Bone morphogenetic protein-7 inhibits apoptosis of human nucleus pulposus cells through activation of PI3K/Akt pathway

doi:10.3969/j.issn.2095-4344.2014.24.009

Abstract

Abstract:

BACKGROUND: Bone morphogenetic protein 7 (BMP-7) can promote extracellular matrix synthesis of human nucleus pulposus cells, and delay intervertebral disk degeneration. Recently scholars proposed that the above effects can be achieved through anti-apoaptosis, but further molecular mechanism remains poorly understood.
OBJECTIVE: To observe the effects of BMP-7 on the apoptotic human nucleus pulposus cells under serum-free induction and the PI3K/Akt pathway, investigate the molecular mechanism underlying the anti-apoptosis effect of BMP-7.
METHODS: Human nucleus pulposus tissue were harvested from 12 patients according to the modified Pfirrmann classification, and human nucleus pulposus cells were obtained from digestion of herniated nucleus pulposus tissue. The collected nucleus pulposus cells were divided into four groups. Blank group: cells were cultured in normal culture medium containing 15% feral bovine serum; positive control group: cells were induced to apoptosis in the serum-free culture medium for 48 hours; treated group: cells were induced to apoptosis in the serum-free culture medium containing different dosages of BMP-7; antagonism group: cells were induced to apoptosis in the serum-free culture medium containing different dosages of BMP-7 and LY294002, an PI3K/Akt pathway inhibitor. Cellular apoptosis rate was quantified by flow cytometry. Immunoflurorescence was performed to observe p-Akt expressions. Changes of Akt, p-Akt, BAD, and Caspase 9 expression were detected with western blot analysis.
RESULTS AND CONCLUSION: Results from flow cytometry showed that, the apoptosis rate of nucleus pulposus cells was significantly decreased as the increase of BMP-7 concentration, under the serum-free induction; after the cells were induced with LY294002, the apoptosis rate was increased again (P < 0.05). The p-Akt immunoflurorescence and western blot analysis demonstrated that, compared with positive control group, the p-Akt expression was significantly increased, while the expression of downstream apoptosis-related proteins such as BAD and Caspase 9, was significantly decreased in the cells treated with BMP-7 (P < 0.05). Furthermore, in the group treated with BMP-7 and LY294002, the p-Akt expression was decreased, while the expression of apoptosis-related proteins was recovered to high levels (P < 0.05). BMP-7 activates the PI3K/Akt pathway, suppresses the downstream BAD and Caspase 9 signaling, and inhibits the apoptosis of human nucleus pulposus cells induced by serum-free situation.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

全文链接：

Key words: apoptosis, bone morphogenetic protein-7, protein kinase, serum

CLC Number:

R318

Yu Hao-tao, Xu Yi-chun, Wang Qi-you, Ou Ding-qiang, Zhou Wei . Bone morphogenetic protein-7 inhibits apoptosis of human nucleus pulposus cells through activation of PI3K/Akt pathway[J]. Chinese Journal of Tissue Engineering Research, 2014, 18(24): 3821-3828.

Figures/Tables 6

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