The C. elegans G-protein-coupled receptor SRA-13 inhibits RAS/MAPK signalling during olfaction and vulval development.
In C. elegans, the RAS/MAPK pathway is used in different tissues to regulate various cell fate decisions. Several positive and negative regulators tightly control the activity of the RAS/MAPK pathway at different steps. We demonstrate a link between a G-protein-coupled receptor signalling pathway and the RAS/MAPK cascade. SRA-13, a member of the SRA family of chemosensory receptors, negatively regulates RAS/MAPK signalling during vulval induction and the olfaction of volatile attractants. Epistasis analysis indicates that SRA-13 inhibits the RAS/MAPK pathway at the level or upstream of MAPK. In both tissues, the vulval precursor cells and the chemosensory neurones, SRA-13 acts through the GPA-5 Galpha protein subunit, suggesting a common mechanism of crosstalk. Moreover, we find that vulval induction is repressed by food withdrawal during larval development and that SRA-13 activity is required for the suppression of vulval induction in response to food starvation. Thus, SRA-13 may serve to adapt the activity of the RAS/MAPK pathway to environmental conditions.
Zoologisches Institut, Universitaet Zurich, Winterthurerstrasse 190, CH 8057, Zurich, Switzerland.
Gopal
G
Battu
Erika Froehli
EF
Hoier
Alex
A
Hajnal
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology / Q000378:metabolism*; D004627:Embryonic Induction / Q000502:physiology; D005260:Female; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D009474:Neurons / Q000502:physiology; D010802:Phylogeny; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D012903:Smell / Q000502:physiology*; D014844:Vulva / Q000196:embryology* / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
D011956:Receptors, Cell Surface; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins