Targets of TGF- Signaling in Caenorhabditis elegans Dauer Formation

Authors: Inoue T.; Thomas J.H.

Source: Developmental Biology, Volume 217, Number 1, January 2000 , pp. 192-204(13)

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Abstract:

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. Copyright 2000 Academic Press.

Keywords: C. elegans; TGF- beta ; Smad; dauer; mosaic analysis

Language: English

Document Type: Research article

Affiliations: Department of Genetics, University of Washington, Seattle, Washington, 98195

Publication date: 2000-01-01