The partnership between mechanical force and alveolar bone remodeling is an important issue in orthodontics because tooth movement is dependent on the response of bone tissue to the mechanical force induced by the appliances used. and inhibited the expression of TWIST by mechanical cyclic tension. It can be found that p21, as a downstream gene of TWIST and E2A, regulates the expression of TWIST by positive feedback and E2A by negative feedback. Research showed that E2A and TWIST could compete with Snail to bind E-box to control the expression of p21WAF/Cip1 and regulate the proliferation and differentiation of osteoblasts . TWIST can also inhibit the expression of p21 by binding to E2-box and E5-box, increase the osteogenic potential of stem cells and maintain the characteristics of senile stem cells . Therefore, we speculated that the transcriptional level of p21 decreased after silencing p21 under the stimulation of cyclic stretch. Failure to bind E2A specifically to p21 promoter resulted in accumulation of E2A, whereas increased binding of E2A to AZD2014 pontent inhibitor TWIST resulted in decreased expression of TWIST. Further review of the literature shows that transcription factor TWIST is a downstream gene of HIF-1 . HIF-1 and TWIST inhibit the differentiation of MSC into osteocytes through direct or indirect discussion with RUNX2. TWIST can inhibit the manifestation of RUNX2 in BMSCs as well as the down-regulation additional osteogenic marker. . RUNX2 may be the most particular gene along the way of osteogenesis, which is early expressed in the osteogenic differentiation of MSCs  fairly. OSTERIX can be a downstream gene of RUNX2, also an important transcription element in osteogenic differentiation. RUNX2 and osterix are both considered as markers of early osteogenic differentiation . OSTERIX is necessary to guide mesenchymal stem Rabbit Polyclonal to USP30 cells to osteoblasts and induce bone formation . We found that cyclic tension can promote the expression of RUNX2 and OSTERIX in BMSCs, and p21 protein was involved in the regulation of osteogenic differentiation. However, p21 had different regulatory effects on RUNX2, OSTERIX and BMP2. Down-regulating p21 increased the expression of RUNX2 and OSTERIX, but decreased BMP2 to some extent. We speculated that p21 may play an important role in the regulation of osteogenic differentiation induced by mechanical cyclic stretch. It can not only be promoted by mechanical stimulation, but also maintain the relative balance between the osteogenic factors. Conclusion In conclusion, we demonstrate that mechanical cycling strain can promote TWIST and inhibit E2A. TWIST and E2A interact in some way and activate the expression of p21. Down-regulating p21 could enhance the osteogenic differentiation. The results suggest that p21 plays an essential role in AZD2014 pontent inhibitor osteogenic differentiation induced by mechanical stimulation, and the mechanism was mediated through TWIST/E2A/p21 axis (Figure 5). Open in a separate window Figure 5 Schematic diagram of the mechanism through E2A-p21 by HIF-TWIST axis in regulating osteogenic differentiation of BMSCs under mechanical stimulation Abbreviations bHLHbasic helixCloopChelixBMSCbone marrow mesenchymal stem cellFBSfetal bovine serumHIF-1hypoxia inducible factor-1PVDFpolyvinylidenedifluorideqPCRquantitative real time RT-PCR Competing Interests The authors declare that there are no competing interests associated with the manuscript. Funding This ongoing work was supported by the National Nature Science Base AZD2014 pontent inhibitor of China [grant amounts 81771102, 11602122]; the China Postdoctoral Research Foundation [offer amount 2017M623396]; the 12.5 Main Task of Army Medical Technology and Research [offer number AWS11J012-04]. Writer Contribution Q.G. participated in style and conception, set up or assortment of data, data.