RESUMO
The aim of this study was to clarify the characteristics of lifestyle and health awareness according to dietary diversity in a Japanese worksite population. The participants were 1,312 men and women aged 20 to 63 years who were living in Tokushima Prefecture, Japan during the period 2012-2013. We obtained anthropometric data and information on lifestyle characteristics using a self-administered questionnaire. Dietary intake was assessed using a food frequency questionnaire, and dietary diversity was determined using the Quantitative Index for Dietary Diversity (QUANTIDD). The characteristics of lifestyle and health awareness according to quartiles of the QUANTIDD score were assessed using the chi-square test and a general linear model. The higher the QUANTIDD score was, the larger were the proportions of participants who knew the appropriate amount of dietary intake and participants who referred to nutritional component information when choosing andâ/âor buying food. Among participants with higher QUANTIDD scores, the proportion of participants who considered their current diet was good was high in women, whereas the proportion of participants who wanted to improve their diet in the future was high in men. Those results indicate that higher dietary diversity was related to better characteristics of lifestyle and awareness of health. J. Med. Invest. 67 : 255-264, August, 2020.
Assuntos
Dieta , Estilo de Vida , Adulto , Conscientização , Estudos Transversais , Feminino , Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
BACKGROUND AND OBJECTIVES: The aim of this study was to determine the associations of dietary diversity with prevalences of allergic diseases. METHODS AND STUDY DESIGN: The participants were 1,317 men and women aged 20 to 63 years who were living in Tokushima Prefecture, Japan during the period 2012-2013. We obtained anthropometric data and information on lifestyle characteristics and current medical histories of allergic diseases using a self-administered questionnaire. Dietary intake was assessed using a food frequency questionnaire, and dietary diversity was determined using the Quantitative Index for Dietary Diversity (QUANTIDD). The ORs and 95% CIs for each of the allergic diseases with a 1 standard deviation (SD) increase in the QUANTIDD score were estimated, controlling for age, family history of allergic diseases, education, smoking, drinking, physical activity, energy intake and BMI. RESULTS: Higher dietary diversity showed significant inverse dose-response relationships with allergic diseases and allergic rhinitis in women. Multivariate-adjusted ORs (95% CI) for allergic diseases and allergic rhinitis with 1 SD increase in the QUANTIDD score were 0.77 (95% CI: 0.60-0.98, p=0.037) and 0.69 (95% CI: 0.53-0.90, p=0.007), respectively, in women. There were no significant associations between dietary diversity and allergic diseases in men. CONCLUSIONS: The results indicate that there is an inverse association between higher dietary diversity and allergic rhinitis in Japanese female workers.
Assuntos
Asma/epidemiologia , Dermatite Atópica/epidemiologia , Dieta/normas , Alimentos/classificação , Rinite Alérgica/epidemiologia , Adulto , Estudos Transversais , Feminino , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Adulto JovemRESUMO
BACKGROUND AND OBJECTIVES: The aim of this study was to determine the associations of intake of soy products and isoflavones with allergic diseases. METHODS AND STUDY DESIGN: We conducted a cross-sectional study in 1437 participants (aged 20-64 years) who were living in Tokushima Prefecture, Japan during the period 2010- 2011. We obtained anthropometric data and information on life style characteristics including dietary intake and current medical histories of allergic diseases using a structural self-administered questionnaire. Multiple logistic regression models were used to assess the associations of soy products and isoflavones with allergic diseases after controlling for age, family history of allergic diseases, smoking, drinking, physical activity, energy intake, BMI and dietary factors. RESULTS: Intake of soy products showed significant inverse dose-response relationships with allergic rhinitis. The third quartile for soy products had an adjusted OR of 0.56 (95% CI: 0.35-0.91) compared to the reference group (first quartile), though intake of soy products showed no dose-response relationship with atopic dermatitis. Intake of soy isoflavones showed a significant inverse dose-response relationship with atopic dermatitis, though the association between intake of soy isoflavones and atopic dermatitis was U-shaped after adjustments for potential confounders. On the other hand, the associations between intake of soy isoflavones and other allergic diseases were not significant. CONCLUSIONS: The results indicate that higher intake of soy products is associated with reduced risk of allergic rhinitis in Japanese workers. Furthermore, moderate intake amounts of soy products and soy isoflavones are associated with inverse risk of atopic dermatitis.
Assuntos
Asma/epidemiologia , Dermatite Atópica/epidemiologia , Glycine max/imunologia , Hipersensibilidade/epidemiologia , Rinite Alérgica/epidemiologia , Alimentos de Soja/efeitos adversos , Adulto , Asma/imunologia , Dermatite Atópica/imunologia , Feminino , Humanos , Isoflavonas/administração & dosagem , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Razão de Chances , Fatores de RiscoRESUMO
Epidemiological investigations have shown that consumption of soybeans or soy foods reduces the risk of the development of cardiovascular disease, cancer and osteoporosis. The aim of this study was to determine the associations between different soy foods and inflammatory markers, including high-sensitivity C-reactive protein (hs-CRP), interleukin (IL)-6, and IL-18, in Japanese workers. The cross-sectional study included 1,426 Japanese workers (1,053 men and 373 women) aged 20 to 64 years. Intake of 12 soy foods was estimated by a validated food frequency questionnaire. Associations of total soy foods, fermented soy food, non-fermented soy food, soy isoflavone with hs-CRP, IL-6, and IL-18 levels were examined by general linear model regression analysis. We found that total fermented soy food intake was inversely associated with multivariable-adjusted geometric concentration of IL-6 in men (Q1:1.03 pg/mL, Q5:0.94 pg /mL;P for trend = 0.031). Furthermore, it was shown that IL-6 concentrations were inversely associated with miso intake (ß = -0.068;p = 0.034) and soy sauce intake in men (ß = -0.074;p = 0.018). This study suggests that intake of total fermented soy food, miso and soy sauce be associated with IL-6 concentrations in Japanese men. J. Med. Invest. 65:74-80, February, 2018.
Assuntos
Proteína C-Reativa/análise , Dieta , Interleucina-18/sangue , Interleucina-6/sangue , Alimentos de Soja , Adulto , Biomarcadores , Feminino , Fermentação , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Type 2 diabetes (T2D) is characterized by decreased insulin sensitivity and higher concentrations of free fatty acids (FFAs) in plasma. Among FFAs, saturated fatty acids (SFAs), such as palmitate, have been suggested to promote inflammatory responses. Although many epidemiological studies have shown a link between periodontitis and T2D, little is known about the clinical significance of SFAs in periodontitis. In this study, we showed that gingival fibroblasts have cell-surface expression of CD36, which is also known as FAT/fatty acid translocase. Moreover, CD36 expression was increased in gingival fibroblasts of high-fat diet-induced T2D model mice, compared with gingival fibroblasts of mice fed a normal diet. DNA microarray analysis revealed that palmitate increased mRNA expression of pro-inflammatory cytokines and chemokines in human gingival fibroblasts (HGF). Consistent with these results, we confirmed that palmitate-induced interleukin (IL)-6, IL-8, and CXCL1 secretion in HGF, using a cytokine array and ELISA. SFAs, but not an unsaturated fatty acid, oleate, induced IL-8 production. Docosahexaenoic acid (DHA), which is one of the omega-3 polyunsaturated fatty acids, significantly suppressed palmitate-induced IL-6 and IL-8 production. Treatment of HGF with a CD36 inhibitor also inhibited palmitate-induced pro-inflammatory responses. Finally, we demonstrated that Porphyromonas gingivalis (P.g.) lipopolysaccharide and heat-killed P.g. augmented palmitate-induced chemokine secretion in HGF. These results suggest a potential link between SFAs in plasma and the pathogenesis of periodontitis.
Assuntos
Diabetes Mellitus Tipo 2/complicações , Fibroblastos/efeitos dos fármacos , Gengiva/efeitos dos fármacos , Ácido Palmítico/farmacologia , Periodontite/etiologia , Animais , Antígenos CD36/metabolismo , Linhagem Celular Tumoral , Citocinas/genética , Citocinas/metabolismo , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/genética , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Fibroblastos/metabolismo , Fibroblastos/patologia , Regulação da Expressão Gênica , Gengiva/metabolismo , Gengiva/patologia , Humanos , Mediadores da Inflamação/metabolismo , Lipopolissacarídeos/farmacologia , Masculino , Camundongos Endogâmicos C57BL , Ácido Palmítico/sangue , Periodontite/sangue , Periodontite/genética , Periodontite/patologia , Porphyromonas gingivalis , Fatores de TempoRESUMO
Insulin stimulates glucose transporter 4 (GLUT4) vesicle recruitment from its intracellular storage site to the plasma membrane. Cysteine string protein 1 (CSP1) is a SNARE-binding protein involved in the vesicular trafficking of neurotransmitters and other exocytic processes. In this study, we investigated the involvement of CSP1 in insulin-dependent GLUT4 recruitment in 3T3-L1 adipocytes. Over-expression of wild-type CSP1 led to attenuated insulin-stimulated glucose uptake without any change in GLUT4 content in the plasma membrane, rather it inhibits docking by blocking the association of VAMP2 with syntaxin 4. In contrast, knockdown of CSP1 enhanced insulin-stimulated glucose uptake. The mRNA and protein expression of CSP1 was elevated in 3T3-L1 adipocytes in insulin resistant states caused by high levels of palmitate and chronic insulin exposure. Taken together, the results of this study suggest that CSP1 is involved in insulin resistance by interrupting GLUT4 vesicle docking with the plasma membrane.
Assuntos
Transportador de Glucose Tipo 4/metabolismo , Proteínas de Choque Térmico HSP40/metabolismo , Resistência à Insulina/fisiologia , Proteínas de Membrana/metabolismo , Células 3T3-L1 , Adipócitos/metabolismo , Animais , Membrana Celular/metabolismo , Técnicas de Silenciamento de Genes , Proteínas de Choque Térmico HSP40/antagonistas & inibidores , Proteínas de Choque Térmico HSP40/genética , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/genética , Camundongos , Proteínas Qa-SNARE/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Regulação para Cima , Proteína 2 Associada à Membrana da Vesícula/metabolismoRESUMO
Current diagnostic tests such as glycemic indicators have limitations for early detection of impaired glucose tolerance (IGT), which leads to diabetes. Oxidative stress induced by various oxidants in a random and destructive manner is considered to play an important role in the pathophysiology of a number of human disorders and diseases such as impaired glucose tolerance. We have developed an improved method for the measurement of in vivo lipid peroxidation, where the presence of 8-iso-prostaglandin F2α (8-iso-PGF2α), hydroxyoctadecadienoic acids (HODEs), hydroxyeicosatetraenoic acids (HETEs), and 7-hydroxycholesterol (7-OHCh), as well as their parent molecules, linoleic acid (LA) and cholesterol (Ch), was determined by performing LC-MS/MS (for 8-iso-PGF2α, HODE, and HETE) and GC-MS (for 7-OHCh, LA, and Ch) after reduction with triphenyl phosphine and saponification by potassium hydroxide. We then applied this method to volunteers (nâ=â57), including normal type (nâ=â43), "high-normal" (fasting plasma glucose, 100-109 mg/dL, nâ=â7), pre-diabetic type (IGT, nâ=â5), and diabetic type (nâ=â2) subjects who are diagnosed by performing oral glucose tolerance tests (OGTTs). Several biomarkers in plasma, such as insulin, leptin, adiponectin, interleukin-6, tumor necrosis factor-α, high sensitivity-C-reactive protein, HbA1c, and glucose levels were measured during OGTT. We found that the fasting levels of (10- and 12-(Z,E)- HODE)/LA increased significantly with increasing levels of HbA1c and glucose during OGTT and with insulin secretion and resistance index. In conclusion, 10- and 12-(Z,E)-HODE may be prominent biomarkers for the early detection of IGT and "high-normal" type without OGTT.
Assuntos
Biomarcadores/sangue , Diabetes Mellitus Tipo 2/diagnóstico , Ácidos Graxos Insaturados/sangue , Ácidos Linoleicos/sangue , Oxigênio Singlete/metabolismo , Adipocinas/sangue , Adulto , Diabetes Mellitus Tipo 2/sangue , Diagnóstico Precoce , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Teste de Tolerância a Glucose , Humanos , Masculino , Pessoa de Meia-Idade , Estresse OxidativoRESUMO
Serotonin (5-hydroxytryptamine, 5-HT) was found to be elevated in the serum of diabetic patients. In this study, we investigate the mechanism of insulin desensitization caused by 5-HT. In 3T3-L1 adipocytes, 5-HT treatment induced the translocation of insulin receptor substrate-1 (IRS-1) from low density microsome (LDM), the important intracellular compartment for its functions, to cytosol, inducing IRS-1 ubiquitination and degradation. Moreover, inhibition of 5-HT-stimulated Akt activation by either ketanserin (a specific 5-HT2A receptor antagonist) or knocking-down the expression of 5-HT2A receptor promoted 5-HT-stimulated IRS-1 dissociation from 14-3-3ß in LDM, leading to drastic ubiquitination. Interestingly, sarpogrelate, another antagonist of 5-HT2A receptor, protected IRS-1 from degradation through activation of Akt. This implicates the importance of Akt activation in extending IRS-1 life span through maintaining their optimal sub-location into adipocytes. Taken together, this study suggest that activation of Akt may be able to compensate the adverse effects of 5-HT by stabilizing IRS-1 in LDM.
Assuntos
Adipócitos Brancos/metabolismo , Proteínas Substratos do Receptor de Insulina/metabolismo , Resistência à Insulina , Proteínas Proto-Oncogênicas c-akt/agonistas , Receptor 5-HT2A de Serotonina/metabolismo , Agonistas do Receptor 5-HT2 de Serotonina/metabolismo , Serotonina/metabolismo , Proteínas 14-3-3/metabolismo , Células 3T3-L1 , Adipócitos Brancos/efeitos dos fármacos , Animais , Citosol/efeitos dos fármacos , Citosol/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Microssomos/efeitos dos fármacos , Microssomos/metabolismo , Estabilidade Proteica/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , Proteólise/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Interferência de RNA , Receptor 5-HT2A de Serotonina/química , Receptor 5-HT2A de Serotonina/genética , Serotonina/efeitos adversos , Serotonina/química , Agonistas do Receptor 5-HT2 de Serotonina/química , Agonistas do Receptor 5-HT2 de Serotonina/farmacologia , Antagonistas do Receptor 5-HT2 de Serotonina/farmacologia , Ubiquitinação/efeitos dos fármacosRESUMO
Although an inverse correlation between insulin sensitivity and the level of Gq/11-coupled receptor agonists, such as endothelin-1, thrombin, and 5-hydroxytryptamine (5-HT), has been reported, its precise mechanism remains unclear. In this report, we provide evidence that 5-HT induced production of heparin-binding epidermal growth factor-like growth factor (HB-EGF) and caused insulin resistance in 3T3-L1 adipocytes, primary adipocytes, and C2C12 myotubes. In 3T3-L1 adipocytes, 5-HT stimulated HB-EGF production by promoting metalloproteinase-dependent shedding of transmembrane protein pro-HB-EGF. HB-EGF then bound and tyrosine-phosphorylated EGF receptors, which activated the mammalian target of rapamycin pathway through ERK1/2 phosphorylation. Mammalian target of rapamycin activation caused serine phosphorylation of insulin receptor substrate-1, which attenuated insulin-stimulated tyrosine phosphorylation of insulin receptor substrate-1 and glucose uptake. Pharmacological inhibition of either Gq/11-coupled receptors or metalloproteinases, as well as either inhibition or knockdown of HB-EGF or Gαq/11, restored insulin signal transduction impaired by 5-HT. Inhibition of metalloproteinase activity also abolished HB-EGF production and subsequent EGF receptor activation by other Gq/11-coupled receptor agonists known to cause insulin resistance, such as endothelin-1 and thrombin. These results suggest that transactivation of the EGF receptor through HB-EGF processing plays a pivotal role in 5-HT-induced insulin resistance.
Assuntos
Resistência à Insulina/fisiologia , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Serotonina/farmacologia , Células 3T3-L1 , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Linhagem Celular , Células Cultivadas , Endotelina-1/farmacologia , Receptores ErbB/genética , Receptores ErbB/metabolismo , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/metabolismo , Glucose/metabolismo , Fator de Crescimento Semelhante a EGF de Ligação à Heparina , Insulina/farmacologia , Proteínas Substratos do Receptor de Insulina/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/fisiologia , Camundongos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Serina-Treonina Quinases TOR/metabolismo , Trombina/farmacologia , Ativação Transcricional/efeitos dos fármacosRESUMO
Insulin resistance and dyslipidemia are both considered to be risk factors for metabolic syndrome. Low levels of IGF1 are associated with insulin resistance. Elevation of low-density lipoprotein cholesterol (LDL-C) concomitant with depression of high-density lipoprotein cholesterol (HDL-C) increase the risk of obesity and type 2 diabetes mellitus (T2DM). Liver secretes IGF1 and catabolizes cholesterol regulated by the rate-limiting enzyme of bile acid synthesis from cholesterol 7alpha-hydroxylase (CYP7A1). NO-1886, a chemically synthesized lipoprotein lipase activator, suppresses diet-induced insulin resistance with the improvement of HDL-C. The goal of the present study is to evaluate whether NO-1886 upregulates IGF1 and CYP7A1 to benefit glucose and cholesterol metabolism. By using human hepatoma cell lines (HepG2 cells) as an in vitro model, we found that NO-1886 promoted IGF1 secretion and CYP7A1 expression through the activation of signal transducer and activator of transcription 5 (STAT5). Pretreatment of cells with AG 490, the inhibitor of STAT pathway, completely abolished NO-1886-induced IGF1 secretion and CYP7A1 expression. Studies performed in Chinese Bama minipigs pointed out an augmentation of plasma IGF1 elicited by a single dose administration of NO-1886. Long-term supplementation with NO-1886 recovered hyperinsulinemia and low plasma levels of IGF1 suppressed LDL-C and facilitated reverse cholesterol transport by decreasing hepatic cholesterol accumulation through increasing CYP7A1 expression in high-fat/high-sucrose/high-cholesterol diet minipigs. These findings indicate that NO-1886 upregulates IGF1 secretion and CYP7A1 expression to improve insulin resistance and hepatic cholesterol accumulation, which may represent an alternative therapeutic avenue of NO-1886 for T2DM and metabolic syndrome.
Assuntos
Ração Animal , Benzamidas/farmacologia , Colesterol 7-alfa-Hidroxilase/metabolismo , Colesterol/metabolismo , Hipolipemiantes/farmacologia , Resistência à Insulina , Fator de Crescimento Insulin-Like I/metabolismo , Compostos Organofosforados/farmacologia , Fator de Transcrição STAT5/metabolismo , Animais , Benzamidas/administração & dosagem , Linhagem Celular Tumoral , Colesterol/administração & dosagem , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Gorduras na Dieta/administração & dosagem , Esquema de Medicação , Humanos , Hiperglicemia/etiologia , Hiperglicemia/prevenção & controle , Hiperinsulinismo/sangue , Hipolipemiantes/administração & dosagem , Fígado/metabolismo , Masculino , Compostos Organofosforados/administração & dosagem , Suínos , Porco Miniatura , Regulação para CimaRESUMO
Insulin resistance is one of the pathophysiological features of obesity and type 2 diabetes. Recent findings have linked insulin resistance to chronic low-grade inflammation in white adipose tissue. Excess storage of saturated fat in white adipose tissue due to a modern life style causes hypertrophy and hyperplasia of adipocytes, which exhibit attenuated insulin signaling due to their production and release of saturated fatty acids. These adipocytes recruit macrophages to white adipose tissue and, together with them, initiate a proinflammatory response. Proinflammatory factors and saturated fatty acids secreted into the bloodstream from white adipose tissue impair insulin signaling in non-adipose tissues, which causes whole-body insulin resistance.
Assuntos
Ácidos Graxos/metabolismo , Resistência à Insulina/fisiologia , Tecido Adiposo Branco/fisiologia , Sistema Endócrino/fisiologia , Metabolismo Energético , Humanos , Inflamação/fisiopatologia , Macrófagos/fisiologia , Obesidade/fisiopatologia , Transdução de SinaisRESUMO
The microenvironment of bone marrow-derived human mesenchymal stem cells (hMSCs) strictly regulates their self-renewal and differentiation. Culturing these cells ex vivo leads to a rapid expansion followed by senescence, which is characterized by a lack of proliferation and differentiation. In this study, 250-Pa polyacrylamide gels, which mimics the elasticity of bone marrow and fat tissues, were coated with a mixture of collagen type 1 and fibronectin. When hMSCs were seeded sparsely on these gels, they halted progression through the cell cycle despite the presence of serum, but when presented with a stiff substrate, these non-proliferative cells reentered the cell cycle. Non-proliferative hMSCs on 250-Pa gels also exhibited the capability to differentiate into adipocytes when cultured in adipogenic induction medium or into osteoblasts if transferred to a stiff substrate and incubated with osteoblast induction medium. These results demonstrate that hMSCs on 250-Pa gels are quiescent but competent to resume proliferation or initiate terminal differentiation with appropriate cues. These observations suggest that mechanical signals from the elasticity of the extracellular matrix may be one of the factors that enable the bone marrow niche to maintain MSCs as a reservoir for a long period.
Assuntos
Resinas Acrílicas/química , Células da Medula Óssea/citologia , Meios de Cultura/química , Células-Tronco Mesenquimais/citologia , Adipócitos/citologia , Adipócitos/fisiologia , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Materiais Revestidos Biocompatíveis/química , Elasticidade , Matriz Extracelular/metabolismo , Géis , Humanos , Células-Tronco Mesenquimais/fisiologia , Osteoblastos/citologia , Osteoblastos/fisiologia , Estimulação Física , Transdução de Sinais , Especificidade por SubstratoRESUMO
Insulin-stimulated GLUT4 recruitment to the plasma membrane is impaired in insulin resistance. We recently reported that a cell permeable phosphoinositide-binding peptide induces GLUT4 recruitment as potently as insulin, but does not activate GLUT4 to initiate glucose uptake. Here we investigated whether the peptide-induced GLUT4 recruitment is intact in insulin resistance. The expression levels of GLUT1 and GLUT4 were unaffected by chronically treating 3T3-L1 adipocytes with insulin. GLUT4 recruitment by acute insulin stimulation after chronic insulin treatment was significantly reduced, but was fully restored by the peptide treatment. However, subsequent acute insulin stimulation to activate GLUT4 failed to increase glucose uptake in peptide-pretreated cells. Insulin-stimulated GLUT1 recruitment was unaffected by the peptide pretreatment. These results suggest that the GLUT4 recruitment signal caused by the peptide is intact in insulin resistance, but GLUT4 activation that occurs subsequent to recruitment is not rescued by the peptide treatment.
Assuntos
Transportador de Glucose Tipo 4/metabolismo , Resistência à Insulina , Peptídeos/farmacologia , Células 3T3-L1 , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Glucose/metabolismo , Insulina/farmacologia , CamundongosRESUMO
Septic shock from bacterial endotoxin, triggered by the release of lipopolysaccharide (LPS) molecules from the outer wall of Gram-negative bacteria, is a major cause of human death for which there is no effective treatment once the complex inflammatory pathways stimulated by these small amphipathic molecules are activated. Here we report that plasma gelsolin, a highly conserved human protein, binds LPS from various bacteria with high affinity. Solid-phase binding assays, fluorescence measurements, and functional assays of actin depolymerizing effects show that gelsolin binds more tightly to LPS than it does to its other known lipid ligands, phosphatidylinositol 4,5-bisphosphate and lysophosphatidic acid. Gelsolin also competes with LPS-binding protein (LBP), a high-affinity carrier for LPS. One result of gelsolin-LPS binding is inhibition of the actin binding activity of gelsolin as well as the actin depolymerizing activity of blood serum. Simultaneously, effects of LPS on cellular functions, including cytoskeletal actin remodeling, and collagen-induced platelet activation by pathways independent of toll-like receptors (TLRs) are neutralized by gelsolin and by a peptide based on gelsolin residues 160-169 (GSN160-169) which comprise part of gelsolin's phosphoinositide binding site. Additionally, TLR-dependent NF-kappaB translocation in astrocytes appears to be blocked by gelsolin. These results show a strong effect of LPS on plasma gelsolin function and suggest that some effects of endotoxin in vivo may be mediated or inhibited by plasma gelsolin.
Assuntos
Gelsolina/sangue , Gelsolina/química , Lipopolissacarídeos/antagonistas & inibidores , Lipopolissacarídeos/metabolismo , Citoesqueleto de Actina/metabolismo , Proteínas de Fase Aguda/química , Proteínas de Fase Aguda/metabolismo , Animais , Astrócitos/metabolismo , Ligação Competitiva , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Linhagem Celular , Células Cultivadas , Gelsolina/antagonistas & inibidores , Humanos , Lipopolissacarídeos/química , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/metabolismo , NF-kappa B/metabolismo , Fragmentos de Peptídeos/antagonistas & inibidores , Fragmentos de Peptídeos/sangue , Fragmentos de Peptídeos/química , Fosfatos de Fosfatidilinositol/química , Fosfatos de Fosfatidilinositol/metabolismo , Inibidores da Agregação Plaquetária/química , Inibidores da Agregação Plaquetária/metabolismo , Ligação Proteica , Transporte Proteico , Coelhos , RatosRESUMO
GLUT4 (glucose transporter 4) plays a pivotal role in insulin-induced glucose uptake to maintain normal blood glucose levels. Here, we report that a cell-permeable phosphoinositide-binding peptide induced GLUT4 translocation to the plasma membrane without inhibiting IRAP (insulin-responsive aminopeptidase) endocytosis. However, unlike insulin treatment, the peptide treatment did not increase glucose uptake in 3T3-L1 adipocytes, indicating that GLUT4 translocation and activation are separate events. GLUT4 activation can occur at the plasma membrane, since insulin was able to increase glucose uptake with a shorter time lag when inactive GLUT4 was first translocated to the plasma membrane by pretreating the cells with this peptide. Inhibition of phosphatidylinositol (PI) 3-kinase activity failed to inhibit GLUT4 translocation by the peptide but did inhibit glucose uptake when insulin was added following peptide treatment. Insulin, but not the peptide, stimulated GLUT1 translocation. Surprisingly, the peptide pretreatment inhibited insulin-induced GLUT1 translocation, suggesting that the peptide treatment has both a stimulatory effect on GLUT4 translocation and an inhibitory effect on insulin-induced GLUT1 translocation. These results suggest that GLUT4 requires translocation to the plasma membrane, as well as activation at the plasma membrane, to initiate glucose uptake, and both of these steps normally require PI 3-kinase activation.