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-cells by ameliorating mitochondrial metabolism
1Department of Physiology, 2Chronic Disease Research Center, Keimyung University School of Medicine, Daegu 700-712; 3Department of Physiology, College of Medicine, Seoul National University, Seoul 110-799; and 4Department of Physiology and Biophysics, College of Medicine, Inje University, Busanjin-Gu, Busan 614-735, Korea
Submitted 7 January 2004 ; accepted in final form 18 July 2004
A low-taurine diet during fetal or early postnatal life causes abnormal pancreatic
-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
-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
-cells. In freshly isolated mitochondria from UCP2-overexpressing insulin-secreting (INS)-1
-cells, methyl pyruvate-mediated mitochondrial Ca2+ increase was significantly ameliorated by taurine. A mitochondrial Ca2+ uniporter blocker, ruthenium red, inhibited the action of taurine. This study suggests that taurine enhances the glucose sensitivity of UCP2-overexpressing
-cells, probably by increasing mitochondrial Ca2+ influx through the Ca2+ uniporter, thereby enhancing mitochondrial metabolic function and increasing the ATP/ADP ratio.
insulin; ATP-sensitive K+ channel; mitochondrial Ca2+; ATP-to-ADP ratio; pancreatic islets; uncoupling protein 2
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