Biology subjects

Vignane, T.

Publications and source records attributed to Vignane, T..

3 recordsLinked to original sources

bioRxiv2024

Endogenously produced hydrogen cyanide serves as a novel mammalian gasotransmitter

Small, gaseous molecules, known as gasotransmitters (NO, CO, H2S), are produced endogenously in mammalian cells and serve important biological roles. Hydrogen cyanide, traditionally considered a cytotoxic molecule in mammals, serves as an endogenous mediator in several plants and bacterial species. Here we show that low concentrations of cyanide are generated endogenously in mouse liver and human hepatocytes. Cyanide production is stimulated by glycine, occurs at the low pH of lysosomes and requires peroxidase activity. Cyanide, in turn, is detectable in several cellular compartments. Cyanide is also detectable basally in the blood of mice; its levels increase after treatment of the animals with glycine. Rhodanese activity regulates endogenous cyanide levels. Cyanide, when generated endogenously at an optimal level, exerts stimulatory effects on mitochondrial bioenergetics, cell metabolism and cell proliferation. Dysregulation of endogenous cyanide, either below or above optimal levels, impairs cellular bioenergetics. The regulatory effects of cyanide are in part mediated by posttranslational modification of cysteine residues via protein cyanylation; cyanylated protein residues can be detected basally, and increase after treatment with glycine. Controlled low-dose cyanide supplementation exhibits cytoprotective effects, as demonstrated in hypoxia and reoxygenation models in vitro and in vivo. However, pathologically elevated cyanide production, as demonstrated in nonketotic hyperglycinemia - an autosomal recessive disease of glycine metabolism - is deleterious to the cells.

biochemistry↗

bioRxiv2023

Protein tyrosine phosphatase receptor kappa regulates glycolysis and de novo lipogenesis to promote hepatocyte metabolic reprogramming in obesity

Fat accumulation, de novo lipogenesis, and glycolysis are key drivers of hepatocyte reprogramming and the consequent metabolic dysfunction-associated steatotic liver disease (MASLD). Here we report that obesity leads to dysregulated expression of hepatic protein-tyrosine phosphatases (PTPs). PTPRK was found to be increased in steatotic hepatocytes in both humans and mice, and positively correlated with PPAR{gamma}-induced lipogenic signalling. High-fat-fed PTPRK knockout mice displayed reduced weight gain and hepatic fat accumulation. Phosphoproteomic analysis in primary hepatocytes and hepatic metabolomics identified fructose-1,6-bisphosphatase 1 and glycolysis as PTPRK targets in metabolic reprogramming. Silencing PTPRK in hepatoma cell lines resulted in reduced colony-forming ability and PTPRK knockout mice developed smaller tumours after diethylnitrosamine-induced hepatocarcinogenesis. Our study defines a novel role for PTPRK in regulating hepatic glycolysis, lipid metabolism, and tumour development. PTPRK inhibition may provide therapeutic possibilities in obesity-associated liver diseases. HighlightsO_LIHepatic receptor-type PTPs are increased in MASLD C_LIO_LIPTPRK is expressed in hepatocytes and upregulated in obesity C_LIO_LIPTPRK deficiency reduces body fat mass and liver steatosis in diet-induced obesity C_LIO_LIPTPRK regulates hepatic glycolysis and lipogenesis, promoting tumorigenesis C_LI

cancer biology↗

bioRxiv2023

Protein thiol alterations drive aberrant phase separation in aging

Cellular homeostasis relies on precise regulation through chemical processes, such as protein posttranslational modifications (PTM) and physical processes, such as biomolecular condensation. Aging disrupts this balance, increasing susceptibility to diseases and death. However, the mechanisms behind age-related pathogenesis remain elusive. In this study, we dissected various cysteine PTMs and their impact on protein-mediated biomolecular condensation in aging brain. Our findings reveal that aging is associated with significant remodeling of cysteine PTMs, which impacts protein ability to participate in liquid-liquid phase separation (LLPS). Specifically, aging leads to an increase in protein sulfenylation and sulfonylation, which promotes LLPS and through conformational change increases the propensity of proteins to aggregate. Protein persulfidation, a protective thiol modification, prevents this by causing condensate dissolution. We demonstrate that age-induced alterations in cysteine PTMs influence the LLPS properties of synapsin-1 and G3BP2, resulting in disruptions in neurotransmitter release and stress granule formation, respectively. Additionally, our study uncovers that GAPDH is susceptible to LLPS and cysteine sulfonylation exacerbates its transition from condensates to aggregates. Mice deficient in cystathionine gamma-lyase, a pro-longevity gene that regulates intracellular persulfide levels, exhibit a shorter lifespan and spontaneous development of neurofibrillary tangles.

biochemistry↗