Nutrient modulation of palmitoylated 24-kilodalton protein in rat pancreatic islets
Nutrient modulation of palmitoylated 24-kilodalton protein in rat pancreatic islets
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DOI：
10.1210/en.2003-0719
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发表时间：
2003-12-01
期刊：
影响因子：
4.8
通讯作者：
Kojima, I
中科院分区：
文献类型：
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作者：
Yamada, S;Komatsu, M;Kojima, I
蛋白质酰化在葡萄糖刺激胰岛素分泌β细胞已牵连。因此，我们试图确定胰岛中酰化的靶标。用[h -3]棕榈酸在37℃下标记大鼠胰岛1 h，用SDS-PAGE和二维凝胶电泳分析全细胞裂解液。化学分析表明，[H-3]棕榈酸对蛋白质的标记是棕榈酰化。四个不同的棕榈酰化被识别出来，当高葡萄糖进行标记时，所有棕榈酰化都显着降低。非常有趣的是，衰减程度在24kda双重态中尤为明显。24 kda双链的棕榈酰化也被线粒体燃料和酰化抑制剂cerulenin优先减弱。无论是否存在高葡萄糖，双链标记的半衰期明显短于胰岛脉搏追逐的其他带（约45分钟）。24 kda双链的棕榈酰化的高葡萄糖衰减被20 mM甘露庚糖（一种葡萄糖激酶抑制剂）部分阻断。双向凝胶电泳显示，该双联体由酸性多肽组成，免疫沉淀表明它不是25 kDa的突触体相关蛋白。我们在胰岛中发现了快速翻转棕榈酰化的24 kDa酸性蛋白，不同于突触体相关的25 kDa酸性蛋白，它们优先被燃料分泌剂调节。这些数据表明棕榈酰化24kda双链在营养刺激胰岛素分泌中的功能作用。
Protein acylation in glucose stimulation of insulin secretion in the beta-cells has been implicated. Accordingly, we attempted to identify the target(s) of acylation in the pancreatic islets. Rat pancreatic islets were labeled with [H-3] palmitic acid for 1 h at 37 C, and the whole cell lysate was analyzed by SDS-PAGE and two-dimensional gel electrophoresis. The labeling of the proteins by [H-3] palmitic acid was shown to be palmitoylation by chemical analyses. Palmitoylation of four distinct bands was recognized, and the palmitoylation was significantly reduced in all of them when the labeling was performed with high glucose. Quite interestingly, the degree of attenuation was particularly dominant for a 24-kDa doublet. Palmitoylation of the 24-kDa doublet was preferentially attenuated also by the mitochondrial fuels and an acylation inhibitor, cerulenin. The half-life of the labeling of the doublet was apparently shorter (approximately 45 min) than that of other bands on pulse chasing of the islets, irrespective of the presence or absence of high glucose. High glucose attenuation of the palmitoylation of the 24-kDa doublet was partially blocked by 20 mM mannoheptulose, a glucokinase inhibitor. Two-dimensional gel electrophoresis revealed that the doublet was composed of acidic peptides, and, by immunoprecipitation, it was shown not to be synaptosome-associated protein of 25 kDa. We identified rapidly turning over palmitoylated 24-kDa acidic proteins distinct from synaptosome-associated protein of 25 kDa in the pancreatic islets, which are preferentially modulated by fuel secretagogues. The data suggested a functional role of the palmitoylated 24-kDa doublet in nutrient stimulation of insulin secretion.