title: Topographical mapping of α- and β-keratins on developing chicken skin integuments: Functional interaction and evolutionary perspectives.
abstract: Avian integumentary organs include feathers, scales, claws, and beaks. They cover the body surface and play various functions to help adapt birds to diverse environments. These keratinized structures are mainly composed of corneous materials made of α-keratins, which exist in all vertebrates, and β-keratins, which only exist in birds and reptiles. Here, members of the keratin gene families were used to study how gene family evolution contributes to novelty and adaptation, focusing on tissue morphogenesis. Using chicken as a model, we applied RNA-seq and in situ hybridization to map α- and β-keratin genes in various skin appendages at embryonic developmental stages. The data demonstrate that temporal and spatial α- and β-keratin expression is involved in establishing the diversity of skin appendage phenotypes. Embryonic feathers express a higher proportion of β-keratin genes than other skin regions. In feather filament morphogenesis, β-keratins show intricate complexity in diverse substructures of feather branches. To explore functional interactions, we used a retrovirus transgenic system to ectopically express mutant α- or antisense β-keratin forms. α- and β-keratins show mutual dependence and mutations in either keratin type results in disrupted keratin networks and failure to form proper feather branches. Our data suggest that combinations of α- and β-keratin genes contribute to the morphological and structural diversity of different avian skin appendages, with feather-β-keratins conferring more possible composites in building intrafeather architecture complexity, setting up a platform of morphological evolution of functional forms in feathers.
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033;
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan;
authors.forename: Chen Siang
authors.initials: CS
authors.lastname: Ng
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033; Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China;
authors.forename: Jie
authors.initials: J
authors.lastname: Yan
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033; Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei 10041, Taiwan; Integrative Stem Cell Center, China Medical University, Taichung 40447, Taiwan;
authors.forename: Yung-Chih
authors.initials: YC
authors.lastname: Lai
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan; Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei 10617, Taiwan;
authors.forename: Chih-Kuan
authors.initials: CK
authors.lastname: Chen
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan;
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Lai
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan;
authors.forename: Siao-Man
authors.initials: SM
authors.lastname: Wu
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan;
authors.forename: Jiun-Jie
authors.initials: JJ
authors.lastname: Chen
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033;
authors.forename: Weiqi
authors.initials: W
authors.lastname: Luo
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033;
authors.forename: Randall B
authors.initials: RB
authors.lastname: Widelitz
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan; Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637; whli@uchicago.edu cmchuong@usc.edu.
authors.forename: Wen-Hsiung
authors.initials: WH
authors.lastname: Li
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033; Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei 10041, Taiwan; Integrative Stem Cell Center, China Medical University, Taichung 40447, Taiwan; Center for the Integrative and Evolutionary Galliform Genomics, National Chung Hsing University, Taichung 40227, Taiwan whli@uchicago.edu cmchuong@usc.edu.
authors.forename: Cheng-Ming
authors.initials: CM
authors.lastname: Chuong
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002642:Chick Embryo; D002874:Chromosome Mapping; D017403:In Situ Hybridization; D053535:Keratin-13 / Q000235:genetics; D007633:Keratins / Q000235:genetics*; D016372:RNA, Antisense / Q000494:pharmacology; D012867:Skin / Q000196:embryology* / Q000378:metabolism; D053800:beta-Keratins / Q000235:genetics*
chemical_list: C507426:KRT13 protein, human; D053535:Keratin-13; D016372:RNA, Antisense; D053800:beta-Keratins; D007633:Keratins
keywords: Evo-Devo; beak; claw; feather; scale; skin appendage