The Caenorhabditis elegans heterochronic regulator LIN-14 is a novel transcription factor that controls the developmental timing of transcription from the insulin/insulin-like growth factor gene ins-33 by direct DNA binding.
A temporal gradient of the novel nuclear protein LIN-14 specifies the timing and sequence of stage-specific developmental events in Caenorhabditis elegans. The profound effects of lin-14 mutations on worm development suggest that LIN-14 directly or indirectly regulates stage-specific gene expression. We show that LIN-14 can associate with chromatin in vivo and has in vitro DNA binding activity. A bacterially expressed C-terminal domain of LIN-14 was used to select DNA sequences that contain a putative consensus binding site from a pool of randomized double-stranded oligonucleotides. To identify candidates for genes directly regulated by lin-14, we employed DNA microarray hybridization to compare the mRNA abundance of C. elegans genes in wild-type animals to that in mutants with reduced or elevated lin-14 activity. Five of the candidate LIN-14 target genes identified by microarrays, including the insulin/insulin-like growth factor family gene ins-33, contain putative LIN-14 consensus sites in their upstream DNA sequences. Genetic analysis indicates that the developmental regulation of ins-33 mRNA involves the stage-specific repression of ins-33 transcription by LIN-14 via sequence-specific DNA binding. These results reinforce the conclusion that lin-14 encodes a novel class of transcription factor.
Hristova
Marta
M
Dartmouth Medical School, Department of Genetics, Hanover, NH 03755, USA.
Birse
Darcy
D
Hong
Yang
Y
Ambros
Victor
V
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D016207:Cytokines / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D050436:Regulatory Elements, Transcriptional / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D029742:Caenorhabditis elegans Proteins; D002843:Chromatin; D016207:Cytokines; C507325:Ins-33 protein, C elegans; C102669:LIN-14 protein, C elegans; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D004247:DNA