GFRalpha-mediated Localization of RET to Lipid Rafts is Required for Effective Downstream Signaling, Differentiation, and Neuronal Survival

The GDNF family ligands (GFLs: GDNF, neurturin, persephin, and artemin) signal through RET and a gly-cosyl-phosphatidylinositol (GPI)-anchored coreceptor (GFRalpha1-alpha4) that binds ligand with high affinity and provides specificity. The importance of the GPI anchor is not fully understood; however, GPI-linked proteins cluster into lipid rafts, structures that may represent highly specialized signaling organelles. Here, we report that GPI-anchored GFRalpha1 recruits RET to lipid rafts after GDNF stimulation and results in RET/Src association. Disruption of RET localization using either transmembrane-anchored or soluble GFRalpha1 results in RET phosphorylation, but GDNF-induced intracellular signaling events are markedly attenuated as are neuronal differentiation and survival responses. Therefore, proper membrane localization of RET via interaction with a raft-localized, GPI-linked coreceptor is of fundamental importance in GFL signaling.