Regulated disruption of inositol 1,4,5-trisphosphate signaling in Caenorhabditis elegans reveals new functions in feeding and embryogenesis.
Inositol 1,4,5-trisphosphate (IP(3)) is an important second messenger in animal cells and is central to a wide range of cellular responses. The major intracellular activity of IP(3) is to regulate release of Ca(2+) from intracellular stores through IP(3) receptors (IP(3)Rs). We describe a system for the transient disruption of IP(3) signaling in the model organism Caenorhabditis elegans. The IP(3) binding domain of the C. elegans IP(3)R, ITR-1, was expressed from heat shock-induced promoters in live animals. This results in a dominant-negative effect caused by the overexpressed IP(3) binding domain acting as an IP(3) "sponge." Disruption of IP(3) signaling resulted in disrupted defecation, a phenotype predicted by previous genetic studies. This approach also identified two new IP(3)-mediated processes. First, the up-regulation of pharyngeal pumping in response to food is dependent on IP(3) signaling. RNA-mediated interference studies and analysis of itr-1 mutants show that this process is also IP(3)R dependent. Second, the tissue-specific expression of the dominant-negative construct enabled us to circumvent the sterility associated with loss of IP(3) signaling through the IP(3)R and thus determine that IP(3)-mediated signaling is required for multiple steps in embryogenesis, including cytokinesis and gastrulation.
Walker
Denise S
DS
Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom.
Gower
Nicholas J D
NJ
Ly
Sung
S
Bradley
Gemma L
GL
Baylis
Howard A
HA
D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000196:embryology / Q000201:enzymology* / Q000502:physiology*; D002455:Cell Division; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005775:Gastrula; D005799:Genes, Dominant; D006358:Hot Temperature; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010614:Pharynx / Q000196:embryology; D010641:Phenotype; D012313:RNA / Q000378:metabolism; D015398:Signal Transduction
D018076:DNA, Complementary; D012313:RNA; D015544:Inositol 1,4,5-Trisphosphate