Molecular physiological and biological studies on the mechanismof impaired glucose-induced insulin secretion in diabetes mellitus

糖尿病葡萄糖诱导胰岛素分泌受损机制的分子生理学和生物学研究

基本信息

批准号：
09671048
负责人：
ISHIDA Hitoshi
金额：
$ 2.05万
依托单位：
Kyorin University (1998-1999)Kyoto University (1997)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

In order to elucidate the molecular mechanism of impairment of glucose-induced insulin secretion in type 2 diabetes mellitus, we examined the altered expression of SNARE proteins (syntaxin 1A and SNAP-25), which are known to play an important role on exocytolic process of insulin secretary granules as sensor molecules for the intracellular CaィイD12+ィエD1 elevation and metabolic signals derived from glucose, in diabetic GK (Goto-Kakizaki) rats. Immunoblot analysis revealed that protein levels of syntaxin 1A and SNAP-25 in GK rat islets decreased to 〜60% of the levels in control rat islets. Restoration of these proteins to normal levels in GK rats was achieved via the recombinant adenovirus-mediated gene transduction system. Glucose-stimulated insulin release from Adex 1CA syntaxin 1A and Adex 1CA SNAP-25-infected GK rat islets increased up to those from normal rat islets. The decreased expression of SNARE proteins is at least in part the defect responsible for impaired insulin secretion. For the screening of the agents, which can augment the CaィイD12+ィエD1 sensitivity of exocytotic mechanism of insulin secretory granules, pimobendan and JTT-608 were examined. Both of them increased the glucose-induced insulin secretion dose-dependently. Using electrically permeabilized rat pancreatic islets, they augmented the sensitivity for intracellular CaィイD12+ィエD1 elevation to trigger the exocytosis. It is revealed that pimobendan can exhibit its effect by in part activating CaィイD12+ィエD1/calmodulin dependent protein kinase II, and that JTT-608 can do it by inhibiting phosphodiesterase activity to increase intracellular cAMP levels. Accordingly, these agents would become novel therapeutic means for the treatment of impaired insulin secretion in type 2 diabetes mellitus.

为了阐明2型糖尿病中葡萄糖诱导的胰岛素分泌损伤的分子机制，我们检查了SNARE蛋白（Syntaxin 1a和Snap-25）的表达改变的改变，这些表达在胰岛素秘密培训2 ins ins ins ins ins ins ins ins ins ins ins ins ins ins ins ins ins ins ins noculins ins ins noculin and ins ins ins ins ins ins nociles dist and insem sector molecules and in cat+糖尿病GK（goto-kakizaki）大鼠衍生自葡萄糖的代谢信号。免疫印迹分析表明，GK大鼠胰岛中索法素1a和SNAP-25的蛋白质水平降低到对照大鼠胰岛中水平的〜60％。通过重组腺病毒介导的基因转移系统，将这些蛋白质恢复为GK大鼠的正常水平。葡萄糖刺激的胰岛素从ADEX 1CA语法1A和ADEX 1CA SNAP-25感染的GK大鼠胰岛释放到正常大鼠胰岛的胰岛素增加。 SNARE蛋白的表达降低至少部分是导致胰岛素分泌受损的缺陷。为了筛选胰岛素分泌颗粒，匹莫本丹和JTT-608的胞外胞毒性机制的CAIY D12+IE D1敏感性。他们俩都以葡萄糖诱导的胰岛素分泌剂量依赖性地增加了。使用电透化的大鼠胰岛胰岛，它们增强了对细胞内CAI D12+E D1升高的敏感性，以触发胞吐作用。据揭示，皮莫本丹可以通过部分激活CAI D12+E D1/钙调蛋白依赖性蛋白激酶II来执行其效果，而JTT-608可以通过抑制磷酸二酯酶活性来提高细胞内cAMP水平来做到这一点。根据这些药物，将成为治疗2型糖尿病中胰岛素分泌受损的新型治疗方法。