title: Protein-Trap Insertional Mutagenesis Uncovers New Genes Involved in Zebrafish Skin Development, Including a Neuregulin 2a-Based ErbB Signaling Pathway Required during Median Fin Fold Morphogenesis.
abstract: Skin disorders are widespread, but available treatments are limited. A more comprehensive understanding of skin development mechanisms will drive identification of new treatment targets and modalities. Here we report the Zebrafish Integument Project (ZIP), an expression-driven platform for identifying new skin genes and phenotypes in the vertebrate model Danio rerio (zebrafish). In vivo selection for skin-specific expression of gene-break transposon (GBT) mutant lines identified eleven new, revertible GBT alleles of genes involved in skin development. Eight genes--fras1, grip1, hmcn1, msxc, col4a4, ahnak, capn12, and nrg2a--had been described in an integumentary context to varying degrees, while arhgef25b, fkbp10b, and megf6a emerged as novel skin genes. Embryos homozygous for a GBT insertion within neuregulin 2a (nrg2a) revealed a novel requirement for a Neuregulin 2a (Nrg2a)-ErbB2/3-AKT signaling pathway governing the apicobasal organization of a subset of epidermal cells during median fin fold (MFF) morphogenesis. In nrg2a mutant larvae, the basal keratinocytes within the apical MFF, known as ridge cells, displayed reduced pAKT levels as well as reduced apical domains and exaggerated basolateral domains. Those defects compromised proper ridge cell elongation into a flattened epithelial morphology, resulting in thickened MFF edges. Pharmacological inhibition verified that Nrg2a signals through the ErbB receptor tyrosine kinase network. Moreover, knockdown of the epithelial polarity regulator and tumor suppressor lgl2 ameliorated the nrg2a mutant phenotype. Identifying Lgl2 as an antagonist of Nrg2a-ErbB signaling revealed a significantly earlier role for Lgl2 during epidermal morphogenesis than has been described to date. Furthermore, our findings demonstrated that successive, coordinated ridge cell shape changes drive apical MFF development, making MFF ridge cells a valuable model for investigating how the coordinated regulation of cell polarity and cell shape changes serves as a crucial mechanism of epithelial morphogenesis.
authors.affiliation: Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota, United States of America; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Westcot
authors.affiliation: Institute for Developmental Biology, University of Cologne, Biocenter, Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Hatzold
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Urban
authors.affiliation: Institute for Developmental Biology, University of Cologne, Biocenter, Cologne, Germany.
authors.forename: Stefânia K
authors.initials: SK
authors.lastname: Richetti
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Skuster
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Rhianna M
authors.initials: RM
authors.lastname: Harm
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Roberto
authors.initials: R
authors.lastname: Lopez Cervera
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Noriko
authors.initials: N
authors.lastname: Umemoto
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Melissa S
authors.initials: MS
authors.lastname: McNulty
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Clark
authors.affiliation: Institute for Developmental Biology, University of Cologne, Biocenter, Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany; Cologne Cluster of Excellence in Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hammerschmidt
authors.affiliation: Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota, United States of America; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Ekker
mesh_terms: D000483:Alleles; D058500:Animal Fins / Q000196:embryology* / Q000378:metabolism; D000818:Animals; D018507:Gene Expression Regulation, Developmental; D016254:Mutagenesis, Insertional; D020880:Neuregulins / Q000235:genetics / Q000378:metabolism*; D018739:Oncogene Proteins v-erbB / Q000235:genetics / Q000378:metabolism*; D038081:Organogenesis / Q000235:genetics*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D012867:Skin / Q000196:embryology* / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D020880:Neuregulins; D018739:Oncogene Proteins v-erbB; D029961:Zebrafish Proteins; D051057:Proto-Oncogene Proteins c-akt