title: Opposing Shh and Fgf signals initiate nasotemporal patterning of the zebrafish retina.
abstract: The earliest known determinants of retinal nasotemporal identity are the transcriptional regulators Foxg1, which is expressed in the prospective nasal optic vesicle, and Foxd1, which is expressed in the prospective temporal optic vesicle. Previous work has shown that, in zebrafish, Fgf signals from the dorsal forebrain and olfactory primordia are required to specify nasal identity in the dorsal, prospective nasal, optic vesicle. Here, we show that Hh signalling from the ventral forebrain is required for specification of temporal identity in the ventral optic vesicle and is sufficient to induce temporal character when activated in the prospective nasal retina. Consequently, the evaginating optic vesicles become partitioned into prospective nasal and temporal domains by the opposing actions of Fgfs and Shh emanating from dorsal and ventral domains of the forebrain primordium. In absence of Fgf activity, foxd1 expression is established irrespective of levels of Hh signalling, indicating that the role of Shh in promoting foxd1 expression is only required in the presence of Fgf activity. Once the spatially complementary expression of foxd1 and foxg1 is established, the boundary between expression domains is maintained by mutual repression between Foxd1 and Foxg1.
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), C/Nicolás Cabrera 1, 28049, Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Hernández-Bejarano
authors.affiliation: Department of Cell and Developmental Biology, University College London, Gower Street, London WC1 6BT, UK.
authors.forename: Gaia
authors.initials: G
authors.lastname: Gestri
authors.affiliation: Department of Cell and Developmental Biology, University College London, Gower Street, London WC1 6BT, UK.
authors.forename: Lana
authors.initials: L
authors.lastname: Spawls
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), C/Nicolás Cabrera 1, 28049, Madrid, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Nieto-López
authors.affiliation: Center of Regenerative Therapies Dresden (CRTD), Biotechnology Center, Dresden University of Technology, 01062 Dresden, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Picker
authors.affiliation: Department of Cell and Developmental Biology, University College London, Gower Street, London WC1 6BT, UK.
authors.forename: Masazumi
authors.initials: M
authors.lastname: Tada
authors.affiliation: Center of Regenerative Therapies Dresden (CRTD), Biotechnology Center, Dresden University of Technology, 01062 Dresden, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Brand
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), C/Nicolás Cabrera 1, 28049, Madrid, Spain CIBER de Enfermedades Raras (CIBERER), C/Nicolás Cabrera 1, 28049, Madrid, Spain.
authors.forename: Paola
authors.initials: P
authors.lastname: Bovolenta
authors.affiliation: Department of Cell and Developmental Biology, University College London, Gower Street, London WC1 6BT, UK s.wilson@ucl.ac.uk fcavodeassi@cbm.csic.es.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Wilson
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), C/Nicolás Cabrera 1, 28049, Madrid, Spain CIBER de Enfermedades Raras (CIBERER), C/Nicolás Cabrera 1, 28049, Madrid, Spain s.wilson@ucl.ac.uk fcavodeassi@cbm.csic.es.
authors.forename: Florencia
authors.initials: F
authors.lastname: Cavodeassi
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D002232:Carbocyanines; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D051858:Forkhead Transcription Factors; D053823:Hedgehog Proteins / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D018613:Microscopy, Confocal; D016548:Prosencephalon / Q000378:metabolism; D012160:Retina / Q000196:embryology*; D015398:Signal Transduction / Q000502:physiology*; D015027:Zebrafish / Q000196:embryology*; D029961:Zebrafish Proteins / Q000378:metabolism*
chemical_list: C582073:1,1'-dioleyl-3,3,3',3'-tetramethylindocarbocyanine; D002232:Carbocyanines; D051858:Forkhead Transcription Factors; D053823:Hedgehog Proteins; C524053:Shha protein, zebrafish; D029961:Zebrafish Proteins; C540570:foxg1a protein, zebrafish; D005346:Fibroblast Growth Factors
keywords: Fgfs; Nasotemporal patterning; Retina; Shh; Zebrafish