Tiam-Rac signaling mediates trans-endocytosis of ephrin receptor EphB2 and is important for cell repulsion.
Ephrin receptors interact with membrane-bound ephrin ligands to regulate contact-mediated attraction or repulsion between opposing cells, thereby influencing tissue morphogenesis. Cell repulsion requires bidirectional trans-endocytosis of clustered Eph-ephrin complexes at cell interfaces, but the mechanisms underlying this process are poorly understood. Here, we identified an actin-regulating pathway allowing ephrinB(+) cells to trans-endocytose EphB receptors from opposing cells. Live imaging revealed Rac-dependent F-actin enrichment at sites of EphB2 internalization, but not during vesicle trafficking. Systematic depletion of Rho family GTPases and their regulatory proteins identified the Rac subfamily and the Rac-specific guanine nucleotide exchange factor Tiam2 as key components of EphB2 trans-endocytosis, a pathway previously implicated in Eph forward signaling, in which ephrins act as in trans ligands of Eph receptors. However, unlike in Eph signaling, this pathway is not required for uptake of soluble ligands in ephrinB(+) cells. We also show that this pathway is required for EphB2-stimulated contact repulsion. These results support the existence of a conserved pathway for EphB trans-endocytosis that removes the physical tether between cells, thereby enabling cell repulsion.
Department of Molecules-Signaling-Development, Max Planck Institute of Neurobiology, 82152 Munich-Martinsried, Germany klein@neuro.mpg.de tgaitanos@neuro.mpg.de.
Thomas N
http://orcid.org/0000-0002-2693-9943
TN
Gaitanos
Department of Molecules-Signaling-Development, Max Planck Institute of Neurobiology, 82152 Munich-Martinsried, Germany.
Jorg
http://orcid.org/0000-0003-0597-312X
J
Koerner
Department of Molecules-Signaling-Development, Max Planck Institute of Neurobiology, 82152 Munich-Martinsried, Germany klein@neuro.mpg.de tgaitanos@neuro.mpg.de.
Ruediger
http://orcid.org/0000-0002-3109-0163
R
Klein
D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D002450:Cell Communication; D002465:Cell Movement; D018920:Coculture Techniques; D004705:Endocytosis; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008856:Microscopy, Fluorescence; D009447:Neuroblastoma / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D009474:Neurons / Q000201:enzymology* / Q000473:pathology; D000072417:Protein Domains; D034622:RNA Interference; D036183:Receptor, EphB2 / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D020662:Guanine Nucleotide Exchange Factors; D011993:Recombinant Fusion Proteins; C122170:TIAM2 protein, human; C066737:RHOA protein, human; C586310:EPHB2 protein, human; D036183:Receptor, EphB2; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein