title: Adaptor protein SLAT modulates Fcgamma receptor-mediated phagocytosis in murine macrophages.
abstract: SLAT (SWAP-70-like adaptor protein of T cells) is an adaptor protein expressed in cells of the hematopoietic system. SLAT interacts with and alters the function of small GTPase Rac1 in fibroblasts. In these nonhematopoietic models, the SLAT-Rac interaction leads to changes in F-actin and causes cytoskeletal reorganization. In T cells, SLAT expression regulates the development of T helper cells through Cdc42- and Rac1-mediated activation of the NF-AT transcription factor. Here we show that SLAT is expressed in macrophages. Overexpression of SLAT in a macrophage cell line inhibits the IgG Fcgamma receptor-mediated phagocytic ability of THP1 cells. In bone marrow-derived macrophages, SLAT protein is recruited to the early phagosomes formed via Fcgamma receptor engagement. SLAT recruitment to the phagosome was most efficient when the macrophages express at least one isoform of Rac (Rac1 or Rac2), because SLAT recruitment was reduced in macrophages of Rac-deficient mice. Macrophages derived from animals lacking SLAT show an elevation in the rate of Fcgamma receptor-mediated phagocytosis. The absence of SLAT is associated with an increase in the amount of F-actin formed around these phagosomes as well as an increase in the amount of Rac1 protein recruited to the phagosome. Our results suggest that SLAT acts as a gatekeeper for the amount of Rac recruited to the phagosomes formed by Fcgamma receptor engagement and thus is able to regulate F-actin re-organization and consequently phagocytosis.
authors.affiliation: Program in Immunobiology and Cancer, Oklahoma Medical Research Foundation, and Department of Cell Biology, University of Oklahoma, Oklahoma City, Oklahoma 73104, USA.
authors.forename: Harshini
authors.initials: H
authors.lastname: Mehta
authors.forename: Michael
authors.initials: M
authors.lastname: Glogauer
authors.forename: Stephane
authors.initials: S
authors.lastname: Bécart
authors.forename: Amnon
authors.initials: A
authors.lastname: Altman
authors.forename: K Mark
authors.initials: KM
authors.lastname: Coggeshall
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D003599:Cytoskeleton / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D050778:NFATC Transcription Factors / Q000235:genetics / Q000378:metabolism; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010587:Phagocytosis / Q000502:physiology*; D010588:Phagosomes / Q000502:physiology*; D017452:Receptors, IgG / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D000097766:RAC2 GTP-Binding Protein
chemical_list: D000199:Actins; D004268:DNA-Binding Proteins; D020662:Guanine Nucleotide Exchange Factors; D050778:NFATC Transcription Factors; D009479:Neuropeptides; D009687:Nuclear Proteins; D017452:Receptors, IgG; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D000097766:RAC2 GTP-Binding Protein; C479750:DEF6 protein, human; C107953:RAC1 protein, human; C484602:Rac1 protein, mouse; C473249:Def6 protein, mouse