Marked increase of insulin gene transcription by suppression of the Rho/Rho-kinase pathway
Marked increase of insulin gene transcription by suppression of the Rho/Rho-kinase pathway
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DOI：
10.1016/j.bbrc.2006.08.192
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发表时间：
2006-11-10
影响因子：
3.1
通讯作者：
Yamasaki, Yoshimitsu
中科院分区：
文献类型：
--
作者：
Nakamura, Yumiko;Kaneto, Hideaki;Yamasaki, Yoshimitsu
2型糖尿病的特征是胰岛β细胞功能障碍和胰岛素抵抗。已有研究表明，Rho/Rho-Kinase是胰岛素信号转导的中介，从而参与胰岛素抵抗的发生、胰岛素作用的调节和血糖稳态，但Rho/Rho-Kinase在胰岛β细胞中的作用尚不清楚。本研究的目的是研究Rho/Rho-Kinase在β细胞功能中的可能作用。免疫组织化学染色显示RhoA在成熟的β细胞中有表达，糖尿病C57BL/KSJ-db/db小鼠的β细胞中RhoA的表达高于非糖尿病小鼠。此外，为了研究Rho/Rho-Kinase在β细胞中的功能作用，我们评估了Rho-Kinase抑制剂对胰岛素生物合成的影响。Northern印迹分析显示，Rho-Kinase抑制剂Y-27632和法舒地尔显著提高了β细胞来源的HIT-T15细胞的胰岛素基因表达水平。此外，利用荧光素酶报告基因分析，Y-27632还显著提高了胰岛素启动子的活性，这与胰岛素基因水平的提高有关。这些结果表明，抑制Rho/Rho-Kinase可增加胰岛素启动子的活性，从而导致胰岛素mRNA水平的升高。综上所述，在糖尿病条件下，Rho/Rho-Kinase在β细胞中被激活，抑制Rho/Rho-Kinase通路可以增加胰岛素基因的转录。这些结果表明，Rho/Rho-Kinase的激活参与了对糖尿病患者胰岛素表达的抑制，抑制Rho/Rho-Kinase通路可能是增强胰岛素基因转录的有用工具。(C)2006 Elsevier Inc.保留所有权利。
The hallmarks of type 2 diabetes are pancreatic beta-cell dysfunction and insulin resistance. It has been suggested that Rho/Rho-kinase is a mediator of insulin signaling, and thereby involved in the development of insulin resistance, regulation of insulin action, and glucose homeostasis, but the role of Rho/Rho-kinase in beta-cells remained unknown. The aim of this study was to examine the possible role of Rho/Rho-kinase in beta-cell function. Immunostaining showed that RhoA was expressed in mature beta-cells, with higher expression observed in beta-cells of diabetic C57BL/KsJ-db/db mice compared to non-diabetic mice. In addition, to examine the functional role of Rho/Rho-kinase in beta-cells, we evaluated the effect of Rho-kinase inhibitors on insulin biosynthesis. Northern blot analysis showed that insulin mRNA levels were markedly increased by Rho-kinase inhibitors, Y-27632 and fasudil, in beta-cell-derived HIT-T15 cells. Furthermore, using the luciferase reporter gene assay, insulin promoter activity was also dramatically increased by Y-27632, which was associated with an increase in the insulin mRNA level. These results suggest that suppression of Rho/Rho-kinase increases insulin promoter activity, which leads to an increase in insulin mRNA level. Taken together, Rho/Rho-kinase is activated in beta-cells under diabetic conditions and suppression of the Rho/Rho-kinase pathway increases insulin gene transcription. These results imply that Rho/Rho-kinase activation is involved in the suppression of insulin expression found in diabetes and that suppression of the Rho/Rho-kinase pathway could be a useful tool to augment insulin gene transcription. (c) 2006 Elsevier Inc. All rights reserved.