Effects Of Cathepsin L On The Death Of SH-SY5Y Cells Induced By 6-OHDA

Aim: To study the role of Cathepsin L in 6-OHDA-induced death of SH-SY5Y cells in PD models, and to investigate the effects of Cathepsin L on initiation of apoptosis.Methods: In this study, SH-SY5Y cells were exposed to 6-OHDA to establish the in vitro model of PD. The treated group was exposed to Cathepsin L inhibitors Z-FY-DMK ( 10μM/L ) before 6-OHDA administration, the activity of lactate dehydrogense (LDH), Annexin V and PI double-staining were determined to study the protetive effect of Z-FY-DMK on 6-OHDA-induced SH-SY5Y cells death. Immunocytochemistry, and Western blot analysis were conducted to study the mechanisms of Cathepsin L involved in death of SH-SY5Y cells.Results: Immunocytochemistry, and Western blot analysis revealed that activity and expression of Cathepsin L increased after 6-OHDA treatment. LDH, Annexin V and PI double-staining demonstrated that Z-FY-DMK exerted a potent neuroprotective effect against 6-OHDA-induced cytotoxicity in SH-SY5Y cells and partly protected SH-SY5Y cells from 6-OHDA-induced apoptosis. Z-FY-DMK inhibited the cleavage of Bid, and downregulated 6-OHDA-induced activation NF-κB, also reduced the apoptotic-relatived protein expression such as Bax,P53,PUMA,Caspase-3,and upregulated the expression of IkB-αand Bcl-2.Conclusions: Cathepsin L played an important role in the toxicity induced by 6-OHDA. Once Cathepsin L translocated from lysosome to cytosol, it can degradate the IkB-α, and cleave Bid, which were followed by activating the intrinsic apoptotic pathway.