title: Shaping organs by a wingless-int/Notch/nonmuscle myosin module which orients feather bud elongation.
abstract: How organs are shaped to specific forms is a fundamental issue in developmental biology. To address this question, we used the repetitive, periodic pattern of feather morphogenesis on chicken skin as a model. Avian feathers within a single tract extend from dome-shaped primordia to thin conical structures with a common axis of orientation. From a systems biology perspective, the process is precise and robust. Using tissue transplantation assays, we demonstrate that a "zone of polarizing activity," localized in the posterior feather bud, is necessary and sufficient to mediate the directional elongation. This region contains a spatially well-defined nuclear β-catenin zone, which is induced by wingless-int (Wnt)7a protein diffusing in from posterior bud epithelium. Misexpressing nuclear β-catenin randomizes feather polarity. This dermal nuclear β-catenin zone, surrounded by Notch1 positive dermal cells, induces Jagged1. Inhibition of Notch signaling disrupts the spatial configuration of the nuclear β-catenin zone and leads to randomized feather polarity. Mathematical modeling predicts that lateral inhibition, mediated by Notch signaling, functions to reduce Wnt7a gradient variations and fluctuations to form the sharp boundary observed for the dermal β-catenin zone. This zone is also enriched for nonmuscle myosin IIB. Suppressing nonmuscle myosin IIB disrupts directional cell rearrangements and abolishes feather bud elongation. These data suggest that a unique molecular module involving chemical-mechanical coupling converts a pliable chemical gradient to a precise domain, ready for subsequent mechanical action, thus defining the position, boundary, and duration of localized morphogenetic activity that molds the shape of growing organs.
authors.affiliation: Department of Pathology, University of Southern California Keck School of Medicine, Los Angeles, CA 90033, USA.
authors.forename: Ang
authors.initials: A
authors.lastname: Li
authors.forename: Meng
authors.initials: M
authors.lastname: Chen
authors.forename: Ting-Xin
authors.initials: TX
authors.lastname: Jiang
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.forename: Qing
authors.initials: Q
authors.lastname: Nie
authors.forename: Randall
authors.initials: R
authors.lastname: Widelitz
authors.forename: Cheng-Ming
authors.initials: CM
authors.lastname: Chuong
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000378:metabolism*; D001973:Bromodeoxyuridine; D016764:Cell Polarity / Q000502:physiology*; D002642:Chick Embryo; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers / Q000235:genetics; D018274:Electroporation; D005241:Feathers / Q000196:embryology*; D017403:In Situ Hybridization; D008954:Models, Biological; D056004:Molecular Dynamics Simulation; D009024:Morphogenesis / Q000502:physiology*; D024501:Nonmuscle Myosin Type IIB / Q000378:metabolism*; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism
chemical_list: D030161:Avian Proteins; D017931:DNA Primers; D051880:Receptors, Notch; C490509:WNT7A protein, Gallus gallus; D051153:Wnt Proteins; D051176:beta Catenin; D024501:Nonmuscle Myosin Type IIB; D001973:Bromodeoxyuridine