title: Grb4 and GIT1 transduce ephrinB reverse signals modulating spine morphogenesis and synapse formation.
abstract: Dendritic spines are small protrusions emerging from dendrites that receive excitatory input. The process of spine morphogenesis occurs both in the developing brain and during synaptic plasticity. Molecules regulating the cytoskeleton are involved in spine formation and maintenance. Here we show that reverse signaling by the transmembrane ligands for Eph receptors, ephrinBs, is required for correct spine morphogenesis. The molecular mechanism underlying this function of ephrinBs involves the SH2 and SH3 domain-containing adaptor protein Grb4 and the G protein-coupled receptor kinase-interacting protein (GIT) 1. Grb4 binds by its SH2 domain to Tyr392 in the synaptic localization domain of GIT1. Phosphorylation of Tyr392 and the recruitment of GIT1 to synapses are regulated by ephrinB activation. Disruption of this pathway in cultured rat hippocampal neurons impairs spine morphogenesis and synapse formation. We thus show an important role for ephrinB reverse signaling in spine formation and have mapped the downstream pathway involved in this process.
authors.affiliation: Max-Planck Institute of Neurobiology, Am Klopferspitz 18, D-82152 Martinsried, Germany.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Segura
authors.forename: Clara L
authors.initials: CL
authors.lastname: Essmann
authors.forename: Stefan
authors.initials: S
authors.lastname: Weinges
authors.forename: Amparo
authors.initials: A
authors.lastname: Acker-Palmer
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D000818:Animals; D018797:Cell Cycle Proteins / Q000502:physiology*; D002478:Cells, Cultured; D049229:Dendritic Spines / Q000502:physiology*; D004622:Embryo, Mammalian; D006624:Hippocampus / Q000166:cytology; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D016296:Mutagenesis / Q000502:physiology; D009474:Neurons / Q000166:cytology; D015513:Oncogene Proteins / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D036081:Receptors, Eph Family / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D013997:Time Factors; D014162:Transfection
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C485647:GIT1 protein, human; D008164:Luminescent Proteins; D008565:Membrane Proteins; C485544:NCK2 protein, human; D015513:Oncogene Proteins; D036081:Receptors, Eph Family