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Metabolic stress-induced activation of FoxO1 triggers diabetic cardiomyopathy in mice.

ABSTRACT: The leading cause of death in diabetic patients is cardiovascular disease; diabetic cardiomyopathy is typified by alterations in cardiac morphology and function, independent of hypertension or coronary disease. However, the molecular mechanism that links diabetes to cardiomyopathy is incompletely understood. Insulin resistance is a hallmark feature of diabetes, and the FoxO family of transcription factors, which regulate cell size, viability, and metabolism, are established targets of insulin and growth factor signaling. Here, we set out to evaluate a possible role of FoxO proteins in diabetic cardiomyopathy. We found that FoxO proteins were persistently activated in cardiac tissue in mice with diabetes induced either genetically or by high-fat diet (HFD). FoxO activity was critically linked with development of cardiomyopathy: cardiomyocyte-specific deletion of FoxO1 rescued HFD-induced declines in cardiac function and preserved cardiomyocyte insulin responsiveness. FoxO1-depleted cells displayed a shift in their metabolic substrate usage, from free fatty acids to glucose, associated with decreased accumulation of lipids in the heart. Furthermore, we found that FoxO1-dependent downregulation of IRS1 resulted in blunted Akt signaling and insulin resistance. Together, these data suggest that activation of FoxO1 is an important mediator of diabetic cardiomyopathy and is a promising therapeutic target for the disease.

SUBMITTER: Battiprolu PK

PROVIDER: S-EPMC3287230 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature

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Metabolic stress-induced activation of FoxO1 triggers diabetic cardiomyopathy in mice.

Battiprolu Pavan K PK Hojayev Berdymammet B Jiang Nan N Wang Zhao V ZV Luo Xiang X Iglewski Myriam M Shelton John M JM Gerard Robert D RD Rothermel Beverly A BA Gillette Thomas G TG Lavandero Sergio S Hill Joseph A JA

The Journal of clinical investigation 20120213 3

The leading cause of death in diabetic patients is cardiovascular disease; diabetic cardiomyopathy is typified by alterations in cardiac morphology and function, independent of hypertension or coronary disease. However, the molecular mechanism that links diabetes to cardiomyopathy is incompletely understood. Insulin resistance is a hallmark feature of diabetes, and the FoxO family of transcription factors, which regulate cell size, viability, and metabolism, are established targets of insulin an ...[more]

PMID: 22326951

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Project description:It is well known that rennin-angiotensin-aldosterone system (RAAS) plays a critical role in the development of diabetic cardiomyopathy. The present study was aimed to clarify the role of a novel member of RAAS, angiotensin IV (Ang IV) and its downstream mediator forkhead box protein O1 (FoxO1), in the pathogenesis of diabetic cardiomyopathy. In vivo, diabetic mice were treated with low-, medium- and high-dose Ang IV, AT4R antagonist divalinal, FoxO1 inhibitor AS1842856 (AS), or their combinations. In vitro, cardiomyocytes and cardiofibroblasts were treated with different concentrations of glucose, low-, medium- and high-dose Ang IV, divalinal, FoxO1-overexpression plasmid (FoxO1-OE), AS or their combinations. The results showed that Ang IV treatment dose-dependently attenuated left ventricular dysfunction, fibrosis, and myocyte apoptosis in diabetic mice. Besides, enhanced autophagy and FoxO1 protein expression by diabetes were dose-dependently suppressed by Ang IV treatment. However, these cardioprotective effects of Ang IV were completely abolished by divalinal administration. Bioinformatics analysis revealed that the differentially expressed genes were enriched in autophagy, apoptosis, and FoxO signaling pathways among control, diabetes, and diabetes+high-dose Ang IV groups. Similar to Ang IV, AS treatment ameliorated diabetic cardiomyopathy in mice. In vitro, high glucose stimulation increased collagen expression, apoptosis, overactive autophagy flux and FoxO1 nuclear translocation in cardiomyocytes, and upregulated collagen and FoxO1 expression in cardiofibroblasts, which were substantially attenuated by Ang IV treatment. However, these protective effects of Ang IV were completely blocked by the use of divalinal or FoxO1-OE, and these detrimental effects were reversed by the additional administration of AS. In summary, Ang IV treatment dose-dependently attenuated left ventricular dysfunction and remodeling in a mouse model of diabetic cardiomyopathy, and the mechanisms involved stimulation of AT4R and suppression of FoxO1-mediated fibrosis, apoptosis, and overactive autophagy.

Project description:Activation of the systemic and myocardial rennin-angiotensin-aldosterone system (RAAS) by hyperglycemia plays a critical role in the development of diabetic cardiomyopathy. To test the hypothesis that AngIV protects against diabetic cardiomyopathy via stimulation of AT4R and inhibition of overactive autophagy, diabetic mice were treated with low-, medium- and high-dose AngIV, AT4R antagonist divalinal, forkhead box protein O1 (FoxO1) inhibitor AS1842856 (AS) or their combinations. In vitro, cardiomyocytes were treated with different concentrations of glucose, low-, medium- and high-dose AngIV, divalinal, FoxO1-overexpression plasmid (FoxO1-OE), AS or their combinations. The results showed that AngIV treatment dose-dependently attenuated left ventricular dysfunction, remodeling, fibrosis, and myocyte apoptosis in diabetic mice. Besides, autophagy and FoxO1 protein expression enhanced by diabetes were dose-dependently suppressed by AngIV treatment. However, these cardioprotective effects of AngIV were completely abolished by divalinal administration. Bioinformatic analyses revealed that the differentially expressed genes were enriched in autophagy, apoptosis, and FoxO signaling pathways among control, diabetes, and diabetes+high-dose AngIV groups. Similar to AngIV, AS treatment ameliorated diabetic cardiomyopathy in mice. In vitro, AngIV inhibited collagen expression, apoptosis, overactive autophagy flux, and FoxO1 nuclear translocation induced by high glucose in cardiomyocytes. However, these protective effects of AngIV were completely blocked by the use of divalinal or FoxO1-OE, and these detrimental effects were reversed by the additional administration of AS. In summary, AngIV treatment dose-dependently attenuated left ventricular dysfunction and remodeling in a mouse model of diabetic cardiomyopathy, and the mechanism involved stimulation of AT4R, suppression of FoxO1 nuclear translocation and inhibition of FoxO1-mediated overactive autophagy.

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Metabolic stress-induced activation of FoxO1 triggers diabetic cardiomyopathy in mice.

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Metabolic stress-induced activation of FoxO1 triggers diabetic cardiomyopathy in mice.

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