title: A conserved ncRNA-binding protein recruits silencing factors to heterochromatin through an RNAi-independent mechanism.
abstract: Long noncoding RNAs (lncRNAs) can trigger repressive chromatin, but how they recruit silencing factors remains unclear. In Schizosaccharomyces pombe, heterochromatin assembly on transcribed noncoding pericentromeric repeats requires both RNAi and RNAi-independent mechanisms. In Saccharomyces cerevisiae, which lacks a repressive chromatin mark (H3K9me [methylated Lys9 on histone H3]), unstable ncRNAs are recognized by the RNA-binding protein Nrd1. We show that the S. pombe ortholog Seb1 is associated with pericentromeric lncRNAs. Individual mutation of dcr1+ (Dicer) or seb1+ results in equivalent partial reductions of pericentromeric H3K9me levels, but a double mutation eliminates this mark. Seb1 functions independently of RNAi by recruiting the NuRD (nucleosome remodeling and deacetylase)-related chromatin-modifying complex SHREC (Snf2-HDAC [histone deacetylase] repressor complex).
authors.affiliation: Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA.
authors.forename: Diana B
authors.initials: DB
authors.lastname: Marina
authors.forename: Smita
authors.initials: S
authors.lastname: Shankar
authors.forename: Prashanthi
authors.initials: P
authors.lastname: Natarajan
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Finn
authors.forename: Hiten D
authors.initials: HD
authors.lastname: Madhani
mesh_terms: D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing / Q000502:physiology*; D006570:Heterochromatin / Q000378:metabolism*; D034622:RNA Interference; D062085:RNA, Long Noncoding / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D006570:Heterochromatin; D062085:RNA, Long Noncoding; D012097:Repressor Proteins; D012261:Ribonucleoproteins; D029702:Schizosaccharomyces pombe Proteins; D033921:Vesicular Transport Proteins; C491210:nrd1 protein, S pombe
keywords: Nrd1; RNAi; SHREC; Seb1; heterochromatin; silencing