title: Ephrin A/EphA controls the rostral turning polarity of a lateral commissural tract in chick hindbrain.
abstract: Most post-crossing commissural axons turn into longitudinal paths to make synaptic connections with their targets. Mechanisms that control their rostrocaudal turning polarity are still poorly understood. We used the hindbrain as a model system to investigate the rostral turning of a laterally located commissural tract, identified as the caudal group of contralateral cerebellar-projecting second-order vestibular neurons (cC-VC). We found that the caudal hindbrain possessed a graded non-permissive/repulsive activity for growing cC-VC axons. This non-permissiveness/repulsion was in part mediated by glycosyl-phosphatidylinositol (GPI)-anchored ephrin A. We further demonstrated that ephrin A2 was distributed in a caudal-high/rostral-low gradient in the caudolateral hindbrain and cC-VC axons expressed EphA receptors. Finally, perturbing ephrin A/EphA signalling both in vitro and in vivo led to rostrocaudal pathfinding errors of post-crossing cC-VC axons. These results suggest that ephrin A/EphA interactions play a key role in regulating the polarity of post-crossing cC-VC axons as they turn into the longitudinal axis.
authors.affiliation: SORST, Japan Science and Technology, Japan. yan.zhu@fbs.osaka-u.ac.jp
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Sarah
authors.initials: S
authors.lastname: Guthrie
authors.forename: Fujio
authors.initials: F
authors.lastname: Murakami
mesh_terms: D000818:Animals; D001369:Axons / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D016764:Cell Polarity; D002531:Cerebellum / Q000737:chemistry / Q000166:cytology / Q000196:embryology; D002642:Chick Embryo / Q000254:growth & development* / Q000378:metabolism; D036383:Ephrin-A2 / Q000032:analysis / Q000378:metabolism*; D036342:Ephrins / Q000032:analysis / Q000378:metabolism; D008024:Ligands; D009475:Neurons, Afferent / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D036081:Receptors, Eph Family / Q000032:analysis / Q000378:metabolism*; D012249:Rhombencephalon / Q000166:cytology / Q000196:embryology* / Q000502:physiology; D015398:Signal Transduction
chemical_list: D036383:Ephrin-A2; D036342:Ephrins; D008024:Ligands; D036081:Receptors, Eph Family