The homeoproteins MAB-18 and CEH-14 insulate the dauer collagen gene col-43 from activation by the adjacent promoter of the Spermatheca gene sth-1 in Caenorhabditis elegans.
Genome searches in this study indicate that the nematode Caenorhabditis elegans genome has 2582 bidirectionally oriented genes that account for more than 25% of the total genes. We analyze the transcriptional repression system for one of these predicted bidirectional promoters, which controls the expression of the spermathecal gene sth-1 and collagen gene col-43. These two genes are separated by 1.3 kb and are transcribed bidirectionally. sth-1 is expressed in spermatheca after the L4 stage and col-43 is expressed in the hypodermal cells of the L2d dauer stage. The upstream regions required for the expression of sth-1 and col-43 shared an overlapped control sequence. Two homeoproteins, MAB-18 and CEH-14, were isolated by yeast one-hybrid screening as binding proteins of the overlapped region. MAB-18 bound to two homeodomain-binding sites and interacted with CEH-14 to repress col-43 expression in spermatheca. These results indicate that the two homeoproteins interact with each other to repress col-43 expression in sth-1-expressing tissues. This is the first report of bidirectional gene regulation analysis in the C.elegans genome.
Bando
Tetsuya
T
Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushima Naka, Okayama City, 700-8530 Japan.
Ikeda
Tatsuji
T
Kagawa
Hiroaki
H
D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D003094:Collagen / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D060850:LIM-Homeodomain Proteins; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
C407044:CEH-14 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; D014157:Transcription Factors; C095405:vab-3 protein, C elegans; D003094:Collagen