Presence and regulation of insulin-regulated aminopeptidase in mouse macrophages

• Published in: Journal of the renin-angiotensin-aldosterone system Vol. 15; no. 4; pp. 466 - 479
• Main Authors: Nikolaou, Alexandros, Stijlemans, Benoit, Laoui, Damya, Schouppe, Elio, Tran, Huyen TT, Tourwé, Dirk, Chai, Siew Y, Vanderheyden, Patrick ML, Van Ginderachter, Jo A
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.12.2014
• Subjects: 3T3-L1 Cells; Animals; Cell Membrane - drug effects; Cell Membrane - metabolism; Cystinyl Aminopeptidase - deficiency; Cystinyl Aminopeptidase - genetics; Cystinyl Aminopeptidase - metabolism; Gene Expression Regulation - drug effects; Glucose - metabolism; Inflammation - pathology; Interferon-gamma - pharmacology; Intracellular Space - drug effects; Intracellular Space - metabolism; Lectins, C-Type - metabolism; Ligands; Lipopolysaccharides - pharmacology; Macrophage Activation - drug effects; Macrophages, Peritoneal - drug effects; Macrophages, Peritoneal - enzymology; Mannose-Binding Lectins - metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; NF-kappa B - metabolism; Phagocytosis - drug effects; Real-Time Polymerase Chain Reaction; Receptors, Cell Surface - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; insulin-regulated aminopeptidase; macrophage; IVDE77; Angiotensin IV; M1
• ISSN: 1470-3203; 1752-8976
• DOI: 10.1177/1470320313507621

Introduction: The insulin-regulated aminopeptidase (IRAP) is expressed in several cell types, where it is mainly located in specialized secretory endosomes that are quickly recruited to the cell surface upon cell type-specific activation. Here we describe for the first time the expression and subcellular distribution of IRAP in macrophages. Methods: IRAP mRNA expression, protein expression and presence at the cell surface was investigated by real-time polymerase chain reaction (PCR), Western blot and [3H]IVDE77 binding, respectively. Results: IRAP mRNA expression was increased by interferon-γ (IFN-γ) and lipopolysaccharide (LPS), but not by anti-inflammatory cytokines (interleukin (IL)-4, IL-10, transforming growth factor β (TGF-β)). IFN-γ increased [3H]IVDE77 binding steadily over time, while LPS quickly and transiently recruited IRAP to the cell surface. Combined stimulations with IFN-γ and LPS showed the same pattern as LPS alone. Latex particles also induced a transient recruitment of IRAP to the cell surface, but no difference was observed in phagocytic uptake between wild-type and IRAP–/– macrophages, suggesting that the enzymatic activity of IRAP is not required for the ingestion of particles. Conclusion: IRAP is more highly expressed in pro-inflammatory M1-activated macrophages and its presence at the cell surface is modulated upon exposure to IFN-γ, LPS or exogenous particles.