Expression of class III Semaphorins and their receptors in the developing chicken (Gallus gallus) inner ear.
Class III Semaphorin (Sema) secreted ligands are known to repel neurites expressing Neuropilin (Nrp) and/or Plexin (Plxn) receptors. There is, however, a growing body of literature supporting that Sema signaling also has alternative roles in development such as synaptogenesis, boundary formation, and vasculogenesis. To evaluate these options during inner ear development, we used in situ hybridization or immunohistochemistry to map the expression of Sema3D, Sema3F, Nrp1, Nrp2, and PlxnA1 in the chicken (Gallus gallus) inner ear from embryonic day (E)5-E10. The resulting expression patterns in either the otic epithelium or its surrounding mesenchyme suggest that Sema signaling could be involved in each of the varied functions reported for other tissues. Sema3D expression flanking the sensory tissue in vestibular organs suggests that it may repel Nrp2- and PlxnA1-expressing neurites of the vestibular ganglion away from nonsensory epithelia, thus channeling them into the sensory domains at E5-E8. Expression of Sema signaling genes in the sensory hair cells of both the auditory and vestibular organs on E8-E10 may implicate Sema signaling in synaptogenesis. In the nonsensory regions of the cochlea, Sema3D in the future tegmentum vasculosum opposes Nrp1 and PlxnA1 in the future cuboidal cells; the abutment of ligand and receptors in adjacent domains may enforce or maintain the boundary between them. In the mesenchyme, Nrp1 colocalized with capillary-rich tissue. Sema3D immediately flanks this Nrp1-expressing tissue, suggesting a role in endothelial cell migration towards the inner ear. In summary, Sema signaling may play multiple roles in the developing inner ear.
['Scott|M Katie|MK|', 'Yue|Jia|J|', 'Biesemeier|Deborah J|DJ|', 'Lee|Joo Won|JW|', 'Fekete|Donna M|DM|']
D000818:Animals D002465:Cell Movement D002642:Chick Embryo D002645:Chickens D007758:Ear, Inner D018507:Gene Expression Regulation, Developmental D008648:Mesoderm D055495:Neurogenesis D039942:Neuropilin-1 D009925:Organ of Corti D039961:Semaphorins D015398:Signal Transduction D013047:Specific Pathogen-Free Organisms D013136:Spiral Ganglion D051153:Wnt Proteins
Semaphorin inner ear Neuropilin Plexin RRID AB_1841228 RRID AB_355445 RRID AB_528098 RRID AB_531974 RRID CVCL_0570 chicken embryo