MCAF Mediates MBD1-Dependent Transcriptional Repression

Abstract

DNA methylation is involved in a variety of genome functions, including gene control and chromatin dynamics. MBD1 is a transcriptional regulator through the cooperation of a methyl-CpG binding domain, cysteine-rich CXXC domains, and a transcriptional repression domain. A yeast two-hybrid screen was performed to investigate the role of MBD1 in methylation-based transcriptional repression. We report a mediator, MBD1-containing chromatin-associated factor (MCAF), that interacts with the transcriptional repression domain of MBD1. MCAF harbors two conserved domains that allow it to interact with MBD1 and enhancer-like transactivator Sp1. MCAF possesses a coactivator-like activity, and it seems to facilitate Sp1-mediated transcription. In contrast, the MBD1-MCAF complex blocks transcription through affecting Sp1 on methylated promoter regions. These data provide a mechanistic basis for direct inhibition of gene expression via methylation-dependent and histone deacetylation-resistant processes.

ACKNOWLEDGMENTS

We thank F. Ishikawa (Kyoto University) for MBD2A and MBD3-expressing plasmids and J. T. Kadonaga (University of California, San Diego) for pPacSp1.

N.F. is a Research Fellow of the Japan Society for the Promotion of Science. This work was supported by a Grant-in-Aid for Scientific Research on Priority Areas and by Special Coordination Funds for Promoting Science and Technology from the Ministry of Education, Culture, Sports, Science and Technology of the Japanese government (M.N.).