title: A splice variant of the Wilms' tumour suppressor Wt1 is required for normal development of the olfactory system.
abstract: Neuronal lineage formation in the developing olfactory epithelium has been extensively studied at the cellular level, but little is known about the genes that control proliferation and differentiation of neuronal progenitor cells. Here, we report that the Wilms' tumour zinc-finger protein, Wt1, is required for normal formation of the olfactory epithelium. Wt1 was detected by immunohistochemistry in the developing olfactory epithelium of wild-type embryos between gestational days E9.5 and E18.5. Embryos with complete lack of Wt1 and embryos with selective ablation of the alternatively spliced Wt1(+KTS) isoform both had thinner olfactory epithelia and fewer neuronal progenitor cells than do normal animals. Mash1 and neurogenin 1, two basic helix-loop-helix transcription factors with critical functions during olfactory neuron development, were reduced in the Wt1(+KTS)-/- mutants compared with the wild-type mice. Stable expression of the Wt1(+KTS) isoform, but not of the Wt1(-KTS) variant, upregulated Mash1 mRNA and protein in vitro. The olfactory epithelia of mouse embryos, which lacked the Wt1(-KTS) protein, appeared normal. However, formation of the neural retina was severely impaired in the Wt1(-KTS)-/- mutants. These findings demonstrate that the Wt1(+KTS) protein, which has been proposed to play a role in mRNA processing, acts upstream of Mash1 to promote the development of the olfactory epithelium. Furthermore, neuron formation depends on distinct functions of alternatively spliced Wt1 products in the embryonic retina and the olfactory epithelium.
authors.affiliation: INSERM U636, Centre de Biochimie, Faculté des Sciences, Nice, France.
authors.forename: Nicole
authors.initials: N
authors.lastname: Wagner
authors.forename: Kay-Dietrich
authors.initials: KD
authors.lastname: Wagner
authors.forename: Annette
authors.initials: A
authors.lastname: Hammes
authors.forename: Karin M
authors.initials: KM
authors.lastname: Kirschner
authors.forename: Valerie P
authors.initials: VP
authors.lastname: Vidal
authors.forename: Andreas
authors.initials: A
authors.lastname: Schedl
authors.forename: Holger
authors.initials: H
authors.lastname: Scholz
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009831:Olfactory Mucosa / Q000196:embryology* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics* / Q000378:metabolism; D012160:Retina / Q000196:embryology; D014157:Transcription Factors / Q000378:metabolism; D025721:WT1 Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D014157:Transcription Factors; D025721:WT1 Proteins; C499317:Ascl1 protein, mouse; C486336:Neurog1 protein, mouse