Normant V, Beaudoin J, Labbé S. An antisense RNA-mediated mechanism eliminates a meiosis-specific copper-regulated transcript in mitotic cells.
J Biol Chem 2015;
290:22622-37. [PMID:
26229103 DOI:
10.1074/jbc.m115.674556]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Indexed: 11/06/2022] Open
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.
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