溶血磷脂酸信号对哺乳动物心肌再生的调节及其机制研究

Promoting proliferation of cardiomyocytes is a strategy of endogenous myocardial regeneration treatment. The signal mechanism of myocardial proliferation is yet to be fully elucidated. Lysophosphatidic acid (LPA) is an endogenous bioactive lipid molecule. Our previous study indicated that expressions of three subtypes of G protein-coupled receptor (GPCR) of LPA ( Lpar1, Lpar3, and Lpar4) in the late prenatal and early postnatal rat heart were relatively higher than mature ones, which suggests that LPA signaling pathway may involve in proliferation of cardiomyocytes during the developemnt of heart.Furthermore, in the preliminary experiment,we confirmed the role of LPA in promoting proliferation of cardiomyocytes and activation of Hippo pathway induced by LPA in cardiomyocytes. Since mechanisms of regeneration should be similar to the mechanisms of development, the present study aims to explore the role of LPA in the process of myocardial regeneration and its signaling pathway in proliferation of myocardium. The first of the study is to investigate the role of LPA signaling to promote proliferation of myocardium by using myocardial regeneration model of neonatal rat apical resection in vivo. Next is to explore the signal pathway of LPA promoting proliferation of cardiomyocytes- - LPA-specific GPCR subtypes - specific G protein-hippo signaling pathway - activation of target genes promoting cardiomyocyte proliferation- - in vitro. Understanding of these pathways will be highly relevant for regenarative approaches and provide new clues to heart disease.

促进心肌细胞增殖是内源性心肌再生治疗的重要策略，调控心肌增殖的信号机制尚待完全阐明。溶血磷脂酸（LPA）是一种内源性生物活性脂类分子，我们前期的研究发现LPA的3种G蛋白耦联受体（GPCR）在胚胎期及出生后早期大鼠心脏高表达，提示LPA信号可能参与发育期的心肌增殖过程，并在预实验中观察到LPA确实可以促进心肌细胞增殖，并且可调控Hippo通路蛋白的表达。鉴于心肌再生与发育机制的相似性，我们推测LPA信号通路可通过促进心肌细胞增殖调节损伤后心肌再生修复。为证实这一假设，我们首先利用大鼠心尖切除后再生模型，从整体水平阐明LPA信号在心肌再生修复中的促心肌增殖作用，其次在细胞水平探讨LPA通过其特异GPCR亚型-特异G蛋白-hippo信号通路-激活细胞周期蛋白等促进心肌细胞增殖的信号机制。本课题将从内源性脂类信号分子这一新的角度阐述心肌细胞增殖和再生的信号机制，为内源性心肌再生治疗提供新线索。

溶血磷脂酸（LPA）是一种内源性生物活性脂类分子，我们前期的研究发现LPA的3种受体（LPA1、LPA3、LPA4）在胚胎期及出生后早期大鼠心脏高表达，本课题旨在探索LPA信号对心肌增殖和再生的调控作用及其机制。本研究首先通过腹腔注射给予新生大鼠LPA或Ki16425（LPA1/3抑制剂），发现给予Ki16425可显著减少BrdU、H3P及Ki67阳性心肌细胞的数量，同时心室壁明显变薄，而给予LPA则可以促进心肌细胞增殖，提示LPA信号在出生后心肌细胞增殖过程中发挥重要调节作用。然后通过心尖切除模型发现给予LPA可促进心肌组织的修复，且纤维组织修复明显少于对照组，增殖评价显示给予LPA可明显促进BrdU和H3P阳性心肌细胞的数量，提示LPA可能通过促进心肌细胞增殖参与心肌再生过程。此外，以体外培养的正常大鼠心肌细胞为研究对象观察LPA对心肌细胞增殖的影响，随后利用siRNA阻断LPA的不同受体亚型，观察其对LPA促心肌细胞增殖的影响，确定LPA1和LPA3介导了LPA的促心肌细胞增殖作用，最后通过对LPA作用后YAP磷酸化水平的变化以及YAP阻断后对LPA促心肌细胞增殖的影响，发现LPA通过激活YAP促进心肌细胞增殖。本课题发现了一种在心脏发育过程中呈现明显变化的内源性脂类信号分子LPA对心肌增殖和再生的调控作用及信号机制，一方面发现了LPA信号的一种新的生物学功能——促进心肌细胞增殖，另一方面从脂类信号分子的角度为心肌细胞增殖和再生这一热点研究提供了新视角，有助于利用新线索对心肌细胞增殖和再生的信号机制进行完善，从而为内源性心肌再生治疗提供新的干预靶点。