Antagonistic Smad transcription factors control the dauer/non-dauer switch in C. elegans

Donha Park, Annette Estevez, Donald L. Riddle

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


The C. elegans daf-8 gene encodes an R-Smad that is expressed in a subset of head neurons, the intestine, gonadal distal tip cells and the excretory cell. We found that DAF-8, which inhibits the DAF-3 Co-Smad, is associated with DAF-3 and the DAF-14 Smad in vivo and in vitro. Overexpression of daf-8 conferred a dauer-defective phenotype and suppressed constitutive dauer formation in daf-8 and daf-14 mutants. In contrast to mammalian systems described thus far, active DAF-3 drives a feedback regulatory loop that represses transcription of daf-7 (a TGF. ligand) and daf-8 by directly binding to their regulatory regions. Hence, DAF-8 and DAF-3 are mutually antagonistic. The feedback repression may reinforce the developmental switch by allowing DAF-3 to freely activate dauer transcription in target tissues, unless sufficiently inhibited by DAF-8 and DAF-14. In the adult, DAF-8 downregulates lag-2 expression in the distal tip cells, thus promoting germ line meiosis. This function does not involve DAF-3, thereby avoiding the feedback loop that functions in the dauer switch.

Original languageEnglish
Pages (from-to)477-485
Number of pages9
Issue number3
Publication statusPublished - 2010 Feb 1

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Developmental Biology


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