Division of Biology, University of California at San Diego, La Jolla, CA 92093-0349, USA; Department of Biology, Colgate University, Hamilton, NY 13323, USA.
Division of Biology, University of California at San Diego, La Jolla, CA 92093-0349, USA.
Dev Biol. 2014 Jun 15;390(2):126-35. doi: 10.1016/j.ydbio.2014.03.017. Epub 2014 Mar 31.
MicroRNAs (miRNAs) are small RNAs that post-transcriptionally regulate gene expression in many multicellular organisms. They are encoded in the genome and transcribed into primary (pri-) miRNAs before two processing steps that ultimately produce the mature miRNA. In order to generate the appropriate amount of a particular miRNA in the correct location at the correct time, proper regulation of miRNA biogenesis is essential. Here we identify the Period protein homolog LIN-42 as a new regulator of miRNA biogenesis in Caenorhabditis elegans. We mapped a spontaneous suppressor of the normally lethal let-7(n2853) allele to the lin-42 gene. Mutations in this allele (ap201) or a second lin-42 allele (n1089) caused increased mature let-7 miRNA levels at most time points when mature let-7 miRNA is normally expressed. Levels of pri-let-7 and a let-7 transcriptional reporter were also increased in lin-42(n1089) worms. These results indicate that LIN-42 normally represses pri-let-7 transcription and thus the accumulation of let-7 miRNA. This inhibition is not specific to let-7, as pri- and mature levels of lin-4 and miR-35 were also increased in lin-42 mutants. Furthermore, small RNA-seq analysis showed widespread increases in the levels of mature miRNAs in lin-42 mutants. Thus, we propose that the period protein homolog LIN-42 is a global regulator of miRNA biogenesis.
微小 RNA（miRNAs）是一类在后转录水平调控多种真核生物基因表达的小 RNA。它们编码在基因组中，在经过两个加工步骤后转录为初级（pri-）miRNAs，最终产生成熟的 miRNA。为了在正确的时间和正确的位置产生特定 miRNA 的适当数量，miRNA 生物发生的适当调节是必不可少的。在这里，我们鉴定出 Period 蛋白同源物 LIN-42 是秀丽隐杆线虫 miRNA 生物发生的新调节剂。我们将一个正常致死 let-7(n2853)等位基因的自发抑制因子映射到 lin-42 基因上。该等位基因（ap201）或第二个 lin-42 等位基因（n1089）的突变导致在正常表达成熟 let-7 miRNA 的大多数时间点上，成熟 let-7 miRNA 的水平增加。lin-42(n1089)蠕虫中 pri-let-7 和 let-7 转录报告基因的水平也增加了。这些结果表明 LIN-42 通常抑制 pri-let-7 转录，从而抑制 let-7 miRNA 的积累。这种抑制不是特异性的，因为 lin-4 和 miR-35 的 pri- 和成熟水平在 lin-42 突变体中也增加了。此外，小 RNA-seq 分析显示 lin-42 突变体中成熟 miRNA 的水平普遍增加。因此，我们提出 Period 蛋白同源物 LIN-42 是 miRNA 生物发生的全局调节剂。
