Oxidative stress, thiol redox signaling methods in epigenetics.

Epigenetics is referred to as heritable changes in gene expression but not encoded in the DNA sequence itself which occurs during posttranslational modifications in DNA and histones. These epigenetic modifications include histone acetylation, deacetylation, and methylation. Acetylation by histone acetyltransferases (HATs) of specific lysine residues on the N-terminal tail of core histones results in uncoiling of the DNA and increased accessibility to transcription factor binding. In contrast, histone deacetylation by histone deacetylases (HDACs) represses gene transcription by promoting DNA winding thereby limiting access to transcription factors. Reactive oxygen species (ROS) are involved in cellular redox alterations, such as amplification of proinflammatory and immunological responses, signaling pathways, activation of transcription factors (NF-kappaB and AP-1), chromatin remodeling (histone acetylation and deacetylation), histone/protein deacetylation by sirtuin 1 (SIRT1) and gene expression. The glutathione redox status plays an important role in protein modifications and signaling pathways, including effects on redox-sensitive transcription factors. Protein S-glutathiolation and mixed disulfide formation as candidate mechanisms for protein regulation during intracellular oxidative stress have gained a renewed impetus in view of their involvements in redox regulation of signaling proteins. A variety of methods are applied to study the epigenetic processes to elucidate the molecular mysteries underlying epigenetic inheritance. These include chromatin immunoprecipitation (ChIP), which is a powerful tool to study protein-DNA interaction and is widely used in many fields to study protein associated with chromatin, such as histone and its isoforms and transcription factors, across a defined DNA domain. Here, we describe some of the contemporary methods used to study oxidative stress and thiol redox signaling involved in epigenetic (histone acetylation, deacetylation, and methylation) and chromatin remodeling (HAT, HDAC, SIRT1) research.