Lentiviral-mediated RNAi targeting p38MAPK ameliorates high glucose-induced apoptosis in osteoblast MC3T3-E1 cell line.

The p38 mitogen activated protein kinase (p38MAPK) pathway is an important signaling cascade involved in cell growth, differentiation and apoptosis. High glucose activates p38MAPK pathway in different cells, including osteoblasts. In the present study, role of p38MAPK in high glucose induced osteoblast apoptosis and potential of RNA interference (RNAi) targeting p38MAPK as a therapy strategy have been reported. Lentiviral-mediated RNAi effectively reduced p38MAPK and p-p38MAPK expressions in osteoblastic cell line (MC3T3-E1) following high glucose (22 mM) induction. Inhibition of p38MAPK activity significantly suppressed high glucose induced apoptosis of MC3T3-E1 cell and was confirmed by flow cytometry and ultra-structural examination by transmission electronic microscope. Inhibition of p38MAPK also significantly attenuates caspase-3 and bax protein expressions, but increased significantly bcl-2 expression as determined by Western blot analysis. The results suggested that p38MAPK mediates high glucose induced osteoblast apoptosis, partly through modulating the expressions of caspase-3, bax and bcl-2. Inhibition of p38MAPK with lentiviral-mediated RNAi or its specific inhibitor provides a new strategy to treat high glucose induced osteoblast apoptosis.

Effect of RNAi targetingp38MAPK on high glucose-induced apoptosis of osteoblast MC3T3-E1 cell line / 中华内分泌代谢杂志

Objective To examine the role of p38MAPK in high glucose-induced apoptosis of osteoblast MC3T3-E1 cell line, and to investigate its effect on the expressions of apoptosis-related molecules including caspase3, bax, and bcl-2. Methods The lentiviral vector containing short hairpin RNA targeting p38MAPK was constructed. The cultured osteoblast MC3T3-E1 cell were divided into 5 groups:normal control group(A group), high glucose group(B group), p38MAPK-shRNA transfection group(C group), signal transduction inhibitor group(D group), and transfection with negative control siRNA group(E group). RT-PCR was used to determine the p38MAPK mRNA expression levels in MC3T3-E1 cells. Flow cytometry(FCM)was employed to detect the cell apoptotic percentage. The protein levels of apoptosis-related molecules p38MAPK, p-p38MAPK, caspase-3, bax, and bcl-2 were assayed by Western blot. Ultrastructural alternation of MC3T3-E1 cell was observed under transmission electron microscopy(TEM). Results The lentiviral vector containing short hairp in RNA targeting p38MAPK was successfully constructed and transfected into MC3T3-E1 cells. RT-PCR result suggested that the siRNA targeting p38MAPK could effectively reduce the p38MAPK mRNA expression level induced by high glucose in MC3T3-E1 cell line. FCM showed siRNA significantly decreased high glucose-induced apoptosis percentage of MC3T3-E1 cells(P＜0.01). Meanwhile, we also found the siRNA significantly attenuated the proteins levels of p38MAPK, p-p38MAPK, caspase-3, and gene bax induced by high glucose in MC3T3-E1 cells, whereas the protein level of gene bcl-2 was enhanced remarkably when compared with high glucose group and negative control siRNA group(P＜0.01, P＜0.05).Conclusion The iRNA targeting p38MAPK suppressed high glucose-induced MC3T3-E1 cell apoptosis via inhibiting the activation of p38MAPK signaling pathway, thereby reducing the expressions levels of p-p38MAPK, caspase-3 and gene bax, and up-regulating the level of gene bcl-2.