title: Synergies between Aip1p and capping protein subunits (Acp1p and Acp2p) in clathrin-mediated endocytosis and cell polarization in fission yeast.
abstract: Aip1p cooperates with actin-depolymerizing factor (ADF)/cofilin to disassemble actin filaments in vitro and in vivo, and is proposed to cap actin filament barbed ends. We address the synergies between Aip1p and the capping protein heterodimer Acp1p/Acp2p during clathrin-mediated endocytosis in fission yeast. Using quantitative microscopy and new methods we have developed for data alignment and analysis, we show that heterodimeric capping protein can replace Aip1p, but Aip1p cannot replace capping protein in endocytic patches. Our quantitative analysis reveals that the actin meshwork is organized radially and is compacted by the cross-linker fimbrin before the endocytic vesicle is released from the plasma membrane. Capping protein and Aip1p help maintain the high density of actin filaments in meshwork by keeping actin filaments close enough for cross-linking. Our experiments also reveal new cellular functions for Acp1p and Acp2p independent of their capping activity. We identified two independent pathways that control polarization of endocytic sites, one depending on acp2(+) and aip1(+) during interphase and the other independent of acp1(+), acp2(+), and aip1(+) during mitosis.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103 Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103 Nanobiology Institute, Yale University, New Haven, CT 06520-8103 Institut Camille Jordan, UMR CNRS 5208, Université de Lyon, 69622 Villeurbanne-Cedex, France Centre de Génétique et de Physiologie Moléculaire et Cellulaire, UMR CNRS 5534, Université de Lyon, 69622 Villeurbanne-Cedex, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Berro
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103 Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103 Department of Cell Biology, Yale University, New Haven, CT 06520-8103 thomas.pollard@yale.edu.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Pollard
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D000199:Actins / Q000737:chemistry / Q000378:metabolism; D016764:Cell Polarity; D002966:Clathrin / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis / Q000235:genetics; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D007399:Interphase; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D018715:Microscopy, Video; D008938:Mitosis / Q000235:genetics; D010766:Phosphorylation; D058105:Polymerization; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D013997:Time Factors; D022161:Transport Vesicles / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D000199:Actins; D002966:Clathrin; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D021122:Protein Subunits; C115237:actin interacting protein 1; C026742:plastin; D010450:Endopeptidases