EphrinB-EphB signalling regulates clathrin-mediated endocytosis through tyrosine phosphorylation of synaptojanin 1.
Recent studies show that Eph receptors act mainly through the regulation of actin reorganization. Here, we show a novel mode of action for EphB receptors. We identify synaptojanin 1 - a phosphatidylinositol 5'-phosphatase that is involved in clathrin-mediated endocytosis - as a physiological substrate for EphB2. EphB2 causes tyrosine phosphorylation in the proline-rich domain of synaptojanin 1, and inhibits both the interaction with endophilin and the 5'-phosphatase activity of synaptojanin 1. Treatment with the EphB ligand, ephrinB2, elevates the cellular level of phosphatidylinositol 4,5-bisphosphate and promotes transferrin uptake. A kinase inactive mutant of EphB2 and a phosphorylation site mutant of synaptojanin 1 both neutralize the increase of transferrin uptake after ephrinB2 treatment. These mutants also inhibit AMPA glutamate receptor endocytosis in hippocampal neurons. Interestingly, incorporated transferrin does not reach endosomes, suggesting dual effects of EphB signalling on the early and late phases of clathrin-mediated endocytosis. Our results indicate that ephrinB-EphB signalling regulates clathrin-mediated endocytosis in various cellular contexts by influencing protein interactions and phosphoinositide turnover through tyrosine phosphorylation of synaptojanin 1.
Irie
Fumitoshi
F
Developmental Neurobiology Program, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA. firie@burnham.org
Okuno
Misako
M
Pasquale
Elena B
EB
Yamaguchi
Yu
Y
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D002966:Clathrin / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D036388:Ephrin-B2 / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009154:Mutation; D016202:N-Methylaspartate / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D019000:Phosphotyrosine / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D036183:Receptor, EphB2 / Q000235:genetics / Q000378:metabolism*; D018091:Receptors, AMPA / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D014168:Transferrin / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D002966:Clathrin; D036388:Ephrin-B2; D009419:Nerve Tissue Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D018091:Receptors, AMPA; C107640:SH3GL2 protein, human; C498434:Sh3gl2 protein, mouse; D014168:Transferrin; D019000:Phosphotyrosine; D016202:N-Methylaspartate; D036183:Receptor, EphB2; C097702:synaptojanin; D010744:Phosphoric Monoester Hydrolases