title: The mouse Foxi3 transcription factor is necessary for the development of posterior placodes.
abstract: The inner ear develops from the otic placode, one of the cranial placodes that arise from a region of ectoderm adjacent to the anterior neural plate called the pre-placodal domain. We have identified a Forkhead family transcription factor, Foxi3, that is expressed in the pre-placodal domain and down-regulated when the otic placode is induced. We now show that Foxi3 mutant mice do not form otic placodes as evidenced by expression changes in early molecular markers and the lack of thickened placodal ectoderm, an otic cup or otocyst. Some preplacodal genes downstream of Foxi3-Gata3, Six1 and Eya1-are not expressed in the ectoderm of Foxi3 mutant mice, and the ectoderm exhibits signs of increased apoptosis. We also show that Fgf signals from the hindbrain and cranial mesoderm, which are necessary for otic placode induction, are received by pre-placodal ectoderm in Foxi3 mutants, but do not initiate otic induction. Finally, we show that the epibranchial placodes that develop in close proximity to the otic placode and the mandibular division of the trigeminal ganglion are missing in Foxi3 mutants. Our data suggest that Foxi3 is necessary to prime pre-placodal ectoderm for the correct interpretation of inductive signals for the otic and epibranchial placodes.
authors.affiliation: Program in Developmental Biology, Baylor College of Medicine, BCM295, 1 Baylor Plaza, Houston, TX 77030, USA.
authors.forename: Onur
authors.initials: O
authors.lastname: Birol
authors.affiliation: USC Caruso Department of Otolaryngology - Head & Neck Surgery, Keck Medicine of USC, University of Southern California, 1501 San Pablo Street, Los Angeles, CA 90033-4503, USA; Zilkha Neurogenetic Institute, Keck Medicine of USC, University of Southern California, 1501 San Pablo Street, Los Angeles, CA 90033-4503, USA.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ohyama
authors.affiliation: Program in Developmental Biology, Baylor College of Medicine, BCM295, 1 Baylor Plaza, Houston, TX 77030, USA.
authors.forename: Renée K
authors.initials: RK
authors.lastname: Edlund
authors.affiliation: Department of Biological Sciences, University of Cyprus, 1 University Avenue, P.O. Box 20537, 1678 Nicosia, Cyprus.
authors.forename: Katerina
authors.initials: K
authors.lastname: Drakou
authors.affiliation: Department of Biological Sciences, University of Cyprus, 1 University Avenue, P.O. Box 20537, 1678 Nicosia, Cyprus.
authors.forename: Pantelis
authors.initials: P
authors.lastname: Georgiades
authors.affiliation: Program in Developmental Biology, Baylor College of Medicine, BCM295, 1 Baylor Plaza, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, BCM295, 1 Baylor Plaza, Houston, TX 77030, USA; Department of Neurosc ience, Baylor College of Medicine, BCM295, 1 Baylor Plaza, Houston, TX 77030, USA. Electronic address: akgroves@bcm.edu.
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Groves
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D004475:Ectoderm / Q000196:embryology* / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D009154:Mutation / Q000235:genetics; D055495:Neurogenesis / Q000235:genetics; D051762:PAX2 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics
chemical_list: D015415:Biomarkers; D051858:Forkhead Transcription Factors; C585346:Foxi3 protein, mouse; D051762:PAX2 Transcription Factor; C497319:Pax2 protein, mouse; D005346:Fibroblast Growth Factors
keywords: Craniofacial Placodes; FGF; Otic Placode; Pre-placodal induction