Netrin-1 Prevents Apoptosis on SH-SH5Y Cells Induced by Dependence Receptor Unc5H4

OBJECTIVE To study on the induction of apoptosis in SH-SH5Y cells by the dependence receptor Unc5H4, while addition of its ligand Netrin-1 can block this effect. METHODS SH-SY5Y cells were transiently transfected with either a mock plasmid or Unc5H4-expressing construct in the presence or absence of Netrin-1, and then colony formation assay was performed. Whether Unc5H4 induced cell apoptosis or this apoptosis was blocked by Netrin-1 was detected. Further on SH-SY5Y cells, under stress of adriamycin(ADR) with or without purified Netrin-1 protein, Unc5H4 protein was detected by Western-blot for cleavaged 60 kDa protein. RESULTS Caspase-3 activity assay showed over-expression of Unc5H4 could induce apoptosis in SH-SY5Y cells, its relative Caspase-3 activity (180%±20%) was obviously higher than that of control (100%) (P<0.01). While additon of Netrin-1, the relative Caspase-3 activity (112%±14%) was much lower than that of group without Netrin-1 (180%±20%, P<0.01). The relative caspase-3 activity in Netrin-1 group and control group were no significance. Next, Unc5H4 plasmid was transit transfected on SH-SY5Y cells. ADR was added for DNA damage. The 60 kDa protein was detected by Unc5H4 antibody, while addition of Netrin-1 protein could block the above. CONCLUSION Dependence receptor Unc5H4 could induce apoptosis in NB cells, while its ligand Netrin-1 could block apotosis by prevention of the cleavage of Unc5H4 to promote cell proliferation.