Increased levels of cardiac protein posttranslational β-linked N-acetylglucosamine (O-GlcNAc) modification are implicated in adverse remodeling seen in hypertrophy and diabetes. Our previous work found elevated O-GlcNAc levels in hearts from diabetic mice, and a chronic increase in O-GlcNAc caused adverse cardiac remodeling. In diabetes, increased cardiac disease risk persists even after patients return to tight glycemic control. Thus, we hypothesize that a transient increase in O-GlcNAc is sufficient to exacerbate adverse cardiac remodeling under subsequent pressure-overload, and we propose that this is due to epigenetic modifications causing persistent changes in gene expression. We used an inducible, cardiomyocyte specific, dominant negative O-GlcNAcase (dnOGA) mouse. After a 2-wk induction (which leads to a 1.8-fold increase in O-GlcNAc levels) and subsequent 2-wk washout, Control (Con) and dnOGA mice undergo transverse-aortic constriction (TAC) or Sham surgery. After 8-wks, cardiac function is measured via echocardiography, gravimetric measures at harvest, and RNA-seq analysis is done on cardiac tissue. In both Con+TAC and dnOGA+TAC vs. Sham groups, systolic function is decreased ( -12%, p < 0.001, -11%, p < 0.01 ), and ventricular weight is increased ( +43%, +69%, both p < 0.0001 ), consistent with cardiac hypertrophy. Interestingly, we see further exacerbation of cardiac hypertrophy ( +29%, p < 0.0001 ) and pulmonary edema ( +36%, p < 0.01 ) between dnOGA+TAC vs. Con+TAC groups. Also, RNA-seq results show distinct transcriptomic profiles between the experimental groups via hierarchical clustering ( |FC| > 1.50, FDR < 0.1 ). A candidate gene approach shows enhanced and exacerbated changes in genes associated with cardiac disease states like heart failure and fibrosis (e.g., Atp2a2, Col1a1, & Nox4 ), consistent with cardiac remodeling. Our results support the hypothesis that transient increase in cardiac O-GlcNAc levels increases susceptibility to subsequent cardiac pathology. Moreover, the exacerbation of pathology is consistent with epigenetic mediated effects of transient O-GlcNAc induction; and pertaining to diabetes, provide a possible mechanism into the continued increased of cardiac disease risk.
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