缺氧性肺动脉高压大鼠肺组织丝裂原活化蛋白激酶、磷酸肌醇3-激酶和缺氧诱导因子2α表达的变化

Mitogen-Activated Protein Kinase and Phosphatidylinositol 3-Kinase Regulated Hypoxia-Inducible Factor 2a Roles on Pulmonary Arteries of Rats With Hypoxia-Induced Pulmonary Hypertension

目的探讨大鼠低氧性肺动脉高压(FPH)形成过程中丝裂原活化蛋白激酶(MAPK)、磷酸肌醇3-激酶(PI3K)和缺氧诱导因子2α(HIF-2α)表达的变化。方法 40只成年雄性Wistar大鼠随机分为对照组和低氧3天、7天、14天、21天组(H3、H7、H14、H21组),每组8只,低氧组复制HPH大鼠模型。测各组大鼠平均肺动脉压(mPAP)、右心室肥大指数(RVHI)、管壁面积与血管总面积比值(WA%)、管腔面积与血管总面积比值(LA%);免疫组织化学或Western blot检测磷酸化ERK(pERK)、磷酸化JNK(p-JNK)、磷酸化P38(p-P38)、磷酸化Akt(p-Akt);原位杂交和免疫组织化学检测HIF-2α的表达。结果与对照组比较,H7组大鼠mPAP开始上升(P<0.05),H14组达高水平并维持于此水平。缺氧14天后出现肺血管重塑,RVH I改变。与对照组比较,p-ERK和p-Akt在H3组表达上升(P<0.05),且在H3组、H7组、H14组和H21组肺小动脉内膜、中膜表达均为阳性。而p-P38、p-JNK蛋白在对照组与低氧组表达均不明显。HIF-2αmRNA在对照组表达弱阳性,在H14组表达升高。HIF-2α蛋白在对照组表达不明显,H7组表达达高峰,H14组和H21组维持在高水平。相关分析表明p-ERK和p-Akt均与HIF-2α蛋白(内膜)和mPAP、RVHI呈正相关(P<0.01)。结论 p-ERK、p-Akt与HIF-2α均在大鼠HPH的发病机制中发挥作用。p-ERK和p-Akt可能通过在蛋白表达水平上调HIF-2α,进而上调下游目标基因,从而参与HPH发生发展。

Objective To investigate the interaction between hypoxia inducible factor 2ct（HIF-2ct） ,Mitogen-activated protein kinase（MAPK） or Phosphatidylinositol 3- kinase（PI3K） during the development of rat hypoxic pulmonary hyper- tension. Methods Male SD rats （n = 40） were randomly divided into 5 groups and exposed to hypoxia for 0,3,7,14 or 21 d, respectively. Mean pulmonary pressure （mPAP）, right ventric hypertrophy index（RVHI） and vessel morphometry were measured. In situ hybridization were used to determine the expression of mRNA. Immunohistochemistry and western blots were adopted to determine the expression of protein. Results mPAP increased significantly after 7d of hypoxia, reaching its peak after 14d of hypoxia, then remained. Pulmonary artery remodeling developed significantly after 14d of hypoxia, p-JNK and p-P38 protein in control group and hypoxia groupe were poorly positive, p-ERK and P-AKT protein in pulmonary arterial intima and tunica of all hypoxia rats were significantly higher than in contro 1 group（ P 〈 0. 05 ）. In pulmonary arterial intima and tuniea,HIF-2a mRNA was barely positive in C group protein,then increased in H14 group（P 〈 0. 05） ,and HIF-2a protein was barely positive in C group protein,then increased in H3 group ,reaching its peak in H7 group. Linear correlation analysis showed p-Akt and p-ERK were positively correlated with HIF-2a protein （tuniea intima） and vessel morphometry, RVHI and mPAP（ P 〈 0.01 ）. Conclusions Under chronic hypoxia, p-ERK and p-AKT may up-regulate the expression of HIF-2a by increasing protein expression, then resulting in the occurrence and development of hypoxie pulmonary hypertension in rat.