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Joshi, K.

Publications and source records attributed to Joshi, K..

41 records · Page 3Linked to original sources

Schizophrenia and autism-associated mutations and disrupted m6A signal by YTHDF1 cause defects in microtubule function and neurodevelopment

Subcellular mRNA localization and local translation are crucial for spatially regulated gene expression in neurons. However, the precise mechanisms governing the selective transport and translation of mRNAs contributing to processes such as axonal growth and branching are only partially understood. Here, we present evidence of N6-methyladenosine (m6A)-mediated translational control of the RNA-binding protein, APC, influencing cytoskeletal dynamics at the growth cone. Our findings demonstrate that m6A modifications occur on Apc mRNA, facilitating its recognition by YTHDF1 to promote APC translation in neuronal somata. Additionally, we observe that disrupting the m6A pathway impairs the transport and local translation of {beta}-actin mRNA in the axon and growth cones, a deficiency that can be rescued by the exogenous expression of APC protein in cultured neurons. Furthermore, we establish the essential role of YTHDF1 in axon development, particularly in callosal projection neurons during cortical development. Our findings suggest a novel mechanism involving m6A-mediated regulation of APC protein translation, linking epitranscriptomics to axonal mRNA targeting, cytoskeletal dynamics, and axon development.

neuroscience↗

Subcellular mRNA localization and local translation of Arhgap11a in radial glial cells regulates cortical development

mRNA localization and local translation enable exquisite spatial and temporal control of gene expression, particularly in highly polarized and elongated cells. These features are especially prominent in radial glial cells (RGCs), which serve as neural and glial precursors of the developing cerebral cortex, and scaffolds for migrating neurons. Yet the mechanisms by which distinct sub-cellular compartments of RGCs accomplish their diverse functions are poorly understood. Here, we demonstrate that subcellular RNA localization and translation of the RhoGAP Arhgap11a controls RGC morphology and mediates cortical cytoarchitecture. Arhgap11a mRNA and protein exhibit conserved localization to RGC basal structures in mice and humans, conferred by a 5'UTR cis-element. Proper RGC morphology relies upon active Arhgap11a mRNA transport and localization to basal structures, where ARHGAP11A is locally synthesized. Thus, RhoA activity is spatially and acutely activated via local translation in RGCs to promote neuron positioning and cortical cytoarchitecture. Altogether, our study demonstrates that mRNA localization and local translation mediate compartmentalization of neural progenitor functions to control brain development. HighlightsO_LIArhgap11a in radial glia non-cell autonomously promotes neuronal migration and lamination C_LIO_LIArhgap11a mRNA localizes to radial glial endfeet via a 5 UTR cis element C_LIO_LIARHGAP11A expression in basal process and endfeet depends upon its localized mRNA C_LIO_LILocalized mRNA and RhoA-GAP activity in endfeet control radial glial morphology C_LI

neuroscience↗

LC/MS-QToF Profiling, Anti-Diabetic and Anti-Adipogenic potential of Divya MadhuKalp: A Novel Herbo-mineral Formulation

The incidence rate of diabetes mellitus is increasing worldwide. Herbal formulations have recently gained importance as an alternative therapeutic option in controlling diabetes without causing any side effects. In the present study, we have demonstrated maintenance of glycemic homeostasis and anti-adipogenic potential of a herbo-mineral formulation Divya MadhuKalp (DMK). Initially, we evaluated the presence of bioactive compounds in DMK using LC/MS-QToF analysis. In-vitro analysis of DMK in L6 (skeletal muscle) cells showed a significant increase in cellular glucose uptake. Similarly, a human equivalent dose of DMK significantly reduced blood glucose level in normoglycemic and oral glucose tolerance rat model. DMK extract also inhibited formation of advanced glycation end product and showed anti--glucosidase activity. Further analysis of DMK in 3T3 L1 pre-adipocytes demonstrated anti-adipogenic activity through reduction in intracellular lipid accumulation and triglyceride contents along with downregulation of major adipogenic transcriptional factors (PPAR-{gamma} and C/EBP) and, adipocytes marker genes (LPL, AP2 and adiponectin). In conclusion, DMK exhibited anti-diabetic and anti-adipogenic activities by synergistic effect of its bioactive compounds and can be considered as a potent herbo-mineral formulation for treating metabolic diseases.

cell biology↗

Cellular internalization of Godanti Bhasma (anhydrous CaSO4) induces massive cytoplasmic reversible vacuolation and survival response of mammalian cells.

Bhasmas are Ayurvedic herbo-mineral formulations that have been used since ancient times for therapeutic benefits. Godanti Bhasma (GB) is an anhydrous calcium sulfate preparation processed by heating of gypsum powder with herbal extracts. Thermo-transformation of gypsum into the anhydrous GB was confirmed by Raman and FT-IR spectroscopy. GB particle showed size range of 0.5-5 {micro}m and neutral surface charge. Exposure to mammalian cells with GB particles showed massive vacuolation in their cytoplasm. Interestingly, no vacuolation was observed with parent gypsum particle. The result indicated that the cytoplasmic vacuolation by GB was due to its unique physicochemical property obtained during the thermo-transformation of gypsum. Using lysosomal inhibitors Bafilomycin A1 (BFA1) and Chloroquine (CQ), the process of vacuole formation was suppressed indicating GB induced vacuolation require acidic environment. The GB induced vacuolation was also found to follow dose and time dependent manner. Vacuolation often accompany with the sign of cell death whereas, in our study, massive vacuolation by GB did not induce any cell death. Moreover, GB treated cells survive with massive vacuolar process, which was reversed following post-treatment with vacuole inhibitors in GB treated cells, suggesting normal vacuolar function is essential for cell survival. Treatment of cells with GB was also found to induce translocation of LC3 protein from the nucleus to vacuolar membrane, indicating LC3 associated phagocytosis (LAP) is involved in the vacuolar process. Interestingly, the LAP function was found to be reversed in the cells treated with vacuole inhibitors. Our results provide a mechanistic correlation with GB induced vacuolation and associated LAP function, essential for cell survival. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=164 SRC="FIGDIR/small/930594v3_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@169ed89org.highwire.dtl.DTLVardef@169c339org.highwire.dtl.DTLVardef@900004org.highwire.dtl.DTLVardef@1f13823_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

Pan-cancer deconvolution of cellular composition identifies molecular correlates of antitumour immunity and checkpoint blockade response

The nature and extent of immune cell infiltration into solid tumours are key determinants of therapeutic response. Here, using a novel DNA methylation-based approach to tumour cell fraction deconvolution, we report the integrated analysis of tumour composition and genomics across a wide spectrum of solid cancers. Initially studying head and neck squamous cell carcinoma, we identify two distinct tumour subgroups: immune hot and immune cold, which display differing prognosis, mutation burden, cytokine signalling, cytolytic activity, and oncogenic driver events. We demonstrate the existence of such tumour subgroups pan-cancer, link clonal-neoantigen burden to hot tumours, and show that transcriptional signatures of hot tumours are selectively engaged in immunotherapy responders. We also find that treatment-naive hot tumours are markedly enriched for known immune-resistance genomic alterations and define a catalogue of novel and known mediators of active antitumour immunity, deriving biomarkers and potential targets for precision immunotherapy.

cancer biology↗