

biophysics↗

bioRxiv2026

Pleiotropic antimalarial activities and immunomodulation exhibited by Himalayan Buransh (Rhododendron arboreum) in human and rodent malaria models

Emerging drug resistance against the malaria parasite is worrisome and necessitates the development of novel antimalarials. Himalayan Buransh (Rhododendron arboreum) is a well-known medicinal plant found in the northern states of India. In this study, we observed the pleiotropic antimalarial activities and immunomodulation exhibited by the aqueous extract of Buransh flower (AEBF). AEBF demonstrated significant IC50 values (16-29 {micro}g/ml) against the asexual stages of various P. falciparum strains (3D7, Dd2-chloroquine-resistant and C580Y-artemisinin resistant). The oral administration of AEBF (200 mg/kg) in mice, suppressed [~]80% P. berghei parasitemia, improved mean survival time (MST-23.5 days) and prevented splenomegaly. Notably, the combination of AEBF and artesunate not only cleared primary infection, but also conferred sustained immunity. This immunomodulatory effect, driven by protective IFN-{gamma} resulted in reduced parasitemia during a homologous challenge without the need for further treatment. It is important to highlight the malaria transmission blocking activity of AEBF, resulting in reduced sexual stage male gametocyte exflagellation. Furthermore, the virtual drug screening of selected bioactive constituents from Buransh flower demonstrated potent binding against multiple P. falciparum proteins, suggested a pleiotropic mode of action. Altogether, our results corroborated the first ever evidence of the multistage antimalarial potential of Buransh flower, supported by in vitro cell studies, in vivo rodent malaria model and in silico docking analyses. Based on our studys findings and the traditional use of Buransh juice as a medicinal beverage in Uttarakhand, India, we propose exploring it as an adjunct therapy for drug-resistant malaria, subject to further clinical validation.

pathology↗

bioRxiv2026

Genome-wide protein-protein interaction analysis between aquaporins and harpin (HrpZ2) through molecular docking and MD simulations to unravel its role in growth and stress management in tomato.

HrpZ2, a harpin protein produced by Pseudomonas syringae, a gram-negative plant pathogenic bacterium, elicits hypersensitive response and pathogen defense in non-host plants. Harpins from various bacterial sources elicit varying responses in different non-host plants, due to its structural variations, their precise mechanisms of action are not yet completely understood. As per previous reports, harpins from diverse bacterial sources interact with distinctive members of integral membrane proteins, known as aquaporins. For example, harpin (Hpa1Xoo) interacts with OsPIP1;3 in rice, whereas, in Arabidopsis the harpins Hpa1 and HrpZ interacts with AtPIP1;4 and AtPIP1;3 respectively. Here, we conducted the first genome-wide computational screening of protein-protein interactions between HrpZ2 and all 47 members of tomato aquaporins. Molecular docking identified nine interactors across five subfamilies of aquaporins, with HrpZ2 N-terminal residues mediating these interactions. We validated these via molecular dynamics (MD) simulations, principal component analysis, and free energy landscape analysis, assessing the stability (RMSD, RMSF, radius of gyration), dynamics, and affinity (MM-GMSA). PIP complexes, especially PIP2;1 (-460.46 kcal/mol) and PIP1;7 (-303.82 kcal/mol), exhibited superior stability, compactness, and defined energy minima, confirming PIPs as primary sensors of harpins. Non-PIP aquaporins like TIP1;1 and NIP4;1 showed moderate stability, outperforming weaker interactors (SIP2;1, XIP1;5, XIP1;3). These findings provide robust evidence that HrpZ2 preferentially targets PIPs in tomato, while engaging TIPs and NIPs as auxiliary partners. This multifaceted interaction profile of harpins suggests complex plant-pathogen recognition, modulating aquaporin-mediated cellular responses like growth and stress management in plants.

plant biology↗

bioRxiv2026

Reproducibility of Diffusion, Shape, and Connectivity Metrics Across Scanners: Implications for Multi-Site Tractography

Multi-site diffusion MRI studies face scanner-induced variability that can obscure biological signal. Harmonization methods such as ComBat have been developed to address this, but have been evaluated primarily on diffusion scalar metrics. Whether scanner reproducibility differs across fundamentally distinct tract-derived representations has not been systematically compared. Here, we compared the reproducibility of three metric families (diffusion, shape, and connectivity) across 36 association tracts using the MASiVar dataset (5 subjects, 4 scanners, 27 sessions). We assessed intraclass correlation coefficients (ICC) and multivariate subject discrimination at baseline, under dimensionality reduction, and after ComBat harmonization. At baseline, shape metrics showed the highest reproducibility (median ICC 0.69), followed by connectivity (0.49) and diffusion (0.34). Shape and connectivity achieved comparable subject discrimination (both 1.75), significantly exceeding diffusion (1.23). ComBat harmonization improved all families but harmonized diffusion (0.58) remained below unharmonized shape (0.69), indicating that metric family selection remains consequential even after harmonization. Under low-dimensional representation, connectivity showed the largest gains (ICC 0.86, subject discrimination 3.0), exceeding other families at any dimensionality. Analysis of principal component loadings identified a small number of cortical regions per tract (median 6) that capture 95% of the reproducible connectivity signal, providing a per-tract reference for selecting the most informative regions in future multi-site studies. These findings indicate that the choice of which tract-derived metrics to analyze in multi-site studies deserves at least as much consideration as how to harmonize them.

neuroscience↗

bioRxiv2026

All-trans retinoic acid recalibrates macrophage transcriptional responses to drug-resistant Mycobacterium tuberculosis through strain-specific immunometabolic reprogramming

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M.tb) remains the leading infectious cause of death worldwide, with multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains presenting an escalating therapeutic crisis. All-trans retinoic acid (ATRA), an active vitamin A metabolite with established immunomodulatory properties, has emerged as a candidate host-directed therapy, yet its genome-wide transcriptional effects on macrophage across strains of differing drug-resistance profiles remain uncharacterized. We performed RNA sequencing of murine peritoneal macrophages infected with drug-susceptible H37Rv, MDR-2261, or XDR-MCY M.tb strains, with and without ATRA treatment, validated by RT-PCR and flow cytometry. All three strains activated a conserved pro-inflammatory program dominated by Nos2, Il1b, and Acod1 induction with progressive suppression of host translational and mitochondrial machinery. XDR-MCY uniquely induced Ifnb1/IFN-{beta}, suppressed Prdx1 and Gpx4, the latter shared with MDR-2261 and showed selective downregulation of MHC-II processing genes, suggesting a multilayered immune evasion strategy. ATRA activated canonical retinoid signaling across all infection states and consistently induced Arg1-mediated resolution signaling, with Nos2 suppression observed in H37Rv- and MDR-infected macrophages. ATRA selectively restored Epas1/HIF-2 in H37Rv- and MDR-infected macrophages without disrupting the HIF-1-driven antimicrobial program or itaconate biosynthesis. ATRA responsiveness progressively attenuated with drug resistance, with XDR-MCY-infected macrophages largely refractory to transcriptional reprogramming. These findings provide a transcriptional rationale for evaluating ATRA as a host-directed adjunct in drug-resistant TB and identify Gpx4 suppression in drug-resistant strains and XDR-specific Ifnb1 induction as vulnerabilities necessitating further investigation.

microbiology↗

bioRxiv2026

Tetrahydrocannabinol exposure to postejaculatory sperm compromises sperm structure, function, the epigenome, and early embryo development

Cannabis (marijuana) is the most widely used recreational drug in the USA accounting for about 62 million users in 2024. Among cannabis users, 26% are of prime reproductive age (18-25 years). Delta-9 tetrahydrocannabinol (THC) is the principal psychoactive component of cannabis and has been detected in human seminal fluids. Although abundant evidence indicates adverse effects of THC exposure on spermatogenesis in different species, acute effects of THC on postejaculatory sperm including fertilization potential and subsequent carryover effects on embryo development are largely unknown. The present study was designed to provide missing information on structural and mechanistic effects of THC exposure to postejaculatory sperm function by evaluating sperm indices often overlooked or masked during clinical evaluation. A bovine embryo continuum model was employed to determine effects of THC on sperm structure, kinematics, bioenergetics, and binding mechanisms. Effects of THC on the sperm genomic and epigenomic landscape were determined, complemented by paternal carry over effects on embryo development as a human translational model to elucidate paternal effects on future development, and to mirror sperm exposure during transport within the female reproductive tract. Cryopreserved bovine sperm from three bulls were independently exposed to physiologically relevant concentrations of THC (0 and 32nM, n = 2 individual replicates/bull) for 24 h under non-capacitating conditions at 25{degrees}C followed by quantification of sperm kinematics at 37{degrees}C. Samples of THC-exposed sperm and vehicle-control (0.1% DMSO) were collected in replicate following immediate addition of THC (0 h) and again at 24 h. DNA damage, acrosome integrity, bioenergetics, changes to DNA methylation and embryo development were quantified. Data were analyzed by logistic regression with a generalized linear mixed effect model. Computer-assisted sperm assessment revealed a reduction in progressive motility of THC-exposed sperm after 24 h while other parameters were not affected. Acrosome integrity as determined by flowcytometric analysis with FITC-PSA was severely compromised in THC-exposed sperm (P [≤] 0.05), despite no detectable difference in capacitation status using merocyanine staining. Similarly, DNA integrity as determined by TUNEL assay was significantly impaired after 24 h of THC exposure (P [≤] 0.05). Mechanistic effects of THC were explored through characterization of the transmembrane G-protein coupled cannabinoid 1 receptor (CB1). CB1 is expressed in the post-acrosomal region and its abundance decreased as compared to unexposed sperm. Alterations to the methylation landscape of sperm were then determined after 24 h of THC exposure through whole-genome Enzymatic Methyl Sequencing. PCA analysis indicated that sperm from different males formed distinct clusters, implying individual differences among bulls, while the effects of THC exposure produced tighter clusters. Paternal carryover effects on embryos derived by in vitro fertilization from THC exposed sperm had reduced 2-cell cleavage, 8-16 cell morula development, and reduced blastocyst development compared to unexposed sperm (46% vs. 33%). In conclusion, post-ejaculatory mammalian sperm exposure to THC compromises acrosome integrity, induces DNA damage, changes the sperm methylome, and reduces developmental potential. Collectively, these data implicate new considerations for recreational and clinical use of cannabis that impact cellular and molecular mechanisms important for sperm function with detrimental consequences for gamete interaction and embryo development.

cell biology↗

bioRxiv2026

Photodynamic priming with Vitamin D and ALA-based PDT induces intratumoral immune cell recruitment and signaling pathway activation in murine cutaneous squamous cell carcinoma

Photodynamic therapy (PDT) is effective for early epithelial pre-cancers, yet its efficacy in fully-developed cutaneous squamous cell carcinoma (SCC) is limited by immunosuppression in the tumor microenvironment. Vitamin D (VitD) has emerged as a potential neoadjuvant to enhance photodynamic priming in several cancers. Here, we investigated how VitD pretreatment modulates local and systemic immune responses to aminolevulinic acid-based PDT in two immunocompetent murine SCC models (chronic UV-induced SCC, and subcutaneously implanted PDVC57B cells). VitD combined with PDT significantly amplified hallmarks of immunogenic cell death, including calreticulin and HMGB1 expression, and increased recruitment of neutrophils, macrophages, dendritic cells, and CD8 T cells into tumors. Importantly, VitD+PDT produced a higher M1/M2 macrophage ratio, and reduced the number of exhausted (PD-1 expressing) T cells compared to PDT alone. Immune profiling of blood demonstrated enhanced T-cell activation (CD69) and reduced TIM-3 expression on cytotoxic T cells. Transcriptomic analysis revealed pathway enrichment for interferon-/{gamma} signaling and suppression of pro-tumorigenic epithelial-mesenchymal transition and of angiogenesis after VitD+PDT. Collectively, these findings demonstrate that VitD reprograms the immune response to PDT by enhancing cytotoxic immunity while limiting immunosuppressive features. This suggests an immune-priming strategy to consider, possibly alongside immune checkpoint blockade, for treating cutaneous SCC.

cancer biology↗

bioRxiv2026

The IKC-leptin axis functions as a molecular bridge between neurodevelopment and endocrine signaling

Kcnb1, a voltage-gated K channel widely expressed in brain, assembles with integrins to form integrin-K channel complexes (IKCs) in cortex and hypothalamus. Pathogenic KCNB1 variants cause Developmental and Epileptic Encephalopathy (DEE), and Kcnb1-null (Null) mice reproduce core neurodevelopmental defects alongside chronic hypoleptinemia, suggesting a leptin-IKC signaling axis. We find that Kcnb1, integrins, and the leptin receptor (LepR) co-immunoprecipitate and co-localize in cortical neurons. Perinatal leptin supplementation in Null mice improves cognition, corrects cortical anatomy, and restores neuronal migration, dendritic arborization, and synaptic functionality. In primary Null cortical neurons, leptin normalizes dendritic growth and actin remodeling via integrin-dependent mechanisms. By contrast, leptin has modest effects in WT animals and neurons; sensitivity is unmasked by pharmacological manipulation of integrins, and, strikingly, LepR blockade in the absence of exogenous leptin is sufficient to induce Null-like defects in WT neurons. These findings argue that hypoleptinemia alone does not drive the Null phenotype. Instead, they reveal a previously unrecognized, dual-mode model in which LepR signaling is regulated by both its ligand and IKCs. This conceptual advance links IKC-LepR coupling to neurodevelopment and DEE and pinpoints their interface as a tractable therapeutic target.

neuroscience↗

bioRxiv2025

A Rapid Gene Expression Profiler Classifies AML Tumor Responsiveness to Standard Therapies

The emergence of transcriptional signatures that define cell types and pathways has made it possible to guide cancer therapy selection through gene expression profiling. We developed a rapid qPCR-based platform to profile cell state, stemness, and BCL2 family gene expression as a companion diagnostic test for acute myeloid leukemia (AML). We validated the stability and utility of the signatures across multiple measurement platforms and using patient samples from two centers. Integrating these signatures with clinical features enables an expedient means to predict the likelihood of patient responses to two standard-of-care therapies: intensive chemotherapy and hypomethylating agent plus venetoclax (HMA+Ven). For patients treated with HMA+Ven, expression levels of the promonocyte-like signature and BCL2 add predictive value for response and overall survival in multivariable models that include genetic features. The incorporation of the rapid profiler into the prospective evaluation of newly diagnosed AML patients may enhance treatment stratification and improve outcomes.

cancer biology↗

bioRxiv2025

NMR assignments and secondary structure analysis of the eIF1-interacting fragment of human eIF3c

Eukaryotic translation initiation involves coordinated assembly of initiation factors on the small ribosomal subunit to form the pre -initiation complex (PIC) and scan mRNA for the start codon. The multi-subunit initiation factor eIF3 plays central roles in PIC assembly, stabilization, and scanning. Within eIF3c, residues 166-266 lie immediately N-terminal of the folded PINT/PCI domain and encompass the reported eIF1-binding site in human eIF3c. This segment is not visible in PIC Cryo-EM structures, except for a small helix contacting eIF1, and is predicted to be intrinsically disordered. Here we report the near-complete backbone and partial side-chain NMR assignments for the eIF3c 166-266 fragment in solution. The 1H-15N HSQC spectrum is consistent with an intrinsically disordered protein region. Several amide resonances were broadened at 25 {degrees}C but recovered at 5 {degrees}C. Secondary structure propensities derived from chemical shift index (CSI) analysis, together with amide 1H chemical shift temperature coefficients (CSTCs), confirm that the protein is disordered, while the CSI analysis also indicates the presence of short segments with modest -helical or {beta}-strand propensity. Three conserved FLKK motifs fall at junctions of these transient structural elements, with Motif 3 located in the subsegment showing slightly greater propensity for transient structure. These residue-specific NMR assignments provide a foundation for future studies of interaction surfaces, binding-induced folding, and conformational dynamics of this conserved eIF3c region in the context of translation initiation.

biophysics↗

bioRxiv2025

Metabolic regulation of copper homeostasis governs the Sec61-dependent protein translocation process in Saccharomyces cerevisiae

Concentration of cellular labile pool of copper must be strictly regulated because disruption in copper homeostasis results in diseases. In Saccharomyces cerevisiae, elevated levels of labile copper impair cell viability by inhibiting Sec61-mediated protein translocation into the endoplasmic reticulum. We investigated how metabolic pathways, specifically mitochondrial respiration and autophagy, contribute to copper homeostasis and the translocation of secretory proteins. We show that copper selectively inhibits protein translocation in yeast cells grown in minimal medium but not in rich medium, highlighting a critical role of nutrients in modulating copper toxicity. Supplementation of specific amino acids suppresses the copper-induced defects in protein translocation and cell death, identifying amino acids suppressors of the copper toxicity. Using a panel of gene deletion mutants affecting mitochondrial functions, autophagy, peroxisomes, and lipid droplets, we demonstrate that metabolic pathways regulate sub-cellular distribution of copper and translocation of secretory proteins. Further, disruption of redox and pH homeostasis, and pharmacological inhibition of respiration, reveals that correct subcellular trafficking of copper is essential to prevent inhibitory effects on protein translocation process. Together, our findings provide mechanistic insights into how metabolic status influences cellular copper homeostasis and the secretory pathway of proteins, with broader implications for understanding diseases of copper metabolism.

cell biology↗

bioRxiv2025

Nitrogen metabolism profiling reveals cell state-specific pyrimidine synthesis pathway choice

Conventional stable isotope tracing assays track one or several metabolites. However, cells use an array of nutrients to sustain nitrogen metabolic pathways. This incongruency hampers a system level understanding of cellular nitrogen metabolism. Therefore, we created a platform to simultaneously trace 30 nitrogen isotope-labeled metabolites. This platform revealed that while primitive cells engage both de novo and salvage pyrimidine synthesis pathways, differentiated cells nearly exclusively salvage uridine despite expressing de novo pathway enzymes. This link between cell state and pyrimidine synthesis routes persisted in physiological contexts, including primary murine and human tissues and tumor xenografts. Mechanistically, we found that Ser1900 phosphorylation of CAD, the first enzyme of the de novo pathway, was enriched in primitive cells and that mimicking this modification in differentiated cells abrogated their preference for pyrimidine salvage. Collectively, we establish a method for nitrogen metabolism profiling and define a mechanism of cell state-specific pyrimidine synthesis pathway choice.

cell biology↗

bioRxiv2025

A transgenic mouse allows to capture the HLA-C*06:02 immunopeptidome in a model of psoriasis

Psoriasis vulgaris is a T cell-mediated autoimmune skin condition affecting around one in fifty people worldwide. Whilst advanced immunomodulatory therapeutic options have become available in recent years, ongoing disease suppression is still required with no curative treatment available to date. The human leukocyte antigen class I allele HLA-C*06:02 is the main genetic risk determinant of psoriasis. Its function is to present peptide antigens to CD8+ T cells and natural killer cells which in turn elicit and perpetuate the immune response, yet little is known about ligands presented by HLA-C*06:02. To gain an understanding which HLA-C*06:02-restricted peptides are presented by epidermal cell populations and might be initiators of the autoimmune response in psoriasis, we have conducted an in depth immunopeptidomics analysis of HLA-C*06:02+ keratinocyte and melanocyte cell lines. Furthermore, we introduce a HLA-C*06:02 transgenic mouse which, in conjunction with the imiquimod model of psoriasis, allowed us to assess the ex vivo immunopeptidome of HLA-C*06:02 in psoriasiform skin. Overall, we detected 20,812 high confidence HLA-C*06:02 bound peptide ligands. Thus, we present a comprehensive coverage HLA-C in vitro immunopeptidomics dataset and the first HLA-C*06:02 ex vivo dataset of psoriasis-relevant peptide antigens that may inform the development of antigen-specific, novel curative therapeutic approaches in psoriasis.

immunology↗

bioRxiv2025

Evi1 is necessary for late activation of delta-notch signaling in sea urchin embryos

Embryonic mesoderm specification and differentiation rely on intricate gene regulatory networks. In sea urchin embryos, Ecotropic Viral Integration Site 1 (Evi1) is identified as a key transcriptional regulator that integrates Nodal and Delta-Notch signaling pathways to drive mesodermal development. Through in situ hybridization, hybridization chain reactions, and morpholino-mediated knockdowns, Evi1 is required for activating Notch135 expression and for the formation of mesodermal derivatives, including muscle progenitors and coelomic pouches. Evi1 expression is positively regulated by Nodal signaling: it is upregulated when the Nodal antagonist Lefty is knocked down and lost with Nodal depletion or BMP overexpression. Functionally, Evi1 operates upstream of Notch135, restoring its expression following early Delta-Notch activity and enabling a second signaling phase necessary for mesodermal differentiation. Knockdown of Evi1 results in significant loss of Astacin4 and Myo88, markers for mesoderm and muscle progenitors respectively, and disrupts Pax6 expression, impairing coelomic pouch formation, a precursor to the larval rudiment and adult body plan. These results establish Evi1 as a crucial mediator between Nodal and Delta-Notch pathways in mesodermal patterning. Given its conserved role across deuterostomes, further investigation into the direct transcriptional targets of Evi1 and its later-stage developmental functions could shed light on its broader contributions to organogenesis.

developmental biology↗

bioRxiv2024

Epithelial-mesenchymal boundary guides cell shapes and axis elongation in embryonic explants

The spatial arrangement of tissues during development establishes regions of tissue-tissue interactions. While such interactions are prominent during gastrulation and organogenesis, how they guide morphogenesis remains unclear. Here, using Xenopus animal cap explants, we show that the coupling between epithelial and mesenchymal tissues is instrumental in robust axis elongation. We find that mesenchymal and epithelial tissues drive elongation hierarchically - the epithelium can elongate independently, while the mesenchyme requires the initial presence of the epithelium. The epithelial-mesenchymal boundary defines the direction of cell shape alignment and the axis of tissue elongation. Prior to explant elongation, epithelial cells align and elongate, a process that propagates into the underlying mesenchyme. These findings reveal how tissue boundaries can organize coherent axis elongation without external patterning cues, providing insights into the self-organization principles that guide embryonic morphogenesis.

developmental biology↗

bioRxiv2024

Sex-specific expression of the human NAFLD-NASH transcriptional signatures in the liver of medaka with a history of ancestral bisphenol A exposure

The progression of fatty liver disease to non-alcoholic steatohepatitis (NASH) is a leading cause of death in humans. Lifestyles and environmental chemical exposures can increase the susceptibility of humans to NASH. In humans, the presence of bisphenol A (BPA) in urine is associated with fatty liver disease, but whether ancestral BPA exposure leads to the activation of human NAFLD-NASH-associated genes in the unexposed descendants is unclear. In this study, using medaka fish as an animal model for human NAFLD, we investigated the transcriptional signatures of human NAFLD-NASH and their associated roles in the pathogenesis of the liver of fish who were not directly exposed but their ancestors were exposed to BPA during embryonic and perinatal development three generations prior. Comparison of bulk RNA-Seq data of the liver in BPA lineage male and female medaka with publicly available human NAFLD-NASH patient data revealed transgenerational alterations in the transcriptional signature of human NAFLD-NASH in medaka liver. Twenty percent of differentially expressed genes (DEGs) were upregulated in both human NAFLD patients and medaka. Specifically in females, among the total shared DEGs in the liver of BPA lineage fish and NAFLD patient groups, 27.69% DEGs were downregulated and 20% DEGs were upregulated. Off all DEGs, 52.31% DEGs were found in ancestral BPA-lineage females, suggesting that NAFLD in females shared majority of human NAFLD gene networks. Pathway analysis revealed beta-oxidation, lipoprotein metabolism, and HDL/LDL-mediated transport processes linked to downregulated DEGs in BPA lineage males and females. In contrast, the expression of genes encoding lipogenesis-related proteins was significantly elevated in the liver of BPA lineage females only. BPA lineage females exhibiting activation of myc, atf4, xbp1, stat4, and cancerous pathways, as well as inactivation of igf1, suggest their possible association with an advanced NAFLD phenotype. The present results suggest that gene networks involved in the progression of human NAFLD and the transgenerational NAFLD in medaka are conserved and that medaka can be an excellent animal model to understand the development and progression of liver disease and environmental influences in the liver.

pharmacology and toxicology↗