RUNX2 17A and 11A constructs have differential biochemical behavior.
A. Transfection comparison of the activities of RUNX2 expression constructs driving RUNX2 sensitive reporter plasmid (p3RRE) in HEK293 cells. pBOS is empty vector control for baseline promoter activity of the RUNX2 responsive plasmids. 23Q/17A construct (17A) has higher activity than the RUNX2 23Q/11A variant allele (11A). On the reporter (p3RRE) the RUNX2 23Q/11A variant was significantly different from the wild type 23Q/17A allele (p = 0.0004) and was similar in expression to rare allelic variants of the glutamine repeat (16Q/17A and 30Q/17A, labeled as 16Q and 30Q, respectively). B. Effect of CBFB cotransfection on the comparison between RUNX2 17A and 11A constructs on a truncated mouse osteocalcin promoter, p147. A difference is observed between RUNX2 17A and 11A constructs in the absence of CBFB. In the presence of CBFB, the p147 target promoter activity is induced and the difference between RUNX2 17A and 11A constructs is eliminated.