Craniofacial defects are among the most frequent congenital abnormalities, constituting 35% of all birth defects. Studies of animal models offer the opportunity to understand the conserved mechanisms regulating vertebrate development that are responsible for congenital defects. This may help finding new ways to prevent, diagnose and treat craniofacial anomalies. We propose to study the mechanisms controlling craniofacial cartilage morphogenesis by employing a powerful combination of genetic, embryological, and molecular methods uniquely available for zebrafish (Danio rerio). We will test the specific hypothesis that Wnt5 and its putative co-receptor glypican Knypek control the elongation of craniofacial cartilage elements by regulation of chondrocyte polarity. We base this hypothesis on the observations that: 1) wnt5 and knypek mutant embryos exhibit dramatic shortening of the cartilage elements, 2) both mutants have similarly disorganized chondrocytes, 3) Knypek and Wnt5 control cell polarity required for normal convergence and extension movements during early developmental stages (gastrulation), and 4) Knypek cooperates with Wnt11 in the control of gastrulation movements. We will verify our hypothesis by realizing the following Specific Aims: 1. Uncover the cellular basis of wnt5 and knypek mutant cartilage morphogenesis defects, i) We will test if all cartilage elements are similarly affected by the loss of Wnt5 and Knypek. Furthermore, with the aid of in vivo confocal microscopy and a transgenic line of zebrafish expressing membrane localized GFP, we will ii) describe morphogenetic movements and Hi) cellular behaviors controlled by Wnt5 and Knypek activity. 2. Determine if Wnt5 and Knypek functionally interact in the control of pharyngeal cartilage morphogenesis. We will examine whether i) knypek and wnt5 have overlapping expression patterns during pharyngeal cartilage morphogenesis. Next, we will ii) investigate the potential role of Knypek in Wnt5 reception and ligand transport. 3. Verify whether Wnt5 and Knypek control cartilage morphogenesis by signaling on a noncanonical Wnt pathway. We will test the ability of well-established elements of the noncanonical signal transduction pathway, such as Dishevelled and Rho associated kinase 2, to suppress knypek and wnt5 mutant phenotypes. ? ? ?

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Research Project (R01)
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Skeletal Biology Development and Disease Study Section (SBDD)
Program Officer
Small, Rochelle K
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Children's Memorial Hospital (Chicago)
United States
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Sisson, Barbara E; Dale, Rodney M; Mui, Stephanie R et al. (2015) A role of glypican4 and wnt5b in chondrocyte stacking underlying craniofacial cartilage morphogenesis. Mech Dev 138 Pt 3:279-90
Cantu, Jorge A; Flowers, G Parker; Topczewski, Jacek (2013) Notum homolog plays a novel role in primary motor innervation. J Neurosci 33:2177-87
Duszynski, Robert J; Topczewski, Jacek; LeClair, Elizabeth E (2013) Divergent requirements for fibroblast growth factor signaling in zebrafish maxillary barbel and caudal fin regeneration. Dev Growth Differ 55:282-300
Moore, Alex C; Mark, Tiffany E; Hogan, Ann K et al. (2012) Peripheral axons of the adult zebrafish maxillary barbel extensively remyelinate during sensory appendage regeneration. J Comp Neurol 520:4184-203
Flowers, G Parker; Topczewska, Jolanta M; Topczewski, Jacek (2012) A zebrafish Notum homolog specifically blocks the Wnt/ýý-catenin signaling pathway. Development 139:2416-25
Topczewski, Jacek; Dale, Rodney M; Sisson, Barbara E (2011) Planar cell polarity signaling in craniofacial development. Organogenesis 7:255-9
Dale, Rodney M; Topczewski, Jacek (2011) Identification of an evolutionarily conserved regulatory element of the zebrafish col2a1a gene. Dev Biol 357:518-31
Duszynski, Robert J; Topczewski, Jacek; LeClair, Elizabeth E (2011) Simple, economical heat-shock devices for zebrafish housing racks. Zebrafish 8:211-9
LeClair, Elizabeth E; Topczewski, Jacek (2010) Development and regeneration of the zebrafish maxillary barbel: a novel study system for vertebrate tissue growth and repair. PLoS One 5:e8737
Drerup, Catherine M; Wiora, Heather M; Topczewski, Jacek et al. (2009) Disc1 regulates foxd3 and sox10 expression, affecting neural crest migration and differentiation. Development 136:2623-32

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