Increased O-GlcNAcylation induces myocardial hypertrophy

Area of Science:

• Biochemistry
• Cardiovascular Biology
• Cellular Metabolism

Background:

• Myocardial hypertrophy, a precursor to heart disease, is linked to high-sugar diets and diabetes.
• O-GlcNAcylation, a protein modification, acts as a nutrient sensor, but its role in cardiac hypertrophy is unclear.
• Hyperglycemia and related conditions increase O-GlcNAcylation.

Purpose of the Study:

• To investigate if excessive O-linked β-N-acetylglucosamine (O-GlcNAc) glycosylation in cardiomyocytes causes cardiac hypertrophy.
• To explore the molecular mechanisms linking O-GlcNAcylation to cardiac hypertrophy.

Main Methods:

• Primary cardiomyocytes and mice were treated with O-GlcNAcase inhibitors (STZ or PUGNAc) to increase O-GlcNAcylation.
• Cardiomyocyte morphology and left ventricular wall thickness were assessed using HE staining.
• mRNA levels of cardiac hypertrophy markers (ANP, β-MHC) and CREB targets (C-fos, C-jun) were measured.
• CREB activity was evaluated by Western blot for phosphorylation and RT-qPCR for downstream targets.

Main Results:

• Increased O-GlcNAcylation induced hypertrophy-like changes in cardiomyocytes and cardiac tissue.
• Expression of cardiac hypertrophy genes (ANP, β-MHC) was upregulated.
• O-GlcNAcylation enhanced cAMP response element-binding protein (CREB) activity, evidenced by increased phosphorylation and downstream gene expression.

Conclusions:

• Elevated O-GlcNAcylation in cardiomyocytes is directly associated with cardiac hypertrophy.
• The findings implicate O-GlcNAcylation as a potential therapeutic target for managing myocardial hypertrophy.
• This research offers insights into treating heart conditions linked to high carbohydrate diets.