Distinct expression patterns of notch family receptors and ligands during development of the mammalian inner ear

The cochlea and vestibular structures of the inner ear labyrinth develop fr om the otic capsule via step-wise regional and cell fate specification. Eac h inner ear structure contains a sensory epithelium, composed of hair cells , the mechanosensory transducers, and supporting cells. We examined the spa tio-temporal expression of genes in the Notch signaling pathway, Notch rece ptors (Notch1-4) and two ligands, Jagged1 and Delta1, in the developing mam malian inner ear. Our results show that Notch1 and Jagged1 are first expres sed in the otic vesicle, likely involved in differentiation of the VIIIth n erve ganglion neurons, and subsequently within the inner ear sensory epithe lia, temporally coincident with initial hair cell differentiation. Notch1 e xpression is specific to hair cells and Jagged1 to supporting cells. Their expression persists into adult. Notch2, Notch3, Notch4, and Delta1 are excl uded from the inner ear epithelia. These data support the hypothesis that N otch signaling is involved in hair cell differentiation during inner ear mo rphogenesis. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.