From the Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine (T.M.-M., S.C., L.C., P.A., G.C., H.G.), University of Coimbra, Portugal.
Center for Innovative Biomedicine and Biotechnology (T.M.-M., S.C., H.G.), University of Coimbra, Portugal.
Circ Res. 2020 May 8;126(10):e97-e113. doi: 10.1161/CIRCRESAHA.119.316502. Epub 2020 Mar 5.
Efficient communication between heart cells is vital to ensure the anisotropic propagation of electrical impulses, a function mainly accomplished by gap junctions (GJ) composed of Cx43 (connexin 43). Although the molecular mechanisms remain unclear, altered distribution and function of gap junctions have been associated with acute myocardial infarction and heart failure.
A recent proteomic study from our laboratory identified EHD1 (Eps15 [endocytic adaptor epidermal growth factor receptor substrate 15] homology domain-containing protein 1) as a novel interactor of Cx43 in the heart.
In the present work, we demonstrate that knockdown of EHD1 impaired the internalization of Cx43, preserving gap junction-intercellular coupling in cardiomyocytes. Interaction of Cx43 with EHD1 was mediated by Eps15 and promoted by phosphorylation and ubiquitination of Cx43. Overexpression of wild-type EHD1 accelerated internalization of Cx43 and exacerbated ischemia-induced lateralization of Cx43 in isolated adult cardiomyocytes. In addition, we show that EHDs associate with Cx43 in human and murine failing hearts.
Overall, we identified EHDs as novel regulators of endocytic trafficking of Cx43, participating in the pathological remodeling of gap junctions, paving the way to innovative therapeutic strategies aiming at preserving intercellular communication in the heart.
心脏细胞之间的有效沟通对于确保电脉冲的各向异性传播至关重要，这一功能主要是通过由 Cx43（连接蛋白 43）组成的缝隙连接（GJ）来完成的。尽管分子机制尚不清楚，但缝隙连接的分布和功能改变与急性心肌梗死和心力衰竭有关。
我们实验室最近的一项蛋白质组学研究发现，EHD1（Eps15[表皮生长因子受体底物 15 同源结构域蛋白 1]衔接蛋白）是心脏中 Cx43 的一种新型相互作用蛋白。
在本工作中，我们证明了 EHD1 的敲低会损害 Cx43 的内化，从而保持心肌细胞中缝隙连接的细胞间偶联。Cx43 与 EHD1 的相互作用由 Eps15 介导，并由 Cx43 的磷酸化和泛素化促进。野生型 EHD1 的过表达加速了 Cx43 的内化，并加剧了分离的成年心肌细胞中缺血诱导的 Cx43 侧向化。此外，我们还表明 EHD 与人类和鼠类衰竭心脏中的 Cx43 相关联。
总的来说，我们确定了 EHD 是 Cx43 内吞运输的新型调节因子，参与缝隙连接的病理性重塑，为旨在维持心脏细胞间通讯的创新治疗策略铺平了道路。
