Pathological stress induces transcriptional gene reprogramming in the heart muscle, leading to myopathy and heart failure. However, little is known about how the pathological stress triggers the restructuring of chromatin to control myopathic gene expression. This research program focuses on how different chromatin-regulating factors act in concert to establish a repressive chromatin environment to control the expression of alpha-myosin heavy chain (-MHC), a molecular motor gene whose repression in the stressed hearts contributes to myopathy and heart failure. Four different chromatin regulators-chromatin remodeler, histone methyltransferase, histone deacetylase and DNA methyltransferase-will be examined for their collaborative repression of -MHC. Because chemical inhibitors are available to inhibit these chromatin factors, it is possible to develop drus to boost - MHC in the failing heart to improve cardiac function. Understanding how these chromatin factors (drug targets) interact will help us design new drugs and understand the synergy/dynamics of potential drugs that inhibit different classes of chromatin regulators.
Aim 1 : Defining specific isoforms of DNA methyltransferase required for -MHC repression and heart failure. We will knock out DNA methyltransferase isoforms in the heart muscle of mice and examine the effects on -MHC repression in the stressed heart and on the progression of heart failure.
Aim 2 : Determine how chromatin remodeler integrates histone and DNA methyltransferases to silence -MHC. We will use animal models, surgical method, and various molecular biology methods (chromatin immunoprecipitation and quantitative PCR) to define the interactions between these chromatin factors crucial for the histone and DNA methylation of -MHC.
Aim 3 : Defining how histone deacetylase coordinates with histone and DNA methyltransferases to repress -MHC promoter. We will use animal models, surgical methods, and various molecular biology methods (chromatin immunoprecipitation, quantitative PCR, and co-immunoprecipitation) to define the interactions between these chromatin factors that are essential for histone methylation and acetylation, as well as DNA methylation of -MHC promoter.
Cardiomyopathy and heart failure is a major cause of morbidity and mortality in our society. Aberrant expression of molecular motor genes in the diseased heart is an essential step toward the development of heart failure. Understanding the mechanisms that control molecular motor gene expression will provide a mechanistic base for designing new treatment for heart failure.
