Conserved role for 14-3-3epsilon downstream of type I TGFbeta receptors.

Schistosoma mansoni receptor kinase-1 (SmRK1) is a divergent type I transforming growth factor beta (TGFbeta) receptor on the surface of adult parasites. Using the intracellular domain of SmRK1 as bait in a yeast two-hybrid screen we identified an interaction with S. mansoni 14-3-3epsilon. The interaction which is phosphorylation-dependent is not specific to schistosomes since 14-3-3epsilon also binds to TbetaRI, the human type I TGFbeta receptor. 14-3-3epsilon enhances TGFbeta-mediated signaling by TbetaRI and is the first TbetaRI-interacting non-Smad protein identified that positively regulates this receptor. The interaction of 14-3-3epsilon with schistosome and human TbetaRI suggests a conserved, but previously unappreciated, role for this protein in TGFbeta signaling pathways.