Claudin-5对线粒体的影响及其在心肌缺血再灌注损伤中保护作用的研究

临床研究表明心肌细胞claudin-5的表达减少与心衰有关，但具体机制不明。我们发现claudin-5大量表达在心肌细胞线粒体上并在缺氧复氧损伤后表达减少，同时伴随着线粒体的碎片化。过表达claudin-5能有效减少缺氧复氧诱导的线粒体分裂和缺血再灌注引起的心肌梗死。我们推测claudin-5对线粒体的形态和功能的维持具有重要作用。本课题拟在心肌细胞缺氧复氧和缺血再灌注损伤模型中应用claudin-5敲低和过表达的方法，观察claudin-5对心肌细胞线粒体形态和功能的影响。本课题将拓展我们对claudin-5在细胞内功能的认识并为心肌缺血再灌注损伤的防治提供新的靶点。我们还将对组胺受体2-TNF-α-ERK1/2通路进行阻断来观察claudin-5是否参与了组胺受体2的激活引起的心肌细胞线粒体功能的紊乱，从而为应用组胺受体2阻断治疗缺血再灌注损伤提供理论依据。

Claudin-5 is a transmembrane cell junction protein on endothelial cell layers that forms tight junctions and controls paracellular permeability. Claudin-5 was mainly localized to the lateral membranes of murine cardiomyocytes and was severely downregulated in cardiomyocytes from the human failing heart in clinic observation and from the mouse model of cardiomyopathy in experimental research. Our preliminary data showed that Claudin-5 was expressed on the cardiomyocyte’s mitochondria and its expression was decreased along with the mitochondrial fragmentation after hypoxia-reoxygenation (H/R) and ischemia reperfusion (I/R) injury in vitro and in vivo. Claudin-5 adenovirus pretreatment significantly decreased the mitochondria fission and myocardial necrosis induced by H/R and I/R. We will utilize claudin-5 knockdown/knockout and overexpression in cardiomyocyte in H/R and I/R model to observe the effect of claudin-5 on mitochondrial morphology and function. This research will expand our understanding on the function of claudin-5 in the cell and may provide new therapeutic target for myocardial I/R injury. We also will utilize histamine receptor 2 (H2R) activation and knockout, TNF-α antagonism and ERK1/2 inhibition to observe the role of claudin-5 on H2R activation-induced mitochondrial dysfunction. The current research will also enhance the theory of using H2R blockade to treat myocardial I/R injury.