A Transient Increase in Cardiomyocyte Protein O-GlcNAcylation Enhances Susceptibility to Pressure Overload-Induced Cardiac Remodeling.

BACKGROUND

The observation that diabetic patients always under tight-glycemic control consistently show better cardiovascular disease outcomes compared to patients who transition to tight-glycemic control after prior conventional glycemic control lead to the concept of metabolic memory. Mechanisms such as epigenetics possibly mediate the lasting metabolic memory effects, our understanding of the underlying mechanisms remains limited. Increased cardiac protein posttranslational O-linked β-N-acetylglucosamine (O-GlcNAc) modification is implicated in cardiac remodeling observed in diabetes, and our previous work shows chronically elevated cardiomyocyte O-GlcNAc causes adverse cardiac changes. Therefore, the current study hypothesized that transiently increased cardiomyocyte O-GlcNAcylation leads to exacerbated adverse cardiac remodeling after subsequent pressure-overload.

METHODS AND RESULTS

Using our previously described inducible cardiomyocyte specific, dominant-negative O-GlcNAcase (dnOGAh) mouse and single transgenic littermate controls (Con), we induced O-GlcNAc levels for 2wk (ON), followed by a 2wk washout (OFF); mice then underwent transverse-aortic constriction (TAC) or Sham surgery. We observed the expected cardiac remodeling in TAC groups, including decreased cardiac function, and increased hypertrophy and fibrosis. Moreover, these pathologic measures were exacerbated in the ON/OFF-TAC vs. Con-TAC mice; additionally, transcriptomic analysis of LV-tissue from each experimental group showed pathways which not only supported our fibrosis, hypertrophy and functional results of exacerbated cardiac remodeling, but also, revealed potential novel molecular pathways underlying this pathologic remodeling.

CONCLUSIONS

We observed exacerbated cardiac pathology between ON/OFF-TAC vs. Con-TAC groups supporting the concept of "O-GlcNAc memory" as a component of metabolic memory. Moreover, transcriptomic analysis provides insight into potential molecular pathways underpinning this metabolic/O-GlcNAc memory such as /CTGF-driven fibrosis, and/or -driven oxidative stress.

CLINICAL PERSPECTIVE

We provide a novel paradigm to study phenotypic and molecular effects of specific, transiently increased cardiomyocyte O-GlcNAcylation on the heart.Our results show exacerbated adverse cardiac remodeling due to transiently increased cardiomyocyte O-GlcNAc with pressure-overload, supporting the concept of "O-GlcNAc memory" as a component of metabolic memory.Transcriptomic insights show gene expression basis for not only observed exacerbated adverse cardiac remodeling (e.g., hypertrophy, fibrosis, cardiac dysfunction), but also potential molecular pathways that could drive cardiac pathology exacerbation of O-GlcNAc memory. This study supports a concept of "O-GlcNAc memory", where previously increased cardiomyocyte protein O-GlcNAcylation can impact the later development of differential cardiac pathology-like the pathology seen in metabolic memory research.The potential role of O-GlcNAc in mediating metabolic memory will help focus future translational research on this modification and downstream cardiac effects in diabetes.Transcriptomic profiling of cardiac remodeling in this model provides an investigational roadmap for future molecular and functional studies to identify novel therapeutics that ameliorate heart disease induced by differential metabolic memory.