Exendin-4 suppresses SRC activation and reactive oxygen species production in diabetic Goto-Kakizaki rat islets in an Epac-dependent manner.
Exendin-4 suppresses SRC activation and reactive oxygen species production in diabetic Goto-Kakizaki rat islets in an Epac-dependent manner.
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作者：
Mukai E;Fujimoto S;Sato H;Oneyama C;Kominato R;Sato Y;Sasaki M;Nishi Y;Okada M;Inagaki N
活性氧（Reactive oxygen species，ROS）是胰岛β细胞代谢分泌偶联受损的重要因素之一。我们最近报道了糖尿病Goto-Kakizaki（GK）大鼠胰岛在高糖下ROS产生升高和ATP产生受损，Src抑制可有效改善，表明Src活性上调。在本研究中，我们研究了胰高血糖素样肽-1信号是否调节Src活性，并改善内源性ROS的产生和ATP的产生在GK胰岛使用exendin-4。从GK和对照Wistar大鼠分离的胰岛用于免疫印迹分析和ROS产生和ATP含量的测量。通过免疫沉淀胰岛裂解物，然后通过免疫印迹检测Src活性。使用分散的胰岛细胞用荧光探针测量ROS产生。Exendin-4显著降低了16.7 mmol/l葡萄糖暴露下GK胰岛中Src Tyr 416的磷酸化，这表明Src活化。葡萄糖诱导的活性氧产生（16.7 mmol/l）在GK胰岛细胞显着减少exendin-4以及PP 2，Src抑制剂的共同曝光。GK胰岛中Src激酶阴性突变体的表达显著降低高糖诱导的ROS产生。Exendin-4以及PP 2显著增加GK胰岛中由高糖引起的受损ATP升高。exendin-4引起的ROS生成减少不受PKA抑制剂H-89的影响，Epac特异性cAMP类似物（8 CPT-2 Me-cAMP）显著降低Src Tyr 416磷酸化和ROS生成。Exendin-4通过依赖于Epac抑制Src活化，降低糖尿病GK大鼠胰岛内源性ROS产生并增加ATP产生。
Reactive oxygen species (ROS) is one of most important factors in impaired metabolism secretion coupling in pancreatic β-cells. We recently reported that elevated ROS production and impaired ATP production at high glucose in diabetic Goto-Kakizaki (GK) rat islets are effectively ameliorated by Src inhibition, suggesting that Src activity is upregulated. In the present study, we investigated whether the glucagon-like peptide-1 signal regulates Src activity and ameliorates endogenous ROS production and ATP production in GK islets using exendin-4. Isolated islets from GK and control Wistar rats were used for immunoblotting analyses and measurements of ROS production and ATP content. Src activity was examined by immunoprecipitation of islet lysates followed by immunoblotting. ROS production was measured with a fluorescent probe using dispersed islet cells. Exendin-4 significantly decreased phosphorylation of Src Tyr416, which indicates Src activation, in GK islets under 16.7 mmol/l glucose exposure. Glucose-induced ROS production (16.7 mmol/l) in GK islet cells was significantly decreased by coexposure of exendin-4 as well as PP2, a Src inhibitor. The Src kinase–negative mutant expression in GK islets significantly decreased ROS production induced by high glucose. Exendin-4, as well as PP2, significantly increased impaired ATP elevation by high glucose in GK islets. The decrease in ROS production by exendin-4 was not affected by H-89, a PKA inhibitor, and an Epac-specific cAMP analog (8CPT-2Me-cAMP) significantly decreased Src Tyr416 phosphorylation and ROS production. Exendin-4 decreases endogenous ROS production and increases ATP production in diabetic GK rat islets through suppression of Src activation, dependently on Epac.