Abstract 9633: Caveolin-3 Nitrative Modification Exacerbates Ischemic Heart Failure in Pre-Diabetic Mice by Disassembling Cardioprotective Signalosomes

Abstract

Rationale: Diabatic heart is “universally” resistant to protective interventions, including insulin, adiponectin exacerbating ischemic heart failure (HF). Caveolin (Cav) serves as scaffolding regulator, coordinating signal transduction in cell survival. However, whether and how diabetes alter Cav3-centered signalosome integrity, contributing to diabetic ischemic HF remains unclear.We hypothesized that preserving Cav3 signalosome integrity restore cardioprotective signaling, protecting against diabetic exacerbation of ischemia HF. Methods and Results: Mice with normal diet (ND) or high-fat-diet (HFD) were subjected to myocardial ischemia and reperfusion (MI/R). Administration of insulin or adiponectin markedly attenuated MI injury (60 minutes MI/24 hours reperfusion) in ND mice, an effect lost in diabetic animals (12 weeks HFD, n=18-20/group). Interestingly, cardioprotective effect of insulin and adiponectin was blunted as early as 4 weeks of HFD (pre-diabetes). In ND heart, Cav3 interacts with AdipoR1 and insulin receptor-β (IRβ), forming signalosomes. Those complexes were significantly reduced in pre-diabetic heart. However, the level of Cav3, AdipoR1, AdipoR2, and IRβ remain unchanged. Among multiple post-translational modifications, Cav3 nitration was the dominant in pre-diabetic heart. SIN-1 (a nitration donor) reduced Cav3/AdipoR1 and Cav3/IRβ complex, and blocked their transmembrane signaling. Mass spectrometry identified Tyr 73 is the site modified in pre-diabetic cardiomyocytes. Phenylalanine substitution of Tyr 73 (Cav3 Y73F ) blocked SIN-1 induced Cav3 nitration, restored signalosome assembling, and rescued insulin and adiponectin transmembrane signaling in diabetic cardiomyocytes. Finally, AAV9-mediated cardiomyocyte specific Cav3 Y73F re-expression blocked HFD-induced Cav3 nitration, restored transmembrane signaling, rescued the protective action against ischemic HF. Conclusion: Nitration of Cav3 at Tyr 73 and complex dissociation is responsible for cardiac insulin/adiponectin resistance in pre-diabetic heart, contributing to ischemic HF progression. Early intervention preserving Cav3-centered signalosome integrity is an effective novel strategy against diabetic ischemic HF.