| Histone deacetylase 3 interacts with runx 2 to repress the osteocalcin promoter and regulate osteoblast differentiation . ^^^ In transient transfection assays , HDAC 3 repressed Runx 2 mediated activation of the osteocalcin promoter . ^^^ In vivo , Runx 2 and HDAC 3 associated with the osteocalcin promoter . ^^^ These data indicate that HDAC 3 regulates Runx 2 mediated transcription of osteoblast genes . ^^^ Suppression of HDAC 3 in MC3T3 preosteoblasts by RNA interference accelerated the expression of Runx 2 target genes , osteocalcin , osteopontin , and bone sialoprotein but did not significantly alter Runx 2 levels . ^^^ |