Functional analysis of pax2/5/8 genes and their genetic interactions in zebrafish ear development

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Title: Functional analysis of pax2/5/8 genes and their genetic interactions in zebrafish ear development
Author: Kwak, Su Jin
Abstract: The vertebrate inner ear is a sensory organ responsible for auditory and vestibular function . Since its complex structure and cell types arise from a simply structured group of ectodermal cells , called the otic placode , the development of the inner ear has been a popular subject in embryology and developmental biology for decades . To date , many regulatory molecules and their functions have been identified in inner ear development showing considerable conservation among vertebrates . In vertebrates , Fgfs (fibroblast growth factors ) from surrounding tissues are the main otic inducer and regulate various otic genes ? ? expression . Under the control of Fgf signals , pax2 /5 /8 genes are expressed in the otic region in the critical stages of otic development suggesting their function in otic development . In order to understand the function of pax2 /5 /8 genes and their interactions in the developing ear , we utilize zebrafish as a model system . Among zebrafish pax2 /5 /8 genes , pax8 is the earliest gene expressed in the preotic region while pax2a and pax2b are expressed slightly later . We found that pax8 is initially required for normal otic induction . Subsequently , pax8 , pax2a and pax2b function redundantly to maintain otic fate . After otic placodes are induced by an Fgf signaling network , expression of Fgf3 , one of otic inducers in zebrafish , persists in the hindbrain rhombomere 4 . To investigate the function of the persistant Fgf3 expression , we examined a mutant with expanded Fgf3 expression in the hindbrain . Together with fgf3 knockdown results , we discovered that Fgf3 has later roles in specifying the anteroposterior (A -P ) axis in the otic vesicle and regulating hair cell formation . We further identified pax5 as one of the genes regulated by the hindbrain Fgf3 activity , and pax5 function to be required for utricular hair cell survival .
URI: http : / /hdl .handle .net /1969 .1 /3864
Date: 2006-08-16

Citation

Functional analysis of pax2/5/8 genes and their genetic interactions in zebrafish ear development. Available electronically from http : / /hdl .handle .net /1969 .1 /3864 .

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