Splicing Factor Spf30 Assists Exosome-Mediated Gene Silencing in Fission Yeast
Splicing Factor Spf30 Assists Exosome-Mediated Gene Silencing in Fission Yeast
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DOI：
10.1128/mcb.01317-09
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发表时间：
2010-03-01
影响因子：
5.3
通讯作者：
Javerzat, Jean-Paul
中科院分区：
文献类型：
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作者：
Bernard, Pascal;Drogat, Julie;Javerzat, Jean-Paul
裂殖酵母中的异染色质组装依赖于通过RNA干扰和外泌体降解途径对同源非编码RNA的加工。最近的证据表明，剪接因子促进了着丝粒转录物共转录加工成小干扰RNA（siRNA）。相比之下，外泌体如何有助于异染色质组装以及它是否也依赖于剪接因子是未知的。我们在这里提供的证据表明，裂殖酵母Spf 30是一个剪接因子参与外泌体途径的异染色质沉默。Spf 30和Dis 3是主要的外泌体RNA酶，共定位于着丝粒异染色质和常染色质基因。在着丝粒，Dis 3有助于招募Spf 30，其缺陷表型模仿dis 3 -54突变体：异染色质受损，如沉默减少和聚腺苷酸化的着丝粒转录物的积累所证明的，但siRNA的产生似乎不受影响。与直接作用一致，Spf 30结合着丝粒转录本并以RNA依赖的方式定位于着丝粒。我们建议，Spf 30，结合到新生的着丝粒转录，也许与其他剪接因子，协助他们的加工外泌体。因此剪接因子的干预可能是基因沉默途径的一个共同特征。
Heterochromatin assembly in fission yeast relies on the processing of cognate noncoding RNAs by both the RNA interference and the exosome degradation pathways. Recent evidence indicates that splicing factors facilitate the cotranscriptional processing of centromeric transcripts into small interfering RNAs (siRNAs). In contrast, how the exosome contributes to heterochromatin assembly and whether it also relies upon splicing factors were unknown. We provide here evidence that fission yeast Spf30 is a splicing factor involved in the exosome pathway of heterochromatin silencing. Spf30 and Dis3, the main exosome RNase, colocalize at centromeric heterochromatin and euchromatic genes. At the centromeres, Dis3 helps recruiting Spf30, whose deficiency phenocopies the dis3-54 mutant: heterochromatin is impaired, as evidenced by reduced silencing and the accumulation of polyadenylated centromeric transcripts, but the production of siRNAs appears to be unaffected. Consistent with a direct role, Spf30 binds centromeric transcripts and locates at the centromeres in an RNA-dependent manner. We propose that Spf30, bound to nascent centromeric transcripts, perhaps with other splicing factors, assists their processing by the exosome. Splicing factor intercession may thus be a common feature of gene silencing pathways.