MicroRNA-34a通过GCH1/BH4调控EPCs介导的老年血管新生障碍的机制研究

Angiogenesis disorders mediated by endothelial progenitor cells (EPCs) is the important reason for high incidence and poor prognosis of myocardial infarction, cerebral infarction and lower extremity arterial occlusive diseases in aged patients. Previous studies confirmed that the quantity and quality of aged EPCs were significantly decreased in elderly, but the underlying mechanism was unknown. Our previous studies showed that miR-34a and ROS increased, GTP cyclohydrolase 1/tetrahydrobiopterin (BH4) and the telomerase activity decreased in aged EPCs, and miR-34a directly targeted GCH1 3’UTR. Hence, we hypothesize that elevated miR-34a suppresses EPCs-mediated angiogenesis via blockade of the GCH1/BH4 pathway. After miR-34a inhibitor or mimic was treated in vitro or in vivo, changes of EPCs functions, aging index and the angiogenesis in Matrigel plugs and lind limb ischemia model will be detected respectively. The outcomes will not only provide a theoretical basis for the prevention and treatment of the obstructive arterial diseases in the elderly but also help to find the therapeutic targets for the treatment of the above diseases.

内皮祖细胞（EPCs）介导的老年血管新生障碍是老年人心肌梗死、脑梗塞及下肢动脉闭塞等疾病发病率高和预后差的重要原因，既往研究证实老年EPCs数量和质量均明显降低，但其具体机制尚未明确。我们前期研究发现老年EPCs中miR-34a和ROS升高、三磷酸鸟苷环化水解酶1（GCH1）/四氢生物蝶呤（BH4）和端粒酶活性降低、miR-34a可直接作用于GCH1的3’ 非编码区，据此提出miR-34a通过GCH1/BH4调控老年血管新生障碍的假说，将在细胞和动物水平，给予miR-34a抑制剂或摹拟物干预，检测EPCs功能及衰老指标的变化，检验其对小鼠血管生成和下肢缺血模型的作用，阐明miR-34a升高导致老年血管新生障碍的具体机制，研究结果不仅为老年人上述重大疾病的预防和治疗提供理论基础，还将有助于寻找潜在的干预靶点和创新治疗技术。

我国老龄化程度在不断加剧，老年人心肌梗死、脑梗塞及下肢动脉闭塞等疾病发病率高，预后差。内皮祖细胞（EPCs）介导的老年血管新生障碍是重要原因，我们研究发现老年EPCs中miR-34a和ROS升高、三磷酸鸟苷环化水解酶1（GCH1）/四氢生物蝶呤（BH4）和端粒酶活性降低、miR-34a可直接作用于GCH1的3’ 非编码区。给予miR-34a抑制剂或摹拟物干预，EPCs血管生成功能中的管型形成能力会相应的改善或下降，EPCs中GCH1蛋白表达相应升高或降低。BH4明显改善miR-34a所致的EPCs衰老，BH4缺乏（hph-1）小鼠患侧下肢血流灌注恢复明显慢于对照组。研究结果证实miR-34a导致GCH1/BH4减少，引起eNOS解偶联，氧化应激增加，致使端粒酶活性降低，细胞衰老加速，导致EPCs血管生成功能降低。随着RNA疫苗技术的不断成熟与完善，miR-34a在老年血管新生障碍性疾病方面将有广阔的应用前景。