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Am J Physiol Endocrinol Metab. 2004 Nov;287(5):E1008-18. Epub 2004 Jul 20.
Taurine increases glucose sensitivity of UCP2-overexpressing {beta}-cells by ameliorating mitochondrial metabolism.
Han J, Bae JH, Kim SY, Lee HY, Jang BC, Lee IK, Cho CH, Lim JG, Suh SI, Kwon TK, Park JW, Ryu SY, Ho WK, Earm YE, Song DK.
Dept. of Physiology, Keimyung University School of Medicine, 194, Dongsan-Dong, Jung-Gu, Daegu 700-712, Korea.
A low-taurine diet during fetal or early postnatal life causes abnormal pancreatic beta-cell development. Tissue and plasma taurine concentrations can also be low in diabetic patients. We examined the effect of taurine on impaired glucose responses in diabetic rat beta-cells adenovirally overexpressing uncoupling protein (UCP)2, which is upregulated in obesity-related type 2 diabetes. We found that taurine pretreatment restored the ATP-to-ADP (ATP/ADP) ratio and glucose-stimulated insulin secretion in UCP2-infected islets. ATP-sensitive K(+) channel sensitivity to dihydroxyacetone, another insulin secretagogue, was similar in both UCP2-infected and control beta-cells. In freshly isolated mitochondria from UCP2-overexpressing insulin-secreting (INS)-1 beta-cells, methyl pyruvate-mediated mitochondrial Ca(2+) increase was significantly ameliorated by taurine. A mitochondrial Ca(2+) uniporter blocker, ruthenium red, inhibited the action of taurine. This study suggests that taurine enhances the glucose sensitivity of UCP2-overexpressing beta-cells, probably by increasing mitochondrial Ca(2+) influx through the Ca(2+) uniporter, thereby enhancing mitochondrial metabolic function and increasing the ATP/ADP ratio.
PMID: 15265758 [PubMed - indexed for MEDLINE] |
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