title: Olfactory and lens placode formation is controlled by the hedgehog-interacting protein (Xhip) in Xenopus.
abstract: The integration of multiple signaling pathways is a key issue in several aspects of embryonic development. In this context, extracellular inhibitors of secreted growth factors play an important role, which is to antagonize specifically the activity of the corresponding signaling molecule. We provide evidence that the Hedgehog-interacting protein (Hip) from Xenopus, previously described as a Hedgehog-specific antagonist in the mouse, interferes with Wnt-8 and eFgf/Fgf-8 signaling pathways as well. To address the function of Hip during early embryonic development, we performed gain- and loss-of-function studies in the frog. Overexpression of Xhip or mHip1 resulted in a dramatic increase of retinal structures and larger olfactory placodes primarily at the expense of other brain tissues. Furthermore, loss of Xhip function resulted in a suppression of olfactory and lens placode formation. Therefore, the localized expression of Xhip may counteract certain overlapping signaling activities, which inhibit the induction of distinct sensory placodes.
authors.affiliation: Department of Developmental Biochemistry, Institute of Biochemistry and Molecular Cell Biology, Georg-August-University of Göttingen, D-37077 Göttingen, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Cornesse
authors.forename: Tomas
authors.initials: T
authors.lastname: Pieler
authors.forename: Thomas
authors.initials: T
authors.lastname: Hollemann
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers; D004475:Ectoderm / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000196:embryology; D044127:Epigenesis, Genetic; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000378:metabolism; D006133:Growth Substances / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D007908:Lens, Crystalline / Q000196:embryology*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D018034:Olfactory Receptor Neurons / Q000196:embryology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000502:physiology*; D051153:Wnt Proteins; D029867:Xenopus Proteins / Q000235:genetics* / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology*
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D006133:Growth Substances; C498037:HHIP protein, Xenopus; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051153:Wnt Proteins; D029867:Xenopus Proteins; C495248:wnt8a protein, Xenopus; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors