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. Author manuscript; available in PMC: 2017 May 27.
Published in final edited form as: Circ Res. 2016 May 27;118(11):1808–1829. doi: 10.1161/CIRCRESAHA.116.306923

Figure 1. Hyperglycemia-induced myocardial protein modification by O-GlcNAc causes increased intracellular Ca++ and delayed afterpolarizations.

Figure 1

Increased intracellular glucose flux provides more substrate for the enzyme O-GlcNAc-transferase (OGT). This increases O-GlcNAc modification of calcium/calmodulin-dependent protein kinase IIδ (CaMKII), causing autonomous CaMKII activation. CaMKII increases intracellular Ca++ by phosphorylating ryanodine receptor 2 (RyR). OGT also modifies transcription complex factors regulating expression of sarcoplasmic reticulum Ca2+-ATPase (SERCA2), reducing SERCA2A expression and contributing toincreased intracellular Ca++. Increased O-GlcNAc modification of these proteins causes delayed afterdepolarizations in cardiomyocytes. PLB, phospholamban.