title: MOM1 and Pol-IV/V interactions regulate the intensity and specificity of transcriptional gene silencing.
abstract: It is commonly observed that onset or release of transcriptional gene silencing (TGS) correlates with alteration of repressive epigenetic marks. The TGS regulator MOM1 in Arabidopsis is exceptional since it regulates transcription in intermediate heterochromatin with only minor changes in epigenetic marks. We have isolated an enhancer of the mom1 mutation that points towards regulatory interplay between MOM1 and RNA polymerase-V (Pol-V). Pol-V transcribes heterochromatic loci, which seems to be required for maintenance of their silencing; however, it is still not clear how Pol-V is targeted to heterochromatin. We now provide evidence that Pol-V is required for MOM1-mediated suppression of transcription at a subset of its chromosomal targets. Thus, Pol-V genetically interacts with MOM1 in the control of gene silencing. Interestingly, functional cooperation of MOM1 and Pol-V not only broadens the range of the controlled loci in comparison to each individual factor, but also determines the degree of TGS.
authors.affiliation: Department of Plant Biology, University of Geneva, Sciences III, Geneva, Switzerland.
authors.forename: Chotika
authors.initials: C
authors.lastname: Yokthongwattana
authors.forename: Etienne
authors.initials: E
authors.lastname: Bucher
authors.forename: Marian
authors.initials: M
authors.lastname: Caikovski
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vaillant
authors.forename: Joël
authors.initials: J
authors.lastname: Nicolet
authors.forename: Ortrun
authors.initials: O
authors.lastname: Mittelsten Scheid
authors.forename: Jerzy
authors.initials: J
authors.lastname: Paszkowski
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D019175:DNA Methylation; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D044127:Epigenesis, Genetic; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000032:analysis; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D014157:Transcription Factors; C499181:RNA polymerase IV, Arabidopsis; C538841:RNA polymerase V, Arabidopsis; D012321:DNA-Directed RNA Polymerases; D000074183:ATPases Associated with Diverse Cellular Activities; C409208:MOM protein, Arabidopsis