ERp46 is reduced by high glucose and regulates insulin content in pancreatic β-cells
ERp46 is reduced by high glucose and regulates insulin content in pancreatic β-cells
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DOI：
10.1152/ajpendo.00053.2009
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发表时间：
2009-09-01
影响因子：
5.1
通讯作者：
Charonis, Aristidis
中科院分区：
文献类型：
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作者：
Alberti, Avra;Karamessinis, Panagiotis;Charonis, Aristidis
Alberti A，Karamessinis P，Peroulis M，Kypreou K，Kavvadas P，Pagakis S，Poltis PK，Charonis A。ERp46被高糖还原并调节胰岛β细胞中的胰岛素含量。AM J生理学内分泌代谢酶297：E812-E821,2009。2009年7月21日首次出版；DOI：10.1152/ajpendo.00053.2009。-我们的研究重点是内质网(ER)成分ERp46，并分析其在葡萄糖毒性和胰岛素产生中的作用。采用蛋白质组学方法，包括双向凝胶电泳法、图像分析和质谱仪，研究了低糖和高糖条件下胰腺β-TC-6细胞蛋白质组的差异。在差异表达的蛋白质中，进一步研究了ERp46，一种新的内质网成分。用免疫细胞化学方法分析ERp46在胰腺切片中的表达，并评价高糖对培养的胰岛细胞、分离的胰岛和db/db糖尿病动物胰腺中ERp46表达的影响。通过siRNA抑制ERp46的表达，研究其在胰岛素产生、分泌和内质网应激中的作用。蛋白质组学分析得到了与23个蛋白质相对应的46个差异表达点。由于ERp46是一种在分泌细胞中可能起关键作用的新蛋白，我们进一步分析了它在β细胞功能中的作用。在高糖浓度下，ERp46在β-TC-6细胞和分离的小鼠胰岛中的表达减少。进一步分析发现，ERp46在胰岛组织中的表达高于外分泌组织。有趣的是，在db/db小鼠的胰岛中发现ERp46的表达显著减少。最重要的是，在培养的β细胞中，siRNA介导的ERp46基因敲除导致胰岛素含量显著下降；但在这些条件下，胰岛素mRNA水平没有观察到变化。此外，siRNA降低ERp46的表达，增加CHOP和peIF2a的表达，提示内质网应激的发生。我们的结论是，ERp46可能是翻译后水平上胰岛素产生的“葡萄糖毒性”现象中的一个重要组成部分。
Alberti A, Karamessinis P, Peroulis M, Kypreou K, Kavvadas P, Pagakis S, Politis PK, Charonis A. ERp46 is reduced by high glucose and regulates insulin content in pancreatic beta-cells. Am J Physiol Endocrinol Metab 297: E812-E821, 2009. First published July 21, 2009; doi:10.1152/ajpendo.00053.2009.-Our studies focus on ERp46, an endoplasmic reticulum (ER) component, and analyze its involvement in glucose toxicity and in insulin production. Differences in pancreatic beta-TC-6 cell proteome under conditions of low vs. high glucose were examined by proteomic approaches, including two-dimensional gel electrophoresis, image analysis, and mass spectrometry. Among differentially expressed proteins, ERp46, a novel endoplasmic reticulum component, was examined further. The expression of ERp46 in pancreatic sections was analyzed by immunocytochemistry, and high glucose-induced alterations of expression were evaluated in cultured beta-cells, in isolated pancreatic islets, and in the pancreas of db/db diabetic animals. Inhibition of ERp46 expression by siRNA was performed to study its role in insulin production, in secretion, and in ER stress. Proteomic analysis led to identification of 46 differentially expressed spots corresponding to 23 proteins. Since ERp46 is a novel protein with a possible crucial role in secretory cells, we further analyzed its role in beta-cell function. ERp46 expression is reduced in high glucose concentration in beta-TC-6 cells and in isolated murine islets. Further analysis revealed high expression of ERp46 in pancreatic islets compared with exocrine tissue. Interestingly, a marked decrease in ERp46 expression was found in the pancreatic islets of db/db mice. Most importantly, siRNA-mediated knockdown of ERp46 in cultured beta-cells led to a significant decrease in the insulin content; however, no alterations in insulin mRNA levels were observed under these conditions. In addition, reduced expression of ERp46 by siRNA increased the expression of CHOP and peIF2a, indicating development of ER stress. We conclude that ERp46 may be an important component in the phenomenon of "glucose toxicity" involved in insulin production at the posttranslational level.