Regulation of rnt-1 expression mediated by the opposing effects of BRO-1 and DBL-1 in the nematode Caenorhabditis elegans.
During development of Caenorhabditis elegans, expression of the RUNX homolog, rnt-1, is tightly regulated both spatially and temporally. In this study, we investigated the mechanism underlying the temporal regulation of rnt-1. We found that rnt-1 contained evolutionarily conserved consensus RUNX binding sequences within one of its introns, and that RNT-1 bound to these intronic sequences both in vitro and in vivo in the presence of BRO-1, suggesting that RNT-1 together with BRO-1 represses its own transcription. Fine deletion and substitution experiments revealed a binding site within the intron that was critical for rnt-1 regulation. Importantly, we found that the TGFbeta homolog, DBL-1, was required for counteracting the repressive activity of BRO-1 at postembryonic stages. Accordingly, ectopic expression of DBL-1 induced transcription of rnt-1 in the lateral hypodermis and other tissues even at the postembryonic stages. Taken together, our data suggest that rnt-1 expression is regulated by the balance between DBL-1-mediated activation and BRO-1-mediated repression at the postembryonic stages.
Shim
Jiwon
J
Research Center for Cellulomics, Institute of Molecular Biology and Genetics, School of Biological Sciences, Seoul National University, 56-1 Gwanak-gu, Shillim-dong, Seoul 151-742, Republic of Korea.
Lee
Junho
J
D000818:Animals; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D040521:Subcutaneous Tissue / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*
C525389:BRO-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; C117509:Dbl-1 protein, C elegans; D009479:Neuropeptides; C493287:RNT-1 protein, C elegans; D012097:Repressor Proteins; D014157:Transcription Factors; D016212:Transforming Growth Factor beta