MBD3L2 interacts with MBD3 and components of the NuRD complex and can oppose MBD2-MeCP1-mediated methylation silencing.
MBD2 and MBD3 are two proteins that contain methyl-CpG binding domains and have a transcriptional repression function. Both proteins are components of a large CpG-methylated DNA binding complex named MeCP1, which consists of the nucleosome remodeling and histone deacetylase complex Mi2-NuRD and MBD2. MBD3L2 (methyl-CpG-binding protein 3-like 2) is a protein with substantial homology to MBD2 and MBD3, but it lacks the methyl-CpG-binding domain. Unlike MBD3L1, which is specifically expressed in haploid male germ cells, MBD3L2 expression is more widespread. MBD3L2 interacts with MBD3 in vitro and in vivo, co-localizes with MBD3 but not MBD2, and does not localize to methyl-CpG-rich regions in the nucleus. In glutathione S-transferase pull-down assays, MBD3L2 is found associated with several known components of the Mi2-NuRD complex, including HDAC1, HDAC2, MTA1, MBD3, p66, RbAp46, and RbAp48. Gel shift experiments with nuclear extracts and a CpG-methylated DNA probe indicate that recombinant MBD3L2 can displace a form of the MeCP1 complex from methylated DNA. MBD3L2 acts as a transcriptional repressor when tethered to a GAL4-DNA binding domain. Repression by GAL4-MBD3L2 is relieved by MBD2 and vice versa, and repression by MBD2 from a methylated promoter is relieved by MBD3L2. The data are consistent with a role of MBD3L2 as a transcriptional modulator that can interchange with MBD2 as an MBD3-interacting component of the NuRD complex. Thus, MBD3L2 has the potential to recruit the MeCP1 complex away from methylated DNA and reactivate transcription.
Jin
Seung-Gi
SG
Division of Biology, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA.
Jiang
Chun-Ling
CL
Rauch
Tibor
T
Li
Hongwei
H
Pfeifer
Gerd P
GP
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D019556:COS Cells; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D003001:Cloning, Molecular; D018899:CpG Islands; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D020224:Expressed Sequence Tags; D005982:Glutathione Transferase / Q000378:metabolism; D006238:Haploidy; D006367:HeLa Cells; D006655:Histone Deacetylases / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex; D051379:Mice; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D009707:Nucleosomes / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D014158:Transcription, Genetic; D014162:Transfection; D020798:Two-Hybrid System Techniques
D004268:DNA-Binding Proteins; C489325:MBD2 protein, human; C115369:MBD3 protein, human; C474632:MBD3L2 protein, human; C489689:MeCP1 histone deacetylase complex, human; D009707:Nucleosomes; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D008156:Luciferases; D005982:Glutathione Transferase; D006655:Histone Deacetylases; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex