title: Observation of autophagosome maturation in the interferon-γ-primed and lipopolysaccharide-activated macrophages using a tandem fluorescent tagged LC3.
abstract: Macrophages are engaged in many essential host functions, and their activation is a dynamic process that results in diverse functional outcomes such as the potentiation of bactericidal activity and production of chemokines, cytokines, and mediators that coordinate the inflammatory response. This pro-inflammatory response is bimodal, comprising a "prime" event, classically through interferon-γ (IFN-γ), and a "trigger," such as lipopolysaccharide (LPS). Recently, autophagy, which is one of the major degradative pathways in eukaryotic cells, has been shown to play an important role in both IFN-γ-primed and LPS-activated macrophages. In this study, we sought to characterize the mechanisms of autophagy activation in primed and activated macrophages. To this end, we established a macrophage RAW 264.7 cell line that expressed high levels of a tandem fluorescently tagged LC3 (tfLC3) autophagy marker. By using this macrophage cell line, autophagosome formation was observed in both IFN-γ- and LPS-stimulated cells. Moreover, our data demonstrated that IFN-γ, but not LPS, facilitated autophagosome maturation to autophagolysosomes, suggesting that 2 distinct mechanisms regulating autophagy exist in IFN-γ-primed and LPS-activated macrophages.
authors.affiliation: School of Veterinary Science, College of Life, Environment, and Advanced Sciences, Osaka Prefecture University, 1-58 Rinku-Ourai Kita, Izumisano, Osaka 598-8531, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Fujiwara
authors.forename: Yui
authors.initials: Y
authors.lastname: Washi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Matsuzawa
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology*; D002478:Cells, Cultured; D003124:Colorimetry; D005453:Fluorescence; D007371:Interferon-gamma / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010588:Phagosomes / Q000502:physiology*
chemical_list: D008070:Lipopolysaccharides; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; D007371:Interferon-gamma
keywords: Autophagy; Interferon-γ; Lipopolysaccharide; Macrophage