Axon guidance cues in auditory development

Abstract

The innervation of the cochlear sensory epithelium is intricately organized, allowing the tonotopy established by the auditory hair cells to be maintained along the ascending auditory pathways. These auditory projections are patterned by several gene families that regulate neurite attraction and repulsion, known as axon guidance cues. In this review, the roles of various axon guidance molecules, including fibroblast growth factor, ephs, semaphorins, netrins and slits, are examined in light of their known contribution to auditory development. Additionally, morphogens are discussed in the context of their recently described influence on axonal pathfinding in other sensory systems. The elucidation of these various mechanisms may guide the development of therapies aimed at maximizing the connectivity of auditory neurons in the context of congenital or acquired sensorineural hearing loss, especially as pertains to cochlear implants. Further afield, improved understanding of the molecular processes which regulate innervation of the organ of Corti during normal development may prove useful in connecting regenerated hair cells to the central nervous system. Anat Rec Part 288A: 390 -396, 2006.

Survival and stimulation of neurite outgrowth in a serum-free culture of spiral ganglion neurons from adult mice

“…However, our understanding of the signaling events that underlie the survival of spiral ganglion neurons and the regeneration of their neurites is incomplete and requires further studies to guide technology development (Bianchi and Raz, 2004;Gillespie and Shepherd, 2005;Webber and Raz, 2006). The primary culture of dissociated spiral ganglion neurons from adult mice would be a useful addition to the experimental armamentarium for such studies.…”

Variable expressivity and genetic heterogeneity involving DPT and SEMA3D genes in autosomal dominant familial Meniere’s disease

“…The Sema3- Nrp-plexin complexes activate the R-ras signalling pathway, and thus decreases the attachment of integrins to the extracellular matrix. 33 Family 1 presented a novel missense variant at chr7:g.84642128 G4A (c.1738C4T) that generates a (p.(Pro580Ser)) change in Semaphorin-3D. This variant segregated the complete MD phenotype in three patients within the same generation, suggesting an autosomal dominant inheritance.…”

Serial Analysis of Gene Expression in the Chicken Otocyst

“…Additional genes with similar roles include ephrin B1 (EFNB1) and ephrin receptors (EPHA4, EPHA5, EPHB3), netrin G1 and the netrin receptor UNC5B, the Slit receptors ROBO1 and ROBO2, as well as the Slit-like transmembrane protein SLITRK6. The possible roles of some of these genes in axon guidance and cell migration has been discussed in the context of the inner ear (Fekete and Campero 2007;Webber and Raz 2006), and their expression patterns and potential function are the focus of intensive research (Battisti and Fekete 2008;Katayama et al 2009;Matilainen et al 2007).…”