title: The two actin-interacting protein 1 genes have overlapping and essential function for embryonic development in Caenorhabditis elegans.
abstract: Disassembly of actin filaments by actin-depolymerizing factor (ADF)/cofilin and actin-interacting protein 1 (AIP1) is a conserved mechanism to promote reorganization of the actin cytoskeleton. We previously reported that unc-78, an AIP1 gene in the nematode Caenorhabditis elegans, is required for organized assembly of sarcomeric actin filaments in the body wall muscle. unc-78 functions in larval and adult muscle, and an unc-78-null mutant is homozygous viable and shows only weak phenotypes in embryos. Here we report that a second AIP1 gene, aipl-1 (AIP1-like gene-1), has overlapping function with unc-78, and that depletion of the two AIP1 isoforms causes embryonic lethality. A single aipl-1-null mutation did not cause a detectable phenotype. However, depletion of both unc-78 and aipl-1 arrested development at late embryonic stages due to severe disorganization of sarcomeric actin filaments in body wall muscle. In vitro, both AIPL-1 and UNC-78 preferentially cooperated with UNC-60B, a muscle-specific ADF/cofilin isoform, in actin filament disassembly but not with UNC-60A, a nonmuscle ADF/cofilin. AIPL-1 is expressed in embryonic muscle, and forced expression of AIPL-1 in adult muscle compensated for the function of UNC-78. Thus our results suggest that enhancement of actin filament disassembly by ADF/cofilin and AIP1 proteins is critical for embryogenesis.
authors.affiliation: Department of Pathology, Emory University, Atlanta, GA 30322, USA. sono@emory.edu
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Ono
authors.forename: Kazumi
authors.initials: K
authors.lastname: Nomura
authors.forename: Sadae
authors.initials: S
authors.lastname: Hitosugi
authors.forename: Domena K
authors.initials: DK
authors.lastname: Tu
authors.forename: Jocelyn A
authors.initials: JA
authors.lastname: Lee
authors.forename: David L
authors.initials: DL
authors.lastname: Baillie
authors.forename: Kanako
authors.initials: K
authors.lastname: Ono
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D051345:Destrin / Q000378:metabolism; D047108:Embryonic Development / Q000235:genetics*; D008840:Microfilament Proteins / Q000235:genetics* / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009474:Neurons / Q000378:metabolism; D010641:Phenotype; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D051345:Destrin; D008840:Microfilament Proteins; D020033:Protein Isoforms; C115237:actin interacting protein 1