Regulation of CacyBP/SIP-mediated Parkin-dependent mitophagy on apoptosis and cycle of dopaminergic neurons / 中华神经医学杂志

ABSTRACT

Objective:To investigate the regulation of Parkin-dependent mitophagy mediated by calcyclin-binding protein and Siah-1 interacting protein (CacyBP/SIP) on apoptosis and cycle of dopaminergic (DA) neurons.Methods:SH-SY5Y cells were divided into model group, control group and CacyBP/SIP group; cells in the model group were treated with 1-methyl-4-phenylpyridine (MPP +, 0.5 mmol/L) for 24 h, and cells in the control group and CacyBP/SIP group were transfected with empty lentivirus or CacyBP/SIP-sgRNA lentivirus on the basis of MMP +(0.5 mmol/L) treatment for 24 h, respectively. Western blotting was used to detect the protein expression levels of CacyBP/SIP, microtubule-associated protein l light chain 3 (LC3), lysosome-associated membrane protein 2 (LAMP2), phosphatase and tensin homolog ten induced kinase 1 (Pink1), Parkin, P53, Bcl-2, and Bax; flow cytometry was used to detect the cell apoptosis and cycle; immunofluorescent single staining was used to detect the expressions of LC3 and LAMP2; immunofluorescent double staining was used to detect the coexpressions of CacyBP/SIP and Parkin. Results:As compared with the model group and control group, the CacyBP/SIP group had significant reduction in protein expressions of CacyBP/SIP, LAMP2, Pink1, and Parkin, LC3-II/I ratio, immunofluorescent staining intensities of LC3-II and LAMP2, and Bcl-2 protein expressions ( P<0.05). As compared with the model group and control group, the CacyBP/SIP group had significantly increased Bax protein expression, significantly decreased Bcl-2/Bax ratio, significantly increased apoptosis rate, significantly increased P53 protein expression, significantly increased proportion of cells at G1 phase, and significantly decreased immunofluorescent intensity of CacyBP/SIP and Parkin co-expressions ( P<0.05). Conclusion:After knocking out CacyBP/SIP gene, the decrease of Parkin protein leads to cell cycle being arrested at G1 stage, and mediates the decrease of Parkin-dependent mitochondrial autophagy, thereby leading to increased cell apoptosis.