title: Exclusion of actin-binding protein p57/coronin-1 from bacteria-containing phagosomes in macrophages infected with Legionella.
abstract: Legionella pneumophila, the causative agent of Legionnaires' disease, is a human pathogen that multiplies within alveolar macrophages. L. pneumophila establishes specialized phagosomes in which it evades the host defense through largely unknown mechanisms. Here we analyzed the role of an actin-binding protein, p57/coronin-1, a member of the coronin protein family, during Legionella infection. On fluorescence microscopy, p57/coronin-1 and F-actin were found to be co-localized at the sites on the plasma membrane where L. pneumophila adhered to U937 human macrophage-like cells. The localization of p57/coronin-1 at the sites of bacterial adherence was inhibited by treatment with cytochalasin D (an inhibitor of actin polymerization), suggesting that p57/coronin-1 is involved in the actin-dependent uptake of L. pneumophila into U937 cells. In addition, we showed that p57/coronin-1 was excluded from phagosomes containing live L. pneumophila throughout the infection, whereas transient accumulation of p57/coronin-1 was observed on phagosomes containing Texas-Red-labeled opsonized zymosan (TROpZ) or heat-killed L. pneumophila at an early stage of phagocytosis. The exclusion of p57/coronin-1 from phagosomes containing live another Legionella species Legionella gratiana at an early stage of infection was also observed. Taken together, these results suggest that the endocytic pathways of live Legionella species are distinct from general phagocytic pathways, which lead to lysosomal degradation.
authors.affiliation: Laboratory of Microbiology and Immunology and the Global COE Program, University of Shizuoka School of Pharmaceutical Sciences, 52-1 Yada, Suruga-ku, Shizuoka, Shizuoka 422-8526, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Hayashi
authors.forename: Masaki
authors.initials: M
authors.lastname: Miyake
authors.forename: Takashi
authors.initials: T
authors.lastname: Fukui
authors.forename: Noriko
authors.initials: N
authors.lastname: Sugaya
authors.forename: Takashi
authors.initials: T
authors.lastname: Daimon
authors.forename: Saotomo
authors.initials: S
authors.lastname: Itoh
authors.forename: Teruaki
authors.initials: T
authors.lastname: Oku
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Tsuji
authors.forename: Satoshi
authors.initials: S
authors.lastname: Toyoshima
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Imai
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D003572:Cytochalasins / Q000378:metabolism; D005456:Fluorescent Dyes; D006801:Humans; D016952:Legionella pneumophila / Q000378:metabolism*; D007877:Legionnaires' Disease / Q000378:metabolism* / Q000382:microbiology; D008264:Macrophages / Q000378:metabolism* / Q000382:microbiology; D008840:Microfilament Proteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D010588:Phagosomes / Q000378:metabolism*; D014966:Xanthenes; D015054:Zymosan / Q000378:metabolism; D054378:Acetogenins
chemical_list: D015107:4-Butyrolactone; D000199:Actins; D002352:Carrier Proteins; D003572:Cytochalasins; D005456:Fluorescent Dyes; D008840:Microfilament Proteins; D014966:Xanthenes; D015054:Zymosan; C034037:F-actin-binding proteins; C438920:coronin acetogenin; D054378:Acetogenins; C034657:Texas red