title: Phospholipase C-related catalytically inactive protein participates in the autophagic elimination of Staphylococcus aureus infecting mouse embryonic fibroblasts.
abstract: Autophagy is an intrinsic host defense system that recognizes and eliminates invading bacterial pathogens. We have identified microtubule-associated protein 1 light chain 3 (LC3), a hallmark of autophagy, as a binding partner of phospholipase C-related catalytically inactive protein (PRIP) that was originally identified as an inositol trisphosphate-binding protein. Here, we investigated the involvement of PRIP in the autophagic elimination of Staphylococcus aureus in infected mouse embryonic fibroblasts (MEFs). We observed significantly more LC3-positive autophagosome-like vacuoles enclosing an increased number of S. aureus cells in PRIP-deficient MEFs than control MEFs, 3 h and 4.5 h post infection, suggesting that S. aureus proliferates in LC3-positive autophagosome-like vacuoles in PRIP-deficient MEFs. We performed autophagic flux analysis using an mRFP-GFP-tagged LC3 plasmid and found that autophagosome maturation is significantly inhibited in PRIP-deficient MEFs. Furthermore, acidification of autophagosomes was significantly inhibited in PRIP-deficient MEFs compared to the wild-type MEFs, as determined by LysoTracker staining and time-lapse image analysis performed using mRFP-GFP-tagged LC3. Taken together, our data show that PRIP is required for the fusion of S. aureus-containing autophagosome-like vacuoles with lysosomes, indicating that PRIP is a novel modulator in the regulation of the innate immune system in non-professional phagocytic host cells.
authors.affiliation: Department of Cellular and Molecular Pharmacology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Kae
authors.initials: K
authors.lastname: Harada-Hada
authors.affiliation: Department of Cellular and Molecular Pharmacology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Kana
authors.initials: K
authors.lastname: Harada
authors.affiliation: Department of Bacteriology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Fuminori
authors.initials: F
authors.lastname: Kato
authors.affiliation: Department of Bacteriology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Junzo
authors.initials: J
authors.lastname: Hisatsune
authors.affiliation: Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Isei
authors.initials: I
authors.lastname: Tanida
authors.affiliation: Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Michinaga
authors.initials: M
authors.lastname: Ogawa
authors.affiliation: Department of Cellular and Molecular Pharmacology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Asano
authors.affiliation: Department of Bacteriology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Sugai
authors.affiliation: Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Hirata
authors.affiliation: Department of Cellular and Molecular Pharmacology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanematsu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001343:Autophagy; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D007113:Immunity, Innate; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D010588:Phagosomes / Q000378:metabolism / Q000382:microbiology; D013203:Staphylococcal Infections / Q000276:immunology* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000502:physiology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; C496391:Plcl1 protein, mouse