Involvement of serine/threonine protein phosphatases 1/2A intolerance established by hypoxic preconditioning inhuman umbilical vein endothelial cells / 中国药理学与毒理学杂志

ABSTRACT

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.