Role of PAR-1 and PAR-2 in Cardiac Remodeling

描述(申请人提供)：由病理性心脏重构和肥厚引起的心脏病是西方世界发病率和死亡率的主要原因。蛋白水解酶激活受体(PARs)在心肌细胞和心脏成纤维细胞中表达。然而，它们在心脏重构中的作用还没有在体内研究。重要的是，我们证明了在心脏缺血-再灌注(I/R)损伤模型中，与野生型相比，PAR-1-/-小鼠在2周时心脏重构和左心室扩张都有所减少。此外，我们还发现，心肌细胞特异性的PAR-1或PAR-2过表达可诱导小鼠心肌肥大。此外，我们还发现PAR-1和PAR-2在心肌肥厚的人和小鼠的心脏中的表达增加。最后，体外研究表明，PAR-1或PAR-2的激活可诱导心肌细胞肥大。基于这些结果，我们推测心肌细胞和心脏成纤维细胞上的PAR-1和PAR-2都参与了I/R损伤后的心脏重构。该提案有两个具体目标。特异靶1将确定PAR-1和PAR-2在I/R损伤后心脏重构中的作用。对于这些实验，我们将使用PAR-1-/-和PAR-2-/-小鼠，以及PAR-1和PAR-2特异性抑制剂。将产生PAR-1FLOX/FLOX小鼠，并与在心肌细胞或心脏成纤维细胞中表达Cre重组酶的小鼠杂交。这些小鼠将被用来确定心肌细胞上表达的PAR-1与心脏成纤维细胞相比在心脏重构中的相对贡献。通过使用药物抑制剂和显性负性突变体抑制MEK5-ERK5、MEK1-ERK1/2和钙调神经磷酸酶信号通路在依赖PAR-1和PAR-2的培养心肌细胞肥大中的作用。此外，我们还将描述在心肌细胞上过度表达PAR-1或PAR-2的小鼠心脏肥大的不同信号通路。这些研究将阐明PAR-1和PAR-2在I/R损伤后心脏重构中的作用，并将确定PAR-1或PAR-2激活诱导心肌肥厚的机制。这一结果可能导致PAR-1和PAR-2抑制剂的开发，它们可能被用作治疗人类病理性心脏重构和肥厚的新疗法。

DESCRIPTION (provided by applicant): Heart disease resulting from pathological cardiac remodeling and hypertrophy is a leading cause of morbidity and mortality in the western world. Protease activated receptors (PARs) are expressed in cardiomyocytes and cardiac fibroblasts. However, their role in cardiac remodeling has not been studied in vivo. Importantly, we demonstrated that PAR-1-/- mice have reduced cardiac remodeling and left ventricle dilation at 2 weeks compared with wild type littermates in a cardiac ischemia-reperfusion (I/R) injury model. Furthermore, we showed that cardiomyocyte-specific overexpression of either PAR-1 or PAR-2 induced cardiac hypertrophy in mice. In addition, we found that PAR-1 and PAR-2 expression was increased in hearts from humans and mice with cardiac hypertrophy. Finally, in vitro studies showed that the activation of PAR-1 or PAR-2 on cardiomyocytes induced hypertrophy. Based on these results, we hypothesize that both PAR-1 and PAR-2 on cardiomyocytes and cardiac fibroblasts contribute to cardiac remodeling after I/R injury. The proposal has two Specific Aims. Specific Aim 1 will determine the role of PAR-1 and PAR-2 in cardiac remodeling after I/R injury. For these experiments, we will use both PAR-1-/- and PAR-2-/- mice, as well as PAR-1 and PAR-2 specific inhibitors. PAR-1flox/flox mice will be generated and crossed with mice expressing the Cre recombinase in either cardiomyocytes or cardiac fibroblasts. These mice will be used to determine the relative contribution of PAR-1 expressed on cardiomyocytes compared with cardiac fibroblasts to cardiac remodeling. Specific Aim 2 will evaluate the role of the MEK5-ERK5, MEK1-ERK1/2 and calcineurin signaling pathways in PAR-1- and PAR-2-dependent hypertrophy of cultured cardiomyocytes by inhibiting these pathways with pharmacologic inhibitors and dominant negative mutants. In addition, we will characterize the different signaling pathways that mediate hypertrophy in the hearts of mice overexpressing either PAR-1 or PAR-2 on cardiomyocytes. These studies will elucidate the role of PAR-1 and PAR-2 in cardiac remodeling after I/R injury and will determine the mechanism by which PAR-1 or PAR-2 activation induces cardiac hypertrophy. The results may lead to the development of PAR-1 and PAR-2 inhibitors that may be used as novel therapies for the treatment of pathological cardiac remodeling and hypertrophy in humans.