R-spondin1/LGR4/β-catenin信号通路参与心梗后心肌损伤和重构的作用和机制研究

Wnt/β-catenin signaling pathway plays an important role in myocardial injury and remodeling after myocardial infarction. R-spondin1 (RSPO1) activates the Wnt/β-catenin signaling pathway by binding to its receptor LGR4. Our previous studies have showed that: 1) Serum levels of RSPO1 were significantly increased in patients with heart failure after myocardial infarction, and negatively correlated with left ventricular ejection fraction; 2) RSPO1 was significantly increased in serum and heart after MI in mice, and neutralization of RSPO1 significantly improved cardiac function and decreased β-catenin activation after myocardial infarction; 3) Defeciency of LGR4 significantly improves cardiac remodeling and dysfunction after myocardial infarction. These above results suggested that ischemia induced the expression and release of RSPO1, which may contribute to post MI injury and left ventricular remodeling via binding to LGR4, and activation of wnt/β-catenin pathway. Therefore, based on this hypothesis, the present project will continue to investigate : 1) the functional role and mechanistic insights of RSPO1/LGR4/β-catenin pathway in myocardial injury and remodeling after myocardial infarction; 2) the regulatory mechanism of RSPO1 expression; 3) the prognostic significance of serum RSPO1 in patients with heart failure after myocardial infarction. These results may pave the way for prevention and treatment of heart failure.

Wnt/β-catenin信号通路在心梗后心肌损伤和重构中起到重要作用，R-spondin1(RSPO1)通过与其受体LGR4结合介导Wnt/β-catenin信号通路激活。前期研究表明: 1)血清RSPO1在心梗后心衰患者显著升高，且与左室射血分数呈负相关；2)小鼠心梗后血清和心脏中RSPO1显著增高，中和RSPO1显著改善心梗后心功能和β-catenin激活；3)敲除LGR4显著改善小鼠心梗后心脏重构和心功能，提示心肌缺血损伤后表达和释放的RSPO1可能通过与其受体LGR4结合，促进Wnt/β-catenin通路激活，加重心梗后心肌损伤和重构。因此，本课题将继续探讨: 1)RSPO1/LGR4/β-catenin通路在心梗后心肌损伤和重构的功能作用及其分子机制；2)RSPO1的表达调控机制；3)从临床方面研究血清RSPO1与心梗后心衰预后的相关性。为心梗后心衰防治提供新思路。

【研究背景】心力衰竭是各种原因引起心脏疾病的终末阶段，心力衰竭的的防治是临床工作中的难点和重点。心力衰竭主要由冠心病和高血压引起，其中Wnt/β-catenin信号通路在心梗后心肌损伤和重构中起到重要作用。.【研究方法】在临床研究方面，连续入组了600例冠脉造影阴性的患者和900例心肌梗死患者。收集血清后用ELISA法检测血清中Rspondin1（RSPO1）水平；心超评估心功能；并进行为期1年的随访，评估RSPO1升高与主要心血管事件发生率相关性。在基础实验方面，构建LGR4基因敲除小鼠，并制作小鼠心肌梗死模型。以及构建RSPO1和LGR4过表达腺相关病毒。应用心超评估心功能，Masson染色及TTC染色评估梗死面积，TUNEL染色评估凋亡细胞数目等。同时，体外培养转染TOPFLASH质粒HEK293细胞检测血清刺激后Wnt/β-catenin激活及以及检测active β-catenin的表达。.【主要结果】研究发现： 1)血清RSPO1在心梗后心衰患者显著升高，且与左室射血分数呈负相关，进一步研究发现RSPO1与心梗后心衰预后相关；2)小鼠心梗后血清和心脏中RSPO1显著增高，中和RSPO1显著改善心梗后心功能并减少β-catenin激活；3)敲除LGR4显著改善小鼠心梗后心脏重构和心功能；4）过表达RSPO1和LGR4增加心肌梗死后心脏损伤，且激活Wnt/β-catenin信号通路。.【结论】心肌梗死后提示心肌缺血损伤后表达和释放的RSPO1通过与其受体LGR4结合，促进Wnt/β-catenin通路激活，加重心梗后心肌损伤和重构。该研究为心梗后心衰防治提供新思路。