Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan; Department of General Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Department of Anatomy and Cell Biology, National Taiwan University, Taipei, Taiwan.
Chem Biol Interact. 2020 Mar 1;319:108979. doi: 10.1016/j.cbi.2020.108979. Epub 2020 Feb 8.
Heart rhythm disturbances have been widely recognized as major triggers of cardiovascular (CV) mortality in chronic kidney disease (CKD) patients. Connexin 43 (Cx43)-composed gap junctions are essential in cardiomyocyte synchronization and may be involved in the pathological response to uremic toxins. Indoxyl sulfate (IS) is one of the most dominant uremic toxins that contribute to CKD-related cardiovascular diseases. In primary cultures of rat neonatal cardiomyocytes, we demonstrated that IS treatment decreased spontaneous contraction without impairing viability. In addition, there was disruption of gap junction intercellular communication (GJIC) between cardiomyocytes after 30 min of IS stimulation. IS caused time- and dose-dependent Cx43 redistribution, and the patterns of Cx43 immunostaining returned to baseline while IS stimulation was removed. Furthermore, IS exposure downregulated Cx43 protein and mRNA levels. Elevated JNK1 and JNK2 phosphorylation was further identified after IS exposure in both rat cardiomyocytes and H9c2 cells. The above changes as well as GJIC and Cx43 suppression were reversed by pretreatment with a JNK inhibitor (SP600125). Inhibition of p-JNK attenuated IS-mediated downward trends in Cx43 transcription and translation. In cardiac muscle from nephrectomy-induced CKD mice, an alteration in Cx43 level was identified at intercalated discs. Our findings disclosed that JNK activation might participate in the remodeling of gap junction and Cx43 expression by uremic toxin-IS both in vitro and in vivo.
心律失常已被广泛认为是慢性肾脏病（CKD）患者心血管（CV）死亡率的主要诱因。连接蛋白 43（Cx43）组成的缝隙连接对于心肌细胞同步化至关重要，并且可能参与对尿毒症毒素的病理反应。硫酸吲哚酚（IS）是导致 CKD 相关心血管疾病的最主要尿毒症毒素之一。在原代培养的新生大鼠心肌细胞中，我们证明 IS 处理会降低自发性收缩而不损害细胞活力。此外，在 IS 刺激 30 分钟后，心肌细胞之间的缝隙连接细胞间通讯（GJIC）被破坏。IS 引起 Cx43 重分布呈时间和剂量依赖性，并且当去除 IS 刺激时，Cx43 免疫染色模式恢复到基线。此外，IS 暴露下调了 Cx43 蛋白和 mRNA 水平。在大鼠心肌细胞和 H9c2 细胞中，IS 暴露后还进一步鉴定出 JNK1 和 JNK2 磷酸化的升高。上述变化以及 GJIC 和 Cx43 抑制作用，通过 JNK 抑制剂（SP600125）预处理而逆转。抑制 p-JNK 减轻了 IS 介导的 Cx43 转录和翻译的下降趋势。在肾切除术诱导的 CKD 小鼠的心肌中，在连接蛋白处鉴定到 Cx43 水平的改变。我们的研究结果表明，JNK 激活可能参与尿毒症毒素 IS 体外和体内的缝隙连接和 Cx43 表达的重塑。
