Acetylation Modification Is Involved In The Regulation Of Osterix, A Key Regulator Of Osteoblast Differentiation

The transcription factor Osterix (Osx) is a key regulator of osteoblast differentiation and bone formation. Previously, we have demonstrated that Osx is ubiquitinated. Here we report that acetylation modification is involved in the regulation of Osx. We found that protein levels of both the endogenous and exogenous Osx increased after treatment with histone deacetylase inhibitors TSA and SAHA, and the increase was in a dose-dependent manner. Immunoprecipitation (IP) assays showed that Osx was acetylated by p300/CBP with the stronger function of CBP. The interaction and colocalization of CBP and Osx was demonstrated by Co-IP and immunofluorescence (IF), respectively. In addition, K307 and K312 were identified as the acetylated sites of Osx. Moreover, we found that HDAC4 was involved in the deacetylation of Osx. And HDAC4 was interacted and colocalizated with Osx. Functionally, acetylation promotes Osx stability, DNA binding ability and transactivation activity as proved by Cycloheximide (CHX) treatment, electrophoretic mobility shift assay (EMSA), luciferase reporter assay, and Real-time PCR, respectively. Taken together, our results provide evidence for the first time that p300/CBP-mediated acetylation and HDAC4 mediated deacetylation may be a critical modification for Osx function.