title: DNA elements reducing transcriptional gene silencing revealed by a novel screening strategy.
abstract: Transcriptional gene silencing (TGS)--a phenomenon observed in endogenous genes/transgenes in eukaryotes--is a huge hindrance to transgenic technology and occurs mainly when the genes involved share sequence homology in their promoter regions. TGS depends on chromosomal position, suggesting the existence of genomic elements that suppress TGS. However, no systematic approach to identify such DNA elements has yet been reported. Here, we developed a successful novel screening strategy to identify such elements (anti-silencing regions-ASRs), based on their ability to protect a flanked transgene from TGS. A silenced transgenic tobacco plant in which a subsequently introduced transgene undergoes obligatory promoter-homology dependent TGS in trans allowed the ability of DNA elements to prevent TGS to be used as the screening criterion. We also identified ASRs in a genomic library from a different plant species (Lotus japonicus: a perennial legume); the ASRs include portions of Ty1/copia retrotransposon-like and pararetrovirus-like sequences; the retrotransposon-like sequences also showed interspecies anti-TGS activity in a TGS-induction system in Arabidopsis. Anti-TGS elements could provide effective tools to reduce TGS and ensure proper regulation of transgene expression. Furthermore, the screening strategy described here will also facilitate the efficient identification of new classes of anti-TGS elements.
authors: Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan.
authors: Naoki
authors: N
authors: Kishimoto
authors: Jun-ichi
authors: J
authors: Nagai
authors: Takehito
authors: T
authors: Kinoshita
authors: Keiichiro
authors: K
authors: Ueno
authors: Yuko
authors: Y
authors: Ohashi
authors: Ichiro
authors: I
authors: Mitsuhara
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D019175:DNA Methylation; D004742:Enhancer Elements, Genetic; D018628:Gene Dosage; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D056726:Genetic Association Studies; D010641:Phenotype; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D018626:Retroelements; D014026:Nicotiana / Q000235:genetics; D014158:Transcription, Genetic; D019076:Transgenes
chemical_list: D018626:Retroelements
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