Date of Award

Spring 5-13-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Kinesiology and Health

First Advisor

Jeffrey Scott Otis

Second Advisor

Christopher Paul Ingalls

Third Advisor

Brett Wong

Fourth Advisor

Mike Hart

Abstract

Background: Myocardial infarction (MI) results in severe biochemical, physiological, and cellular changes that lead to alterations in the structure and function of the myocardium. Oxidative stress potentiates this remodeling response and is associated with progressive worsening of cardiac function. Accordingly, we used a powerful antioxidant-based therapeutic strategy to improve cardiac health and study redox-dependent signaling. Methods: MI was surgically induced in rats by ligating the left anterior descending coronary artery. Subgroups of MI rats received resveratrol (i.p., 10 mg/kg/day for 28 days beginning immediately post-MI). Cardiac histology and biochemical analyses of genes and proteins implicated in cardiac fibrosis, hypertrophy, and apoptosis, and redox-dependent signaling were analyzed. Results: As expected, MI resulted in profound structural changes to the myocardium. Further, we observed a sharp reduction in nuclear factor-erythroid 2-related factor 2 (Nrf2) and Krüppel-like factor 15 (KLF15), factors that are responsible for maintaining the endogenous antioxidant capacity and regulating cardiac gene expression, respectively. It is likely that disruption of normal KLF15 signaling permitted the expression of several cardiac genes associated with progressive cardiac remodeling. Importantly, daily treatment with resveratrol ameliorated cardiac remodeling, improved redox state, restored Nrf2 expression, and up-regulated KLF15 expression. Further, induction of KLF15 signaling following resveratrol treatment is associated with attenuated expression of several genes implicated in cardiac remodeling. Conclusions: Chronic oxidative stress potentiates cardiac remodeling post-infarct, in part, by suppressing Nrf2 and KLF15 expression. Importantly, we demonstrate that normal KLF15 signaling may be rescued with an antioxidant-based therapy, which may be an attractive therapeutic target to support cardiac health post-MI.

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