Double-stranded RNA-dependent protein kinase is not required for double-stranded RNA-induced nitric oxide synthase expression or nuclear factor-κB activation by islets
Double-stranded RNA-dependent protein kinase is not required for double-stranded RNA-induced nitric oxide synthase expression or nuclear factor-κB activation by islets
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DOI：
10.2337/diabetes.50.2.283
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发表时间：
2001-02-01
期刊：
影响因子：
7.7
通讯作者：
Corbett, JA
中科院分区：
文献类型：
--
作者：
Blair, LA;Heitmeier, MR;Corbett, JA
环境因素，如病毒感染，已经涉及在自身免疫性糖尿病的发展过程中β细胞的破坏。病毒复制过程中产生的双链RNA（dsRNA）是病毒感染的活性成分，可刺激受感染细胞的抗病毒反应。先前的研究已经表明，用dsRNA与γ-干扰素（IFN-γ）组合处理大鼠胰岛导致葡萄糖刺激的胰岛素分泌的一氧化氮依赖性抑制。本研究探讨了核因子-κ B（NF-κ B）和dsRNA依赖性蛋白激酶（PKR）在dsRNA + IFN-γ诱导的大鼠、小鼠和人类胰岛一氧化氮合酶（iNOS）表达和一氧化氮产生中的作用。用聚肌苷酸-聚胞苷酸（poly IC）和IFN-γ形式的dsRNA处理大鼠和人胰岛导致iNOS表达和一氧化氮产生。NF-κ B激活的抑制剂-脯氨酸酶体抑制剂MG-132和抗氧化剂吡咯烷-二硫代氨基甲酸酯（PDTC）-阻止聚IC + IFN-γ诱导的iNOS表达和一氧化氮产生。用单独的聚IC或聚IC + IFN-γ孵育大鼠胰岛3小时或人胰岛2小时导致NF-κ B核转位和NF-κ B抑制剂蛋白I κ B的降解，这些事件被MG-132阻止。PKR已被证明参与dsRNA诱导的NF-κ B在许多细胞类型中的活化，包括小鼠胚胎成纤维细胞。然而，聚IC刺激NF-κ B核转位和I κ B降解，在从缺乏PKR的小鼠（PKR-/-）和野生型小鼠（PKR-/-）分离的胰岛中达到相似的水平。此外，PKR的遗传缺失不影响dsRNA + IFN-γ诱导的iNOS表达、一氧化氮产生或这些药剂对葡萄糖刺激的胰岛素分泌的抑制作用。这些结果表明，1）dsRNA + IFN-γ诱导的iNOS表达需要NF-κ B活化，2）胰岛的dsRNA诱导的NF-κ B活化或dsRNA + IFN-γ诱导的iNOS表达不需要PKR，和3）胰岛的葡萄糖刺激的胰岛素分泌的dsRNA + IFN-γ诱导的抑制不需要PKR。
Environmental factors, such as viral infection, have been implicated in the destruction of beta -cells during the development of autoimmune diabetes. Double-stranded RNA (dsRNA), produced during viral replication, is an active component of a viral infection that stimulates antiviral responses in infected cells. Previous studies have shown that treatment of rat islets with dsRNA in combination with gamma -interferon (IFN-gamma) results in a nitric oxide-dependent inhibition of glucose-stimulated insulin secretion. This study examines the role of nuclear factor-kappaB (NF-kappaB) and the dsRNA-dependent protein kinase (PKR) in dsRNA + IFN-gamma -induced nitric oxide synthase (iNOS) expression and nitric oxide production by rat, mouse, and human islets. Treatment of rat and human islets with dsRNA in the form of polyinosinic-polycytidylic acid (poly IC) and IFN-gamma resulted in iNOS expression and nitric oxide production. Inhibitors of NF-kappaB activation-the prroteasome inhibitor MG-132 and the antioxidant pyrrolidine-dithiocarbamate (PDTC)-prevented poly IC + IFN-gamma -induced iNOS expression and nitric oxide production. Incubation of rat islets for 3 h or human islets for 2 h with poly IC alone or poly IC + IFN-gamma resulted in NF-kappaB nuclear translocation and degradation of the NF-kappaB inhibitor protein, I kappaB, events that are prevented by MG-132. PKR has been shown to participate in dsRNA-induced NF-kappaB activation in a number of cell types, including mouse embryonic fibroblasts. However, poly IC stimulated NF-kappaB nuclear translocation and I kappaB degradation to similar levels in islets isolated from mice devoid of PKR (PKR-/-) and wild-type mice (PKR-/-). Furthermore, the genetic absence of PKR did not affect dsRNA + IFN-gamma -induced iNOS expression, nitric oxide production, or the inhibitory actions of these agents on glucose-stimulated insulin secretion. These results suggest that 1) NF-kappaB activation is required for dsRNA + IFN-gamma -induced iNOS expression, 2) PKR is not required for either dsRNA-induced NF-kappaB activation or dsRNA + IFN-gamma -induced iNOS expression by islets, and 3) PKR is not required for dsRNA + IFN-gamma -induced inhibition of glucose-stimulated insulin secretion by islets.