MBD3 and HDAC1, two components of the NuRD complex, are localized at Aurora-A-positive centrosomes in M phase.

MBD3, a component of the histone deacetylase NuRD complex, contains the methyl-CpG-binding domain (MBD), yet does not possess appreciable mCpG-specific binding activity. The functional significance of MBD3 in the NuRD complex remains enigmatic, partly because of the limited availability of biochemical approaches, such as immunoprecipitation, to analyze MBD3. In this study, we stably expressed the FLAG-tagged version of MBD3 in HeLa cells. We found that MBD3-FLAG was incorporated into the NuRD complex, and the MBD3-FLAG-containing NuRD complex was efficiently immunoprecipitated by anti-FLAG antibodies. By exploiting this system, we found that MBD3 is phosphorylated in vivo in the late G(2) and early M phases. Moreover, we found that Aurora-A, a serine/threonine kinase active specifically in the late G(2) and early M phases, phosphorylates MBD3 in vitro, physically associates with MBD3 in vivo, and co-localizes with MBD3 at the centrosomes in the early M phase. Interestingly, HDAC1 is distributed at the centrosomes in a manner similar to MBD3. These results suggest the highly dynamic nature of the temporal and spatial distributions, as well as the biochemical modification, of the NuRD complex in M phase, probably through an interaction with kinases, including Aurora-A. These observations will contribute significantly to the elucidation of the yet-uncharacterized cell cycle-controlled functions of the NuRD complex.