Dual regulation of the lin-14 target mRNA by the lin-4 miRNA.
microRNAs (miRNAs) are ∼22 nt regulatory RNAs that in animals typically bind with partial complementarity to sequences in the 3' untranslated (UTR) regions of target mRNAs, to induce a decrease in the production of the encoded protein. The relative contributions of translational inhibition of intact mRNAs and degradation of mRNAs caused by binding of the miRNA vary; for many genetically validated miRNA targets, translational repression has been implicated, whereas some analyses of other miRNA targets have revealed only modest translational repression and more significant mRNA destabilization. In Caenorhabditis elegans, the lin-4 miRNA accumulates during early larval development, binds to target elements in the lin-14 mRNA, and causes a sharp decrease in the abundance of LIN-14 protein. Here, we monitor the dynamics of lin-14 mRNA and protein as well as lin-4 miRNA levels in finely staged animals during early larval development. We find complex regulation of lin-14, with the abundance of lin-14 mRNA initially modestly declining followed by fluctuation but little further decline of lin-14 mRNA levels accompanied by continuing and more dramatic decline in LIN-14 protein abundance. We show that the translational inhibition of lin-14 is dependent on binding of the lin-4 miRNA to multiple lin-4 complementary sites in the lin-14 3'UTR. Our results point to the importance of translational inhibition in silencing of lin-14 by the lin-4 miRNA.
Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America ; Biological Sciences in Dental Medicine Program, Harvard Medical School, Boston, Massachusetts, United States of America.
Zhen
Z
Shi
Gabriel
G
Hayes
Gary
G
Ruvkun
D020413:3' Untranslated Regions / Q000502:physiology*; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000096:biosynthesis* / Q000235:genetics; D020868:Gene Silencing / Q000502:physiology*; D007814:Larva; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D014176:Protein Biosynthesis / Q000502:physiology; D020871:RNA Stability / Q000502:physiology; D018510:RNA, Helminth / Q000235:genetics / Q000378:metabolism*
D020413:3' Untranslated Regions; D029742:Caenorhabditis elegans Proteins; C102669:LIN-14 protein, C elegans; D035683:MicroRNAs; D009687:Nuclear Proteins; D018510:RNA, Helminth; C452194:lin-4 microRNA, C elegans