title: WAVE/SCAR promotes endocytosis and early endosome morphology in polarized C. elegans epithelia.
abstract: Cells can use the force of actin polymerization to drive intracellular transport, but the role of actin in endocytosis is not clear. Studies in single-celled yeast demonstrate the essential role of the branched actin nucleator, Arp2/3, and its activating nucleation promoting factors (NPFs) in the process of invagination from the cell surface through endocytosis. However, some mammalian studies have disputed the need for F-actin and Arp2/3 in Clathrin-Mediated Endocytosis (CME) in multicellular organisms. We investigate the role of Arp2/3 during endocytosis in Caenorhabditis elegans, a multicellular organism with polarized epithelia. Arp2/3 and its NPF, WAVE/SCAR, are essential for C. elegans embryonic morphogenesis. We show that WAVE/SCAR and Arp2/3 regulate endocytosis and early endosome morphology in diverse tissues of C. elegans. Depletion of WAVE/SCAR or Arp2/3, but not of the NPF Wasp, severely disrupts the distribution of molecules proposed to be internalized via CME, and alters the subcellular enrichment of the early endosome regulator RAB-5. Loss of WAVE/SCAR or of the GEFs that regulate RAB-5 results in similar defects in endocytosis in the intestine and coelomocyte cells. This study in a multicellular organism supports an essential role for branched actin regulators in endocytosis, and identifies WAVE/SCAR as a key NPF that promotes Arp2/3 endocytic function in C. elegans.
authors.affiliation: Department of Pathology and Laboratory Medicine, UMDNJ--Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA.
authors.forename: Falshruti B
authors.initials: FB
authors.lastname: Patel
authors.forename: Martha C
authors.initials: MC
authors.lastname: Soto
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes; D049452:Green Fluorescent Proteins; D008954:Models, Biological; D009024:Morphogenesis / Q000502:physiology*; D034622:RNA Interference; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D029742:Caenorhabditis elegans Proteins; C558452:Rab-5 protein, C elegans; D033921:Vesicular Transport Proteins; C532811:wve-1 protein, C elegans; D049452:Green Fluorescent Proteins