MR-1通过抑制PERK/Nrf2途径减轻缺氧/复氧诱导的心肌细胞凋亡

Myofibrillogenesis regulator 1 attenuates hypoxia/reoxygenation-induced apoptosis of cardiomyocytes by inhibiting PERK/Nrf2 pathway

目的:研究肌原纤维形成调节因子1(MR-1)是否通过抑制蛋白激酶R样内质网激酶(PERK)/核因子E2相关因子2(Nrf2)途径减轻缺氧/复氧(H/R)诱导的心肌细胞凋亡。方法:在原代培养的乳大鼠心肌细胞H/R模型上,采用Annexin V/PI双标法检测心肌细胞的凋亡率;以Western blotting检测葡萄糖调节蛋白78(GRP78)、磷酸化PERK、Nrf2、活化转录因子4(ATF4)、C/EBP同源蛋白(CHOP)、Bcl-2和Bax的蛋白水平,研究过表达或敲低对于H/R致心肌细胞凋亡的影响及其与PERK/Nrf2途径活化的关系。结果:H/R引起心肌细胞凋亡;过表达MR-1减轻H/R引起的细胞凋亡(P<0.01),下调CHOP表达(P<0.05),引起Bcl-2/Bax值升高(P<0.01),并抑制H/R诱导的PERK磷酸化、Nrf2核转位和ATF4表达(P<0.01)。敲低MR-1加重H/R引起的细胞凋亡(P<0.01)、CHOP表达上调(P<0.05)和Bcl-2/Bax值下降(P<0.01),并加重H/R诱导的PERK磷酸化(P<0.05)、Nrf2核转位和ATF4表达(P<0.01)。结论:MR-1通过抑制PERK/Nrf2途径而减轻缺氧/复氧诱导的心肌细胞凋亡。

AIM： To investigate the effect of myofibrillogenesis regulator 1 （MR-1） on hypoxia/reoxygenation （H/R）-induced apoptosis of cardiomyocytes and to study the role of protein kinase R-like endoplasmic reticulum kinase （PERK）/nuclear factor E2-related factor 2 （Nrf2） pathway. METHODS： In the H/R model of primarily cultured neo- natal rat cardiomyocytes, the apoptosis was assessed by Annexin V/PI double staining. Western blotting was used to detect the protein levels of glucose-regulated protein 78 （ GRP78）, phosphorylated PERK, Nrf2, activating transcription factor 4 （ATF4）, C/EBP homologous protein （CHOP）, Bcl-2 and Bax. The effects of over-expression or knockdown of MR-1 on the apoptosis and the PERK/Nrf2 pathway were determined. RESULTS： H/R induced the apoptosis of cardiomyocytes. Compared with H/R group, MR-1 over-expression attenuated H/R-induced apoptosis （ P 〈 0.01 ）, down-regulated CHOP expression （P 〈 0.05 ）, and increased Bcl-2/Bax ratio （ P 〈 0.01 ）. MR-1 over-expression suppressed H/R-induced PERK phosphorylation, Nrf2 nuclear translocation and ATF4 expression （P 〈 0.01 ）. However, MR-1 knockdown aggrava- ted H/R-induced apoptosis （P 〈 0.01 ）, up-regulated CHOP expression （P 〈 0.05 ）, and decreased Bcl-2/Bax ratio （P 〈 0. 01 ）. MR-1 knockdown up-regulated H/R-induced PERK phosphorylation （P 〈 0.05 ）, Nrf2 nuclear translocation and ATF4 expression （P 〈 0.01 ）. CONCLUSION： MR-1 suppresses H/R-induced cardiomyocyte apoptosis by inhibiting PERK/Nrf2 pathway.