Suppression of Peroxisome Proliferator-Activated Receptor γ-Coactivator-1α Normalizes the Glucolipotoxicity-Induced Decreased BETA2/NeuroD Gene Transcription and Improved Glucose Tolerance in Diabetic Rats

Peroxisome proliferator-activated receptor γ-coactivator-1α (PGC-1α) is significantly elevated in the islets of animal models of diabetes. However, the molecular mechanism has not been clarified. We investigated whether the suppression of PGC-1α expression protects against β-cell dysfunction in vivo...

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Published in:Endocrinology (Philadelphia) 2009-09, Vol.150 (9), p.4074-4083
Main Authors: Kim, Ji-Won, You, Young-Hye, Ham, Dong-Sik, Cho, Jae-Hyoung, Ko, Seung-Hyun, Song, Ki-Ho, Son, Ho-Young, Suh-Kim, Haeyoung, Lee, In-Kyu, Yoon, Kun-Ho
Format: Article
Language:English
Subjects:
Biological and medical sciences
Diabetes. Impaired glucose tolerance
Endocrine pancreas. Apud cells (diseases)
Endocrinopathies
Etiopathogenesis. Screening. Investigations. Target tissue resistance
Fundamental and applied biological sciences. Psychology
Medical sciences
Vertebrates: endocrinology
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Summary:Peroxisome proliferator-activated receptor γ-coactivator-1α (PGC-1α) is significantly elevated in the islets of animal models of diabetes. However, the molecular mechanism has not been clarified. We investigated whether the suppression of PGC-1α expression protects against β-cell dysfunction in vivo and determined the mechanism of action of PGC-1α in β-cells. The studies were performed in glucolipotixicity-induced primary rat islets and INS-1 cells. In vitro and in vivo approaches using adenoviruses were used to evaluate the role of PGC-1α in glucolipotoxicity-associated β-cell dysfunction. The expression of PGC-1α in cultured β-cells increased gradually with glucolipotoxicity. The overexpression of PGC-1α also suppressed the expression of the insulin and β-cell E-box transcription factor (BETA2/NeuroD) genes, which was reversed by PGC-1α small interfering RNA (siRNA). BETA2/NeuroD, p300-enhanced BETA2/NeuroD, and insulin transcriptional activities were significantly suppressed by Ad-PGC-1α but were rescued by Ad-siPGC-1α. PGC-1α binding at the glucocorticoid receptor site on the BETA2/NeuroD promoter increased in the presence of PGC-1α. Ad-siPGC-1α injection through the celiac arteries of 90% pancreatectomized diabetic rats improved their glucose tolerance and maintained their fasting insulin levels. The suppression of PGC-1α expression protects the glucolipotoxicity-induced β-cell dysfunction in vivo and in vitro. A better understanding of the functions of molecules such as PGC-1α, which play key roles in intracellular fuel regulation, could herald a new era of the treatment of patients with type 2 diabetes mellitus by providing protection from glucolipotoxicity, which is an important cause of the development and progression of the disease. PGC-1α inhibits insulin and BETA2/NeuroD transcription levels and attenuating PGC-1α overexpression protects against glucolipotoxicity-induced β-cell dysfunction both in vivo and in vitro.
ISSN:0013-7227
1945-7170
DOI:10.1210/en.2009-0241