Biology subjects

Tanwar, A.

Publications and source records attributed to Tanwar, A..

6 recordsLinked to original sources

bioRxiv2026

Alcohol-Evoked Calcium Signaling Drives Distinct Responses in Zebrafish Hepatocytes and Pancreatic Acinar Cells

Alcohol exposure perturbs intracellular calcium (Ca2+) homeostasis in digestive organs, yet whether common or organ-specific mechanisms coordinate this response remains unclear. Using an acute ethanol paradigm in zebrafish, single-cell transcriptomics revealed broad up-regulation of Ca2+-signaling genes in hepatocytes and pancreatic acinar cells. In vivo Ca2+ buffering with SpiCee, a genetically encoded chelator, demonstrated a shared requirement for Ca2+ flux: in hepatocytes, lineage-restricted buffering was associated with pronounced cytoplasmic vacuolation composed of lipid-negative vesicles, consistent with stalled lysosomes or autophagosomes; in pancreatic acinar cells, it was associated with accumulation of aggregated/misfolded protein. Mechanistic experiments using pharmacological inhibitors implicated distinct molecular contributors in each tissue. In hepatocytes, inhibition of Pikfyve or its downstream effector, the lysosomal Ca2+ channel TRPML1, phenocopied Ca2+ buffering. While, in acinar cells, Pick1 inhibition produced analogous associations. These data position Pikfyve and Pick1 as organ-specific components linked to the Ca2+-coupled alcohol response. Notably, pharmacologic activation of TRPML1 in hepatocytes recapitulated alcohol-like Ca2+ dynamics but increased macrophage recruitment and cell death, indicating that Ca2+ signaling is required for the alcohol response yet can be detrimental when amplified. Together, our results support a model in which alcohol elicits a shared Ca2+ dynamics across liver and pancreas, modulated by tissue-specific molecular nodes.

cell 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 translational checkpoint couples proline sensing to mitochondrial proline catabolism in Candida glabrata

Proline catabolism represents a central metabolic and regulatory hub integrating nutrient sensing, stress adaptation, and energy production across diverse organisms. Despite its biological importance, the regulatory mechanisms controlling proline catabolism remain poorly understood in eukaryotic microbes. Here, we describe the transcriptional and translational coordination to catabolize the proline to maintain the cellular homeostasis under stress in the human fungal pathogen Candida glabrata. We identified proline utilisation trigger global translation repression to activates the stress-sensing kinase Gcn2, which phosphorylates eIF2, thereby promoting the activation of the transcription factor Gcn4. Activated Gcn4 upregulates the transcription factor Put3 and the proline transporter Put4. Put3 orchestrates expression of the mitochondrial catabolic enzymes Put1 and Put2, ensuring efficient proline utilization, mitochondrial function, and redox balance. Genetic disruption of PUT3 abolishes proline utilization, impairs mitochondrial function, and severely compromises cellular fitness. Importantly, Put3-mediated proline catabolism is also critical for C. glabrata survival within macrophages and for virulence in systemic infection models. These findings reveal a mechanistic link between proline catabolism, translational regulation, and amino acid sensing in C. glabrata. We propose a regulatory cascade wherein Gcn2-Gcn4-Put3 signaling aligns translational reprogramming with metabolic demands to optimize proline utilization. Thus, this study establishes proline catabolism as a signaling-driven adaptive mechanism essential for fungal metabolism and persistence, rather than merely a nutritional pathway. AUTHOR SUMMARYProline is a versatile amino acid that is essential for cellular metabolism, signaling, stress adaptation, and redox equilibrium. Proline catabolism has been implicated in cancer biology and is increasingly recognized as a key determinant of virulence in diverse pathogens. Although the enzymatic processes of proline use are well characterized, the regulatory mechanisms that sense proline availability and coordinate its metabolic integration remain poorly understood. Here, we identify a hitherto unknown regulatory axis linking proline catabolism to translational reprogramming in Candida glabrata, which seems to be similarly present in numerous fungi. We demonstrate that proline utilization triggers global translational repression via Gcn2-dependent phosphorylation of eIF2, thereby activating the transcription factor Gcn4. Gcn4 is essential for proline utilization, as it controls the expression of PUT3 and PUT4. Notably, PUT3 has no known human counterpart. Our findings establish proline as a metabolic signal that couples translational control to virulence, revealing new opportunities for antifungal intervention.

microbiology↗

bioRxiv2025

Orai3 orchestrates gemcitabine resistance in pancreatic cancer via NFATc1-SLIT3 axis

Pancreatic Cancer (PC) is one of the most aggressive cancers and is associated with poor prognosis. Gemcitabine is the first-line chemotherapy for PC. While gemcitabine-based regimes offer survival benefits, the acquired gemcitabine resistance leads to reoccurrence, metastasis and the long-term survival rate remains dismal. Although there is substantial clinical evidence for gemcitabine resistance, the cellular and molecular mechanisms driving gemcitabine resistance remain largely unappreciated. Here, we reveal that Orai3, a Ca2+ selective channel, is a crucial driver of gemcitabine resistance. We demonstrate that Orai3 is upregulated in gemcitabine-resistant PC cells. Orai3 silencing in these cells decreases proliferation, induces cell cycle arrest, enhances apoptosis, and moderates stemness characteristics. Notably, studies in zebrafish model corroborate the significance of Orai3 in gemcitabine resistance in vivo. Mechanistically, our unbiased RNA-seq analysis coupled with robust functional studies show that SLIT3 works downstream of Orai3 to drive gemcitabine resistance. Finally, we report that NFATc1 transcription factor bridges Orai3 to SLIT3 transcription. Taken together, this study identifies Orai3 as a key orchestrator of gemcitabine resistance and uncovers a unique Orai3-NFATc1-SLIT3 signaling module that drives chemoresistance. Hence, this work reveals Orai3 as a promising target for synergistic therapeutic approach to combat chemoresistance. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=197 HEIGHT=200 SRC="FIGDIR/small/671673v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@16fea2org.highwire.dtl.DTLVardef@1a77a3forg.highwire.dtl.DTLVardef@4aef28org.highwire.dtl.DTLVardef@19b62a3_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights{Rightarrow} Orai3 is upregulated in gemcitabine-resistant pancreatic cancer cells {Rightarrow}Orai3 is essential for chemo-sensitivity, migration, invasion and stemness in vitro {Rightarrow}Orai3 regulates metastasis of gemcitabine-resistant pancreatic cancer cells in vivo {Rightarrow}Unbiased RNA-seq reveals that SLIT3 functions downstream of Orai3 to drive gemcitabine resistance {Rightarrow}NFATc1 transcription factor bridges Orai3 to SLIT3 transcription

cancer biology↗

bioRxiv2022

Toroidal displacement of Klebsiella pneumoniae by Pseudomonas aeruginosa is a unique mechanism to avoid competition for iron

Competition for resources is one of the major drivers for evolution and retention of new traits in microbial communities. Quorum-dependent traits of opportunistic human pathogen Pseudomonas aeruginosa allow it to survive and thrive in nature. Here, we report a unique surfactant-driven pushing mechanism that P. aeruginosa employs specifically against Klebsiella pneumoniae. The pushing is accomplished in a manner that is dependent on nutrient limitation and quorum sensing. We find that P. aeruginosa employs neither proteases nor toxic secondary metabolites against K. pneumoniae. Rhamnolipid biosurfactant appears to be the only factor required to displace Klebsiella effectively. Both rhamnolipid production and the pushing ability of P. aeruginosa are suppressed by iron supplementation. We show that both these bacteria produce several siderophores in minimal medium and rapidly deplete iron. Under these conditions, P. aeruginosa pushes Klebsiella away from the substratum using rhamnolipid, reducing the competition for iron. Our study describes a unique quorum and iron-responsive mechanism in P. aeruginosa to support its own growth during resource competition.

microbiology↗

bioRxiv2022

Synergistic Regulation of Notch Signaling by Different O-Glycans Promotes Hematopoiesis

Glycosylation of Notch receptors by O-fucose glycans regulates Notch ligand binding and Notch signaling during hematopoiesis. However, roles in hematopoiesis for other O-glycans that modify Notch receptors have not been determined. Here we show that the EGF domain-specific GlcNAc transferase EOGT is required in mice for the optimal production of lymphoid and myeloid cells. The phenotype of Eogt null mice was largely cell-autonomous, and Notch target gene expression was reduced in T cell progenitors. Moreover, EOGT supported residual Notch signaling following conditional deletion of Pofut1 in hematopoietic stem cells (HSC). Eogt:Pofut1 double mutant HSC had more severe defects in bone marrow, and in T and B cell development in thymus and spleen, compared to deletion of Pofut1 alone. The combined results show that EOGT and O-GlcNAc glycans are required for optimal hematopoiesis and T and B cell development, and that they act synergistically with POFUT1 and O-fucose glycans to promote Notch signaling in lymphoid and myeloid differentiation. Key pointsO_LIO-GlcNAc glycans and EOGT promote lymphopoiesis and myelopoiesis C_LIO_LIEOGT supports Notch signaling in the absence of POFUT1 and O-fucose glycans C_LI

immunology↗