title: Prevention of transcriptional silencing by a replicator-binding complex consisting of SWI/SNF, MeCP1, and hnRNP C1/C2.
abstract: Transcriptional silencing selectively impedes gene expression. Silencing is often accompanied by replication delay and can be prevented by replicator sequences. Here we report a replicator-binding protein complex involved in the prevention of transcriptional silencing. The protein complex interacts with an essential asymmetric region within the human β-globin Rep-P replicator and includes hnRNP C1/C2, SWI/SNF complex, and MeCP1, which are members of the locus control region (LCR)-associated remodeling complex (LARC). Interaction between LARC and Rep-P prevented transcriptional silencing and replication delay. Transgenes that did not contain the asymmetric LARC-binding region of Rep-P replicated late and exhibited stable silencing that could not be affected by a DNA methylation inhibitor. In contrast, transgenes that contain a mutation of the asymmetric region of Rep-P that could not bind LARC exhibited a silent state that could transiently be reactivated by DNA demethylation. The effect of DNA demethylation was transient, and prolonged exposure to a methylation inhibitor induced distinct, stable, methylation-independent silencing. These observations suggest that the interaction of LARC complex with replicators plays a role in preventing gene silencing and provides support for a novel, epigenetic mechanism of resistance to methylation inhibitors.
authors.affiliation: Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Huang
authors.forename: Haiqing
authors.initials: H
authors.lastname: Fu
authors.forename: Chii Mei
authors.initials: CM
authors.lastname: Lin
authors.forename: Amy L
authors.initials: AL
authors.lastname: Conner
authors.forename: Ya
authors.initials: Y
authors.lastname: Zhang
authors.forename: Mirit I
authors.initials: MI
authors.lastname: Aladjem
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D044127:Epigenesis, Genetic; D020868:Gene Silencing; D034482:Heterogeneous-Nuclear Ribonucleoprotein Group C; D006655:Histone Deacetylases; D006801:Humans; D019901:Locus Control Region; D051379:Mice; D046912:Multiprotein Complexes / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors; D014158:Transcription, Genetic; D019076:Transgenes
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D034482:Heterogeneous-Nuclear Ribonucleoprotein Group C; C489689:MeCP1 histone deacetylase complex, human; D046912:Multiprotein Complexes; C445179:SWI-SNF-B chromatin-remodeling complex; D014157:Transcription Factors; D006655:Histone Deacetylases