title: The role of the ELAV homologue EXC-7 in the development of the Caenorhabditis elegans excretory canals.
abstract: The exc mutations of Caenorhabditis elegans alter the position and shape of the apical cytoskeleton in polarized epithelial cells. Mutants in exc-7 form small cysts throughout the tubular excretory canals that regulate organismal osmolarity. We have cloned the exc-7 gene, the closest nematode homologue to the neural RNA-binding protein ELAV. EXC-7 is expressed in the canal for a short time midway through embryogenesis. Cysts in exc-7 mutants do not develop until several hours later, beginning at the time of hatching. We find that the first larval period is when the canal completes the majority of its outgrowth, and adds new apical cytoskeleton at a rapid rate. Ultrastructural studies show that exc-7 mutant defects resemble loss of beta(H)-spectrin (encoded by sma-1) at the distal ends of the excretory canals. In addition, exc-7 mutants exhibit synergistic excretory canal defects with mutations in sma-1, and EXC-7 binds sma-1 mRNA. These data imply that EXC-7 protein may affect expression of sma-1 and other genes to effect proper development of the excretory canals.
authors.affiliation: Department of Biology, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodaicho, Nadaku, Kobe 657-8501, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Fujita
authors.forename: Dana
authors.initials: D
authors.lastname: Hawkinson
authors.forename: Kevin V
authors.initials: KV
authors.lastname: King
authors.forename: David H
authors.initials: DH
authors.lastname: Hall
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Matthew
authors.initials: M
authors.lastname: Buechner
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D051959:ELAV Proteins; D018507:Gene Expression Regulation, Developmental; D008854:Microscopy, Electron; D009154:Mutation; D016601:RNA-Binding Proteins / Q000235:genetics*; D012261:Ribonucleoproteins / Q000235:genetics* / Q000378:metabolism; D014551:Urinary Tract / Q000196:embryology / Q000648:ultrastructure
chemical_list: D029742:Caenorhabditis elegans Proteins; D051959:ELAV Proteins; C473926:EXC-7 protein, C elegans; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins