Wnt信号通路介导老龄心肌缺血损伤的分子机制及其临床意义

Aging is a risk factor for ischemic heart disease, our previous study found that overexpression of cardiac MMP-9 in aging mice and enhanced inflammatory cell infiltration are important causes of ischemic cardiac rupture and acute pump failure. Wnt pathway in aging myocardial was significantly activated than that in younger myocardial, but the mechanism is unclear. Studies showed that the over-expression of FrzA gene to inhibit Wnt pathway activation can reduce the incidence of cardiac rupture and improve heart function in younger mice. Accordingly, the project intends to use double strand recombinant AAV-9 vector carrying FrzA gene, with cardiomyocytes transfection experiments in vitro, we can clarify the regulation effects of critical target gene of FrzA on Wnt signaling pathway and reveal the molecular mechanisms of crosis and apoptosis of cardiomyocytes mediated by Wnt pathway activation. Based on intervention experiments of in vivo exogenous import of FrzA in aged mice, we can explore the molecular mechanisms of Wnt signal transduction pathway mediated ischemic injury in aging myocardial to determine utility of exogenous FrzA as the therapeutic target for myocardial ischemia. The feasibility and effectiveness of FrzA as new molecular diagnostic markers for myocardial ischemic injury was verified in clinical samples. The discovery will lay the foundation for gene therapy for aging ischemic heart disease and new targets for clinical intervention and follow-up.

老龄是缺血性心脏病发病的高危因素，我们前期研究发现老龄心肌中MMP-9的过度表达和炎性细胞浸润增强是缺血性心脏破裂和急性泵衰竭的重要原因，且老龄心肌中Wnt通路较年轻心肌显著激活，但机制不清楚。研究表明FrzA基因的过表达抑制Wnt通路的激活能减轻年轻小鼠心脏破裂的发生率、改善心功能。据此，本项目拟采用携带FrzA基因的双链重组AAV-9载体，通过体外心肌细胞转染实验，明确FrzA对Wnt信号通路关键靶基因调控，揭示Wnt通路激活介导心肌细胞缺血损伤的分子机制。基于老龄鼠体内外源导入FrzA干预实验，探讨Wnt信号转导通路在老龄急性心肌缺血损伤中的作用机制，确定外源FrzA作为心肌缺血损伤治疗靶标的效用；验证临床样本FrzA作为新的心肌缺血损伤诊断分子标志物的可行性和有效性，为老龄缺血性心脏疾病的基因治疗，发现新的临床干预和随访靶标奠定基础。

老龄是缺血性心脏病发病的高危因素，前期研究发现老龄心肌中Wnt 通路较年轻心肌显著激活，但机制不清楚。本研究探索了FrzA基因靶向转导防治老龄心肌缺血的可行性及其机制。在体内，通过老龄小鼠在体心肌梗死模型发现Sfrp1可以作为小分子基因治疗药物，具有靶向抑制Wnt/β-catenin信号通路活性，改善心功能、减少心肌纤维化、抑制心肌细胞凋亡。在体外，利用心肌细胞缺氧/复氧模型，研究Sfrp1过表达可有效减轻缺氧/复氧造成的心肌细胞凋亡。这种抗凋亡作用有可能是通过抑制Wnt/β-catenin信号通路从而调节线粒体凋亡途径来实现的。在心肌成纤维细胞增殖模型，研究Sfrp1过表达抑制Wnt/β-catenin信号通路活性，可有效抑制心肌成纤维细胞增殖，胶原合成，肌成纤维细胞的分化，从而达到抗心肌纤维化的作用。进一步深入研究了Wnt/β-catenin信号通路基因多态性与新疆汉族人群心肌梗死的遗传易感性，发现SFRP1基因多态性改变与心肌梗死发病风险相关，T等位基因携带者发生心肌梗死的风险性显著增加。蛋白组学研究也发现wnt信号通路蛋白在急性心肌梗死时出现差异表达。因此，我们的研究将为老年缺血性心脏病的基因治疗奠定基础，也是临床干预的新靶点。