多核糖核苷酸核苷转移酶1在氧糖剥夺诱导心肌细胞凋亡损伤中的作用

目的 探讨多核糖核苷酸核苷转移酶1 (PNPT1)对氧糖剥夺（OGD）诱导心房肌细胞凋亡的影响和作用机制。方法 体外培养HL-1心房肌细胞，PNPT1-siRNA转染HL-1细胞。实验分组为：正常组（Control）、OGD组、NC-siRNA组（转染乱码RNA）、PNPT1- siRNA组、OGD+NC-siRNA组和OGD+PNPT1- siRNA组。通过CCK-8检测细胞存活率，qPCR检测ACTB mRNA和TUBA mRNA的含量，Western blot检测PNPT1蛋白水平，流式细胞术检测HL-1细胞凋亡率，JC-1试剂盒检测线粒体膜电位，透射电镜观察线粒体形态。结果 随OGD诱导时间延长，HL-1细胞质中PNPT1的蛋白表达水平呈上升趋势（P<0.05）。与NCsiRNA相比，PNPT1-siRNA明显减少细胞内PNPT1表达。OGD条件下，ACTB mRNA和TUBA mRNA降解增加（P<0.05），HL-1心房肌细胞凋亡率增加（P<0.05）；相反地，PNPT1-siRNA则抑制ACTB mRNA和TUBA mRNA降解（P<0.05），同时降低HL-1心房肌细胞凋亡率（P<0.05），并且改善线粒体膜电位以及线粒体形态。结论 抑制PNPT1可改善线粒体损伤并减少凋亡相关mRNA的降解，从而减轻OGD诱导的HL-1心房肌细胞凋亡损伤。

Role of PNPT1 in cardiomyocyte apoptosis induced by oxygen-glucose deprivation

Objective To explore the effect of inhibiting polyribonucleotide nucleotidyl-transferase 1 (PNPT1) on oxygen-glucose deprivation (OGD)-induced apoptosis of mouse atrial myocytes. Methods Cultured mouse atrial myocytes (HL-1 cells) with or without OGD were transfected with PNPT1-siRNA or a negative control siRNA (NC-siRNA group), and the cell survival ratewas detected using CCK-8 assay. The expression levels of ACTB and TUBA mRNA were detected with qPCR, and the protein expression of PNPT1 was detected with Western blotting. The apoptosis rate of the treated cells was determined with flow cytometry, the mitochondrial membrane potential was detected using JC-1 kit, and the mitochondrial morphology was observed using transmission electron microscope. Results With the extension of OGD time, the protein expression levels of PNPT1 increased progressively in the cytoplasm of HL-1 cells (P<0.05). Transfection with PNPT1-siRNA significantly reduced PNPT1 expression in HL-1 cells (P<0.05). Exposure to OGD significantly enhanced degradation of ACTB and TUBA mRNA (P<0.05) and markedly increased the apoptosis rate of HL-1 cells (P<0.05), and these changes were significantly inhibited by transfection with PNPT1-siRNA (P<0.05), which obviously increased mitochondrial membrane potential and improved mitochondrial morphology of HL-1 cells exposed to OGD. Conclusion Inhibition of PNPT1 improves mitochondrial damage and reduces degradation of apoptotic-associated mRNAs to alleviate OGD-induced apoptosis of mouse atrial myocyte.