Osteopontin protects the islets and β-cells from interleukin-1 β-mediated cytotoxicity through negative feedback regulation of nitric oxide
Osteopontin protects the islets and β-cells from interleukin-1 β-mediated cytotoxicity through negative feedback regulation of nitric oxide
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DOI：
10.1210/en.2006-0970
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发表时间：
2007-02-01
期刊：
影响因子：
4.8
通讯作者：
Dafoe, Donald C.
中科院分区：
文献类型：
--
作者：
Arafat, Hwyda A.;Katakam, Anand K.;Dafoe, Donald C.
骨桥蛋白 (OPN) 是一种与整合素结合基序结合的磷酸化糖蛋白，已被证明可以通过抑制诱导的一氧化氮合酶 (iNOS) 合成来调节一氧化氮 (NO) 的产生。在移植的胰岛中，由于胰岛被炎症细胞浸润并产生促炎细胞因子，因此产生了 iNOS 和有毒量的 NO。在这里，我们证明，在新鲜分离的大鼠胰岛中，在IL-1β之前添加OPN可以剂量依赖性地改善葡萄糖刺激的胰岛素分泌，并以精氨酸-甘氨酸-天冬氨酸依赖的方式抑制IL-1β诱导的NO产生。在 RINm5F β 细胞中瞬时转染 OPN 基因可完全阻止 IL-1 β 的毒性作用，其浓度可在 3 天内使存活率降低 50%。 OPN 预防 IL-1 β 诱导的毒性，同时抑制 iNOS 转录 80%，导致有毒 NO 的形成减少 50%。在OPN转染的细胞中，IL-1β诱导的核因子κB活性显着降低。暴露于 IL-1 beta 的胰岛显示出自然发生的早期 OPN 转录上调。当 IL-1β、IL-1β 诱导的 NO 和 NO 合成诱导剂存在时，OPN 启动子活性增加。这些数据表明，IL-1β 和 OPN 途径之间存在串扰，并且存在独特的反式调节机制，其中 IL-1β 诱导的 NO 合成反馈通过上调 OPN 基因转录来调节自身。我们的数据还表明，影响 OPN 表达代表了一种影响细胞因子诱导的信号转导的方法，以防止或减少胰岛移植后下游破坏性效应级联的激活。
Osteopontin (OPN), a phosphorylated glycoprotein that binds to an integrin-binding motif, has been shown to regulate nitric oxide ( NO) production via inhibition of induced NO synthase ( iNOS) synthesis. In the transplanted islets, iNOS and toxic amounts of NO are produced as a result of islets infiltration with inflammatory cells and production of proinflammatory cytokines. Here, we demonstrate that addition of OPN before IL-1 beta in freshly isolated rat islets improved their glucose stimulated insulin secretion dose-dependently and inhibited IL-1 beta-induced NO production in an arginine-glycine-aspartate-dependent manner. Transient transfection of OPN gene in RINm5F beta-cells fully prevented the toxic effect of IL-1 beta at concentrations that reduced the viability by 50% over 3 d. OPN prevention of IL-1 beta-induced toxicity was accompanied by inhibited transcription of iNOS by 80%, resulting in 50% decreased formation of the toxic NO. In OPN-transfected cells, the IL-1 beta-induced nuclear factor-kappa B activity was significantly reduced. Islets exposed to IL-1 beta revealed a naturally occurring early up-regulated OPN transcription. OPN promoter activity was increased in the presence of IL-1 beta, IL-1 beta-induced NO, and an inducer of NO synthesis. These data suggest the presence of a cross talk between the IL-1 beta and OPN pathways and a unique trans-regulatory mechanism in which IL-1 beta-induced NO synthesis feedback regulates itself through upregulation of OPN gene transcription. Our data also suggest that influencing OPN expression represents an approach for affecting cytokine-induced signal transduction to prevent or reduce activation of the cascade of downstream devastating effects after islet transplantation.