title: Subcellular localization and role of lipin-1 in human macrophages.
abstract: The lipins have been described as metabolic enzymes that regulate lipid biosynthesis and also signaling processes by controlling the cellular concentration of bioactive lipids, phosphatidic acid, and diacylgycerol. In the present work we have studied the subcellular localization and role of lipin-1 in human monocyte-derived macrophages. Human macrophages express lipin-1 isoforms α and β. A transfected lipin-1α-enhanced GFP construct associates with membranes of cellular organelles that can be stained with Nile Red. Colocalization experiments with lipid droplet (LD)-specific proteins such as adipophilin/adipose differentiation-related protein/perilipin 2 or TIP47/perilipin 3 show that both proteins colocalize with lipin-1α in the same cellular structures. Reduction of the expression levels of lipin-1 by small interfering RNA technology does not impair triacylglycerol biosynthesis but reduces the size of LDs formed in response to oleic acid. In agreement with these data, peritoneal macrophages from animals that carry a mutation in the Lpin-1 gene (fld animals) also produce less and smaller LDs in response to oleic acid. Mass spectrometry determinations demonstrate that the fatty acid composition of triacylglycerol in isolated LDs from lipin-1-deficient cells differs from that of control cells. Moreover, activation of cytosolic group IVA phospholipase A(2)α, a proinflammatory enzyme that is also involved in LD biogenesis, is also compromised in lipin-1-deficient cells. Collectively, these data suggest that lipin-1 associates with LDs and regulates the activation of cytosolic group IVA phospholipase A(2)α in human monocyte-derived macrophages.
authors.affiliation: Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, 47003 Valladolid, Spain.
authors.forename: Martín
authors.initials: M
authors.lastname: Valdearcos
authors.forename: Esperanza
authors.initials: E
authors.lastname: Esquinas
authors.forename: Clara
authors.initials: C
authors.lastname: Meana
authors.forename: Luis
authors.initials: L
authors.lastname: Gil-de-Gómez
authors.forename: Carlos
authors.initials: C
authors.lastname: Guijas
authors.forename: Jesús
authors.initials: J
authors.lastname: Balsinde
authors.forename: María A
authors.initials: MA
authors.lastname: Balboa
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism; D054513:Group IV Phospholipases A2 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007425:Intracellular Membranes / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D050356:Lipid Metabolism; D008055:Lipids / Q000032:analysis; D008264:Macrophages / Q000201:enzymology / Q000378:metabolism*; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D019301:Oleic Acid / Q000494:pharmacology; D010078:Oxazines; D000070780:Perilipin-2; D000070796:Perilipin-3; D010711:Phosphatidate Phosphatase; D016133:Polymerase Chain Reaction; D011257:Pregnancy Proteins / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D014280:Triglycerides / Q000096:biosynthesis; D033921:Vesicular Transport Proteins
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008055:Lipids; D008565:Membrane Proteins; D009687:Nuclear Proteins; D010078:Oxazines; C000602982:PLIN2 protein, human; C038196:PLIN3 protein, human; D000070780:Perilipin-2; D000070796:Perilipin-3; C000602983:Plin2 protein, mouse; D011257:Pregnancy Proteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D014280:Triglycerides; D033921:Vesicular Transport Proteins; D019301:Oleic Acid; D054513:Group IV Phospholipases A2; C485999:LPIN1 protein, human; D010711:Phosphatidate Phosphatase; C044808:nile red