RT Journal Article SR Electronic T1 EphA4 mediates ephrinB1-dependent adhesion in retinal ganglion cells JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP e0043242024 DO 10.1523/JNEUROSCI.0043-24.2024 A1 Murcia-Belmonte, Verónica A1 Chauvin, Géraud A1 Coca, Yaiza A1 Escalante, Augusto A1 Klein, Rüdiger A1 Herrera, Eloísa YR 2024 UL http://www.jneurosci.org/content/early/2024/11/26/JNEUROSCI.0043-24.2024.abstract AB Eph/ephrin signaling is crucial for organizing retinotopic maps in vertebrates. Unlike other EphAs, which are expressed in the embryonic ventral retina, EphA4 is found in the retinal ganglion cell (RGC) layer at perinatal stages, and its role in mammalian visual system development remains unclear. Using classic in vitro stripe assays, we demonstrate that, while RGC axons are repelled by ephrinB2, they grow on ephrinB1 stripes through EphA4-mediated adhesion. In vivo, retinal axons from EphA4-deficient mice from either sex show impaired arborization in the medial, but not lateral, regions of the superior colliculus that express ephrinB1. Gain-of-function experiments further reveal that ephrinB1-mediated adhesion depends on EphA4 tyrosine kinase activity but it is independent of its Sterile Alpha Motif. Together, our findings suggest that EphA4/ephrinB1 forward signaling likely facilitates adhesion between retinal axon terminals and cells in the medial colliculus, contributing to the establishment of proper connectivity within the visual system.Significance statement The significance of our findings goes beyond unveiling the mechanisms underlying topographic visual map formation. By discovering a dual role for EphA4 in mediating both repulsion and adhesion, which challenges the conventional understanding of EphA4/ephrin interactions, this work opens up new avenues for exploring EphA4 broader implications in other cellular contexts, including cell differentiation, migration and synaptic plasticity.