Biology subjects

Negi, V.

Publications and source records attributed to Negi, V..

5 recordsLinked to original sources

bioRxiv2026

Hepatocyte TEAD1 drives epithelial-stromal remodeling during cholestatic liver injury

Background & AimsPrimary sclerosing cholangitis (PSC) is a progressive cholangiopathy characterized by ductular remodeling, inflammation, and periportal fibrosis, for which effective medical therapies remain limited. The Hippo pathway effector TEAD1 has been implicated in liver regeneration and fibrogenesis; however, its role in cholestatic injury remains poorly defined. We investigated whether hepatocyte TEAD1 regulates injury-associated remodeling in a PSC-mimicking model and whether this mechanism is conserved in human PSC liver. MethodsHepatocyte-specific TEAD1 knockout mice (Alb-TEAD1-/-) and littermate controls were subjected to DDC-induced cholestatic injury. Ductular reaction, fibrosis, inflammation, and bile acid-related gene programs were assessed by histology, immunostaining, and gene expression analyses. Translational relevance was evaluated using bulk and single-cell transcriptomic datasets from human PSC liver. ResultsHepatocyte TEAD1 deletion attenuated DDC-induced fibrosis, ductular expansion, and inflammatory cell accumulation, while preserving hepatocyte proliferative responses. TEAD1-deficient livers exhibited reduced expression of profibrotic mediators, including Spp1, Ctgf, and Cyr61, with decreased extracellular matrix deposition. In contrast, canonical transcriptional adaptations to cholestatic stress, including suppression of bile acid uptake, induction of efflux pathways, and repression of bile acid synthesis genes, were preserved in the absence of TEAD1. Analysis of human PSC datasets demonstrated coordinated upregulation of TEAD1 and TEAD-associated target genes. Single-cell transcriptomic analysis further revealed hepatocyte-enriched TEAD1 expression and activation of a TEAD1 target gene program across all hepatic zones in PSC, with effect sizes exceeding those observed in non-parenchymal populations. TEAD1 activation was accompanied by co-expression of profibrotic mediators and downregulation of hepatocyte differentiation markers, consistent with a maladaptive hepatocyte state. ConclusionsHepatocyte TEAD1 drives ductular, inflammatory, and fibrogenic remodeling during cholestatic injury without disrupting bile acid metabolic adaptation. These findings identify TEAD1 as a hepatocyte-intrinsic regulator of epithelial-stromal crosstalk and establish conserved activation of this pathway in human PSC, supporting TEAD-directed signaling as a therapeutic target.

pathology↗

bioRxiv2025

TEAD1 is a novel regulator of NRF2 and oxidative stress response in cardiomyocytes

BACKGROUNDTEAD1, the mammalian Hippo pathway-regulated transcription factor, plays a critical and non-redundant role in maintaining cardiomyocyte (CM) homeostasis. However, the specific cellular pathways regulated by TEAD1 in CMs remain poorly defined. We hypothesized that TEAD1 has an essential, cell-autonomous role in the CM oxidative stress response by directly regulating the transcription of NRF2, the master regulator of oxidative stress response. METHODS AND RESULTSTamoxifen-induced conditional CM-specific TEAD1 deletion in adult mice leads to acute heart failure (HF) and altered expression of antioxidant genes. In silico analysis of publicly available RNA-seq data from human hearts with end-stage dilated (DCM) and ischemic (ICM) cardiomyopathy revealed significant downregulation of TEAD1 transcript levels and a positive correlation between TEAD1 and NRF2 gene expression. ChIP-seq and ATAC-seq in adult mouse hearts confirmed TEAD1 occupancy at promoter/enhancer elements within open chromatin regions of multiple antioxidant genes, including NRF2 and its targets. Ex vivo and in vitro TEAD1 knockout in primary neonatal and adult murine CMs, as well as in H9C2 cells, resulted in significantly increased cellular and mitochondrial ROS le, accompanied by a marked decrease in NRF2 expression and promoter-luciferase activity, under both basal and oxidative stress conditions. Mosaic, conditional deletion of TEAD1 in [~]40-50% of murine heart CMs provided a novel in vivo model for studying TEAD1-regulated pathways in the heart, independent of the confounding effects of HF. This model demonstrated reduced NRF2 expression and heightened oxidative stress in neonatal and adult TEAD1 mosaic knockout hearts. Notably, 8OHdG staining identified oxidative DNA damage in TEAD1-deficient CMs compared to TEAD1-expressing CMs within the mosaic knockout hearts. Upon in vivo AngII infusion, TEAD1 mosaic knockout hearts showed a significant increase in oxidative stress markers and an impaired NRF2 response. Overexpression of human TEAD1 restored NRF2 activity and mitigated ROS accumulation in TEAD1 knockout CMs in vitro. Furthermore, TEAD1 deletion in human iPSC-derived CMs resulted in increased oxidative stress and downregulation of NRF2 expression and functional activity, confirming the requirement of TEAD1 in NRF2-mediated oxidative stress response in human CMs. Collectively, these findings establish that TEAD1 is essential for NRF2 expression and activity under both basal and AngII-induced conditions and plays a crucial role in the oxidative stress response in CMs. CONCLUSIONSTEAD1 is a cell-autonomous, direct transcriptional regulator of NRF2 and the cardiomyocyte (CM) oxidative stress response. Its gene expression, which directly correlates with NRF2 transcript levels in the human myocardium, is significantly downregulated in human end-stage heart failure, potentially compromising the oxidative stress response in the failing heart.

molecular biology↗

bioRxiv2022

The Role of EBP50 in Regulating Endothelial-To-Mesenchymal Transition in Pulmonary Hypertension

ObjectivePulmonary hypertension (PH) is a cardiopulmonary disease manifesting in increased pulmonary arterial pressure and right ventricular dysfunction. PH pathogenesis involves extensive pulmonary vascular remodeling precipitated, at least in part, by endothelial reprogramming. Mounting evidence points to endothelial-to-mesenchymal transition (EndMT) as an important potentiator of endothelial reprogramming in PH, yet progress in dissecting these processes remains limited. Approach and ResultsLung samples from pulmonary arterial hypertension (PAH) patients and two rodent models of PH were used. Expression of the scaffolding protein ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50, or NHERF1) was downregulated in PAH patient pulmonary arteries and isolated pulmonary arterial endothelial cells (PAECs), and in PH animal lung tissue and mouse isolated PAECs. In human PAECs in vitro, EBP50 was downregulated by PH-relevant stimuli, hypoxia and proinflammatory cytokine interleukin-1 beta (IL-1{beta}). Phenocopy of EBP50 reduction in PAECs time-dependently increased expression and nuclear abundance of EndMT transcription factors Snail and Zeb1, and potentiated hypoxia-driven upregulation of Slug. Loss of EBP50 also drove expression of mesenchymal markers S100A4, fibronectin, N-cadherin, and transgelin (SM22), and inhibited cell proliferation and barrier function. In vivo studies on female EBP50+/- mice demonstrated that downregulation of EBP50 exacerbated the chronic hypoxia-induced rise in RV maximum pressure. ConclusionsThese data identify EBP50 as a key regulator of EndMT in PH whose expression is downregulated in PH patient pulmonary endothelium and whose partial deletion exacerbates PH disease manifestations in rodents, opening doors for future therapeutic strategies to target EBP50 restoration to reverse PH.

cell biology↗

bioRxiv2020

Bromodomain protein inhibition protects β-cells from cytokine-induced death and dysfunction via antagonism of NF-κB pathway.

Cytokine induced {beta}-cell apoptosis is the major pathogenic mechanism in type 1 diabetes (T1D). Despite significant advances in understanding underlying mechanisms, few drugs have been translated to protect {beta}-cells in T1D. Epigenetic modulators such as bromodomain-containing BET (Bromo- and Extra-Terminal) proteins are important regulators of immune responses. Pre-clinical studies have demonstrated a protective effect of BET inhibitors in NOD (non-obese diabetes) mouse model of T1D. However, the role of BET proteins in {beta}-cell function in response to cytokines is unknown. Here we demonstrate that I-BET, a BET protein inhibitor, protected {beta}-cells from cytokine induced dysfunction and death. In vivo administration of I-BET to mice exposed to low-dose STZ (streptozotocin), a model of T1D, significantly reduced {beta}-cell apoptosis and preserved {beta}-cell mass, suggesting a cytoprotective function of I-BET. Furthermore, human islets treated with I-BET displayed better glucose stimulated insulin secretion compared to controls, when exposed to cytokines. Mechanistically, RNA-Seq analysis revealed I-BET treatment suppressed pathways involved in apoptosis, including NF-kB signaling, while maintaining the expression of genes critical for {beta}-cell function, such as Pdx1 and Ins1. Taken together, this study demonstrates that I-BET is effective in protecting {beta}-cells from cytokine-induced dysfunction and apoptosis, and may have potential therapeutic values in T1D.

molecular biology↗

bioRxiv2020

Tead1 reciprocally regulates adult β-cell proliferation and function

Proliferative quiescence in {beta}-cells is required to maintain functional competence. While this presents a significant hurdle in regenerative therapy for diabetes, the molecular underpinnings of this reciprocal relationship remain unclear. Here, we demonstrate that TEAD1, the transcription effector of the mammalian-Hippo pathway, drives developmental stage-specific {beta}-cell proliferative capacity in conjunction with its functional maturation. TEAD1 promotes adult {beta}-cell mature identity by direct transcriptional control of a network of critical {beta}-cell transcription factors, including, Pdx1, Nkx6.1, and MafA, while its regulation of Cdkn2a maintains proliferative quiescence. Consequently, mice with either constitutive or inducible genetic deletion of TEAD1 in {beta}-cells developed overt diabetes due to a severe loss of secretory function despite induction of proliferation. Furthermore, we show that TEAD1 has a similar regulatory role in human {beta}-cells. Consistent with this function in {beta}-cells, variants in TEAD1 have been associated with c-HOMA-B in American Indians. We propose that TEAD1 is an essential intrinsic molecular switch coordinating adult {beta}-cell proliferative quiescence with mature identity and its differential modulation may be necessary to overcome the challenge of inducing proliferation with functional competence in human beta cells.

molecular biology↗