内皮祖细胞DNA羟甲基化修饰在糖尿病血管并发症发病中的作用及机制

Diabetes is disabling and even life threatening, which is mainly a result of diabetic vascular complications (DVC) whose pathogenesis is still unknown and there is no effective treatment yet. According to recent publications and our studies, DNA epigenetic modification regulates endothelial progenitor cells (EPCs) functions, and its dysfunction may contributes to the pathogenesis of DVC. In EPCs from DVC patients, there are reductions of CXCR4 expression, TET1 mRNA level and 5-hydroxymethylcytosine (5hmC) abundance, which are associated with abnormal EPCs migration. Therefore we hypothesize that, abnormal DNA modification with 5hmC affect the migration, adhesion and differentiation of EPCs by regulating certain genes expression, resulting in lower vascular repair capacity and lack of compensatory neovascularization. It would be a very important pathological mechanism in DVC occurrence and development. This project will study the effect of EPCs DNA hydroxymethylation in the pathogenesis of DVC at levels of genomic DNA, cell and animal models, clarify the mechanism for DNA hydroxymethylated EPCs participate in DVC incidence, and therapeutic effect of regulation of EPCs 5hmC level on DVC. The significance would be that investigating the pathogenesis of DVC and exploring its new intervention strategy from a new perspective of epigenetic modification.

糖尿病血管并发症(DVC)是糖尿病致残致死的主要原因，发病机制不明且缺乏有效治疗手段。新近文献及我们前期研究发现，DNA表观遗传修饰改变通过调控内皮祖细胞（EPCs）功能在DVC发病中可能起重要作用；DVC患者内皮祖细胞CXCR4表达减少，双加氧酶1(TET1)和5-羟甲基胞嘧啶(5hmC)水平降低与EPCs迁移能力异常相关。据此提出假说：DNA羟甲基化修饰通过影响EPCs功能相关基因表达，导致其迁移、粘附、分化等功能障碍，机体血管损伤修复能力降低，新生血管代偿不足，是DVC发生发展中尚未认识的病理机制。为验证该假说，本项目拟从基因组DNA、细胞和动物水平进行研究，证实内皮祖细胞DNA羟甲基化修饰在DVC发病中的作用，阐明DNA羟甲基化修饰EPCs参与DVC发病的机制，调控内皮祖细胞5hmC对DVC的治疗作用。其意义在于，从DNA表观遗传修饰的新视角揭示DVC的发病机制并探讨干预策略。

糖尿病血管并发症（Diabetic Vascular Complications, DVC）已成为糖尿病患者致残致死的主要原因。内皮祖细胞(Endothelial Progenitor Cells, EPCs)参与血管新生和血管内皮损伤后修复。糖尿病患者EPCs功能异常。DNA 甲基化(DNA Methylation)和去甲基化(demethylation)对EPCs的功能具有重要调节作用。本研究发现，DVC患者外周血EPCs基因组DNA 5-hmC水平明显下降，TET1 mRNA和蛋白水平均明显下降。Tet1通过调节AKT和ERK蛋白水平及活性，直接影响胰岛素信号传递过程。DVC患者外周血EPCs生物学特性发生改变，包括数量减少，凋亡增加，增殖能力减退，粘附能力减退，迁移能力减退，旁分泌水平减少，分化为内皮细胞能力减退。自体外周血EPCs治疗DVC能有效促进患者血管新生，增加下肢血流，是一种安全、有效的治疗方法。