Caenorhabditis elegans SDF-9 enhances insulin/insulin-like signaling through interaction with DAF-2

Abstract

SDF-9 is a modulator of Caenorhabditis elegans insulin/IGF-1 signaling that may interact directly with the DAF-2 receptor. SDF-9 is a tyrosine phosphatase-like protein that, when mutated, enhances many partial loss-of-function mutants in the dauer pathway except for the temperature-sensitive mutant daf-2(m41). We propose that SDF-9 stabilizes the active phosphorylated state of DAF-2 or acts as an adaptor protein to enhance insulin-like signaling.

Figure 1.—

Response of sdf-9(m708) to dauer pheromone. The pheromone extract and plates were made as previously described (Golden and Riddle 1984b) and used in the amounts given. (A and B) Each data point ± standard error represents results from two or three plates, each started with ∼40 eggs laid in situ by three gravid adults, which were subsequently removed. Plates were scored for dauer formation on the first day of adulthood. At 25.5°, sdf-9(m708) showed increased sensitivity to pheromone for repeated experiments even when compared to unc-31(e928), previously reported to be sensitive to pheromone at 25.4° (Ailion and Thomas 2000). (C) Using the same method, hypersensitivity to pheromone was also observed at 20°.