Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London W12 0NN, UK.
Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark.
Int J Mol Sci. 2020 Jun 17;21(12):4311. doi: 10.3390/ijms21124311.
Intercellular communication mediated by cationic fluxes through the Connexin family of gap junctions regulates glucose-stimulated insulin secretion and beta cell defense against inflammatory stress. Rotigaptide (RG, ZP123) is a peptide analog that increases intercellular conductance in cardiac muscle cells by the prevention of dephosphorylation and thereby uncoupling of Connexin-43 (Cx43), possibly via action on unidentified protein phosphatases. For this reason, it is being studied in human arrhythmias. It is unknown if RG protects islet cell function and viability against inflammatory or metabolic stress, a question of considerable translational interest for the treatment of diabetes.
Apoptosis was measured in human islets shown to express Cx43, treated with RG or the control peptide ZP119 and exposed to glucolipotoxicity or IL-1β + IFNɣ. INS-1 cells shown to lack Cx43 were used to examine if RG protected human islet cells via Cx43 coupling. To study the mechanisms of action of Cx43-independent effects of RG, NO, IkBα degradation, mitochondrial activity, ROS, and insulin mRNA levels were determined.
RG reduced cytokine-induced apoptosis ~40% in human islets. In Cx43-deficient INS-1 cells, this protective effect was markedly blunted as expected, but unexpectedly, RG still modestly reduced apoptosis, and improved mitochondrial function, insulin-2 gene levels, and accumulated insulin release. RG reduced NO production in Cx43-deficient INS-1 cells associated with reduced iNOS expression, suggesting that RG blunts cytokine-induced NF-κB signaling in insulin-producing cells in a Cx43-independent manner.
RG reduces cytokine-induced cell death in human islets. The protective action in Cx43-deficient INS-1 cells suggests a novel inhibitory mechanism of action of RG on NF-κB signaling.
通过间隙连接家族的阳离子流介导的细胞间通讯调节葡萄糖刺激的胰岛素分泌和β细胞对炎症应激的防御。Rotigaptide（RG，ZP123）是一种肽类似物，通过防止去磷酸化和因此使 Connexin-43（Cx43）解偶联，从而增加心肌细胞的细胞间电导，这可能是通过对未鉴定的蛋白磷酸酶的作用。出于这个原因，它正在人类心律失常中进行研究。尚不清楚 RG 是否能保护胰岛细胞功能和活力免受炎症或代谢应激的影响，这对于糖尿病的治疗具有重要的转化意义。
用 RG 或对照肽 ZP119 处理表达 Cx43 的人胰岛，然后使其暴露于糖脂毒性或 IL-1β+IFNγ，测量凋亡。使用被证明缺乏 Cx43 的 INS-1 细胞来研究 RG 是否通过 Cx43 偶联来保护人胰岛细胞。为了研究 RG 对 Cx43 独立作用的作用机制，测定了 NO、IkBα 降解、线粒体活性、ROS 和胰岛素 mRNA 水平。
RG 降低了约 40%人胰岛中细胞因子诱导的凋亡。在缺乏 Cx43 的 INS-1 细胞中，这种保护作用如预期的那样明显减弱，但出乎意料的是，RG 仍然适度地降低了凋亡，并改善了线粒体功能、胰岛素-2 基因水平和胰岛素积累释放。RG 降低了缺乏 Cx43 的 INS-1 细胞中的 NO 产生，同时伴随 iNOS 表达减少，这表明 RG 以 Cx43 非依赖性方式减弱了胰岛素产生细胞中细胞因子诱导的 NF-κB 信号转导。
RG 降低了人胰岛中细胞因子诱导的细胞死亡。在缺乏 Cx43 的 INS-1 细胞中的保护作用表明 RG 对 NF-κB 信号转导具有新的抑制作用机制。
