丝氨酸/苏氨酸蛋白磷酸酶1/2A在缺氧预处理诱导人脐静脉内皮细胞耐受中的作用

摘要

目的 研究丝氨酸/苏氨酸蛋白磷酸酶1/2A (PP1/2A)在调节人脐静脉内皮细胞(HUVEC)对缺氧耐受相关信号转导中的作用.方法 采用缺氧预处理诱导HUVEC对缺氧损伤的耐受.采用细胞存活率、乳酸脱氢酶(LDH)释放及总抗氧化能力(T-AOC)评价HUVEC的耐受性.免疫细胞化学联合蛋白质印迹法检测核因子E2相关因子2(Nrf2)的亚细胞定位.蛋白质印迹法检测应激蛋白血红素氧合酶1(HO-1)的表达. 结果 缺氧90 min导致HUVEC存活率及T-AOC 降低,LDH释放增加.缺氧预处理(缺氧10 min 后4, 8及24 h)可提高HUVEC对随后缺氧90 min的耐受,细胞存活率及T-AOC较缺氧组显著提高,LDH 释出显著降低,并诱导Nrf2由胞浆向胞核移位,上调其下游信号分子HO-1的表达.缺氧预处理前用PP1/2A特异性抑制剂冈田酸(40 nmol·L-1)孵育HUVEC 10 min可部分抑制缺氧预处理诱导的Nrf2向核移位、HO-1表达及细胞耐受性.结论 PP1/2A至少部分参与缺氧预处理诱导HUVEC对缺氧损伤的耐受,其机制可能与调节Nrf2向核移位及HO-1表达有关.%AIM To investigate the role of serine/threonine protein phosphatases 1 and 2A (PP1/2A) in regulation of cell signal transduction involved in the tolerance of human umbilical vein endothelial cells (HUVEC) to hypoxia. METHODS HUVEC tolerance was established by hypoxic preconditioning. The tolerance of HUVEC was evaluated by the cell survival rate, lactic dehydrogenase (LDH) releasing and total antagonistic-oxidative capability (T-AOC). Subcellular localization of nuclear factor E2-related factor 2 (Nrf2) was determined by immunocytochemistry combined with Western blot. The expression of stress protein of heme oxygenase-1 (HO-1) was measured by Western blot. RESULTS Hypoxia 90 min decreased the survival rate and T-AOC of HUVEC significantly, increased the release of LDH in cultured HUVEC. Compared with the hypoxic group, hypoxic preconditioning (4, 8 and 24 h after hypoxia 10 min) up-regulated the tolerance against hypoxia in HUVEC, the survival rate of HUVEC and T-AOC increased and the release of LDH down-regulated when insulted with hypoxia (90 min) in HUVEC. Hypoxic preconditioning established the translocation of Nrf2 from cytoplasm to nucleus and up-regulated the expression of downstream protein HO-1. Pretreatment with okadaic acid (40 nmol·L-1), a powerful inhibitor of PP1/2A, for 10 min in hypoxic preconditioning HUVEC partly inhibited the translocation of Nrf2 from cytoplasm to nucleus and the expression of HO-1, abolished the tolerance of HUVEC established by hypoxic preconditioning. CONCLUSION PP1/2A at least partly take part in Regulation of translocation of Nrf2 and expression of HO-1, with is associated with the tolerance of HUVEC established by hypoxic preconditioning.