Effects of Harmine Inducing Apoptosis on Mitochondrial Fusion and Division in PC 12 Cells / 医药导报

ABSTRACT

Objective To investigate the effects of harmine(HM)on the expression level of mitochondrion fusion related proteins and mitochondrial function injury in PC 12 cells.Methods PC 12 cells were divided into cell control group,HM group,mitochondrion mitosis inhibitor Mdivi-1 group,HM+Mdivi-1 group,mitochondrion fission agonist WY14643 group,HM+WY14643 group,with drug concentrations of 1,10,25,50,100 μmol·L-1.After 24 h treatment,the MTT method was used to detect the cell survival rate,and a microscope was used to observe the cell morphology,MitoTracker Red probe staining was used to observe the mitochondrial morphology and the length ratio of vertical and horizontal axes,JC-1 staining was used to detect the mitochondrial membrane potential,and a kit was used to detect ATP level and lactate dehydrogenase(LDH)activity.Immunofluorescence staining and Western blotting were used to assess the expression levels of caspase-3,apoptosis-promoting protein(Bax)cytochrome C(cyt-c),mitochondrial fusion protein(Mfn2)and mitochondrial mitotic protein(Drp-1).The interference sequence of Drp1 was transfected by electroporation,and the siRNA sequence with good transfection effect was screened.The related indicators were detected by fluorescence method,MTT method,and immunoblotting method in cooperation with drug intervention.Results MTT results showed that compared with the cell control group,the survival rate of HM group,Mdivi-1 group,HM+Mdivi-1 group,WY14643 group and HM+WY14643 group decreased significantly(P＜0.01),and the EC50 were(11.48±2.32),(12.35±1.67),(14.88±2.07),(39.14±3.25),(20.09±1.97),respectively.According to this,subsequent experiments selected 20 μmol·L-1for HM,WY 14643 and HM+WY14643 as working concentrations to construct PC 12 cell model.Microscopic observation and MitoTracker Red probe staining showed that the cell density in the drug group decreased in varying degrees,and a transition from branched to round morphology in the drug-treated groups was observed.The morphology of mitochondria tended to be round,and the ratio of the length of the longitudinal axis to transverse axis was(3.33±0.72)in the cell control group,(2.19±0.58)in the HM group,(2.45±0.44)in Mdivi-1 group,and(1.43±0.62)in HM+Mdivi-1 group,respectively.The results of JC-1 staining showed that compared with the cell control group,the mitochondrial mode potential of the HM group significantly decreased(P＜0.01).ROS significantly increased(P＜0.01)and ATP levels decreased(P＜0.01),and LDH enzyme activity increased(P＜0.01).Immunofluorescence staining and Western blotting results showed that compared with the cell control group,the expression levels of proapoptotic proteins Bax,cytochrome C,and caspase-3 in the HM group were significantly increased(all P＜0.01).Compared with the cell control group,the expression level of mitochondrial fission related protein Drp1 in HM group was significantly higher(P＜0.01).The expression level of mitochondrial fusion related protein Mfn2 significantly decreased(P＜0.01).After specific interference with Drp1 and synergistic intervention with HM,the survival rate of PC 12 cells in each interference group decreased compared to each drug intervention group.The expression of Drp1 and Mfn2 was downregulated,and the differences were statistically significant(P＜0.05 or P＜0.01).Conclusion HM can reduce the mitochoudrial membrane potential and ATP levels by accumulating ROS,there by activating the caspase-3 apoptosis pathway and promoting cell apoptosis.Mitochondrial fusion division may be involved in the damage of PC12 cells caused by HM,initiating apoptosis through the mitochondrial pathway.