title: The C. elegans Chp/Wrch Ortholog CHW-1 Contributes to LIN-18/Ryk and LIN-17/Frizzled Signaling in Cell Polarity.
abstract: Wnt signaling controls various aspects of developmental and cell biology, as well as contributing to certain cancers. Expression of the human Rho family small GTPase Wrch/RhoU is regulated by Wnt signaling, and Wrch and its paralog Chp/RhoV are both implicated in oncogenic transformation and regulation of cytoskeletal dynamics. We performed developmental genetic analysis of the single Caenorhabditis elegans ortholog of Chp and Wrch, CHW-1. Using a transgenic assay of the distal tip cell migration, we found that wild-type CHW-1 is likely to be partially constitutively active and that we can alter ectopic CHW-1-dependent migration phenotypes with mutations predicted to increase or decrease intrinsic GTP hydrolysis rate. The vulval P7.p polarity decision balances multiple antagonistic Wnt signals, and also uses different types of Wnt signaling. Previously described cooperative Wnt receptors LIN-17/Frizzled and LIN-18/Ryk orient P7.p posteriorly, with LIN-17/Fz contributing approximately two-thirds of polarizing activity. CHW-1 deletion appears to equalize the contributions of these two receptors. We hypothesize that CHW-1 increases LIN-17/Fz activity at the expense of LIN-18/Ryk, thus making the contribution of these signals unequal. For P7.p to polarize correctly and form a proper vulva, LIN-17/Fz and LIN-18/Ryk antagonize other Wnt transmembrane systems VANG-1/VanGogh and CAM-1/Ror. Our genetic data suggest that LIN-17/Fz represses both VANG-1/VanGogh and CAM-1/Ror, while LIN-18/Ryk represses only VANG-1. These data expand our knowledge of a sophisticated signaling network to control P7.p polarity, and suggests that CHW-1 can alter ligand gradients or receptor priorities in the system.
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors.forename: Ambrose R
authors.initials: AR
authors.lastname: Kidd
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Muñiz-Medina
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America; Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors.forename: Channing J
authors.initials: CJ
authors.lastname: Der
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America; Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, United States of America; Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors.forename: Adrienne D
authors.initials: AD
authors.lastname: Cox
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America; Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, United States of America; Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center and College of Medicine, Houston, Texas, 77030, United States of America.
authors.forename: David J
authors.initials: DJ
authors.lastname: Reiner
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D016764:Cell Polarity; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D015398:Signal Transduction; D060449:Wnt Signaling Pathway
chemical_list: C469743:CHP1 protein, human; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins; C101684:LIN-17 protein, C elegans; D043562:Receptors, G-Protein-Coupled; C492691:LIN-18 protein, C elegans; D020794:Receptor Protein-Tyrosine Kinases