Down-regulation of Connexin43 in early myocardial ischemia and protective effect by ischemic preconditioning in rat hearts in vivo
Down-regulation of Connexin43 in early myocardial ischemia and protective effect by ischemic preconditioning in rat hearts in vivo
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DOI：
10.1536/jhj.45.1007
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发表时间：
2004-11-01
期刊：
影响因子：
--
通讯作者：
Yoshida, K
中科院分区：
文献类型：
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作者：
Hatanka, K;Kawata, H;Yoshida, K
缝隙连接蛋白43（Cx43）是缝隙连接的主要组成部分，参与细胞间的电化学通讯。Cx43在早期缺血中经历去磷酸化。我们研究了Cx43是否在早期心肌缺血中与去磷酸化相关降解，以及缺血预处理（IP）是否影响大鼠冠状动脉闭塞后的降解。雄性Sprague-Dawley大鼠接受冠状动脉闭塞1、2或3小时，或在用钙调磷酸酶抑制剂（环孢菌素A）、蛋白酶体抑制剂（PSI）或溶酶体抑制剂（E64 c）处理后1小时，或在单独IP后或在蛋白激酶C（PKC）抑制剂（白屈菜红碱）预处理后1小时。IP通过3分钟缺血和5分钟再灌注的三个循环来提供。大部分的磷酸化Cx43（pCx 43）的膜部分被去磷酸化，而一小部分在缺血1小时降解。抑制剂的作用是去磷酸化和降解钙调磷酸酶和蛋白酶体/溶酶体，分别。IP抑制pCx 43的降低和dCx 43的升高，而PKC抑制剂白屈菜红碱仅抑制前者。Cx43 mRNA水平在缺血3小时降低，但在缺血1小时不降低，与IP无关。我们认为，Cx43是去磷酸化和降解在早期缺血，而Cx43转录抑制在缺血后期。
Connexin 43 (Cx43), a primary component of gap junctions, contributes to intercellular electrochemical communication. Cx43 Undergoes dephosphorylation in early ischemia. We examined whether Cx43 is degraded in association with dephosphorylation during early myocardial ischemia and whether ischemic preconditioning (IP) affects the degradation after rat coronary artery occlusion. Male Sprague-Dawley rats underwent coronary artery occlusion for 1, 2, or 3 hours, or for 1 hour following treatment either with a calcineurin inhibitor (cyclosporine A), proteasome inhibitor (PSI), or lysosomal inhibitor (E64c), or following IP alone or after protein kinase C (PKC) inhibitor (chelerythrine) pretreatment. The IP was afforded by three cycles of 3 minute ischemia and 5 minute reperfusion. A large portion of the phosphorylated Cx43 (pCx43) in the membrane fraction was dephosphorylated, while a small portion was degraded at 1 hour of ischemia. The effects of the inhibitors were dephosphorylation and degradation by calcineurin and proteasome/lysosome, respectively. IP suppressed the decrease in pCx43 and increase in dCx43, while only the former was inhibited by the PKC inhibitor chelerythrine. The Cx43 mRNA level was reduced at 3 hours, but not at 1 hour of ischemia, irrespective of IP. We believe that Cx43 is dephosphorylated and degraded in early ischemia, whereas Cx43 transcription was suppressed at a later phase of ischemia.