Bone-specific Transcription Factor Runx2 on the Role of Antagonistic Bone Loss In Space

To construct a stable expression of Runx2 in C2C12, MG63 cells, and primarily investigate the role of Runx2 against bone loss induced by spaceflight. Myoblast C2C12 and pre-osteoblast MG63 was transfected with Runx2 and selected overexpressing cell clone with G418. The stably transfected C2C12, MG63 cell lines with Runx2 were identified by westernblot and named C2C12-Runx2 and MG63-Runx2 respectively. The expression of genes regulated by Runx2 were determined using Real-time Quantitative PCR. The stable cell lines and untransfected cell lines were cultured in clinostat to simulate microgravity condition and detected the expression of Runx2 and its downstream genes by Real-time Quantitative PCR. C2C12-Runx2, MG63-Runx2 cell lines were gained which were overexpressing Runx2. The mRNA expression level of Alkaline Phosphatase (ALP) and Col1a1 increased in C2C12-Runx2 andMG63-Runx2 cells. The mRNA expression of ALP and Col1a1 decreased in the clinorotation group compared with the control group in MG63, C2C12-Runx2 and MG63-Runx2 cells. The decreased degree of ALP, Col1a1 mRNA expression in both transfected cell lines was lower than in untransfected cell lines under simulated microgravity condition. C2C12-Runx2, MG63-Runx2 cell lines were successfully constructed. The data from clinorotation and Real-time Quantitative PCR suggest that Runx2 can partly antagonize the decreased expression of osteogenic specific molecules induced by simulated microgravity.