Is Homocysteine a Biomarker of Environmental Health Risk and Epigenetic-DNA Methylation: Links to Cardiovascular Pathogenesis and B Vitamins

HomocysteineHomocysteine (Hcy), metabolite of essential amino acid methionine, is a non-proteinogenic sulfhydryl amino acid, which cell physiologically produce in one-carbon metabolismOne-carbon metabolism process. During that process transfer of the methyl group is carried out, representing typical example of environment-gene interaction. Hcy-related vitaminsVitamins (B2, B6, B9/folate, B12), and various enzymes and gasotransmitters participate in one-carbon metabolism. HyperhomocysteinemiaHyperhomocysteinemia (HHcy) (HHcy) can be physiologically dependent (agingAging, male sex, increased muscle mass) or consequence of genetic reasons (polymorphisms or defects of CBS or MTHFR enzymes), bad lifestyle habits (nutrition, drugs, pollutantsPollutants, stressStress, physical inactivity etc.), and in certain clinical conditions (cardiovascular diseasesCardiovascular diseases, neurodegenerative diseases, kidney diseases, hypothyroidism and hyperproliferative diseases). Elevated levels of Hcy alters DNA methylationDNA methylation, but cause cellular toxicity (especially thiolactone metabolites) including cardiotoxicityCardiotoxicity and neurotoxicity, ROS and RNS stress, oxidation of LDL, inflammationInflammation, apoptosisApoptosis, certain enzymes inhibition, cellular respiration inhibition, protein structure and functional changes (protein S- and N-homocysteinylation).