Signal transduction of c-Jun N-terminal kinase against beta-amyloid protein 1-40 induced neuronal toxicity to cortical progenitor cells of embryonic rats

Rong YAN; Xiaoguang LUO; Chaodong ZHANG

ABSTRACT

BACKGROUND:

The primary pathophysiology of Alzheimer disease (AD) is linked to β-amyloid (Aβ)protein. Neural progenitor cells (NPCs), which have the ability of multipotency, self-renewal and repair,have been detected in the central nerve system (CNS) of adult rat recently. But effective function of these neural progenitor cells are not seen in the AD brain ,which mechanism is unclear.It is unclear if Aβ1-40protein is compromised by the signal pathway of c-Jun N-termial kinase associated with the neurotoxicity to the progenitor cells on the cortex of embryonic rats.

OBJECTIVE:

To investigate the mechanism of c-Jun N-terminal kinase signal transduction pathway of Aβ1-40 protein, which has neuronal toxicity to progenitor cells(CPC)on the cortex of embryonic rats . To detect the neuroprotective effects of c-Jun N-termial kinase inhibitor (SP600125) against Aβ1-40-induced neuronal toxicity to the cortical progenitor cells on the cortex of embryonic rats.

DESIGN:

A randomized and controlled trial with cells as objects.

SETTING:

Department of Neurology, First Hospital Affiliated to China Medical UniversityMATERIALS This experiment was carried out at the Central Laboratory,China Medical University from May to October 2005. Embryos at age of 14 days from Wistar rats were used in this experiment.

METHODS:

Cortical progenitor cells harvested from Wistar embryonic rats were cultured in vitro, passaged and identified. Embryonic rat cortical progenitor cells of rats with good growth state were randomly divided into 4groupsAβ1-40 group (10 nmol/L Aβ1-40 in each well);SP600125+Aβ1-40group (10 μmol/L SP600125 for 30 minutes and then with 10 nmol/L Aβ1-40 in each well); SP600125 group ( 10 μmol/L SP600125 in each well); Normal saline group (same volume of normal saline). The incubated durations were 0,2 hours, 4 hours, 6 hours, 12 hours, 24 hours respectively,8 wells for each time point. The cell survival rate was measured by MTF assay (The concentration of cortical progenitor cells on the cortex was 1×10s L-1 in each group), the apoptosis rate was detected by flow cytometer (The concentration of cortical progenitor cells on the cortex was 1 ×1010 L-1in each group) and the expression of c-Jun N-termial kinase and p-c-Jun N-termial kinase, c-Jun,p-c-Jun were measured by Western Blot(The concentration of cortical progenitor cells on the cortex was 1×1013 L-1 in each group). t test was adopted for the comparison of difference in measurement data.sion of c-Jun N-terminal kinase, p-c-Jun N-termial kinase ,c-Jun and p-c-Jun of embryonic rat CPC .ture time in Aβ group and SP600125 +Aβ group, decreased obviously at 4hours; cellular survival rate in Aβ1-40 group was lower obviously than that in the other 3 groups at 0,2,4,6,12,24 hours (P ＜ 0.01); Cellular survival rate in SP60025 +Aβ1-40 group was lower obviously than that in SP600125 group and normal saline group at 2,4,6,12,24 hours (P ＜ 0.01);Compared with normal saline group, the difference of cell survival rate was not significant without time-dependent manner in SP600125 group (P＞ 0.05).amyloid protein group and SP600125 +Aβ group, increased obviously at 4hours; cell apoptosis rate in Aβ1-40 group was higher obviously than that of the other 3 groups at 0,2,4,6,12,24 hours(P ＜ 0.01); Cellular apoptosis rate in SP60025+Aβ1-40 group was higher obviously than that in the SP600125 group and normal saline group at 2,4,6,12,24 hours (P ＜ 0.01);Compared with normal saline group, the difference of cellular apoptosis rate was not significant without time-dependent manner in SP600125 group 12,24 hours without changes in Aβ1-40 group; the expression of p-c-Jun N-terminal kinase and p-c-Jun in Aβ1-40 group were seen at 0hour ,increased gradually, reached to the peak at hour 4 and decreased gradually.

CONCLUSION:

Aβ1-40 could inhibit the cell activity of CPC , reduce cellular survival rate and induce cellular apoptosis. c-Jun N-terminal kinase signal transduction pathway may mediate the Aβ1-40 inducd neurnal apoptosis in AD which may be one reason for unseen rescue mechanism in AD. SP600125 (c-Jun N-terminal kinase inhibitor) could inhibit the activation of c-Jun N-terminal kinase and c-Jun and protect the embryonic rats CPC from the Aβ1-40-induced neurotoxicity.