Connexin 43 hyper-phosphorylation at serine 282 triggers apoptosis in rat cardiomyocytes via activation of mitochondrial apoptotic pathway
Connexin 43 hyper-phosphorylation at serine 282 triggers apoptosis in rat cardiomyocytes via activation of mitochondrial apoptotic pathway
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DOI：
10.1038/s41401-021-00824-z
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发表时间：
2021-12-20
影响因子：
8.2
通讯作者：
Luo, Da-li
中科院分区：
文献类型：
--
作者：
Fu, Zhi-ping;Wu, Lu-lin;Luo, Da-li
Cx43是心室缝隙连接中的主要连接蛋白，在相邻心肌细胞间的电和代谢通讯中起关键作用。我们以前发现，Cx43丝氨酸282（pS282）去磷酸化引起心肌细胞凋亡，这是参与心肌缺血/再灌注损伤。在这项研究中，我们研究了Cx43-S282过度磷酸化是否可以保护心肌细胞免于凋亡。将携带大鼠Cx43全长基因（Cx43-wt）或S282天冬氨酸突变基因（S282 D）的腺病毒转染或注射到新生大鼠心室肌细胞（NRVM）中。采用大鼠腹主动脉缩窄模型（AAC）检测Cx43-S282磷酸化状态。我们发现，在转染后24小时，与Cx43-wt细胞相比，S282处的Cx43磷酸化增加了2倍以上，而pS262和pS368没有改变。与Cx43-wt细胞相比，S282 D转染细胞显示增强的间隙连接通讯，增加的基础细胞内Ca 2+浓度和自发性Ca 2+瞬变。S282 D转染NRVMs 34 h后，NRVMs出现自发性凋亡。转染S282 D的大鼠心室肌细胞也表现出凋亡反应，包括Bax/Bcl-xL比值增加、细胞色素c释放以及caspase-3和caspase-9活性增加，而Fas/Fas相关死亡结构域表达和caspase-8活性保持不变。此外，与Sham心室相比，AAC诱导的肥大心室具有Cx43-S282过度磷酸化的凋亡损伤。总之，Cx43在S282处的过度磷酸化，作为去磷酸化，也触发心肌细胞凋亡，但通过激活线粒体凋亡途径，提供维持心肌细胞功能和存活所需的微调Cx43-S282磷酸化范围。
Cx43 is the major connexin in ventricular gap junctions, and plays a pivotal role in control of electrical and metabolic communication among adjacent cardiomyocytes. We previously found that Cx43 dephosphorylation at serine 282 (pS282) caused cardiomyocyte apoptosis, which is involved in cardiac ischemia/reperfusion injury. In this study we investigated whether Cx43-S282 hyper-phosphorylation could protect cardiomyocytes against apoptosis. Adenovirus carrying rat full length Cx43 gene (Cx43-wt) or a mutant gene at S282 substituted with aspartic acid (S282D) were transfected into neonatal rat ventricular myocytes (NRVMs) or injected into rat ventricular wall. Rat abdominal aorta constriction model (AAC) was used to assess Cx43-S282 phosphorylation status. We showed that Cx43 phosphorylation at S282 was increased over 2-times compared to Cx43-wt cells at 24 h after transfection, while pS262 and pS368 were unaltered. S282D-transfected cells displayed enhanced gap junctional communication, and increased basal intracellular Ca2+ concentration and spontaneous Ca2+ transients compared to Cx43-wt cells. However, spontaneous apoptosis appeared in NRVMs transfected with S282D for 34 h. Rat ventricular myocardium transfected with S282D in vivo also exhibited apoptotic responses, including increased Bax/Bcl-xL ratio, cytochrome c release as well as caspase-3 and caspase-9 activities, while factor-associated suicide (Fas)/Fas-associated death domain expression and caspase-8 activity remained unaltered. In addition, AAC-induced hypertrophic ventricles had apoptotic injury with Cx43-S282 hyper-phosphorylation compared with Sham ventricles. In conclusion, Cx43 hyper-phosphorylation at S282, as dephosphorylation, also triggers cardiomyocyte apoptosis, but through activation of mitochondrial apoptosis pathway, providing a fine-tuned Cx43-S282 phosphorylation range required for the maintenance of cardiomyocyte function and survival.