title: Dynamic expression patterns of Robo (Robo1 and Robo2) in the developing murine central nervous system.
abstract: The Robo family of molecules is important for axon guidance across the midline during central nervous system (CNS) development in invertebrates and vertebrates. Here we describe the patterns of Robo protein expression in the developing mouse CNS from embryonic day (E) 9.5 to postnatal day (P) 4, as determined by immunohistochemical labeling with an antibody (S3) raised against a common epitope present in the Robo ectodomain of Robos 1 and 2. In the spinal cord, midline-crossing axons are initially (at E11) S3-positive. At later times, midline Robo expression disappears, but is strongly upregulated in longitudinally running postcrossing axons. It is also strongly expressed in noncrossing longitudinal axons. Differential expression of Robo along axons was also found in axons cultured from E14 spinal cord. These findings resemble those from the Drosophila ventral nerve cord and indicate that in vertebrates a low level of Robo expression occurs in the initial crossing of the midline, while a high level of expression in the postcrossing fibers prevents recrossing. Likewise, Robo-positive ipsilateral axons are prevented from crossing at all. However, in the brain different rules appear to apply. Most commissural axons including those of the corpus callosum are strongly S3-positive along their whole length from their time of formation to postnatal life, but some have more complex age-dependent expression patterns. S3 labeling of the optic pathway is also complex, being initially strong in the retinal ganglion cells, optic tract, and chiasma but thereafter being lost except in a proportion of postchiasmal axons. The corticospinal tract is strongly positive throughout its course at all stages examined, including its decussation, formed at about P2 in the central part of the medulla oblongata.
authors.affiliation: Medical Research Council Centre for Developmental Neurobiology, Guys Hospital Campus, Kings College London, London Bridge, SE1 1UL, UK. vasi.sundaresan@kcl.ac.uk
authors.forename: Vasi
authors.initials: V
authors.lastname: Sundaresan
authors.forename: Elvira
authors.initials: E
authors.lastname: Mambetisaeva
authors.forename: William
authors.initials: W
authors.lastname: Andrews
authors.forename: Adelaide
authors.initials: A
authors.lastname: Annan
authors.forename: Bernd
authors.initials: B
authors.lastname: Knöll
authors.forename: Guy
authors.initials: G
authors.lastname: Tear
authors.forename: Lawrence
authors.initials: L
authors.lastname: Bannister
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000502:physiology*; D002490:Central Nervous System / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism; D000939:Epitopes / Q000276:immunology; D005260:Female; D005333:Fetus; D007839:Functional Laterality / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D020439:Growth Cones / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins; D009434:Neural Pathways / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D011712:Pyramidal Tracts / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism*; D013116:Spinal Cord / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D014795:Visual Pathways / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D000097905:Roundabout Proteins
chemical_list: D000939:Epitopes; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D000097905:Roundabout Proteins; C498888:Robo2 protein, mouse