Helen Hoffmeister et al. (2017) Nucleic Acids Research; PMID: 28977666

CHD3 and CHD4 (Chromodomain Helicase DNA bind-ing protein), two highly similar representatives of theMi-2 subfamily of SF2 helicases, are coexpressed inmany cell lines and tissues and have been reportedto act as the motor subunit of the NuRD complex(nucleosome remodeling and deacetylase activities).Besides CHD proteins, NuRD contains several re-pressors like HDAC1/2, MTA2/3 and MBD2/3, argu-ing for a role as a transcriptional repressor. However,the subunit composition varies among cell- and tis-sue types and physiological conditions. In particular,it is unclear if CHD3 and CHD4 coexist in the sameNuRD complex or whether they form distinct NuRDcomplexes with specific functions. We mapped theCHD composition of NuRD complexes in mammaliancells and discovered that they are isoform-specific,containing either the monomeric CHD3 or CHD4 AT-Pase. Both types of complexes exhibit similar in-tranuclear mobility, interact with HP1 and rapidly ac-cumulate at UV-induced DNA repair sites. But, CHD3and CHD4 exhibit distinct nuclear localization pat-terns in unperturbed cells, revealing a subset of spe-cific target genes. Furthermore, CHD3 and CHD4 differ in their nucleosome remodeling and positioningbehaviour in vitro. The proteins form distinct CHD3-and CHD4-NuRD complexes that do not only repress,but can just as well activate gene transcription ofoverlapping and specific target genes.