Biology subjects

Joshi, M. B.

Publications and source records attributed to Joshi, M. B..

5 recordsLinked to original sources

bioRxiv2026

Protein import-driven mitochondrial hyperactivation dictates angiogenesis independently of HIF-1α

Angiogenesis is essential for sustained neoplastic progression, yet its initiation has largely been framed through hypoxia-dependent HIF signalling. In OXPHOS driven tumours, how mitochondrial function contributes to angiogenic induction remains poorly understood. Here, we uncover a non-canonical mechanism linking tumour cell mitochondrial hyperactivity to a pro-angiogenic response. Mitochondrial function critically depends on the import of nuclear-encoded proteins, largely mediated by TIM23 translocase. We found Timm44, the central scaffold of this translocase, to be broadly upregulated across angiogenesis-dependent malignancies. Using gain-of-function system that recapitulate tumour-associated Timm44 amplification, we enhanced mitochondrial protein import capacity, thereby remodelling mitochondrial gene expression and driving hyperactivation of the electron transport chain, particularly Complex I. This hyperactive mitochondrial state generated a signalling-competent ROS-enrich environment that induces VEGFA expression independently of HIF-1 stabilization, via a redox-licensed TRX-ASK1-p38MAPK-SP1 axis, thereby promoting endothelial sprouting and proliferation. These findings define protein import-driven mitochondrial hyperfunction as an alternative driver of tumour angiogenesis, extending current paradigms beyond classical hypoxia-dependent mechanisms and highlighting new therapeutic vulnerabilities.

cancer biology↗

bioRxiv2024

Hydrogen sulfide (H2S) coordinates redox balance, carbon metabolism, and mitochondrial bioenergetics to suppress SARS-CoV-2 infection.

Viruses exploit host metabolism for replication and immune-regulation. Understanding how SARS-CoV-2 alters the host metabolism may lead to treatments for COVID-19. We report that a ubiquitous gaseous molecule, hydrogen sulfide (H2S), regulates redox, metabolism, and mitochondrial bioenergetics to control SARS-CoV-2. Virus replication is associated with down-regulation of the H2S-producing enzymes cystathionine-{beta}-synthase (CBS), cystathionine-{gamma}-lyase (CTH), and 3-mercaptopyruvate sulfurtransferase (3-MST), resulting in diminished endogenous H2S levels. Inhibition of CTH resulted in SARS-CoV-2 proliferation. A slow-releasing H2S donor, GYY4137, diminished virus replication by inducing Nrf2/Keap1 pathway, restoring redox balance and mitochondrial bioenergetics. Treatment of SARS-CoV-2-infected animals with GYY4137 suppressed viral replication, ameliorated respiratory pathology, and restored antioxidant gene expression. Notably, whole-body plethysmography showed improved pulmonary function variables, including pulmonary obstruction and end-expiratory pause upon GYY4137 treatment in vivo. Data extend our understanding of H2S-mediated regulation of viral-infections, and open new avenues for investigating the pathogenic mechanisms and therapeutic opportunities for coronavirus-associated disorders.

microbiology↗

bioRxiv2023

Deciphering the Metabolic Shifts in The Hippocampus of Mice Subjected to Near Low Dose Radiation: Insights from Metabolomics and Integrated Multi-omics

Recent years have witnessed a drastic upsurge in neurological disorders, with sporadic cases contributing more than ever to their cause. Radiation exposure through diagnostic or therapeutic routes often results in neurological injuries indicative of neurodegenerative pathogenesis. Nevertheless, the impact of low doses of radiation on the brain remains a subject of extensive discussion, as research findings have presented conflicting evidence regarding potential harm and benefits. In the present study, C57/BL mice were exposed to a whole-body single dose of 0.5 Gy X-ray. Fourteen days after treatment, the animals were euthanized, and the hippocampus was isolated and processed for metabolomic analysis. Statistical and bioinformatic analysis revealed 115 metabolites altered in the radiation-exposed group, while pathway enrichment analysis unveiled alterations in tyrosine, phenylalanine, aminoacyl-tRNA metabolism, arginine biosynthesis, glutathione, arginine, proline metabolism, etc. Furthermore, a multiomics interaction network of the genes and the metabolites was constructed to gather an overview of their interaction with the neighboring genes and metabolites in different pathways. These metabolic pathways correlate with synthesizing neurotransmitters such as dopamine and neurodegenerative diseases such as Alzheimers, Parkinsons, and dementia. The present study findings unveiled metabolomic level regulation of low-dose radiation-induced neurotoxicity and its implication in the pathogenesis of neurological disorders.

neuroscience↗

bioRxiv2022

Detailed investigation on the role of lipid metabolizing enzymes in the pathogenesis of retinopathy of prematurity among preterm infants.

PurposeExtremely preterm infants are at risk of developing retinopathy of prematurity (ROP), characterized by an initial insufficient vascular network development in the retina (due to hyperoxia) that progress to neovascularization and neuroinflammation (hypoxic phase) ultimately leading to partial or total vision loss. Lipid metabolism has been shown to be a significant pathway that is involved in the regulation of angiogenesis, inflammation, and apoptosis in oxygen induced retinopathy mouse model, however, it is not explored in human ROP patients. The present study aimed to explore the association of lipid metabolizing, angiogenic and apoptotic genes with altered lipid metabolites in the ROP patients with different severity. MethodsThe blood, vitreous humor (VH), and fibrovascular membrane (FVM) samples were collected from premature infants diagnosed with ROP and controls. Gene expression of lipid metabolizing enzymes, angiogenesis, and apoptotic genes were performed using semi-quantitative PCR in blood. Lipid metabolites were identified and quantified by LC-MS in VH and were correlated with gene expression. The expression of key lipid metabolizing enzymes in severe stages of ROP was assessed by measuring their expression in FVM by immunohistochemistry. ResultsGenes coding for the lipid metabolizing enzymes such as CYP1B1, CYP2C8, COX2, and ALOX15 were upregulated while EPHX2 responsible for the conversion of epoxide fatty acids into diol fatty acids was significantly downregulated in ROP cases. The increase in the metabolic intermediates generated from the lipid metabolism pathway further confirmed the role of these enzymes in ROP. except for EPHX2 which did not show any change in its activity. The glial cells in the FVM of ROP infants too showed a lack of EPHX2 expression. A significantly higher expression of genes involved in angiogenesis (VEGF165/189, NOTCH1, and APH1B) and apoptosis (CASP3/8) correlated with altered activity of lipid metabolizing enzymes (based on metabolites levels) among ROP cases. ConclusionsLipid metabolism may play a significant role in ROP development and progression. EPHX2 activity is a key step in the metabolic pathway of arachidonic acid that mediates and regulates inflammation and vascular pathology in preterm infants.

genomics↗

bioRxiv2021

Short homology-directed repair using optimized Cas9 in the pathogen Cryptococcus neoformans enables rapid gene deletion and tagging

Cryptococcus neoformans, the most common cause of fungal meningitis, is a basidiomycete haploid budding yeast with a complete sexual cycle. Genome modification by homologous recombination is feasible using biolistic transformation and long homology arms, but the method is arduous and unreliable. Recently, multiple groups have reported the use of CRISPR-Cas9 as an alternative to biolistics, but long homology arms are still necessary, limiting the utility of this method. Since the S. pyogenes Cas9 derivatives used in prior studies were not optimized for expression in C. neoformans, we designed, synthesized, and tested a fully C. neoformans-optimized Cas9. We found that a Cas9 harboring only common C. neoformans codons and a consensus C. neoformans intron together with a TEF1 promoter and terminator and a nuclear localization signal (C. neoformans-optimized CAS9 or "CnoCAS9") reliably enabled genome editing in the widely-used KN99 C. neoformans strain. Furthermore, editing was accomplished using donors harboring short (50 bp) homology arms attached to marker DNAs produced with synthetic oligonucleotides and PCR amplification. We also demonstrated that prior stable integration of CnoCAS9 further enhances both transformation and homologous recombination efficiency; importantly, this manipulation does not impact virulence in animals. We also implemented a universal tagging module harboring a codon-optimized fluorescent protein (mNeonGreen) and a tandem Calmodulin Binding Peptide-2X FLAG Tag that allows for both localization and purification studies of proteins for which the corresponding genes are modified by short homology-directed recombination. These tools enable short-homology genome engineering in C. neoformans.

microbiology↗