DAip1, a Dictyostelium homologue of the yeast actin-interacting protein 1, is involved in endocytosis, cytokinesis, and motility

• Published in: The Journal of cell biology Vol. 146; no. 2; pp. 453 - 464
• Main Authors: Konzok, A, Weber, I, Simmeth, E, Hacker, U, Maniak, M, Muller-Taubenberger, A
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 26.07.1999; The Rockefeller University Press
• Subjects: actin; Actin Depolymerizing Factors; Actins; Actins - metabolism; Amino Acid Sequence; amino acid sequences; Animals; binding proteins; Bridged Bicyclo Compounds, Heterocyclic - pharmacology; Cell Division; Cell Movement; Cell nucleus; cell structures; Cells; Cellular biology; complementary DNA; cytochemistry; Cytokines; Cytokinesis; Cytoplasm - drug effects; Cytoplasm - metabolism; Daughter cells; dictostelium discoideum; Dictyostelium; Dictyostelium - cytology; Dictyostelium - drug effects; Dictyostelium - genetics; Dictyostelium - growth & development; endocytosis; Endocytosis - drug effects; genbank/u51923; Gene Deletion; Gene Expression; Giant Cells - cytology; Giant Cells - metabolism; immunocytochemistry; Microfilament Proteins - chemistry; Microfilament Proteins - genetics; Microfilament Proteins - metabolism; Microfilaments; Molecular Sequence Data; motility; mutants; nucleotide sequences; Original; Phagocytes; Phagocytosis; Phagocytosis - drug effects; phenotype; Pinocytosis - drug effects; Polymers - metabolism; Proteins; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Sequence Homology, Amino Acid; Thiazoles - pharmacology; Thiazolidines; Yeast; Yeasts
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.146.2.453

The 64-kD protein DAip1 from Dictyostelium contains nine WD40-repeats and is homologous to the actin-interacting protein 1, Aip1p, from Saccharomyces cerevisiae, and to related proteins from Caenorhabditis, Physarum, and higher eukaryotes. We show that DAip1 is localized to dynamic regions of the cell cortex that are enriched in filamentous actin: phagocytic cups, macropinosomes, lamellipodia, and other pseudopodia. In cells expressing green fluorescent protein (GFP)-tagged DAip1, the protein rapidly redistributes into newly formed cortical protrusions. Functions of DAip1 in vivo were assessed using null mutants generated by gene replacement, and by overexpressing DAip1. DAip1-null cells are impaired in growth and their rates of fluid-phase uptake, phagocytosis, and movement are reduced in comparison to wild-type rates. Cytokinesis is prolonged in DAip1-null cells and they tend to become multinucleate. On the basis of similar results obtained by DAip1 overexpression and effects of latrunculin-A treatment, we propose a function for DAip1 in the control of actin depolymerization in vivo, probably through interaction with cofilin. Our data suggest that DAip1 plays an important regulatory role in the rapid remodeling of the cortical actin mesh-work.