FGF signaling functions in the hypodermis to regulate fluid balance in C. elegans.
Signaling by the Caenorhabditis elegans fibroblast growth factor receptor EGL-15 is activated by LET-756, a fibroblast growth factor, and attenuated by CLR-1, a receptor tyrosine phosphatase. Hyperactive EGL-15 signaling results in a dramatic Clr phenotype characterized by the accumulation of clear fluid within the pseudocoelomic space, suggesting that regulated EGL-15 signaling is essential for fluid homeostasis in C. elegans. To determine the cellular focus of EGL-15 signaling, we identified an enhancer element (e15) within the egl-15 promoter, which is both necessary for the promoter activity and sufficient when duplicated to drive either egl-15 or clr-1 rescue activity. This enhancer drives GFP expression in hypodermal cells. Consistent with this finding, immunofluorescence studies of EGL-15 indicate that EGL-15 is expressed in hypodermal cells, and hypodermal promoters can drive full clr-1 and egl-15 rescue activity. Moreover, a mosaic analysis of mpk-1, which acts downstream of egl-15, suggests that its suppression of Clr (Soc) function is required in the hypodermis. These results suggest that EGL-15 and CLR-1 act in the hypodermis to regulate fluid homeostasis in worms.
Huang
Peng
P
Yale University School of Medicine, Department of Genetics, I-354 SHM, PO Box 208005, New Haven, CT 06520-8005, USA.
Stern
Michael J
MJ
D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1; D009030:Mosaicism; D009928:Organ Specificity; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D054557:Receptor-Like Protein Tyrosine Phosphatases; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D040521:Subcutaneous Tissue / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000502:physiology*
D029742:Caenorhabditis elegans Proteins; C112493:EGL-15 protein, C elegans; C402375:Let-756 protein, C elegans; D008164:Luminescent Proteins; D017468:Receptors, Fibroblast Growth Factor; D049452:Green Fluorescent Proteins; D005346:Fibroblast Growth Factors; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; C085697:mpk-1 protein, C elegans; C112492:CLR-1 protein, C elegans; D017027:Protein Tyrosine Phosphatases; D054557:Receptor-Like Protein Tyrosine Phosphatases