MKP1 Alleviates Aβ-induced Neurotoxicity In The PC12 Cells Via Modulating JNK Signaling

Objective: Aβ can induce neural inflammation and apoptosis by activating MAPK signaling pathway Aβ-induced neurotoxicity is the key reason of Alzheimer disease.But the specific molecular mechanism that Aβ activates MAPK signaling pathway has not been fully clarified.This study is to make a preliminary discussion by testing Aβ-stimulated MKP1 protein levels of the PC12 cells, that Aβ-stimulated ROS, SOD, MDA, p-JNK, TNF-α, IL-1β m RNA, LDH, Caspase3, neural damage levels of the MKP1 knockdown and overpressed PC12 cells, that SP600125-stimulated ROS, SOD, MDA, TNF-α, IL-1β, LDH, neural damage level of the MKP1 knockdown PC12 cells.Hoping this study can be useful to research and develop medicines to treat Alzheimer disease targeting MAPK signaling pathway.Methods: Subjects included wild-type PC12 cells, MKP1 knockdown and overpressed PC12 cells. To examine the effect of Aβ42(Sigma-Aldrich, MO, USA)on the activity of the wild-type PC12 cells,different concentrations of Aβ42(0 μM,0.1μM,1μM,10μM and 100μM)was joined in the cell culture medium.The activity of wild-type PC12 cells was detected by CCK-8 after treatment about twenty-four hours.10μM Aβ42 was joined in the cell culture medium to detect the expression of Aβ-induced MKP1 in the PC12 cells. The expression of MKP1 was detected at the different time points(0 h, 6 h, 12 h, 18 h and 24 h) by q RT-PCR and Western blot.To detect the effect of MKP1 on Aβ-induced neurotoxicity, the wild-type PC12 cells were divided in control group(Control) and Aβ42 group, that the MKP1 knockdown cells were Aβ42+MKP1 KD group, the MKP1 overpressed cells were Aβ42+MKP1 group.The last three groups were placed in an incubator about twenty-four hours after joining 10μM Aβ42 to carry out CCK-8 and other tests.To detect the greater effect of JNK signaling pathway on neural damage via knockdowning MKP1, MKP1 KD cells were divided into control group and SP600125 group which were joined in 10μM Aβ42. SP600125(Sigma-Aldrich)2 μM which was The JNK inhibitor were joined in SP600125 group.The two groups were placed in an incubator about twenty-four hours to carry out CCK-8 and other tests.All of these datas were analyzed via the statistic software IBM SPSS Statistics 23.0.Results: This results showed that activity of PC12 cells was inhibited and expression of MKP1(MAPK important regulatory factor)was declined depending on time under the stimulation of Aβ. The levels of Aβ-induced p-p38 and p-JNK were reduced in the PC12 cells owing to overexpression of MKP1, and the levels of ROS, TNF-α, IL-1β, cell death were decreased. Knockdowning MKP1 could be increase the effect of oxidative stress, inflammation and cellular damage Aβ-induced PC12 cells. Further results showed that SP600125 which was The JNK inhibitor could offset the greater affect of Aβ-induced neurotoxicity owing to knockdowning MKP1.Conclusions: 1. This study shows that Aβ can down-regulate the expression of MKP1 to activate MAPK signaling pathway. 2. Overpressing MKP1 can decrease apoptosis and neural inflammation by inhibiting JNK signaling pathway to protect neurons.