Nox4 and Epigenetics in chronically enhanced cardiac protein O-GlcNAcylation - PROJECT SUMMARY Global diabetes prevalence is nearing 10%, and despite advancements in treatments, compared to non-diabetic, individuals with diabetes have 2-fold higher rates of heart failure, as well as increased mortality due to cardiovascular disease. Specifically, diabetic cardiomyopathy (DCM) is a diagnosis based on cardiac insufficiency attributable only to diabetes, and characterized by the triad of cardiac hypertrophy, fibrosis, and apoptosis. We believe these are consequences of and contributors to epigenetic changes that regulate expression of genes responsible for the pathological state. Epigenetic changes are stable, yet reversible modifications to chromatin and genetic material (e.g., histones, DNA). It is an established regulator of gene expression associated with diabetes and heart failure—with the field studying the intersection of these topics still relatively young. Additionally, our prior work found that glucose can signal through a specific post-translational protein modification, O-linked -N-acetyl-glucosamine (O-GlcNAc), and building upon current literature, our lab has shown using our novel mouse model that chronically enhanced O-GlcNAc is sufficient to cause pathology associated with diabetic hearts. My work focuses on identifying and studying molecular pathways regulated by DNA methylation changes during chronic O-GlcNAc which lead to pathology. Upon RNA-sequencing, my prior analysis identified significantly increased NADPH Oxidase 4 (Nox4) with chronically increased cardiac protein O-GlcNAc. Similarly, methylation-sequencing of DNA from cardiac tissue of diabetic mice revealed hypo- methylation (an epigenetic mark associated with increased gene expression) at the Nox4 promoter associated CPG island. Nox4 is a significant producer of reactive oxygen species (ROS), and its activity is governed by levels of expression. The field of Nox4 in the context of chronic diabetic hearts is relatively young, and little is known about its regulatory mechanisms. With these opportunities and encouraging preliminary data, I seek to build upon the rigors of past research to contribute novel knowledge and develop resources to study Nox4’s regulation and role in chronic diabetic hearts. I hypothesize that with chronically enhanced protein O-GlcNAc (a key facet of diabetic hearts), cardiac Nox4 is induced via DNA hypomethylation, and its upregulation is necessary to promote cardiac dysfunction and pathology. The proposal will test the following two aims: (1) Determine the mechanism of O-GlcNAcylation initiated DNA methylation changes leading to cardiac Nox4 upregulation. (2) Establish that Nox4 depletion can prevent cardiac remodeling seen during chronically enhanced cardiac protein O-GlcNAc. In summary, this proposal will determine a new regulatory mechanism for Nox4 and provide foundational research for the development of precision therapeutics to treat underlying pathological mechanisms driving disease in diabetic hearts. This proposal will also provide the foundation for my career as a physician- scientist with the scientific reasoning, research, and translational skills in cardiovascular research/medicine.
