Enhanced phosphoinositide 3-kinase(p110α) activity prevents diabetes-induced cardiomyopathy and superoxide generation in a mouse model of diabetes

R. H. Ritchie, Jane E Love, K. Huynh, B. C. Bernardo, D. C. Henstridge, H. Kiriazis, Y. K. Tham, Geeta Sapra, C Qin, Nelly Cemerlang, Esther J H Boey, K. Jandeleit-Dahm, X. J. Du, J. R. McMullen

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Abstract

Aims/hypothesis Diabetic cardiomyopathy is characterised by diastolic dysfunction, oxidative stress, fibrosis, apoptosis and pathological cardiomyocyte hypertrophy. Phosphoinositide 3-kinase (PI3K)(p110α) is a cardioprotective kinase, but its role in the diabetic heart is unknown. The aim of this study was to assess whether PI3K(p110α) plays a critical role in the induction of diabetic cardiomyopathy, and whether increasing PI3K(p110α) activity in the heart can prevent the development of cardiac dysfunction in a setting of diabetes. Methods Type 1 diabetes was induced with streptozotocin in adult male cardiac-specific transgenic mice with increased PI3K(p110α) activity (constitutively active PI3K [p110α], caPI3K] or decreased PI3K(p110α) activity (dominantnegative PI3K [p110α], dnPI3K) and non-transgenic (Ntg) mice for 12 weeks. Cardiac function, histological and molecular analyses were performed. Results Diabetic Ntg mice displayed diastolic dysfunction and increased cardiomyocyte size, expression of atrial and B-type natriuretic peptides (Anp, Bnp), fibrosis and apoptosis, as well as increased superoxide generation and increased protein kinase C β2 (PKCβ2), p22phox and apoptosis signalregulating kinase 1 (Ask1) expression. Diabetic dnPI3K mice displayed an exaggerated cardiomyopathy phenotype compared with diabetic Ntg mice. In contrast, diabetic caPI3K mice were protected against diastolic dysfunction, pathological cardiomyocyte hypertrophy, fibrosis and apoptosis. Protection in diabetic caPI3K mice was associated with attenuation of left ventricular superoxide generation, attenuated Anp, Bnp, PKCβ2, Ask1 and p22phox expression, and elevated AKT. Further, in cardiomyocyte-like cells, increased PI3K(p110α) activity suppressed high glucose-induced superoxide generation and enhanced mitochondrial function. Conclusions/interpretation These results demonstrate that reduced PI3K activity accelerates the development of diabetic cardiomyopathy, and that enhanced PI3K(p110α) activity can prevent adverse cardiac remodelling and dysfunction in a setting of diabetes.

Original languageEnglish
Pages (from-to)3369-3381
Number of pages13
JournalDiabetologia
Volume55
Issue number12
DOIs
Publication statusPublished - Dec 2012

Keywords

  • Diabetes
  • Fibrosis
  • Hypertrophy
  • Left ventricular function
  • Myocardium
  • NADPH oxidase
  • PI3K
  • PKC2
  • Reactive oxygen species

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