title: DNA topoisomerase I affects polycomb group protein-mediated epigenetic regulation and plant development by altering nucleosome distribution in Arabidopsis.
abstract: It has been perplexing that DNA topoisomerases, enzymes that release DNA supercoils, play specific roles in development. In this study, using a floral stem cell model in Arabidopsis thaliana, we uncovered a role for TOPOISOMERASE1α (TOP1α) in Polycomb Group (PcG) protein-mediated histone 3 lysine 27 trimethylation (H3K27me3) at, and transcriptional repression of, the stem cell maintenance gene WUSCHEL (WUS). We demonstrated that H3K27me3 deposition at other PcG targets also requires TOP1α. Intriguingly, the repression of some, as well as the expression of many, PcG target genes requires TOP1α. The mechanism that unifies the opposing effects of TOP1α appears to lie in its role in decreasing nucleosome density, which probably allows the binding of factors that either recruit PcG, as we demonstrated for AGAMOUS at the WUS locus, or counteract PcG-mediated regulation. Although TOP1α reduces nucleosome density at all genes, the lack of a 5' nucleosome-free region is a feature that distinguishes PcG targets from nontargets and may condition the requirement for TOP1α for their expression. This study uncovers a connection between TOP1α and PcG, which explains the specific developmental functions of TOP1α.
authors: Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, California 92521 Key Laboratory of Agricultural Water Resource, Hebei Laboratory of Agricultural Water-Saving, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China.
authors: Xigang
authors: X
authors: Liu
authors: Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, California 92521.
authors: Lei
authors: http://orcid.org/0000-0002-6488-0292
authors: L
authors: Gao
authors: Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, California 92521.
authors: Thanh Theresa
authors: TT
authors: Dinh
authors: Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, California 92521 College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
authors: Ting
authors: T
authors: Shi
authors: Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, California 92521 Key Laboratory of Agricultural Water Resource, Hebei Laboratory of Agricultural Water-Saving, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China.
authors: Dongming
authors: D
authors: Li
authors: Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, California 92521 College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China.
authors: Ruozhong
authors: R
authors: Wang
authors: Key Laboratory of Agricultural Water Resource, Hebei Laboratory of Agricultural Water-Saving, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China.
authors: Lin
authors: L
authors: Guo
authors: College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China.
authors: Langtao
authors: L
authors: Xiao
authors: Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, California 92521 Howard Hughes Medical Institute, University of California, Riverside, California 92521 xuemei.chen@ucr.edu.
authors: Xuemei
authors: X
authors: Chen
mesh_terms: D026342:AGAMOUS Protein, Arabidopsis / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D044127:Epigenesis, Genetic; D035264:Flowers / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant / Q000235:genetics*; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D009154:Mutation; D009707:Nucleosomes / Q000378:metabolism*; D018520:Plant Shoots / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D063146:Polycomb-Group Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D026342:AGAMOUS Protein, Arabidopsis; D029681:Arabidopsis Proteins; D006657:Histones; D018398:Homeodomain Proteins; D009707:Nucleosomes; D063146:Polycomb-Group Proteins; C116421:WUSCHEL protein, Arabidopsis; D004264:DNA Topoisomerases, Type I; C469258:TOP1alpha protein, Arabidopsis