Hyperglycemia-Induced Protein Kinase C β2 Activation Induces Diastolic Cardiac Dysfunction in Diabetic Rats by Impairing Caveolin-3 Expression and Akt/eNOS Signaling

Shaoqing Lei, Haobo Li, Jinjin Xu, Yanan Liu, Xia Gao, Junwen Wang, Kwok F.J. Ng, Wayne Bond Lau, Xin Liang Ma, Brian Rodrigues, Michael G. Irwin, Zhengyuan Xia

Research output: Contribution to journalArticle

73 Scopus citations

Abstract

Protein kinase C (PKC)β2 is preferably overexpressed in the diabetic myocardium, which induces cardiomyocyte hypertrophy and contributes to diabetic cardiomyopathy, but the underlying mechanisms are incompletely understood. Caveolae are critical in signal transduction of PKC isoforms in cardiomyocytes. Caveolin (Cav)-3, the cardiomyocyte-specific caveolar structural protein isoform, is decreased in the diabetic heart. The current study determined whether PKCβ2 activation affects caveolae and Cav-3 expression. Immunoprecipitation and immunofluorescence analysis revealed that high glucose (HG) increased the association and colocalization of PKCb2 and Cav-3 in isolated cardiomyocytes. Disruption of caveolae by methyl-β-cyclodextrin or Cav-3 small interfering (si)RNA transfection prevented HG-induced PKCb2 phosphorylation. Inhibition of PKCb2 activation by compound CGP53353 or knockdown of PKCβ2 expression via siRNA attenuated the reductions of Cav-3 expression and Akt/endothelial nitric oxide synthase (eNOS) phosphorylation in cardiomyocytes exposed to HG. LY333531 treatment (for a duration of 4 weeks) prevented excessive PKCβ2 activation and attenuated cardiac diastolic dysfunction in rats with streptozotocin-induced diabetes. LY333531 suppressed the decreased expression of myocardial NO, Cav-3, phosphorylated (p)-Akt, and p-eNOS and also mitigated the augmentation of O2 2, nitrotyrosine, Cav-1, and iNOS expression. In conclusion, hyperglycemia-induced PKCb2 activation requires caveolae and is associated with reduced Cav-3 expression in the diabetic heart. Prevention of excessive PKCb2 activation attenuated cardiac diastolic dysfunction by restoring Cav-3 expression and subsequently rescuing Akt/eNOS/NO signaling.

Original languageEnglish (US)
Pages (from-to)2318-2328
Number of pages11
JournalDiabetes
Volume62
Issue number7
DOIs
StatePublished - Jul 2013

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism

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    Lei, S., Li, H., Xu, J., Liu, Y., Gao, X., Wang, J., Ng, K. F. J., Lau, W. B., Ma, X. L., Rodrigues, B., Irwin, M. G., & Xia, Z. (2013). Hyperglycemia-Induced Protein Kinase C β2 Activation Induces Diastolic Cardiac Dysfunction in Diabetic Rats by Impairing Caveolin-3 Expression and Akt/eNOS Signaling. Diabetes, 62(7), 2318-2328. https://doi.org/10.2337/db12-1391