Targets of TGF-beta signaling in Caenorhabditis elegans dauer formation

Dev Biol. 2000 Jan 1;217(1):192-204. doi: 10.1006/dbio.1999.9545.


Caenorhabditis elegans dauer formation is controlled by multiple environmental factors. The chemosensory neuron ASI regulates dauer formation by secretion of DAF-7/TGF-beta, but the molecular targets of the DAF-7 ligand are incompletely defined and the cellular targets are unknown. We genetically characterized and cloned a putative transducer of DAF-7 signaling called daf-14 and found that it encodes a Smad protein. DAF-14 Smad has a highly unusual structure completely lacking the N-terminal domain found in all other Smad proteins known to date. daf-14 genetically interacts with daf-8, which encodes another Smad, and the interaction suggests partial functional redundancy between these two Smad proteins. We also studied the cellular targets of DAF-7 signaling by studying the sites of action of daf-14 and daf-4, the putative receptor for DAF-7. daf-14::gfp is expressed in multiple tissues that are remodeled during dauer formation. However, analysis of mosaics generated by free duplication loss and tissue-specific expression constructs indicate cell-nonautonomous function of daf-4, arguing against direct DAF-7 signaling to tissues throughout the animal. Instead, these experiments suggest the nervous system as a target of DAF-7 signaling and that the nervous system in turn regulates dauer formation by other tissues.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Animals
  • Animals, Genetically Modified
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins*
  • Cloning, Molecular
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics*
  • Green Fluorescent Proteins
  • Luminescent Proteins / genetics
  • Molecular Sequence Data
  • Mosaicism
  • Promoter Regions, Genetic
  • Recombinant Fusion Proteins / genetics
  • Signal Transduction*
  • Smad Proteins
  • Trans-Activators / chemistry
  • Trans-Activators / genetics*
  • Transforming Growth Factor beta / metabolism*


  • Caenorhabditis elegans Proteins
  • DAF-14 protein, C elegans
  • DNA-Binding Proteins
  • Luminescent Proteins
  • Recombinant Fusion Proteins
  • Smad Proteins
  • Trans-Activators
  • Transforming Growth Factor beta
  • Green Fluorescent Proteins