MBD2 and Multiple Domains of CHD4 Are Required for Transcriptional Repression by Mi-2/NuRD Complexes

Abstract

Mi-2/nucleosome remodeling and deacetylase (NuRD) chromatin remodeling complexes are important regulators of chromatin structure and DNA accessibility. We examined requirements for individual domains of chromodomain helicase DNA-binding protein 4 (CHD4), a core catalytic component of NuRD complexes, as well as the NuRD subunit methyl-binding domain protein 2 (MBD2) and methylated DNA, for NuRD function in the context of tissue-specific transcription. By itself, loss of NuRD activity is not sufficient for transcriptional activation. However, NuRD complexes greatly reduce activation of the B cell-specific mb-1 (Cd79a) gene by the transcription factors EBF1 and Pax5. Using our B cell model system, we determined that the two chromodomains and ATPase/helicase and C-terminal domains (CTD) of CHD4 are all necessary for repression of mb-1 promoters by NuRD. All of these domains except the CTD are required for efficient association of CHD4 with mb-1 promoter chromatin. Loss of MBD2 expression or of DNA methylation impaired association of CHD4 with mb-1 promoter chromatin and enhanced its transcription. We conclude that repressive functions of MBD2-containing NuRD complexes are dependent on cooperative interactions between the major domains of CHD4 with histones and DNA and on binding of methylated DNA by MBD2.

ACKNOWLEDGMENTS

We thank C. Musselman for helpful discussions, C. Hennessy and D. Schwartz for invaluable assistance with pyrosequencing, G. Blobel for the CHD4 cDNA plasmid, and K. Lukin for assistance with preparation of figures.

This research was supported by NIH grants R01 AI054661 and AI081878 to J.H. and GM096863 and CA113472 to T.G.K. J.R. was supported by a generous grant from the Rocky Mountain Chapter of the Arthritis Foundation and NIH postdoctoral training grant T32 AI07405. C.D. is supported by the Cancer Research Institute Predoctoral Emphasis Pathway in Tumor Immunology Fellowship.

We declare that we do not have any conflicts of interest.