Action of valproic acid on chromatin structure and function

Abstract

The action of Valproic Acid (VPA), a histone deacetylase inhibitor, has been investigated in several cell models under various experimental conditions. VPA has also been considered for clinical applications because of its modulating activity on gene expression. VPA affects different types of epigenetic marks through mechanisms that vary, depending on cell types and their physiological/pathological conditions, and which are not fully understood. Described VPA action mechanisms involve interference on levels of histone acetylation with predominance of induction of H3K9 and H4K8 acetylation, DNA demethylation and histone methylation and/or demethylation. Present proposal aims to bring contribution on how different metabolic pathways of the VPA action express at chromatin structural and functional levels in some cell types. The issues addressed are the following: 1. What changes are promoted by VPA at the H3K9/14 acetylation levels that could reflect on differential gene expression in certain genetic pathways of interest in a liver cell model under hyperglycemic microenvironment? 2. What is the level of DNA methylation that is affected by VPA in cells where this drug inhibits histone deacetylases and promotes H3K9 and H4K8 acetylation and chromatin remodeling, and how this phenomenon works (passive or active via)? 3. By what mechanism VPA allows unraveling of heterochromatic bodies without involvement of H3K9 and H4K8 acetylation? The methodology will involve ChIP-seq and RNA-seq assays, immunoassays, bioinformatics, image analysis, flow cytometry, confocal microscopy, laser microsurgery and infrared microspectroscopy. (AU)