title: Arp2/3 promotes junction formation and maintenance in the Caenorhabditis elegans intestine by regulating membrane association of apical proteins.
abstract: It has been proposed that Arp2/3, which promotes nucleation of branched actin, is needed for epithelial junction initiation but is less important as junctions mature. We focus here on how Arp2/3 contributes to the Caenorhabditis elegans intestinal epithelium and find important roles for Arp2/3 in the maturation and maintenance of junctions in embryos and adults. Electron microscope studies show that embryos depleted of Arp2/3 form apical actin-rich microvilli and electron-dense apical junctions. However, whereas apical/basal polarity initiates, apical maturation is defective, including decreased apical F-actin enrichment, aberrant lumen morphology, and reduced accumulation of some apical junctional proteins, including DLG-1. Depletion of Arp2/3 in adult animals leads to similar intestinal defects. The DLG-1/AJM-1 apical junction proteins, and the ezrin-radixin-moesin homologue ERM-1, a protein that connects F-actin to membranes, are required along with Arp2/3 for apical F-actin enrichment in embryos, whereas cadherin junction proteins are not. Arp2/3 affects the subcellular distribution of DLG-1 and ERM-1. Loss of Arp2/3 shifts both ERM-1 and DLG-1 from pellet fractions to supernatant fractions, suggesting a role for Arp2/3 in the distribution of membrane-associated proteins. Thus, Arp2/3 is required as junctions mature to maintain apical proteins associated with the correct membranes.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
authors.forename: Yelena Y
authors.initials: YY
authors.lastname: Bernadskaya
authors.forename: Falshruti B
authors.initials: FB
authors.lastname: Patel
authors.forename: Hsiao-Ting
authors.initials: HT
authors.lastname: Hsu
authors.forename: Martha C
authors.initials: MC
authors.lastname: Soto
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D047108:Embryonic Development; D007365:Intercellular Junctions / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000196:embryology / Q000378:metabolism / Q000648:ultrastructure; D007422:Intestines / Q000166:cytology*; D007814:Larva / Q000166:cytology / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D010590:Phalloidine / Q000378:metabolism; D010641:Phenotype; D021381:Protein Transport; D034622:RNA Interference; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D029742:Caenorhabditis elegans Proteins; D003598:Cytoskeletal Proteins; C488174:ERM-1 protein, C elegans; C450822:GEX-3 protein, C elegans; D008565:Membrane Proteins; D046912:Multiprotein Complexes; C532811:wve-1 protein, C elegans; D010590:Phalloidine