title: E3 ubiquitin ligase NKLAM is a macrophage phagosome protein and plays a role in bacterial killing.
abstract: Macrophages are a critically important component of the innate and adaptive immune systems. They are equipped with oxidative and non-oxidative mechanisms to kill ingested pathogens. Natural Killer Lytic-Associated Molecule (NKLAM) is an E3 ubiquitin ligase expressed in macrophages and natural killer cells. We show that NKLAM expression in macrophages was enhanced by Toll-like receptor agonists and pro-inflammatory cytokines. Using confocal microscopy, we found that NKLAM colocalized with ingested Escherichia coli. In assays using IgG-opsonized latex beads as targets, we demonstrated that NKLAM translocated to the phagosome early during maturation at a time that coincided with elevated levels of ubiquitinated phagosome proteins. In killing assays with bone marrow-derived macrophages from wild type and NKLAM-deficient mice, we found that NKLAM-deficient macrophages demonstrated less killing of E. coli than wild type macrophages. Collectively, our data show that NKLAM is a novel component of macrophage phagosomes and is involved in macrophage bactericidal functions.
authors.affiliation: Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO 63104, United States.
authors.forename: Donald W
authors.initials: DW
authors.lastname: Lawrence
authors.forename: Jacki
authors.initials: J
authors.lastname: Kornbluth
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D004926:Escherichia coli / Q000276:immunology* / Q000502:physiology; D005434:Flow Cytometry; D054884:Host-Pathogen Interactions / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D010587:Phagocytosis / Q000276:immunology; D010588:Phagosomes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000819:agonists / Q000276:immunology / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000276:immunology* / Q000378:metabolism
chemical_list: D008070:Lipopolysaccharides; D008565:Membrane Proteins; C120864:NK lytic-associated molecule; D051197:Toll-Like Receptor 4; D044767:Ubiquitin-Protein Ligases