title: An antisense RNA-mediated mechanism eliminates a meiosis-specific copper-regulated transcript in mitotic cells.
abstract: Sense and antisense transcripts produced from convergent gene pairs could interfere with the expression of either partner gene. In Schizosaccharomyces pombe, we found that the iss1(+) gene produces two transcript isoforms, including a long antisense mRNA that is complementary to the meiotic cum1(+) sense transcript, inhibiting cum1(+) expression in vegetative cells. Inhibition of cum1(+) transcription was not at the level of its initiation because fusion of the cum1(+) promoter to the lacZ gene showed that activation of the reporter gene occurs in response to low copper conditions. Further analysis showed that the transcription factor Cuf1 and conserved copper-signaling elements (CuSEs) are required for induction of cum1(+)-lacZ transcription under copper deficiency. Insertion of a multipartite polyadenylation signal immediately downstream of iss1(+) led to the exclusive production of a shorter iss1(+) mRNA isoform, thereby allowing accumulation of cum1(+) sense mRNA in copper-limited vegetative cells. This finding suggested that the long iss1(+) antisense mRNA could pair with cum1(+) sense mRNA, thereby producing double-stranded RNA molecules that could induce RNAi. We consistently found that mutant strains for RNAi (dcr1Δ, ago1Δ, rdp1Δ, and clr4Δ) are defective in selectively eliminating cum1(+) sense transcript in the G1 phase of the cell cycle. Taken together, these results describe the first example of a copper-regulated meiotic gene repressed by an antisense transcription mechanism in vegetative cells.
authors.affiliation: From the Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada.
authors.forename: Vincent
authors.initials: V
authors.lastname: Normant
authors.affiliation: From the Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada.
authors.forename: Jude
authors.initials: J
authors.lastname: Beaudoin
authors.affiliation: From the Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada Simon.Labbe@USherbrooke.ca.
authors.forename: Simon
authors.initials: S
authors.lastname: Labbé
mesh_terms: D016193:G1 Phase / Q000502:physiology; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D008540:Meiosis / Q000502:physiology*; D008938:Mitosis / Q000502:physiology*; D016372:RNA, Antisense / Q000096:biosynthesis* / Q000235:genetics; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C474030:Cuf1 protein, S pombe; D016372:RNA, Antisense; D012331:RNA, Fungal; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors
keywords: RNA interference (RNAi); antisense RNA; copper; meiosis; mitosis; yeast