title: Identifying domains of EFHC1 involved in ciliary localization, ciliogenesis, and the regulation of Wnt signaling.
abstract: EFHC1 encodes a ciliary protein that has been linked to Juvenile Myoclonic Epilepsy. In ectodermal explants, derived from Xenopus laevis embryos, the morpholino-mediated down-regulation of EFHC1b inhibited multiciliated cell formation. In those ciliated cells that did form, axoneme but not basal body formation was inhibited. EFHC1b morphant embryos displayed defects in central nervous system (CNS) and neural crest patterning that were rescued by a EFHC1b-GFP chimera. EFHC1b-GFP localized to ciliary axonemes in epidermal, gastrocoele roof plate, and neural tube cells. In X. laevis there is a link between Wnt signaling and multiciliated cell formation. While down-regulation of EFHC1b led to a ~2-fold increase in the activity of the β-catenin/Wnt-responsive TOPFLASH reporter, EFHC1b-GFP did not inhibit β-catenin activation of TOPFLASH. Wnt8a RNA levels were increased in EFHC1b morphant ectodermal explants and intact embryos, analyzed prior to the on-set of ciliogenesis. Rescue of the EFHC1b MO's ciliary axonemal phenotypes required the entire protein; in contrast, the EFHC1b morpholino's Wnt8a, CNS, and neural crest phenotypes were rescued by a truncated form of EFHC1b. The EFHC1b morpholino's Wnt8a phenotype was also rescued by the injection of RNAs encoding secreted Wnt inhibitors, suggesting that these phenotypes are due to effects on Wnt signaling, rather than the loss of cilia, an observation of potential relevance to understanding EFHC1's role in human neural development.
authors.affiliation: Molecular, Cellular & Developmental Biology, University of Colorado Boulder Boulder, Colorado 80309-0347, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Molecular, Cellular & Developmental Biology, University of Colorado Boulder Boulder, Colorado 80309-0347, USA.
authors.forename: Jianli
authors.initials: J
authors.lastname: Shi
authors.affiliation: Molecular, Cellular & Developmental Biology, University of Colorado Boulder Boulder, Colorado 80309-0347, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Winey
authors.affiliation: Molecular, Cellular & Developmental Biology, University of Colorado Boulder Boulder, Colorado 80309-0347, USA. Electronic address: klym@colorado.edu.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Klymkowsky
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002923:Cilia / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D009024:Morphogenesis; D009154:Mutation; D009432:Neural Crest / Q000166:cytology / Q000196:embryology; D054259:Neural Tube / Q000196:embryology; D010641:Phenotype; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D015398:Signal Transduction; D015854:Up-Regulation; D051153:Wnt Proteins / Q000378:metabolism*; D060449:Wnt Signaling Pathway; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology*; D051176:beta Catenin / Q000378:metabolism
chemical_list: D002135:Calcium-Binding Proteins; C000609516:EFHC1 protein, Xenopus; D051153:Wnt Proteins; D029867:Xenopus Proteins; D051176:beta Catenin; C495248:wnt8a protein, Xenopus; D049452:Green Fluorescent Proteins; D012313:RNA
keywords: Ciliogenesis; Myoclonic epilepsy; Wnt signaling; Xenopus embryo