FIGURE 3.

Runx2 acetylation and p300 are required for Erk-induced Runx2 stabilization. A, overexpression of HDAC4 or HDAC5 blocked an Erk-mediated increase in Runx2 protein and acetylation. 293T cells were transiently transfected with FLAG-Runx2, MEK1, Myc-HDAC4, and Myc-HDAC5 expression vectors as indicated. Twenty-four hours after transfection, IP and IB analysis was performed. B, knockdown of p300 using siRNA suppressed Erk-mediated Runx2 acetylation and stabilization. 293T cells were transfected with siRNAs for p300 (sip300) and a non-targeting control siRNA (siControl). Six hours after transfection, a second transfection with Myc-Runx2 and MEK1 expression vector was performed, and the cells were incubated for an additional 32 h, then IP and IB analysis was performed. AcK, anti-acetylated lysine antibody.