Aleksandar Ivovic, Justin Hou Ming Yung, A. Oprescu, Filip Vlavcheski, Yusaku Mori, S. Rahman, Wenyue Ye, Judith A. Eversley, Michael B Wheeler, Minna Woo, E. Tsiani, Adria Giacca
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引用次数: 0
Abstract
Abstract In the classical insulin target tissues of liver, muscle, and adipose tissue, chronically elevated levels of free fatty acids (FFA) impair insulin signaling. Insulin signaling molecules are also present in β-cells where they play a role in β-cell function. Therefore, inhibition of the insulin/insulin-like growth factor 1 pathway may be involved in fat-induced β-cell dysfunction. To address the role of β-cell insulin resistance in FFA-induced β-cell dysfunction we co-infused bisperoxovanadate (BPV) with oleate or olive oil for 48 hours in rats. BPV, a tyrosine phosphatase inhibitor, acts as an insulin mimetic and is devoid of any antioxidant effect that could prevent β-cell dysfunction, unlike most insulin sensitizers. Following fat infusion, rats either underwent hyperglycemic clamps for assessment of β-cell function in vivo or islets were isolated for ex vivo assessment of glucose-stimulated insulin secretion (GSIS). We also incubated islets with oleate or palmitate and BPV for in vitro assessment of GSIS and Akt (protein kinase B) phosphorylation. Next, mice with β-cell specific deletion of PTEN (phosphatase and tensin homolog; negative regulator of insulin signaling) and littermate controls were infused with oleate for 48 hours, followed by hyperglycemic clamps or ex vivo evaluation of GSIS. In rat experiments, BPV protected against fat-induced impairment of β-cell function in vivo, ex vivo, and in vitro. In mice, β-cell specific deletion of PTEN protected against oleate-induced β-cell dysfunction in vivo and ex vivo. These data support the hypothesis that β-cell insulin resistance plays a causal role in FFA-induced β-cell dysfunction.
期刊介绍:
The mission of Endocrinology is to be the authoritative source of emerging hormone science and to disseminate that new knowledge to scientists, clinicians, and the public in a way that will enable "hormone science to health." Endocrinology welcomes the submission of original research investigating endocrine systems and diseases at all levels of biological organization, incorporating molecular mechanistic studies, such as hormone-receptor interactions, in all areas of endocrinology, as well as cross-disciplinary and integrative studies. The editors of Endocrinology encourage the submission of research in emerging areas not traditionally recognized as endocrinology or metabolism in addition to the following traditionally recognized fields: Adrenal; Bone Health and Osteoporosis; Cardiovascular Endocrinology; Diabetes; Endocrine-Disrupting Chemicals; Endocrine Neoplasia and Cancer; Growth; Neuroendocrinology; Nuclear Receptors and Their Ligands; Obesity; Reproductive Endocrinology; Signaling Pathways; and Thyroid.