| Co-Investigator(Kenkyū-buntansha) |
UEKI Koh jiro The University of Tokyo, Faculty of Medicine, Associate Professor (00396714)
YAMAUCHI Toshimasa The University of Tokyo, Faculty of Medicine, Project Associate Professor (40372370)
HARA Kazuo The University of Tokyo, Faculty of Medicine, Lecturer (50359600)
KUBOTA Naoto The University of Tokyo, Faculty of Medicine, Project Associate Professor (50396719)
戸辺 一之 東京大学, 医学部附属病院, 教授 (30251242)
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| Budget Amount *help |
¥50,440,000 (Direct Cost: ¥38,800,000、Indirect Cost: ¥11,640,000)
Fiscal Year 2007: ¥11,570,000 (Direct Cost: ¥8,900,000、Indirect Cost: ¥2,670,000)
Fiscal Year 2006: ¥38,870,000 (Direct Cost: ¥29,900,000、Indirect Cost: ¥8,970,000)
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| Research Abstract |
Adiponectin plays a central role as an antidiabetic and antiatherogenic adipokine. AdipoR1 and AdipoR2 serve as receptors for adiponectin in vitro, and their reduction in obesity seems to be correlated with reduced adiponectin sensitivity. In this study, we show that adenovirus-mediated expression of AdipoR1 and R2 in the liver of Lepr(-/-) mice increased AMP-activated protein kinase (AMPK) activation and peroxisome proliferator-activated receptor (PPAR)-alpha signaling pathways, respectively. Activation of AMPK reduced gluconeogenesis, whereas expression of the receptors in both cases increased fatty acid oxidation and lead to an amelioration of diabetes. Alternatively, targeted disruption of AdipoR1 resulted in the abrogation of adiponectin-induced AMPK activation, whereas that of AdipoR2 resulted in decreased activity of PPAR-alpha signaling pathways. Simultaneous disruption of both AdipoR1 and R2 abolished adiponectin binding and actions, resulting in increased tissue triglyceride
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content, inflammation and oxidative stress, and thus leading to insulin resistance and marked glucose intolerance. Therefore, AdipoR1 and R2 serve as the predominant receptors for adiponectin in vivo and play important roles in the regulation of glucose and lipid metabolism, inflammation and oxidative stress in vivo (Nat. Med. 13:332, 2007).
We next examined the effects of adiponectin in the central nervous system, In this study, we show that adiponectin enhances AMPK activity in the arcuate hypothalamus (ARH) via its receptor AdipoR1 to stimulate food intake; this stimulation of food intake by adiponectin was attenuated by dominant-negative AMPK expression in the ARE Moreover, adiponectin also decreased energy expenditure. Adiponectin-deficient mice showed decreased AMPK phosphorylation in the ARH, decreased food intake, and increased energy expenditure, exhibiting resistance to high-fat-diet-induced obesity. Serum and cerebrospinal fluid levels of Adiponectin (Clin. Chem. 53:1541, 2007) and expression of AdipoR1 in the ARH were increased during fasting and decreased after refeeding. We conclude that adiponectin stimulates food intake and decreases energy expenditure during fasting through its effects in the central nervous system (Cell Metab. 6:55, 2007; FEBS Lett. 582:74, 2008). Less
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