RESUMEN
Here we have identified a surface protein, TIGIT, containing an immunoglobulin variable domain, a transmembrane domain and an immunoreceptor tyrosine-based inhibitory motif that was expressed on regulatory, memory and activated T cells. Poliovirus receptor, which is expressed on dendritic cells, bound TIGIT with high affinity. A TIGIT-Fc fusion protein inhibited T cell activation in vitro, and this was dependent on the presence of dendritic cells. The binding of poliovirus receptor to TIGIT on human dendritic cells enhanced the production of interleukin 10 and diminished the production of interleukin 12p40. Knockdown of TIGIT with small interfering RNA in human memory T cells did not affect T cell responses. TIGIT-Fc inhibited delayed-type hypersensitivity reactions in wild-type but not interleukin 10-deficient mice. Our data suggest that TIGIT exerts immunosuppressive effects by binding to poliovirus receptor and modulating cytokine production by dendritic cells.
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Células Dendríticas/inmunología , Tolerancia Inmunológica , Proteínas de la Membrana/metabolismo , Receptores Inmunológicos/metabolismo , Linfocitos T/inmunología , Secuencia de Aminoácidos , Animales , Células CHO , Comunicación Celular , Diferenciación Celular , Células Cultivadas , Cricetinae , Cricetulus , Células Dendríticas/citología , Células Dendríticas/metabolismo , Regulación hacia Abajo , Humanos , Memoria Inmunológica , Interleucina-10/biosíntesis , Subunidad p40 de la Interleucina-12/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Ratones , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Unión Proteica , Receptores Inmunológicos/química , Receptores Inmunológicos/genética , Receptores Virales/genética , Receptores Virales/metabolismo , Alineación de Secuencia , Linfocitos T/metabolismoRESUMEN
Asthma is canonically thought of as a disorder of excessive Th2-driven inflammation in the airway, although recent studies have described heterogeneity with respect to asthma pathophysiology. We have previously described distinct phenotypes of asthma based on the presence or absence of a three-gene "Th2 signature" in bronchial epithelium, which differ in terms of eosinophilic inflammation, mucin composition, subepithelial fibrosis, and corticosteroid responsiveness. In the present analysis, we sought to describe Th2 inflammation in human asthmatic airways quantitatively with respect to known mediators of inflammation and intercellular communication. Using whole-genome microarray and quantitative real-time PCR analysis of endobronchial biopsies from 27 mild-to-moderate asthmatics and 13 healthy controls with associated clinical and demographic data, we found that asthmatic Th2 inflammation is expressed over a variable continuum, correlating significantly with local and systemic measures of allergy and eosinophilia. We evaluated a composite metric describing 79 coexpressed genes associated with Th2 inflammation against the biological space comprising cytokines, chemokines, and growth factors, identifying distinctive patterns of inflammatory mediators as well as Wnt, TGF-ß, and platelet-derived growth factor family members. This integrated description of the factors regulating inflammation, cell migration, and tissue remodeling in asthmatic airways has important consequences for the pathophysiological and clinical impacts of emerging asthma therapeutics targeting Th2 inflammation.
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Asma/inmunología , Bronquios/inmunología , Comunicación Celular/inmunología , Regulación de la Expresión Génica/inmunología , Células Th2/inmunología , Células Th2/patología , Adulto , Asma/patología , Asma/fisiopatología , Biopsia , Bronquios/patología , Bronquios/fisiopatología , Comunicación Celular/genética , Femenino , Regulación de la Expresión Génica/genética , Humanos , Hipersensibilidad/inmunología , Hipersensibilidad/patología , Hipersensibilidad/fisiopatología , Inmunofenotipificación/métodos , Inflamación/genética , Inflamación/inmunología , Inflamación/fisiopatología , Mediadores de Inflamación/metabolismo , Mediadores de Inflamación/fisiología , Masculino , Persona de Mediana Edad , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Mucosa Respiratoria/inmunología , Mucosa Respiratoria/patología , Mucosa Respiratoria/fisiopatología , Células Th2/metabolismo , Adulto JovenRESUMEN
Experimental nonhuman primate models of asthma exhibit multiple features that are characteristic of an eosinophilic/T helper 2 (Th2)-high asthma subtype, characterized by the increased expression of Th2 cytokines and responsive genes, in humans. Here, we determine the molecular pathways that are present in a house dust mite-induced rhesus asthma model by analyzing the genomewide lung gene expression profile of the rhesus model and comparing it with that of human Th2-high asthma. We find that a prespecified human Th2 inflammation gene set from human Th2-high asthma is also present in rhesus asthma and that the expression of the genes comprising this gene set is positively correlated in human and rhesus asthma. In addition, as in human Th2-high asthma, the Th2 gene set correlates with physiologic markers of allergic inflammation and disease in rhesus asthma. Comparison of lung gene expression profiles from human Th2-high asthma, the rhesus asthma model, and a common mouse asthma model indicates that genes associated with Th2 inflammation are shared by all three species. However, some pathophysiologic aspects of human asthma (ie, subepithelial fibrosis, angiogenesis, neural biology, and immune host defense biology) are better represented in the gene expression profile of the rhesus model than in the mouse model. Further study of the rhesus asthma model may yield novel insights into the pathogenesis of human Th2-high asthma.
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Asma/genética , Asma/fisiopatología , Regulación de la Expresión Génica , Pulmón/inmunología , Pulmón/fisiopatología , Macaca mulatta/inmunología , Transducción de Señal/genética , Animales , Antígenos Dermatofagoides/inmunología , Asma/complicaciones , Asma/inmunología , Modelos Animales de Enfermedad , Perfilación de la Expresión Génica , Humanos , Inmunización , Inflamación/complicaciones , Inflamación/genética , Inflamación/inmunología , Inflamación/patología , Pulmón/metabolismo , Ratones , Pyroglyphidae/inmunología , Células Th2/inmunología , Regulación hacia Arriba/genéticaRESUMEN
Objective: Social Security Disability is a common external incentive in neuropsychological evaluations. This study determined base rates of invalidity when patients referred for routine clinical evaluations have Social Security Disability as an external incentive. Method: Patients (n = 242) were grouped as validly or invalidly performing based on the use of multiple performance validity tests. Frequency analyses were then conducted. Results: As a whole, 46.0% of clinically referred patients with Social Security Disability as an external incentive produced invalid data. When divided by disability pursuit status, 58.6% of individuals already receiving Social Security Disability, 44.6% of individuals actively seeking Social Security Disability, and 39.3% of individuals considering seeking Social Security Disability produced invalid data. By comparison, only 8.5% of clinically referred patients without known external incentives produced invalid data. Conclusions: Beyond establishing base rates, these data indicate that the external incentive, not necessarily the evaluation setting, increases the rate of invalidity, as obtained base rates mirror those observed in independent medical examinations. In addition, this study highlights that even patients who report that they are considering but have not committed themselves to pursuing an external incentive frequently invalidate testing.
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Personas con Discapacidad , Seguridad Social , Evaluación de la Discapacidad , Humanos , Motivación , Pruebas NeuropsicológicasRESUMEN
OBJECTIVE: This is the first systematic review and meta-analysis of the Test of Memory Malingering (TOMM) in pediatric examinees. It adheres to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. METHOD: A systematic literature search was conducted using PsycINFO and PubMed, reviewing articles from January 1997 to July 2019. Books providing data on pediatric validity testing were also reviewed for references to relevant articles. Eligibility criteria included publication in a peer-reviewed journal, utilizing a pediatric sample, providing sufficient data to calculate specificity and/or sensitivity, and providing a means for evaluating validity status external to the TOMM. After selection criteria were applied, 9 articles remained for meta-analysis. Samples included clinical patients and healthy children recruited for research purposes; ages ranged from 5 to 18. Fixed and random effects models were used to calculate classification accuracy statistics. RESULTS: Traditional adult-derived cutoffs for Trial 2 and Retention were highly specific (0.96-0.99) in pediatric examinees for both clinical and research samples. Sensitivity was relatively strong (0.68-0.70), although only two studies reported sensitivity rates. A supplemental review of the literature corroborated these findings, revealing that traditional adult-based TOMM cutoffs are supported in most pediatric settings. However, limited research exists on the impact of very young age, extremely low cognitive functioning, and varying clinical diagnoses. CONCLUSIONS: The TOMM, at traditional adult cutoffs, has strong specificity as a performance validity test in pediatric neuropsychological evaluations. This meta-analysis found that specificity values in children are comparable to those of adults. Areas for further research are discussed.
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Simulación de Enfermedad , Pruebas de Memoria y Aprendizaje , Adulto , Niño , Cognición , Humanos , Simulación de Enfermedad/diagnóstico , Trastornos de la Memoria/diagnóstico , Trastornos de la Memoria/etiología , Pruebas NeuropsicológicasRESUMEN
This corrects the article DOI: 10.1038/ncomms11473.
RESUMEN
Viruses encode secreted and cell-surface expressed proteins essential to modulate host immune defenses and establish productive infections. However, to date there has been no systematic study of the extracellular interactome of any human virus. Here we utilize the E3 proteins, diverse and rapidly evolving transmembrane-containing proteins encoded by human adenoviruses, as a model system to survey the extracellular immunomodulatory landscape. From a large-scale protein interaction screen against a microarray of more than 1,500 human proteins, we find and validate 51 previously unidentified virus-host interactions. Our results uncover conserved strategies as well as substantial diversity and multifunctionality in host targeting within and between viral species. Prominent modulation of the leukocyte immunoglobulin-like and signalling lymphocyte activation molecule families and a number of inhibitory receptors were identified as hubs for viral perturbation, suggesting unrecognized immunoregulatory strategies. We describe a virus-host extracellular interaction map of unprecedented scale that provides new insights into viral immunomodulation.
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Adenovirus Humanos/inmunología , Inmunomodulación/inmunología , Mapas de Interacción de Proteínas/inmunología , Proteínas Virales/inmunología , Células A549 , Adenovirus Humanos/metabolismo , Adenovirus Humanos/fisiología , Animales , Células CHO , Línea Celular Tumoral , Células Cultivadas , Cricetulus , Espacio Extracelular/inmunología , Espacio Extracelular/metabolismo , Células HEK293 , Células HeLa , Interacciones Huésped-Patógeno/inmunología , Humanos , Células Jurkat , Células K562 , Unión Proteica , Proteoma/inmunología , Proteoma/metabolismo , Proteínas Virales/metabolismoRESUMEN
Vascular endothelial cells are a critical component of the hematopoietic microenvironment that regulates blood cell production. Recent studies suggest the existence of functional cross-talk between hematologic malignancies and vascular endothelium. Here we show that human acute myeloid leukemia (AML) localizes to the vasculature in both patients and in a xenograft model. A significant number of vascular tissue-associated AML cells (V-AML) integrate into vasculature in vivo and can fuse with endothelial cells. V-AML cells acquire several endothelial cell-like characteristics, including the upregulation of CD105, a receptor associated with activated endothelium. Remarkably, endothelial-integrated V-AML shows an almost fourfold reduction in proliferative activity compared with non-vascular-associated AML. Primary AML cells can be induced to downregulate the expression of their hematopoietic markers in vitro and differentiate into phenotypically and functionally defined endothelial-like cells. After transplantation, these leukemia-derived endothelial cells are capable of giving rise to AML. These novel functional interactions between AML cells and normal endothelium along with the reversible endothelial cell potential of AML suggest that vascular endothelium may serve as a previously unrecognized reservoir for AML.
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Endotelio Vascular/metabolismo , Leucemia Mieloide Aguda/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Animales , Antígenos CD/metabolismo , Diferenciación Celular , Línea Celular , Supervivencia Celular , Células Cultivadas , Endoglina , Femenino , Humanos , Hibridación Fluorescente in Situ , Leucemia Mieloide Aguda/metabolismo , Masculino , Ratones , Ratones Endogámicos NOD , Persona de Mediana Edad , Trasplante de Neoplasias , Fenotipo , Receptores de Superficie Celular/metabolismo , Recurrencia , Adulto JovenRESUMEN
Genome-wide association studies (GWAS) in several populations have demonstrated significant association of the IL23R gene with IBD (Crohn's disease (CD) and ulcerative colitis (UC)) and psoriasis, suggesting that perturbation of the IL-23 signaling pathway is relevant to the pathophysiology of these diseases. One particular variant, R381Q (rs11209026), confers strong protection against development of CD. We investigated the effects of this variant in primary T cells from healthy donors carrying IL23R(R381) and IL23R(Q381) haplotypes. Using a proprietary anti-IL23R antibody, ELISA, flow cytometry, phosphoflow and real-time RT-PCR methods, we examined IL23R expression and STAT3 phosphorylation and activation in response to IL-23. IL23R(Q381) was associated with reduced STAT3 phosphorylation upon stimulation with IL-23 and decreased number of IL-23 responsive T-cells. We also observed slightly reduced levels of proinflammatory cytokine secretion in IL23R(Q381) positive donors. Our study shows conclusively that IL23R(Q381) is a loss-of-function allele, further strengthening the implication from GWAS results that the IL-23 pathway is pathogenic in human disease. This data provides an explanation for the protective role of R381Q in CD and may lead to the development of improved therapeutics for autoimmune disorders like CD.
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Sustitución de Aminoácidos/genética , Predisposición Genética a la Enfermedad , Enfermedades Inflamatorias del Intestino/genética , Polimorfismo de Nucleótido Simple/genética , Receptores de Interleucina/genética , Secuencia de Aminoácidos , Arginina/genética , Línea Celular Transformada , Células Clonales , Secuencia Conservada/genética , Humanos , Interleucina-23/farmacología , Leucocitos Mononucleares/efectos de los fármacos , Leucocitos Mononucleares/metabolismo , Recuento de Linfocitos , Modelos Biológicos , Datos de Secuencia Molecular , Fosforilación/efectos de los fármacos , Receptores de Interleucina/química , Factores de Transcripción STAT/metabolismo , Especificidad de la Especie , Linfocitos T/efectos de los fármacos , Linfocitos T/metabolismo , Donantes de TejidosRESUMEN
BACKGROUND: Genome-wide microarray expression analysis creates a comprehensive picture of gene expression at the cellular level. The aim of this study was to investigate differential intestinal gene expression in patients with Crohn's disease (CD) and controls with subanalysis of confirmed CD susceptibility genes, associated pathways, and cell lineage. METHODS: In all, 172 biopsies from 53 CD and 31 control subjects were studied. Paired endoscopic biopsies were taken at ileocolonoscopy from five specific anatomical locations including the terminal ileum (TI) for RNA extraction and histology. The 41,058 expression sequence tags were analyzed using the Agilent platform. RESULTS: Analysis of all CD biopsies versus controls showed 259 sequences were upregulated and 87 sequences were downregulated. Upregulated genes in CD included SAA1 (fold change [FC] +7.5, P = 1.47 × 10(-41)) and REGL (FC +7.3, P = 2.3 × 10(-16)), whereas cellular detoxification genes including-SLC14A2 (FC-2.49, P = 0.00002) were downregulated. In the CD TI biopsies diubiquitin (FC+11.3, P < 1 × 10(-45)), MMP3 (FC+7.4, P = 1.3 × 10(-11)), and IRTA1 (FC-11.4, P = 4.7 × 10(-12)) were differentially expressed compared to controls. In the colon SAA1 (FC+6.3, P = 5.3 × 10(-8)) was upregulated and thymic stromal lymphopoietin (TSLP) (FC-2.3, P = 2.7 × 10(-6)) was downregulated comparing noninflamed CD and control biopsies, and the colonic inflammatory CD signature was characterized by downregulation of the organic solute carriers-SLC38A4, SLC26A2, and OST alpha. Of CD susceptibility genes identified by genome-wide association scan IL-23A, JAK2, and STAT3 were upregulated in the CD group, confirming the dysregulation of Th17 signaling. CONCLUSIONS: These data characterize the dysregulation of a series of specific inflammatory pathways highlighting potential pathogenic mechanisms as well as areas for translation to therapeutic targets.
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Biomarcadores/metabolismo , Enfermedad de Crohn/genética , Perfilación de la Expresión Génica , Mucosa Intestinal/metabolismo , Adulto , Estudios de Casos y Controles , Colon/metabolismo , Colon/patología , Enfermedad de Crohn/metabolismo , Enfermedad de Crohn/patología , Femenino , Estudios de Seguimiento , Estudio de Asociación del Genoma Completo , Humanos , Íleon/metabolismo , Íleon/patología , Intestinos/patología , Masculino , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Multiple sclerosis and its preclinical model, experimental autoimmune encephalomyelitis, are marked by perivascular inflammation and demyelination. Myeloid cells, derived from circulating progenitors, are a prominent component of the inflammatory infiltrate and are believed to directly contribute to demyelination and axonal damage. How the cytotoxic activity of these myeloid cells is regulated is poorly understood. We identify CMRF-35-like molecule-1 (CLM-1) as a negative regulator of autoimmune demyelination. CLM-1 is expressed on inflammatory myeloid cells present in demyelinating areas of the spinal cord after immunization of mice with MOG35-55 (myelin oligodendrocyte glycoprotein) peptide. Absence of CLM-1 resulted in significantly increased nitric oxide and proinflammatory cytokine production, along with increased demyelination and worsened clinical scores, whereas T cell responses in the periphery or in the spinal cord remained unaffected. This study thus identifies CLM-1 as a negative regulator of myeloid effector cells in autoimmune demyelination.
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Encefalomielitis Autoinmune Experimental/inmunología , Esclerosis Múltiple/inmunología , Células Mieloides/inmunología , Receptores Inmunológicos/inmunología , Animales , Citocinas/genética , Citocinas/inmunología , Encefalomielitis Autoinmune Experimental/inducido químicamente , Encefalomielitis Autoinmune Experimental/genética , Encefalomielitis Autoinmune Experimental/patología , Glicoproteínas/efectos adversos , Glicoproteínas/farmacología , Inflamación/inducido químicamente , Inflamación/genética , Inflamación/inmunología , Mediadores de Inflamación/metabolismo , Ratones , Ratones Noqueados , Esclerosis Múltiple/inducido químicamente , Esclerosis Múltiple/genética , Esclerosis Múltiple/patología , Glicoproteína Mielina-Oligodendrócito , Células Mieloides/patología , Óxido Nítrico/genética , Óxido Nítrico/inmunología , Fragmentos de Péptidos/efectos adversos , Fragmentos de Péptidos/farmacología , Receptores Inmunológicos/genéticaRESUMEN
To understand the genetic predisposition to selective immunoglobulin A deficiency (IgAD), we performed a genome-wide association study in 430 affected individuals (cases) from Sweden and Iceland and 1,090 ethnically matched controls, and we performed replication studies in two independent European cohorts. In addition to the known association of HLA with IgAD, we identified association with a nonsynonymous variant in IFIH1 (rs1990760G>A, P = 7.3 x 10(-10)) which was previously associated with type 1 diabetes and systemic lupus erythematosus. Variants in CLEC16A, another known autoimmunity locus, showed suggestive evidence for association (rs6498142C>G, P = 1.8 x 10(-7)), and 29 additional loci were identified with P < 5 x 10(-5). A survey in IgAD of 118 validated non-HLA autoimmunity loci indicated a significant enrichment for association with autoimmunity loci as compared to non-autoimmunity loci (P = 9.0 x 10(-4)) or random SNPs across the genome (P < 0.0001). These findings support the hypothesis that autoimmune mechanisms may contribute to the pathogenesis of IgAD.
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Autoinmunidad/genética , ARN Helicasas DEAD-box/genética , Deficiencia de IgA/genética , Alelos , Enfermedades Autoinmunes/complicaciones , Enfermedades Autoinmunes/genética , Estudios de Casos y Controles , Finlandia , Ligamiento Genético , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Humanos , Islandia , Deficiencia de IgA/etiología , Deficiencia de IgA/inmunología , Helicasa Inducida por Interferón IFIH1 , Riesgo , España , Suecia , Estudios de Validación como AsuntoRESUMEN
Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disease with a complex spectrum of cellular and molecular characteristics including several dramatic changes in the populations of peripheral leukocytes. These changes include general leukopenia, activation of B and T cells, and maturation of granulocytes. The manifestation of SLE in peripheral blood is central to the disease but is incompletely understood. A technique for rigorously characterizing changes in mixed populations of cells, microarray expression deconvolution, has been applied to several areas of biology but not to SLE or to blood. Here we demonstrate that microarray expression deconvolution accurately quantifies the constituents of real blood samples and mixtures of immune-derived cell lines. We characterize a broad spectrum of peripheral leukocyte cell types and states in SLE to uncover novel patterns including: specific activation of NK and T helper lymphocytes, relationships of these patterns to each other, and correlations to clinical variables and measures. The expansion and activation of monocytes, NK cells, and T helper cells in SLE at least partly underlie this disease's prominent interferon signature. These and other patterns of leukocyte dynamics uncovered here correlate with disease severity and treatment, suggest potential new treatments, and extend our understanding of lupus pathology as a complex autoimmune disease involving many arms of the immune system.
Asunto(s)
Lupus Eritematoso Sistémico/sangre , Activación de Linfocitos , Linfocitos B/inmunología , Estudios de Casos y Controles , Humanos , Lupus Eritematoso Sistémico/inmunología , Linfocitos T/inmunologíaRESUMEN
Tissue-resident macrophages play an important role in defense against pathogens and perform key functions in organ homeostasis, innate and adaptive immunity. Tissue macrophages originate from blood monocytes that infiltrate virtually every organ in the body. Macrophages in different tissues share many characteristics, including their ability to migrate, phagocytose particles, metabolize lipids and present antigens. Morphologically they are quite heterogeneous, and some distinct functions have been reported. The gene expression profile of macrophages is reflective of both their shared and distinct biological functions. Here, we show that macrophages from murine spleen, liver and peritoneum display dramatically different expression profiles. Clusters of genes were found to represent unique biological functions related to adhesion, antigen presentation, phagocytosis, lipid metabolism and signal transduction. Some gene families, such as integrins, are differentially expressed among the macrophages resident in different tissues, suggesting that the tissue of residence influences their biological function.
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Perfilación de la Expresión Génica , Macrófagos/citología , Macrófagos/inmunología , Familia de Multigenes , Animales , Presentación de Antígeno/genética , Antígenos de Diferenciación/genética , Antígeno CD11b/biosíntesis , Adhesión Celular/genética , Linaje de la Célula/genética , Linaje de la Célula/inmunología , Separación Celular , Citometría de Flujo , Metabolismo de los Lípidos/genética , Ratones , Especificidad de Órganos , Fagocitosis/genética , Transducción de Señal/genética , Diseño de SoftwareRESUMEN
Genome-wide association (GWA) studies offer a powerful unbiased method for the identification of multiple susceptibility genes for complex diseases. Here we report the results of a GWA study for Crohn's disease (CD) using family trios from the Quebec Founder Population (QFP). Haplotype-based association analyses identified multiple regions associated with the disease that met the criteria for genome-wide significance, with many containing a gene whose function appears relevant to CD. A proportion of these were replicated in two independent German Caucasian samples, including the established CD loci NOD2 and IBD5. The recently described IL23R locus was also identified and replicated. For this region, multiple individuals with all major haplotypes in the QFP were sequenced and extensive fine mapping performed to identify risk and protective alleles. Several additional loci, including a region on 3p21 containing several plausible candidate genes, a region near JAKMIP1 on 4p16.1, and two larger regions on chromosome 17 were replicated. Together with previously published loci, the spectrum of CD genes identified to date involves biochemical networks that affect epithelial defense mechanisms, innate and adaptive immune response, and the repair or remodeling of tissue.
Asunto(s)
Enfermedad de Crohn/genética , Efecto Fundador , Predisposición Genética a la Enfermedad , Genoma Humano , Alelos , Cromosomas Humanos Par 17 , Cromosomas Humanos Par 3 , Cromosomas Humanos Par 4 , Enfermedad de Crohn/patología , Francia/etnología , Marcadores Genéticos , Genética de Población , Haplotipos , Humanos , Proteína Adaptadora de Señalización NOD2/genética , Mapeo Físico de Cromosoma , Quebec , Receptores de Interleucina/genética , Reproducibilidad de los Resultados , Factores de RiesgoRESUMEN
Rat hearts were perfused for 1 h with 5 mm glucose with or without palmitate or oleate at concentrations characteristic of the fasting state. The inclusion of fatty acids resulted in increased activities of the alpha-1 or the alpha-2 isoforms of AMP-activated protein kinase (AMPK), increased phosphorylation of acetyl-CoA carboxylase and a decrease in the tissue content of malonyl-CoA. Activation of AMPK was not accompanied by any changes in the tissue contents of ATP, ADP, AMP, phosphocreatine or creatine. Palmitate increased phosphorylation of Thr172 within AMPK alpha-subunits and the activation by palmitate of both AMPK isoforms was abolished by protein phosphatase 2C leading to the conclusion that exposure to fatty acid caused activation of an AMPK kinase or inhibition of an AMPK phosphatase. In vivo, 24 h of starvation also increased heart AMPK activity and Thr172 phosphorylation of AMPK alpha-subunits. Perfusion with insulin decreased both alpha-1 and alpha-2 AMPK activities and increased malonyl-CoA content. Palmitate prevented both of these effects. Perfusion with epinephrine decreased malonyl-CoA content without an effect on AMPK activity but prevented the activation of AMPK by palmitate. The concept is discussed that activation of AMPK by an unknown fatty acid-driven signalling process provides a mechanism for a 'feed-forward' activation of fatty acid oxidation.
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Ácidos Grasos/farmacología , Complejos Multienzimáticos/metabolismo , Miocardio/enzimología , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Quinasas Activadas por AMP , Nucleótidos de Adenina/metabolismo , Agonistas Adrenérgicos/farmacología , Animales , Activación Enzimática , Ayuno , Ácidos Grasos/química , Corazón/efectos de los fármacos , Insulina/farmacología , Cinética , Masculino , Técnicas de Cultivo de Órganos , Fosforilación , Ratas , Ratas Sprague-Dawley , Transducción de SeñalRESUMEN
A large-scale effort, termed the Secreted Protein Discovery Initiative (SPDI), was undertaken to identify novel secreted and transmembrane proteins. In the first of several approaches, a biological signal sequence trap in yeast cells was utilized to identify cDNA clones encoding putative secreted proteins. A second strategy utilized various algorithms that recognize features such as the hydrophobic properties of signal sequences to identify putative proteins encoded by expressed sequence tags (ESTs) from human cDNA libraries. A third approach surveyed ESTs for protein sequence similarity to a set of known receptors and their ligands with the BLAST algorithm. Finally, both signal-sequence prediction algorithms and BLAST were used to identify single exons of potential genes from within human genomic sequence. The isolation of full-length cDNA clones for each of these candidate genes resulted in the identification of >1000 novel proteins. A total of 256 of these cDNAs are still novel, including variants and novel genes, per the most recent GenBank release version. The success of this large-scale effort was assessed by a bioinformatics analysis of the proteins through predictions of protein domains, subcellular localizations, and possible functional roles. The SPDI collection should facilitate efforts to better understand intercellular communication, may lead to new understandings of human diseases, and provides potential opportunities for the development of therapeutics.