Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 13 de 13
Filtrar
Mais filtros











Base de dados
Intervalo de ano de publicação
1.
Cell Metab ; 35(9): 1613-1629.e8, 2023 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-37572666

RESUMO

Hypothalamic gliosis associated with high-fat diet (HFD) feeding increases susceptibility to hyperphagia and weight gain. However, the body-weight-independent contribution of microglia to glucose regulation has not been determined. Here, we show that reducing microglial nuclear factor κB (NF-κB) signaling via cell-specific IKKß deletion exacerbates HFD-induced glucose intolerance despite reducing body weight and adiposity. Conversely, two genetic approaches to increase microglial pro-inflammatory signaling (deletion of an NF-κB pathway inhibitor and chemogenetic activation through a modified Gq-coupled muscarinic receptor) improved glucose tolerance independently of diet in both lean and obese rodents. Microglial regulation of glucose homeostasis involves a tumor necrosis factor alpha (TNF-α)-dependent mechanism that increases activation of pro-opiomelanocortin (POMC) and other hypothalamic glucose-sensing neurons, ultimately leading to a marked amplification of first-phase insulin secretion via a parasympathetic pathway. Overall, these data indicate that microglia regulate glucose homeostasis in a body-weight-independent manner, an unexpected mechanism that limits the deterioration of glucose tolerance associated with obesity.


Assuntos
Microglia , NF-kappa B , Humanos , Microglia/metabolismo , NF-kappa B/metabolismo , Obesidade/metabolismo , Peso Corporal/fisiologia , Glucose/metabolismo , Hipotálamo/metabolismo , Dieta Hiperlipídica
2.
Br J Anaesth ; 125(3): 298-307, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32624183

RESUMO

BACKGROUND: Postoperative cognitive decline (PCD) requires microglial activation. Voltage-gated Kv1.3 potassium channels are involved in microglial activation. We determined the role of Kv1.3 in PCD and the efficacy and safety of inhibiting Kv1.3 with phenoxyalkoxypsoralen-1 (PAP-1) in preventing PCD in a mouse model. METHODS: After institutional approval, we assessed whether Kv1.3-deficient mice (Kv1.3-/-) exhibited PCD, evidenced by tibial-fracture surgery-induced decline in aversive freezing behaviour, and whether PAP-1 could prevent PCD and postoperative neuroinflammation in PCD-vulnerable diet-induced obese (DIO) mice. We also evaluated whether PAP-1 altered either postoperative peripheral inflammation or tibial-fracture healing. RESULTS: Freezing behaviour was unaltered in postoperative Kv1.3-/- mice. In DIO mice, PAP-1 prevented postoperative (i) attenuation of freezing behaviour (54 [17.3]% vs 33.4 [12.7]%; P=0.03), (ii) hippocampal microglial activation by size (130 [31] pixels vs 249 [49]; P<0.001) and fluorescence intensity (12 000 [2260] vs 20 800 [5080] absorbance units; P<0.001), and (iii) hippocampal upregulation of interleukin-6 (IL-6) (14.9 [5.7] vs 25.6 [10.4] pg mg-1; P=0.011). Phenoxyalkoxypsoralen-1 neither affected surgery-induced upregulation of plasma IL-6 nor cartilage and bone components of the surgical fracture callus. CONCLUSIONS: Microglial-mediated PCD requires Kv1.3 activity, determined by genetic and pharmacological targeting approaches. Phenoxyalkoxypsoralen-1 blockade of Kv1.3 prevented surgery-induced hippocampal microglial activation and neuroinflammation in mice known to be vulnerable to PCD. Regarding perioperative safety, these beneficial effects of PAP-1 treatment occurred without impacting fracture healing. Kv1.3 blockers, currently undergoing clinical trials for other conditions, may represent an effective and safe intervention to prevent PCD.


Assuntos
Disfunção Cognitiva/prevenção & controle , Encefalite/prevenção & controle , Canal de Potássio Kv1.3/antagonistas & inibidores , Complicações Pós-Operatórias/prevenção & controle , Cicatrização/fisiologia , Animais , Modelos Animais de Doenças , Camundongos
3.
J Clin Invest ; 129(10): 4124-4137, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-31265435

RESUMO

Pancreatic beta cells (ß-cells) differentiate during fetal life, but only postnatally acquire the capacity for glucose-stimulated insulin secretion (GSIS). How this happens is not clear. In exploring what molecular mechanisms drive the maturation of ß-cell function, we found that the control of cellular signaling in ß-cells fundamentally switched from the nutrient sensor target of rapamycin (mTORC1) to the energy sensor 5'-adenosine monophosphate-activated protein kinase (AMPK), and that this was critical for functional maturation. Moreover, AMPK was activated by the dietary transition taking place during weaning, and this in turn inhibited mTORC1 activity to drive the adult ß-cell phenotype. While forcing constitutive mTORC1 signaling in adult ß-cells relegated them to a functionally immature phenotype with characteristic transcriptional and metabolic profiles, engineering the switch from mTORC1 to AMPK signaling was sufficient to promote ß-cell mitochondrial biogenesis, a shift to oxidative metabolism, and functional maturation. We also found that type 2 diabetes, a condition marked by both mitochondrial degeneration and dysregulated GSIS, was associated with a remarkable reversion of the normal AMPK-dependent adult ß-cell signature to a more neonatal one characterized by mTORC1 activation. Manipulating the way in which cellular nutrient signaling pathways regulate ß-cell metabolism may thus offer new targets to improve ß-cell function in diabetes.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Células Secretoras de Insulina/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Transdução de Sinais , Proteínas Quinases Ativadas por AMP/genética , Animais , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patologia , Secreção de Insulina/genética , Células Secretoras de Insulina/patologia , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Camundongos , Camundongos Knockout
4.
Nat Metab ; 1(3): 314-320, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-32694719

RESUMO

Tissue-resident myeloid cells initiate local inflammation in response to infectious or injurious stimuli. Sixteen years ago, macrophages in the adipose tissue (ATMs) were shown to undergo a form of activation in response to diet-induced obesity, thus leading to the conclusion that these macrophages sense a type of pro-inflammatory injury. ATMs are now known to be central to adipose tissue development, plasticity, maintenance and function. Indeed, their involvement in obesity may represent hijacking of these functions. More recently, microglia, 'CNS macrophages', have been shown to accumulate and undergo activation in response to dietary excess in the mediobasal hypothalamus (MBH), and early studies have implicated these cells as injury-responsive mediators of hypothalamic dysfunction. However, microglia are amazingly diverse cells now known to have moment-to-moment sensory functions and to communicate with neighbouring neurons to maintain and shape brain circuitry. Here, we build on this view, detailing our rapidly evolving understanding of microglial heterogeneity in the MBH and their roles as nutrient and environmental sensors. We propose that microglia, instead of simply responding to diet-induced damage, act as critical metabolic regulators that may coordinate a complex cellular network in the MBH. Understanding their roles in hypothalamic development and function should reveal unexpected mechanistic information relevant to important diseases such as obesity.


Assuntos
Hipotálamo/fisiologia , Microglia/metabolismo , Tecido Adiposo/metabolismo , Animais , Dieta , Metabolismo Energético , Humanos , Hipotálamo/citologia , Hipotálamo/metabolismo , Macrófagos/metabolismo , Células Mieloides/metabolismo
5.
Cell Metab ; 26(1): 185-197.e3, 2017 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-28683286

RESUMO

Dietary excess triggers accumulation of pro-inflammatory microglia in the mediobasal hypothalamus (MBH), but the components of this microgliosis and its metabolic consequences remain uncertain. Here, we show that microglial inflammatory signaling determines the immunologic response of the MBH to dietary excess and regulates hypothalamic control of energy homeostasis in mice. Either pharmacologically depleting microglia or selectively restraining microglial NF-κB-dependent signaling sharply reduced microgliosis, an effect that includes prevention of MBH entry by bone-marrow-derived myeloid cells, and greatly limited diet-induced hyperphagia and weight gain. Conversely, forcing microglial activation through cell-specific deletion of the negative NF-κB regulator A20 induced spontaneous MBH microgliosis and cellular infiltration, reduced energy expenditure, and increased both food intake and weight gain even in absence of a dietary challenge. Thus, microglial inflammatory activation, stimulated by dietary excess, orchestrates a multicellular hypothalamic response that mediates obesity susceptibility, providing a mechanistic rationale for non-neuronal approaches to treat metabolic diseases.


Assuntos
Regulação do Apetite , Metabolismo Energético , Hipotálamo/imunologia , Inflamação/imunologia , Microglia/imunologia , Obesidade/imunologia , Animais , Hiperfagia/imunologia , Hiperfagia/metabolismo , Hiperfagia/fisiopatologia , Hipotálamo/metabolismo , Hipotálamo/fisiopatologia , Inflamação/metabolismo , Inflamação/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Microglia/patologia , Células Mieloides/imunologia , Células Mieloides/metabolismo , Células Mieloides/patologia , NF-kappa B/imunologia , NF-kappa B/metabolismo , Obesidade/metabolismo , Obesidade/fisiopatologia , Transdução de Sinais
6.
JCI Insight ; 2(7): e91229, 2017 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-28405620

RESUMO

Surgery can induce cognitive decline, a risk that increases with advancing age. In rodents, postoperative cognitive decline (POCD) is associated with the inflammatory activation of hippocampal microglia. To examine the role of microglia in POCD, we inhibited the colony-stimulating factor 1 receptor (CSF1R) in adult mice, effectively depleting CNS microglia. Surgical trauma (tibial fracture) reduced the ability of mice to remember a conditioned response learned preoperatively, a deficit more pronounced and persistent in mice with diet-induced obesity (DIO). Whereas microglial depletion by itself did not affect learning or memory, perioperative microglial depletion remarkably protected mice, including those with DIO, from POCD. This protection was associated with reduced hippocampal levels of inflammatory mediators, abrogation of hippocampal recruitment of CCR2+ leukocytes, and higher levels of circulating inflammation-resolving factors. Targeting microglia may thus be a viable strategy to mitigate the development of POCD, particularly in those with increased vulnerability.


Assuntos
Disfunção Cognitiva/fisiopatologia , Inflamação/fisiopatologia , Microglia/citologia , Complicações Pós-Operatórias/psicologia , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/antagonistas & inibidores , Animais , Anti-Inflamatórios não Esteroides/farmacologia , Disfunção Cognitiva/etiologia , Modelos Animais de Doenças , Medo , Hipocampo/citologia , Hipocampo/fisiopatologia , Lipoxinas/sangue , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/patologia , Neurônios/citologia , Neurônios/patologia , Compostos Orgânicos/farmacologia , Receptores CCR2/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fraturas da Tíbia/cirurgia
7.
Biochim Biophys Acta ; 1861(9 Pt A): 1083-1095, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27317983

RESUMO

Adipogenesis is the process of differentiation of immature mesenchymal stem cells into adipocytes. Elucidation of the mechanisms that regulate adipocyte differentiation is key for the development of novel therapies for the control of obesity and related comorbidities. Cytosolic group IVA phospholipase A2 (cPLA2α) is the pivotal enzyme in receptor-mediated arachidonic acid (AA) mobilization and attendant eicosanoid production. Using primary multipotent cells and cell lines predetermined to become adipocytes, we show here that cPLA2α displays a proadipogenic function that occurs very early in the adipogenic process. Interestingly, cPLA2α levels decrease during adipogenesis, but cPLA2α-deficient preadipocytes exhibit a reduced capacity to differentiate into adipocytes, which affects early and terminal adipogenic transcription factors. Additionally, the absence of the phospholipase alters proliferation and cell-cycle progression that takes place during adipogenesis. Preconditioning of preadipocytes with AA increases the adipogenic capacity of these cells. Moreover, animals deficient in cPLA2α show resistance to obesity when fed a high fat diet that parallels changes in the expression of adipogenic transcription factors of the adipose tissue. Collectively, these results show that preadipocyte cPLA2α activation is a hitherto unrecognized factor for adipogenesis in vitro and in vivo.


Assuntos
Adipogenia/genética , Diferenciação Celular/genética , Fosfolipases A2 do Grupo IV/genética , Obesidade/genética , Células 3T3-L1 , Adipócitos/metabolismo , Animais , Citosol/enzimologia , Dieta Hiperlipídica , Fosfolipases A2 do Grupo IV/metabolismo , Metabolismo dos Lipídeos/genética , Células-Tronco Mesenquimais/enzimologia , Células-Tronco Mesenquimais/metabolismo , Camundongos , Obesidade/patologia
8.
Cell Rep ; 14(11): 2611-23, 2016 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-26971994

RESUMO

Diets rich in saturated fatty acids (SFAs) produce a form of tissue inflammation driven by "metabolically activated" macrophages. We show that SFAs, when in excess, induce a unique transcriptional signature in both mouse and human macrophages that is enriched by a subset of ER stress markers, particularly IRE1α and many adaptive downstream target genes. SFAs also activate the NLRP3 inflammasome in macrophages, resulting in IL-1ß secretion. We found that IRE1α mediates SFA-induced IL-1ß secretion by macrophages and that its activation by SFAs does not rely on unfolded protein sensing. We show instead that the ability of SFAs to stimulate either IRE1α activation or IL-1ß secretion can be specifically reduced by preventing their flux into phosphatidylcholine (PC) or by increasing unsaturated PC levels. Thus, IRE1α is an unrecognized intracellular PC sensor critical to the process by which SFAs stimulate macrophages to secrete IL-1ß, a driver of diet-induced tissue inflammation.


Assuntos
Endorribonucleases/metabolismo , Ácidos Graxos/farmacologia , Inflamassomos/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Animais , Células da Medula Óssea/citologia , Células Cultivadas , Dieta , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Humanos , Interleucina-1beta/metabolismo , Lipopolissacarídeos/toxicidade , Macrófagos/citologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fosfatidilcolinas/metabolismo , Análise de Componente Principal , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais/efeitos dos fármacos , Proteína 1 de Ligação a X-Box/genética , Proteína 1 de Ligação a X-Box/metabolismo
9.
J Immunol ; 193(9): 4614-22, 2014 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-25252959

RESUMO

Lipin-1 is a Mg(2+)-dependent phosphatidic acid phosphatase involved in the de novo synthesis of phospholipids and triglycerides. Using macrophages from lipin-1-deficient animals and human macrophages deficient in the enzyme, we show in this work that this phosphatase acts as a proinflammatory mediator during TLR signaling and during the development of in vivo inflammatory processes. After TLR4 stimulation lipin-1-deficient macrophages showed a decreased production of diacylglycerol and activation of MAPKs and AP-1. Consequently, the generation of proinflammatory cytokines like IL-6, IL-12, IL-23, or enzymes like inducible NO synthase and cyclooxygenase 2, was reduced. In addition, animals lacking lipin-1 had a faster recovery from endotoxin administration concomitant with a reduced production of harmful molecules in spleen and liver. These findings demonstrate an unanticipated role for lipin-1 as a mediator of macrophage proinflammatory activation and support a critical link between lipid biosynthesis and systemic inflammatory responses.


Assuntos
Lipídeos/biossíntese , Ativação de Macrófagos/imunologia , Macrófagos/imunologia , Macrófagos/metabolismo , Proteínas Nucleares/genética , Fosfatidato Fosfatase/genética , Receptores Toll-Like/metabolismo , Animais , Análise por Conglomerados , Citocinas/metabolismo , Endotoxinas/administração & dosagem , Feminino , Expressão Gênica , Perfilação da Expressão Gênica , Humanos , Inflamação/genética , Inflamação/imunologia , Mediadores da Inflamação/metabolismo , Ativação de Macrófagos/genética , Masculino , Camundongos , Camundongos Knockout , Proteínas Nucleares/deficiência , Proteínas Nucleares/metabolismo , Fosfatidato Fosfatase/deficiência , Fosfatidato Fosfatase/metabolismo , Transdução de Sinais , Receptores Toll-Like/agonistas , Transcriptoma
10.
J Biol Chem ; 287(14): 10894-904, 2012 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-22334674

RESUMO

Lipin-2 is a member of the lipin family of enzymes, which are key effectors in the biosynthesis of lipids. Mutations in the human lipin-2 gene are associated with inflammatory-based disorders; however, the role of lipin-2 in cells of the immune system remains obscure. In this study, we have investigated the role of lipin-2 in the proinflammatory action of saturated fatty acids in murine and human macrophages. Depletion of lipin-2 promotes the increased expression of the proinflammatory genes Il6, Ccl2, and Tnfα, which depends on the overstimulation of the JNK1/c-Jun pathway by saturated fatty acids. In contrast, overexpression of lipin-2 reduces the release of proinflammatory factors. Metabolically, the absence of lipin-2 reduces the cellular content of triacylglycerol in saturated fatty acid-overloaded macrophages. Collectively, these studies demonstrate a protective role for lipin-2 in proinflammatory signaling mediated by saturated fatty acids that occurs concomitant with an enhanced cellular capacity for triacylglycerol synthesis. The data provide new insights into the role of lipin-2 in human and murine macrophage biology and may open new avenues for controlling the fatty acid-related low grade inflammation that constitutes the sine qua non of obesity and associated metabolic disorders.


Assuntos
Ácidos Graxos/farmacologia , Macrófagos/citologia , Macrófagos/efeitos dos fármacos , Proteínas Nucleares/metabolismo , Fosfatidato Fosfatase/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Linhagem Celular , Citocinas/biossíntese , Ativação Enzimática/efeitos dos fármacos , Ácidos Graxos/metabolismo , Humanos , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Macrófagos/metabolismo , Camundongos , Monócitos/citologia , Proteínas Nucleares/deficiência , Fosfatidato Fosfatase/deficiência , Fator de Transcrição AP-1/metabolismo , Triglicerídeos/metabolismo , Regulação para Cima/efeitos dos fármacos
11.
J Immunol ; 186(10): 6004-13, 2011 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-21478406

RESUMO

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 ß. 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.


Assuntos
Fosfolipases A2 do Grupo IV/metabolismo , Macrófagos/metabolismo , Proteínas Nucleares/metabolismo , Animais , Proteínas de Ligação a DNA/metabolismo , Fosfolipases A2 do Grupo IV/genética , Humanos , Immunoblotting , Membranas Intracelulares/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Metabolismo dos Lipídeos , Lipídeos/análise , Macrófagos/enzimologia , Espectrometria de Massas , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Mutação , Proteínas Nucleares/genética , Ácido Oleico/farmacologia , Oxazinas , Perilipina-2 , Perilipina-3 , Fosfatidato Fosfatase , Reação em Cadeia da Polimerase , Proteínas da Gravidez/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , RNA Interferente Pequeno , Triglicerídeos/biossíntese , Proteínas de Transporte Vesicular
12.
J Lipid Res ; 51(2): 388-99, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19717620

RESUMO

Group IVA cytosolic phospholipase A(2)alpha (cPLA(2)alpha) plays a role in the microbicidal machinery of immune cells by translocating to phagosomes to initiate the production of antimicrobial eicosanoids. In this work, we have studied the involvement of the cationic cluster of cPLA(2)alpha (Lys(488)/Lys(541)/Lys(543)/Lys(544)) in the translocation of the enzyme to the phagosomal cup in human macrophages responding to opsonized zymosan. Phagocytosis was accompanied by an increased mobilization of free arachidonic acid, which was strongly inhibited by pyrrophenone. In transfected cells, a catalytically active enhanced green fluorescent protein-cPLA(2)alpha translocated to the phagocytic cup, which was corroborated by frustrated phagocytosis experiments using immunoglobulin G-coated plates. However, a cPLA(2)alpha mutant in the polybasic cluster that cannot bind the anionic phospholipid phosphatidylinositol 4, 5-bisphosphate (PIP(2)) did not translocate to the phagocytic cup. Moreover, an enhanced yellow fluorescent protein (EYFP)-cPLA(2)alpha and an enhanced cyan fluorescent protein-pleckstrin homology (PH) domain of the phospholipase Cdelta1 (PLCdelta(1)) construct that specifically recognizes endogenous PIP(2) in the cells both localized at the same sites on the phagosome. High cellular expression of the PH domain inhibited EYFP-cPLA(2)alpha translocation. On the other hand, group V-secreted phospholipase A(2) and group VIA calcium-independent phospholipase A(2) were also studied, but the results indicated that neither of these translocated to the phagosome. Collectively, these data indicate that the polybasic cluster of cPLA(2)alpha (Lys(488)/Lys(541)/Lys(543)/Lys(544)) regulates the subcellular localization of the enzyme in intact cells under physiologically relevant conditions.


Assuntos
Fosfolipases A2 do Grupo IV/química , Fosfolipases A2 do Grupo IV/metabolismo , Lisina , Macrófagos/citologia , Macrófagos/metabolismo , Fagossomos/metabolismo , Domínio Catalítico , Ativação Enzimática/efeitos dos fármacos , Proteínas de Fluorescência Verde/metabolismo , Fosfolipases A2 do Grupo IV/genética , Humanos , Mutação , Fagocitose , Transporte Proteico , Zimosan/metabolismo , Zimosan/farmacologia
13.
J Immunol ; 183(4): 2767-74, 2009 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-19625654

RESUMO

Eicosanoids are a broad family of lipids that play a critical role in host defense against bacterial and fungal infections. The first enzyme in the metabolic pathway for the generation of eicosanoids is group IVA phospholipase A(2), also known as cytosolic phospholipase A(2)alpha (cPLA(2)alpha). During phagocytosis, cPLA(2)alpha has been found to translocate to the phagosome, although the molecular mechanism involved in such a translocation has not been elucidated. By using enhanced GFP-tagged proteins we show in this work that a nonphosphorylatable cPLA(2)alpha mutant (S505A) does not translocate to the phagosomes, but a mutant that mimics phosphorylation on Ser(505) (S505E) does it so readily. During phagocytosis, endogenous cPLA(2)alpha is phosphorylated at Ser(505), and inhibitors of JNK, but not of other related kinases such as p38 or the extracellular-regulated kinases 1 and 2, completely block such a phosphorylation. Inhibition of JNK activity also inhibits the translocation of cPLA(2)alpha to phagosomal membranes, as well as arachidonic acid release to the extracellular medium. Moreover, the S505E mutant makes the enzyme refractory to JNK inhibition, translocating normally to phagosomal membranes. Collectively, these data support a key role for JNK-mediated cPLA(2)alpha phosphorylation at Ser(505) in the sequence of events leading to translocation and activation of the enzyme to phagosomal membranes in human macrophages.


Assuntos
Fosfolipases A2 do Grupo IV/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/fisiologia , Macrófagos/metabolismo , Fagossomos/metabolismo , Células Cultivadas , Eicosanoides/biossíntese , Ativação Enzimática/imunologia , Humanos , Macrófagos/enzimologia , Macrófagos/imunologia , Fagocitose/imunologia , Fagossomos/enzimologia , Fagossomos/imunologia , Fosforilação , Ligação Proteica/imunologia , Transporte Proteico/imunologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA