Biology subjects

Kozich, V.

Publications and source records attributed to Kozich, V..

3 recordsLinked to original sources

bioRxiv2024

Sulfite oxidase deficiency causes persulfidation loss and H2S release

Sulfite oxidase (SOX) deficiency is a rare inborn error of cysteine metabolism resulting in severe neurological damage. In patients, sulfite accumulates to toxic levels causing a raise in downstream products S-sulfocysteine (SSC), mediating excitotoxicity, and thiosulfate, a catabolic intermediate/product of H2S metabolism. Here, we report a full-body knock-out mouse model for SOX deficiency (SOXD) with a severely impaired phenotype. Amongst the urinary biomarkers, thiosulfate showed a 45-fold accumulation in SOXD mice representing the major excreted S-metabolite. Consistently, we found increased plasma H2S, which was derived from sulfite-induced release from persulfides as demonstrated in vitro and in vivo. Mass spectrometric analysis of total protein persulfidome identified a major loss of persulfidation in 20% of the proteome affecting enzymes in amino acids and fatty acid metabolism. Urinary amino acid profiles indicate metabolic rewiring suggesting partial reversal of the TCA cycle thus identifying a novel contribution of H2S metabolism and persulfidation in SOXD.

biochemistry↗

bioRxiv2022

Cysteine Restriction-Specific Effects of Sulfur Amino Acid Restriction on Lipid Metabolism

Decreasing dietary intake of methionine exerts robust anti-adiposity effects in rodents but modest effects in humans. Since cysteine can be synthesized from methionine, animal diets are formulated by decreasing methionine and eliminating cysteine. Such diets exert both methionine restriction (MR) and cysteine restriction (CR), i.e., sulfur amino acid restriction (SAAR). Contrarily, human diets used in clinical studies did not eliminate cysteine and thus might have exerted only MR. Epidemiological studies positively correlate body adiposity with plasma cysteine but not with methionine, suggesting that CR, but not MR, is responsible for the antiadiposity effects of SAAR in rodents. Whether this is true, and if so, the underlying mechanisms are unknown. Using multiple diets with variable concentrations of methionine and cysteine, we demonstrate that the anti-adiposity effects of SAAR are due to CR. CR increased serinogenesis (serine biosynthesis from non-glucose substrates) by diverting substrates from glyceroneogenesis, essential for fatty acid/triglyceride cycling. Molecular data suggest that the CR results in glutathione depletion, which induces Nrf2 and downstream targets Phgdh (the serine biosynthetic enzyme) and Pepck-M. Using multiple mouse models, we show that the magnitude of SAAR-induced changes in molecular markers depends on dietary fat concentration (60 fat>10% fat), gender (males>females), and age-at-onset (young>adult). Our findings are translationally relevant as we found a negative correlation of plasma serine with triglycerides and metabolic syndrome criteria in a cross-sectional epidemiological study. SAAR-like diets with high polyunsaturated fatty acids increased plasma serine in a short-term human feeding study. Serinogenesis might be a potential target to correct hypertriglyceridemia.

biochemistry↗

bioRxiv2018

A proactive genotype-to-patient-phenotype map for cystathionine beta-synthase

Success in precision medicine depends on our ability to determine which rare human genetic variants have functional effects. Classical homocystinuria--characterized by elevated homocyst(e)ine in plasma and urine--is caused by primarily-rare variants in the cystathionine beta-synthase (CBS) gene. About half of patients respond to vitamin B6 therapy. With early detection in newborns, existing therapies are highly effective. Functional CBS variants, especially those that respond to vitamin B6, can be detected based on their ability to restore growth in yeast cells lacking CYS4 (the yeast ortholog of CBS). This assay has previously been carried out only reactively after first observation of a variant in patients. Here we describe a proactive comprehensive missense variant effect map for human CBS. Together, saturation codon-replacement mutagenesis, en masse growth selection at different vitamin B6 levels, and sequencing yielded a look-up table for CBS missense variant function and vitamin B6-remediability in yeast. The CBS variant effect map identified disease variants and predicted both disease severity (r = 0.82) and human clinical response to vitamin B6 (r = 0.89). Thus, highly-multiplexed cell-based assays can yield proactive maps of variant function and patient response to therapy, even for rare variants not previously seen in the clinic.

genetics↗