Identification of the docked granule pool responsible for the first phase of glucose-stimulated insulin secretion
Identification of the docked granule pool responsible for the first phase of glucose-stimulated insulin secretion
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DOI：
10.2337/diabetes.48.9.1686
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发表时间：
1999-09-01
期刊：
影响因子：
7.7
通讯作者：
Sharp, GWG
中科院分区：
文献类型：
--
作者：
Daniel, S;Noda, M;Sharp, GWG
葡萄糖刺激胰岛素释放第一阶段的机制基本上是未知的，该阶段的恶化标志着 1 型和 2 型糖尿病的早期阶段。在许多假设中，有人认为第一阶段是由于易于释放的含胰岛素颗粒池所致。我们利用胞吐作用机制和参与质膜上颗粒对接的蛋白质的现有知识来检验这一假设。通过用特定抗体对质膜蛋白突触蛋白进行免疫沉淀，并通过可溶性 N-乙基马来酰亚胺敏感因子附着物的共免疫沉淀，鉴定了易于释放颗粒的对接池。 Protein-25 (SNAP-25) 和颗粒蛋白 synaptobrevin 和 synaptotagmin。四种 SNARE 蛋白相互共免疫沉淀，从而识别出与对接颗粒相关的核心复合物。使用共免疫沉淀作为对接颗粒的标记，我们发现对接池在葡萄糖刺激胰岛素释放的第一阶段快速排出，并在第二阶段重新填充。其他促分泌剂也释放池，而生理抑制剂去甲肾上腺素阻止其释放。对这组颗粒的性质的进一步研究应该能够揭示其在糖尿病早期阶段恶化的原因以及胰岛素释放不足的原因。
The mechanisms underlying the first phase of glucose-stimulated insulin release, the deterioration of which marks the early stages of both type 1 and type 2 diabetes, are essentially unknown. Among many hypotheses, one holds that the first phase is due to a readily releasable pool of insulin-containing granules, We used current knowledge of the mechanisms of exocytosis and the proteins involved in docking granules at the plasma membrane to test this hypothesis, A docked pool of readily releasable granules was identified by immunoprecipitation of the plasma membrane protein syntaxin with a specific antibody and by co-immunoprecipitation of soluble N-ethylmaleimide-sensitive factor attachment protein-25 (SNAP-25) and the granule proteins synaptobrevin and synaptotagmin. The four SNARE proteins co-immunoprecipitated each other, thus identifying the core complex associated with docked granules, Using co-immunoprecipitation as a marker for docked granules, we found that the docked pool was rapidly discharged during the first phase of glucose-stimulated insulin release and refilled during the second phase, Other secretagogues also released the pool, whereas the physiological inhibitor norepinephrine blocked its release. Further studies on the nature of this pool of granules should shed light on the causes of its deterioration in the early stages of diabetes and the reasons for deficient insulin release.