title: Control of DEMETER DNA demethylase gene transcription in male and female gamete companion cells inArabidopsis thaliana.
abstract: The DEMETER (DME) DNA glycosylase initiates active DNA demethylation via the base-excision repair pathway and is vital for reproduction inArabidopsis thalianaDME-mediated DNA demethylation is preferentially targeted to small, AT-rich, and nucleosome-depleted euchromatic transposable elements, influencing expression of adjacent genes and leading to imprinting in the endosperm. In the female gametophyte,DMEexpression and subsequent genome-wide DNA demethylation are confined to the companion cell of the egg, the central cell. Here, we show that, in the male gametophyte,DMEexpression is limited to the companion cell of sperm, the vegetative cell, and to a narrow window of time: immediately after separation of the companion cell lineage from the germline. We define transcriptional regulatory elements ofDMEusing reporter genes, showing that a small region, which surprisingly lies within theDMEgene, controls its expression in male and female companion cells.DMEexpression from this minimal promoter is sufficient to rescue seed abortion and the aberrant DNA methylome associated with the nulldme-2mutation. Within this minimal promoter, we found short, conserved enhancer sequences necessary for the transcriptional activities ofDMEand combined predicted binding motifs with published transcription factor binding coordinates to produce a list of candidate upstream pathway members in the genetic circuitry controlling DNA demethylation in gamete companion cells. These data show how DNA demethylation is regulated to facilitate endosperm gene imprinting and potential transgenerational epigenetic regulation, without subjecting the germline to potentially deleterious transposable element demethylation.
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea.
authors.forename: Jin-Sup
authors.initials: JS
authors.lastname: Park
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Frost
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea.
authors.forename: Kyunghyuk
authors.initials: K
authors.lastname: Park
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea.
authors.forename: Hyonhwa
authors.initials: H
authors.lastname: Ohr
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea.
authors.forename: Guen Tae
authors.initials: GT
authors.lastname: Park
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea.
authors.forename: Seohyun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea.
authors.forename: Hyunjoo
authors.initials: H
authors.lastname: Eom
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea.
authors.forename: Ilha
authors.initials: I
authors.lastname: Lee
authors.affiliation: Department of Science, Seoul Foreign School, Seoul 120-823, Korea.
authors.forename: Janie S
authors.initials: JS
authors.lastname: Brooks
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720; rfischer@berkeley.edu yhc@snu.ac.kr.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Fischer
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea; rfischer@berkeley.edu yhc@snu.ac.kr.|Plant Genomics and Breeding Institute, Seoul 151-921, Korea.
authors.forename: Yeonhee
authors.initials: Y
authors.lastname: Choi
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D045647:DNA Glycosylases; D019175:DNA Methylation / Q000235:genetics*; D004251:DNA Transposable Elements; D056625:Endosperm / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D018392:Genomic Imprinting; D005854:Germ Cells; D009154:Mutation; D009699:N-Glycosyl Hydrolases / Q000235:genetics*; D056771:Ovule / Q000235:genetics*; D011058:Pollen / Q000235:genetics*; D011401:Promoter Regions, Genetic; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D004251:DNA Transposable Elements; D015534:Trans-Activators; C463261:DEMETER protein, Arabidopsis; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases
keywords: DNA demethylation; DNA enhancer elements; cell-specific transcription; central cell; vegetative cell