title: Multiple mechanisms are involved in regulating the expression of the developmental timing regulator lin-28 in Caenorhabditis elegans.
abstract: The timing of postembryonic developmental programs in Caenorhabditis elegans is regulated by a set of so-called heterochronic genes, including lin-28 that specifies second larval programs. lin-66 mutations described herein cause delays in vulval and seam cell differentiation, indicating a role for lin-66 in timing regulation. A mutation in daf-12/nuclear receptor or alg-1/argonaute dramatically enhances the retarded phenotypes of the lin-66 mutants, and these phenotypes are suppressed by a lin-28 null allele. We further show that the LIN-28 protein level is upregulated in the lin-66 mutants and that this regulation is mediated by the 3'UTR of lin-28. We have also identified a potential daf-12-response element within lin-28 3'UTR and show that two microRNA (miRNA) (lin-4 and let-7)-binding sites mediate redundant inhibitory activities that are likely lin-66-independent. Quantitative PCR data suggest that the lin-28 mRNA level is affected by lin-14 and miRNA regulation, but not by daf-12 and lin-66 regulation. These results suggest that lin-28 expression is regulated by multiple independent mechanisms including LIN-14-mediated upregulation of mRNA level, miRNAs-mediated RNA degradation, LIN-66-mediated translational inhibition and DAF-12-involved translation promotion.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309, USA.
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Morita
authors.forename: Min
authors.initials: M
authors.lastname: Han
mesh_terms: D020413:3' Untranslated Regions / Q000378:metabolism; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D002455:Cell Division; D005260:Female; D018507:Gene Expression Regulation, Developmental; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D035683:MicroRNAs / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D010641:Phenotype; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D013997:Time Factors; D014844:Vulva / Q000196:embryology
chemical_list: D020413:3' Untranslated Regions; D029742:Caenorhabditis elegans Proteins; C410905:DAF-12 protein, C elegans; C105157:Egl-17 protein, C elegans; D036341:Intercellular Signaling Peptides and Proteins; C102669:LIN-14 protein, C elegans; C452195:LIN-28 protein, C elegans; D035683:MicroRNAs; D009687:Nuclear Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D020794:Receptor Protein-Tyrosine Kinases