ABSTRACT
Objective To explore the effects of early growth response gene-1 (Egr-1) on bone marrow mesenchymal stem cells (BMSC) proliferation and osteogenic differentiation,which is aimed at providing new molecular targets for the treatment of osteoporosis.Methods Bone marrow was collected from adult men and the BMSCs were cultured primarily and observed by microscope.Meanwhile,flow cytometry was used for BMSCs phenotypic identification;After transfection of pcDNA3.1/Egr-1 into BM SCs,the level of BMSCs proliferation was determined by MTT respectively on the 2 d,4 d and 6 d;On the 7 d after transfection,the ALP activity assay was used for testing the ALP activity in BMSCs.And then,alizarin red S-calcium kit was used for measuring the calcified knots respectively on the 7 d,14 d and 21 d;On the 21 d after transfection,real-time qPCR and Western blotting were used respectively for measuring the expression of mRNA and protein of Egr-1,Runx2 and NDRG1;Further,BMSCs were transfected with Egr-1 siRNA,and the content of calcium nodules,ALP activity,the expression of Egr-1,Runx2 and NDRG1 were detected as above methods.Results The cells cultured in vitro showed high level of CD90 and CD29 and very low level of CD34 and CD45,which is accorded with the characteristic of BMSCs.The pcDNA3.1/Egr-1 transfection for BMSCs had no effect on cells prolifera tion.However,the calcified knots,ALP activity and the expression of Egr 1,Runx2 and NDRG1 were increased after transfection of pcDNA3.1/Egr-1 for BMSCs.In addition,Egr-1 siRNA showed the opposite effect with pcDNA3.1/Egr-1 transfection for BMSCs.Conclusion Egr-1 induces osteogenic differentiation of BMSCs by promoting NDRG1 but has no effects on proliferation of BMSCs.