The Effect And Mechanism Of RAGE-mediated JNK/AP-1/Caspase3 Signaling Pathway On PD Mice Model

Objective To investigate the damage effect of RAGE/JNK/AP-1/caspase3 signal pathway on Parkinson disease(PD)mice model which induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP).Methods C57BL/6 male mice in 12-week were divided into 6 groups(n=10): control group,MPTP group,RAGE-NC group,siRNA-RAGE group,RAGE-NC+MPTP group,siRNA-RAGE+MPTP group.Stereotactic injected with lentivirus small interference RNA for RAGE or negative control lentivirus into substantia nigra of PD mice by stereotaxic apparatus.The mice in MPTP group,RAGE-NC+MPTP group and siRNARAGE+MPTP group were treated with intraperitoneal injection of MPTP 30 mg·kg-1 twice per week for 5 weeks.Meanwhile the control group mice were treated with equivalent saline twice per week for 5 weeks.The changes of mice behaviors were testing by pole-jumping test.TH-positive neurons in PD mice substantia nigra were detected by immunohistofluorescence stain.The protein level of RAGE,JNK,p-JNK,Bcl-2,Bax,caspase3 and TH was measured by western blots.Results 1.In pole-jumping test,compared with control group,the the mice turning aroud time and total time in MPTP group and RAGE-NC+MPTP group were both increased(P<0.01);the mice turning aroud time and total time in RAGE-NC group and siRNA-RAGE+MPTP group were decreased campared with the RAGE-NC+MPTP group mice(P<0.05).2.In comparison with control group,the TH-positive neurons of substantia nigra of PD mice in MPTP and RAGE-NC+MPTP group reduced obviously(P<0.05);compared with RAGE-NC+MPTP group,the TH-positive neurons of substantia nigra of PD mice in RAGE-NC group and siRNA-RAGE+MPTP group enhanced apparently(P<0.05).In the meantime,there is no difference in the RAGE-NC& siRNA-RAGE group with control group.3.Western blots results showed that the expression of RAGE(P<0.001),caspase3(P<0.001)and p-JNK/JNK(P<0.001)ratio in MPTP and RAGE-NC+MPTP group were increased than control group,while the TH protein(P<0.001)and Bcl-2/Bax(P<0.001)ratio were decreased.The expression of RAGE(P<0.01),caspase3(P<0.001)and pJNK/JNK(P<0.01)ratio were decreased,while the TH protein(P<0.05)and Bcl-2/Bax(P<0.001)ratio were significantly increased in siRNA-RAGE+MPTP group than RAGENC+MPTP group.4.HPLC results suggested that DA and its metabolites DOPAC,HVA in MPTP and RAGE-NC+MPTP group were significantly lower than the control group(P<0.001);compared with RAGE-NC+MPTP group,the content of DA and its metabolites DOPAC,HVA in siRNA-RAGE+MPTP group and RAGE-NC group were increased apparently(P<0.05).Conclusion The results suggested that RAGE damage the dopaminergic neurons of PD mice model via JNK/AP-1/caspase3 signal pathway,which mechanism is accomplished through the apoptosis response.Consequently,inhibiting the expression of the RAGE has a potential neuroprotective effect.