title: Global effects on gene expression in fission yeast by silencing and RNA interference machineries.
abstract: Histone modifications influence gene expression in complex ways. The RNA interference (RNAi) machinery can repress transcription by recruiting histone-modifying enzymes to chromatin, although it is not clear whether this is a general mechanism for gene silencing or whether it requires repeated sequences such as long terminal repeats (LTRs). We analyzed the global effects of the Clr3 and Clr6 histone deacetylases, the Clr4 methyltransferase, the zinc finger protein Clr1, and the RNAi proteins Dicer, RdRP, and Argonaute on the transcriptome of Schizosaccharomyces pombe (fission yeast). The clr mutants derepressed similar subsets of genes, many of which also became transcriptionally activated in cells that were exposed to environmental stresses such as nitrogen starvation. Many genes that were repressed by the Clr proteins clustered in extended regions close to the telomeres. Surprisingly few genes were repressed by both the silencing and RNAi machineries, with transcripts from centromeric repeats and Tf2 retrotransposons being notable exceptions. We found no correlation between repression by RNAi and proximity to LTRs, and the wtf family of repeated sequences seems to be repressed by histone deacetylation independent of RNAi. Our data indicate that the RNAi and Clr proteins show only a limited functional overlap and that the Clr proteins play more global roles in gene silencing.
authors.affiliation: Department of Genetics, Institute of Molecular Biology, University of Copenhagen, Øster Farimagsgade 2A, Copenhagen 1353 K, Denmark.
authors.forename: Klavs R
authors.initials: KR
authors.lastname: Hansen
authors.forename: Gavin
authors.initials: G
authors.lastname: Burns
authors.forename: Juan
authors.initials: J
authors.lastname: Mata
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Volpe
authors.forename: Robert A
authors.initials: RA
authors.lastname: Martienssen
authors.forename: Jürg
authors.initials: J
authors.lastname: Bähler
authors.forename: Geneviève
authors.initials: G
authors.lastname: Thon
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D015825:Chromosomes, Fungal; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D034622:RNA Interference; D018626:Retroelements; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism; D013223:Statistics as Topic; D020079:Terminal Repeat Sequences; D014158:Transcription, Genetic
chemical_list: D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D018626:Retroelements; D029702:Schizosaccharomyces pombe Proteins; D043244:Ribonuclease III; D006655:Histone Deacetylases