title: Functional validation of a constitutive autonomous silencer element.
abstract: Sequences of the genome that are capable of silencing gene expression are thought to play a key role in gene regulation. However, very few silencer elements capable of functioning in mammalian cells have been described, and only a fraction of these have been tested for the ability to function in an autonomous fashion. We report here the characterization and functional validation of a constitutive autonomous silencer element from the human genome called T39, and the comparison of T39 to three other putative silencer elements previously described by others. Functional analysis included one assay for enhancer-blocking insulator activity and two independent assays for silencer activity, all based on stable transfection and comparison to a neutral spacer control. In erythroid K562 cells, T39 exhibited potent silencer activity, the previously described element PRE2-S5 exhibited modest silencer activity, and the two other previously described elements exhibited no silencer activity. T39 was further found to be capable of silencing three disparate promoters, of silencing gene expression in three disparate cell lines, and of functioning as a single copy in a topology-independent manner. Of the four elements analyzed, only T39 exhibits a constitutive pattern of DNase hypersensitivity and binding by CTCF. In its native location the T39 element also exhibits a unique interaction profile with a subset of distal putative regulatory elements. Taken together, these studies validate T39 as a constitutive autonomous silencer, identify T39 as a defined control for future studies of other regulatory elements such as insulators, and provide a basic chromatin profile for one highly potent silencer element.
authors.affiliation: CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China; Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States of America.
authors.forename: Heyuan
authors.initials: H
authors.lastname: Qi
authors.affiliation: Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States of America.
authors.forename: Mingdong
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States of America; Institutional Biosafety Committee Services, WIRB-Copernicus Group, Puyallup, WA, United States of America.
authors.forename: David W
authors.initials: DW
authors.lastname: Emery
authors.affiliation: Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States of America.
authors.forename: George
authors.initials: G
authors.lastname: Stamatoyannopoulos
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly; D004351:Drug Resistance / Q000235:genetics; D015870:Gene Expression; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D056426:Genetic Loci; D015894:Genome, Human; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D015203:Reproducibility of Results; D037941:Silencer Elements, Transcriptional
chemical_list: D002843:Chromatin