Ischaemia-induced autophagy leads to degradation of gap junction protein connexin43 in cardiomyocytes
Ischaemia-induced autophagy leads to degradation of gap junction protein connexin43 in cardiomyocytes
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DOI：
10.1042/bj20141370
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发表时间：
2015-04-15
影响因子：
4.1
通讯作者：
Girao, Henrique
中科院分区：
文献类型：
--
作者：
Martins-Marques, Tania;Catarino, Steve;Girao, Henrique
心肌细胞之间的间隙连接细胞间通讯（gap junction intercellular communication，GJIC）是心脏同步收缩的关键，依赖于含有连接蛋白（connexin，Cx）的通道。Cx43的增加的分解通常与各种心脏疾病有关。然而，Cx43在缺血性心脏中降解的机制仍然未知。本研究使用HL-1细胞和器官型心脏培养物获得的结果表明，模拟缺血会诱导Cx43降解，而自噬的化学或遗传抑制剂可以防止这种降解。此外，缺血诱导的Cx43降解导致HL-1细胞中GJIC受损，其可以通过自噬抑制来恢复。在心肌细胞中，泛素通过招募泛素结合蛋白Eps 15（表皮生长因子受体底物15）和p62（通过LC 3（轻链3）帮助Cx43内化并靶向自噬囊泡），向Cx43发出自噬降解信号。此外，我们确定缺血或I/R（缺血/再灌注）中Cx43的降解依赖于不同的分子参与者。事实上，缺血早期Cx43的降解依赖于AMPK（AMP活化蛋白激酶），而在缺血晚期和I/R Beclin 1是必需的。在Langendorff灌注的心脏中，Cx43在缺血中去磷酸化并在I/R期间降解，其中Cx43降解与自噬激活相关。总之，本研究的结果提供了新的证据，Cx43在缺血中降解的分子机制，这可能有助于开发新的策略，旨在保护缺血心脏的GJIC和心脏功能。
GJIC (gap junction intercellular communication) between cardiomyocytes is essential for synchronous heart contraction and relies on Cx (connexin)-containing channels. Increased breakdown of Cx43 has been often associated with various cardiac diseases. However, the mechanisms whereby Cx43 is degraded in ischaemic heart remain unknown. The results obtained in the present study, using both HL-1 cells and organotypic heart cultures, show that simulated ischaemia induces degradation of Cx43 that can be prevented by chemical or genetic inhibitors of autophagy. Additionally, ischaemia-induced degradation of Cx43 results in GJIC impairment in HL-1 cells, which can be restored by autophagy inhibition. In cardiomyocytes, ubiquitin signals Cx43 for autophagic degradation, through the recruitment of the ubiquitin-binding proteins Eps15 (epidermal growth factor receptor substrate 15) and p62, that assist in Cx43 internalization and targeting to autophagic vesicles, via LC3 (light chain 3). Moreover, we establish that degradation of Cx43 in ischaemia or I/R (ischaemia/reperfusion) relies upon different molecular players. Indeed, degradation of Cx43 during early periods of ischaemia depends on AMPK (AMP-activated protein kinase), whereas in late periods of ischaemia and I/R Beclin 1 is required. In the Langendorff-perfused heart, Cx43 is dephosphorylated in ischaemia and degraded during I/R, where Cx43 degradation correlates with autophagy activation. In summary, the results of the present study provide new evidence regarding the molecular mechanisms whereby Cx43 is degraded in ischaemia, which may contribute to the development of new strategies that aim to preserve GJIC and cardiac function in ischaemic heart.