Biology subjects

Bhatt, D. P.

Publications and source records attributed to Bhatt, D. P..

6 recordsLinked to original sources

bioRxiv2025

Mapping of the hSOX10 protein interactome in human melanoma

The transcription factor SOX10 is a central regulator of melanoma biology, influencing tumor initiation, progression, phenotypic plasticity, and therapeutic resistance. However, the molecular mechanisms underlying these diverse functions remain incompletely understood. To elucidate the protein-protein interactions (PPIs) that mediate SOX10 activity in melanoma, we mapped the human SOX10 (hSOX10) interactome for the first time in human melanoma cells (A375 line). Given the challenges of capturing transient and weak transcription factor interactions, we employed miniTurbo (mT) proximity-dependent biotinylation coupled with mass spectrometry (MS). Stable A375 cell lines expressing N- and C-terminal mT-tagged hSOX10 fusion proteins at physiologically relevant levels were generated, enabling unbiased biotinylation and MS-based identification of candidate interacting proteins. This approach revealed 847 melanoma-enriched candidate interactors, including 213 high-confidence hits. These included both known hSOX10 partners and previously unidentified putative interactors. Functional annotation of our hSOX10 interactome highlighted associations with chromatin remodeling, transcriptional regulation, SUMOylation, and DNA damage response pathways. Western blot validation of select interactors supported the robustness of our dataset. This first comprehensive map of the hSOX10 interactome in melanoma provides a critical foundation for future investigations into SOX10-driven transcriptional networks and their potential as therapeutic targets and biomarkers in melanoma.

cancer biology↗

bioRxiv2024

Suppression of NRF2-dependent cancer growth by a covalent allosteric molecular glue

The NRF2 transcription factor is constitutively active in cancer where it functions to maintain oxidative homeostasis and reprogram cellular metabolism. NRF2-active tumors exhibit NRF2-dependency and resistance to chemo/radiotherapy. Here we characterize VVD-065, a first-in-class NRF2 inhibitor that acts via an unprecedented allosteric molecular glue mechanism. In the absence of stress or mutation, NRF2 is rapidly degraded by the KEAP1-CUL3 ubiquitin-ligase complex. VVD-065 specifically and covalently engages C151 on KEAP1, which in turn promotes KEAP1-CUL3 complex formation, leading to enhancement of NRF2 degradation. Previously reported C151-directed compounds decrease KEAP1-CUL3 interactions and stabilize NRF2, thus establishing KEAP1_C151 as a tunable regulator of the KEAP1-CUL3 complex and NRF2 stability. VVD-065 inhibited NRF2-dependent tumor growth and sensitized cancers to chemo/radiotherapy, supporting an open Phase I clinical trial (NCT05954312).

cancer biology↗

bioRxiv2021

Protein proximity networks and functional evaluation of the Casein Kinase 1 γ family reveals unique roles for CK1γ3 in WNT signaling

The WNT/{beta}-catenin signaling pathway is evolutionarily conserved and controls normal embryonic development, adult tissue homeostasis and regeneration. Aberrant activation or suppression of WNT signaling contributes to cancer initiation and progression, developmental disorders, neurodegeneration, and bone disease. Despite great need and more than 40 years of research, targeted therapies for the WNT pathway have yet to be fully realized. Kinases are exceptionally druggable and occupy key nodes within the WNT signaling network, but several pathway-relevant kinases remain understudied and dark. Here we studied the function of the CSNK1{gamma} subfamily of human kinases. miniTurbo-based proximity biotinylation and mass spectrometry analysis of CSNK1{gamma}1, CSNK1{gamma}2, and CSNK1{gamma}3 revealed numerous established components of the {beta}-catenin- dependent and independent WNT signaling pathway, as well as novel interactors. In gain-of- function experiments leveraging a panel of transcriptional reporters, CSNK1{gamma}3 but not CSNK1{gamma}1 or CSNK1{gamma}2 activated {beta}-catenin-dependent WNT signaling and the Notch pathway. Within the family, CSNK1{gamma}3 expression uniquely induced LRP6 phosphorylation. Conversely, siRNA- mediated silencing of CSNK1{gamma}3 alone had no impact on WNT signaling, though co-silencing of all three family members decreased WNT pathway activity. We characterized two moderately selective and potent small molecule inhibitors of the CSNK1{gamma} family. These inhibitors and a CSNK1{gamma}3 kinase dead mutant suppressed but did not eliminate WNT-driven LRP6 phosphorylation and {beta}-catenin stabilization. Our data suggest that while CSNK1{gamma}3 expression uniquely drives pathway activity, potential functional redundancy within the family necessitates loss of all three family members to suppress the WNT signaling pathway.

cell biology↗

bioRxiv2021

Systematic analysis of SARS-CoV-2 infection of an ACE2-negative human airway cell

Established in vitro models for SARS-CoV-2 infection are limited and include cell lines of non-human origin and those engineered to overexpress ACE2, the cognate host cell receptor. We identified human H522 lung adenocarcinoma cells as naturally permissive to SARS-CoV-2 infection despite complete absence of ACE2. Infection of H522 cells required the SARS-CoV-2 spike protein, though in contrast to ACE2-dependent models, spike alone was not sufficient for H522 infection. Temporally resolved transcriptomic and proteomic profiling revealed alterations in cell cycle and the antiviral host cell response, including MDA5-dependent activation of type-I interferon signaling. Focused chemical screens point to important roles for clathrin-mediated endocytosis and endosomal cathepsins in SARS-CoV-2 infection of H522 cells. These findings imply the utilization of an alternative SARS-CoV-2 host cell receptor which may impact tropism of SARS-CoV-2 and consequently human disease pathogenesis.

microbiology↗

bioRxiv2020

Early-life mitochondrial DNA damage results in lifelong deficits in energy production mediated by redox signaling in Caenorhabditis elegans

The consequences of damage to the mitochondrial genome (mtDNA) are poorly understood, although mtDNA is more susceptible to damage than nuclear DNA (nucDNA), and many environmental toxicants target the mitochondria. Reports from the toxicological literature suggest that exposure to early-life mitochondrial damage could lead to deleterious consequences later in life (the "Developmental Origins of Health and Disease" paradigm) but reports from other fields often report beneficial ("mitohormetic") responses to such damage. Here, we test the effects of low (causing no change in lifespan) levels of ultraviolet C (UVC)-induced, irreparable mtDNA damage during early development in Caenorhabditis elegans. This exposure led to life-long reductions in mtDNA copy number and steady-state ATP levels, accompanied by increased oxygen consumption and altered metabolite profiles, suggesting inefficient mitochondrial function. Exposed nematodes were also developmentally delayed, reached smaller adult size, and were rendered more susceptible to subsequent exposure to chemical mitotoxicants. Metabolomic and genetic analysis of key signaling and metabolic pathways supported redox signaling during early development as a mechanism for establishing these persistent alterations. Our results highlight the importance of early-life exposures to environmental pollutants, especially in the context of exposure to chemicals that target mitochondria.

cell biology↗

bioRxiv2020

Deglutarylation of GCDH by SIRT5 controls lysine metabolism in mice

ABSTRACTA wide range of protein acyl modifications has been identified on enzymes across various metabolic processes; however, the impact of these modifications remains poorly understood. Protein glutarylation is a recently identified modification that can be non-enzymatically driven by glutaryl-CoA. In mammalian systems, this unique metabolite is only produced in the lysine and tryptophan oxidative pathways. To better understand the biology of protein glutarylation, we studied the relationship between enzymes within the lysine/tryptophan catabolic pathways, protein glutarylation, and regulation by the deglutarylating enzyme Sirtuin 5 (SIRT5). Here, we identify glutarylation on the lysine oxidation pathway enzyme glutaryl-CoA dehydrogenase (GCDH). We show increased GCDH glutarylation when glutaryl-CoA production is stimulated by lysine catabolism. Our data reveal glutarylation of GCDH impacts its function, ultimately decreasing lysine oxidation. We then demonstrate the ability of SIRT5 to deglutarylate GCDH, restoring its enzymatic activity. Finally, metabolomic and bioinformatic analyses indicate an expanded role for SIRT5 in regulating amino acid metabolism. Together, these data support a model whereby a feedback loop exists within the lysine/tryptophan oxidation pathway, in which glutaryl-CoA is produced, in turn inhibiting GCDH function via glutaryl modification of GCDH lysine residues, and can be relieved by SIRT5 deacylation activity.View Full Text

biochemistry↗