title: Forced notch signaling inhibits commissural axon outgrowth in the developing chick central nerve system.
abstract: BACKGROUND
  A collection of in vitro evidence has demonstrated that Notch signaling plays a key role in the growth of neurites in differentiated neurons. However, the effects of Notch signaling on axon outgrowth in an in vivo condition remain largely unknown.
  
  
  RESULTS
  In this study, the neural tubes of HH10-11 chick embryos were in ovo electroporated with various Notch transgenes of activating or inhibiting Notch signaling, and then their effects on commissural axon outgrowth across the floor plate midline in the chick developing central nerve system were investigated. Our results showed that forced expression of Notch intracellular domain, constitutively active form of RBPJ, or full-length Hes1 in the rostral hindbrain, diencephalon and spinal cord at stage HH10-11 significantly inhibited commissural axon outgrowth. On the other hand, inhibition of Notch signaling by ectopically expressing a dominant-negative form of RBPJ promoted commissural axonal growth along the circumferential axis. Further results revealed that these Notch signaling-mediated axon outgrowth defects may be not due to the alteration of axon guidance since commissural axon marker TAG1 was present in the axons in floor plate midline, and also not result from the changes in cell fate determination of commissural neurons since the expression of postmitotic neuron marker Tuj1 and specific commissural markers TAG1 and Pax7 was unchanged.
  
  
  CONCLUSIONS
  We first used an in vivo system to provide evidence that forced Notch signaling negatively regulates commissural axon outgrowth.
authors.affiliation: Department of Neurology, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Shi
authors.forename: Zhirong
authors.initials: Z
authors.lastname: Liu
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Lv
authors.forename: Minhua
authors.initials: M
authors.lastname: Zheng
authors.forename: Fang
authors.initials: F
authors.lastname: Du
authors.forename: Gang
authors.initials: G
authors.lastname: Zhao
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Jiayin
authors.initials: J
authors.lastname: Chen
authors.forename: Hua
authors.initials: H
authors.lastname: Han
authors.forename: Yuqiang
authors.initials: Y
authors.lastname: Ding
mesh_terms: D000818:Animals; D001369:Axons; D002490:Central Nervous System / Q000254:growth & development*; D002642:Chick Embryo; D016501:Neurites; D009474:Neurons; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D019076:Transgenes / Q000502:physiology
chemical_list: D051880:Receptors, Notch