Objective:To study the effects of Nrf2 on proliferation

apoptosis and differentiation of C2C12 cells during osteoblastic differentiation. Methods:The recombination lentivirus of nuclear factor erythroid 2 p45 related factor 2（Nrf2）and its siRNA were constructed in order to investigate the function of gene Nrf2 on apoptosis during osteogenic differentiation of C2C12 cells. The plasmids p WPT-GFP-Nrf2

p WPT-GFP-si NRF2 and p WPT-GFP-siATF4 were co-transfected respectively with other two lentivirus packaging plasmids into 293 T cells to produce Lv-Nrf2

Lv-si Nrf2 and Lv-siATF4 virus particles. Different treatment groups of lentivirus were set under the induction of bone morphogenetic protein 2（BMP2）

the proliferation

apoptosis and expression of osteogenic-differentiation-related marker proteins were detected respectively. Results:FCM analysis showed that the apoptosis rate in BMP2+Lv-Nrf2 group was lower than that in BMP2+Lv-GFP group;the apoptosis rate in BMP2+Lv-si Nrf2 group was higher than that in BMP2+Lv-GFP group;the apoptosis rate in BMP2+Lv-Nrf2+Lv-siATF4 group was lower than that in BMP2+Lv-siATF4 group;the results of Western blotanalysis were consistent with those of FCM. Cell immunochemistry staining showed that the expression levels of osteocalcin and alkaline phosphatasewere higher in BMP2+Lv-Nrf2 group than in control group BMP2+Lv-GFP

lower in BMP2+Lv-si Nrf2 groupthan in control group

lower in combined treatment group BMP2 +Lv-Nrf2 +Lv-siATF4 than in control group and single treatment group BMP2+Lv-Nrf2. Conclusion :Under the induction of BMP2

gene Nrf2 could inhibit the apoptosis and promote the osteogenic differentiation of C2C12 cells. Additionally

gene Nrf2 could rescue the increased cell apoptosis level

but could not rescue the decreased osteogenic differentiation level both caused by ATF4 deficiency.