RESUMEN
Pseudoxanthoma elasticum (PXE) is an autosomal recessive metabolic disorder characterized by ectopic mineralization of soft connective tissue. Histopathology findings include fragmented, mineralized elastic fibers and calcium deposits in the mid-dermis. Nonlinear microscopy (NLM) can be used for visualization of these histopathological alterations of the mid-dermis in PXE-affected skin sections. Upon introducing a normalized 3D color vector representation of emission spectra of three of the main tissue components (collagen, elastin and calcification) we found that due to their broad, overlapping emission spectra, spectral separation of emission from elastin and calcification is practically impossible in fresh-frozen or unstained, deparaffinized PXE sections. However, we found that the application of a low concentration Phloxine B staining after the deparaffinization process creates an imaging contrast for these two tissue components, which enables spectral decomposition of their fluorescence images. The obtained concentration maps for calcium deposits can be well suited for the determination of illness severity by quantitative analysis.
RESUMEN
Administration of second-generation antipsychotic drugs (SGAs) often leads to weight gain and consequent cardio-metabolic side effects. We observed that clozapine but not six other antipsychotic drugs reprogrammed the gene expression pattern of differentiating human adipocytes ex vivo, leading to an elevated expression of the browning marker gene UCP1, more and smaller lipid droplets and more mitochondrial DNA than in the untreated white adipocytes. Laser scanning cytometry showed that up to 40% of the differentiating single primary and Simpson-Golabi-Behmel syndrome (SGBS) adipocytes had the characteristic morphological features of browning cells. Furthermore, clozapine significantly upregulated ELOVL3, CIDEA, CYC1, PGC1A and TBX1 genes but not ZIC1 suggesting induction of the beige-like and not the classical brown phenotype. When we tested whether browning induced by clozapine can be explained by its known pharmacological effect of antagonizing serotonin (5HT) receptors, it was found that browning cells expressed 5HT receptors 2A, 1D, 7 and the upregulation of browning markers was diminished in the presence of exogenous 5HT. Undifferentiated progenitors or completely differentiated beige or white adipocytes did not respond to clozapine administration. The clozapine-induced beige cells displayed increased basal and oligomycin-inhibited (proton leak) oxygen consumption, but these cells showed a lower response to cAMP stimulus as compared with control beige adipocytes indicating that they are less capable to respond to natural thermogenic anti-obesity cues. Our data altogether suggest that novel pharmacological stimulation of these masked beige adipocytes can be a future therapeutic target for the treatment of SGA-induced weight gain.
Asunto(s)
Adipocitos Beige/efectos de los fármacos , Adipocitos Marrones/efectos de los fármacos , Adipocitos Blancos/efectos de los fármacos , Antipsicóticos/farmacología , Diferenciación Celular/efectos de los fármacos , Clozapina/farmacología , Expresión Génica/efectos de los fármacos , Proteína Desacopladora 1/genética , Adulto , Anciano , Arritmias Cardíacas/genética , Células Cultivadas , AMP Cíclico/farmacología , ADN Mitocondrial/genética , Femenino , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Gigantismo/genética , Cardiopatías Congénitas/genética , Humanos , Discapacidad Intelectual/genética , Gotas Lipídicas/efectos de los fármacos , Masculino , Persona de Mediana Edad , Consumo de Oxígeno/efectos de los fármacos , Fenotipo , Receptores de Serotonina/genética , Termogénesis/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacos , Aumento de Peso/efectos de los fármacos , Adulto JovenRESUMEN
Retinal pigment epithelial (RPE) cells can undergo different forms of cell death, including autophagy-associated cell death during age-related macular degeneration (AMD). Failure of macrophages or dendritic cells (DCs) to engulf the different dying cells in the retina may result in the accumulation of debris and progression of AMD. ARPE-19 and primary human RPE cells undergo autophagy-associated cell death upon serum depletion and oxidative stress induced by hydrogen peroxide (H2O2). Autophagy was revealed by elevated light-chain-3 II (LC3-II) expression and electron microscopy, while autophagic flux was confirmed by blocking the autophago-lysosomal fusion using chloroquine (CQ) in these cells. The autophagy-associated dying RPE cells were engulfed by human macrophages, DCs and living RPE cells in an increasing and time-dependent manner. Inhibition of autophagy by 3-methyladenine (3-MA) decreased the engulfment of the autophagy-associated dying cells by macrophages, whereas sorting out the GFP-LC3-positive/autophagic cell population or treatment by the glucocorticoid triamcinolone (TC) enhanced it. Increased amounts of IL-6 and IL-8 were released when autophagy-associated dying RPEs were engulfed by macrophages. Our data suggest that cells undergoing autophagy-associated cell death engage in clearance mechanisms guided by professional and non-professional phagocytes, which is accompanied by inflammation as part of an in vitro modeling of AMD pathogenesis.
Asunto(s)
Autofagia/efectos de los fármacos , Medio de Cultivo Libre de Suero/farmacología , Peróxido de Hidrógeno/farmacología , Macrófagos/efectos de los fármacos , Fagocitosis/efectos de los fármacos , Epitelio Pigmentado de la Retina/efectos de los fármacos , Adenina/análogos & derivados , Adenina/farmacología , Autofagia/genética , Biomarcadores/metabolismo , Línea Celular , Cloroquina/farmacología , Técnicas de Cocultivo , Expresión Génica , Genes Reporteros , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Interleucina-6/biosíntesis , Interleucina-6/metabolismo , Interleucina-8/biosíntesis , Interleucina-8/metabolismo , Macrófagos/citología , Macrófagos/inmunología , Degeneración Macular/genética , Degeneración Macular/inmunología , Degeneración Macular/patología , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/inmunología , Modelos Biológicos , Estrés Oxidativo , Cultivo Primario de Células , Epitelio Pigmentado de la Retina/inmunología , Epitelio Pigmentado de la Retina/patología , Triamcinolona/farmacologíaRESUMEN
Obesity leads to adipose tissue inflammation that is characterized by increased release of proinflammatory molecules and the recruitment of activated immune cells. Although macrophages are present in the highest number among the immune cells in obese adipose tissue, not much is known about their direct interaction with adipocytes. We have introduced an ex vivo experimental system to characterize the cellular interactions and the profile of secreted cytokines in cocultures of macrophages and human adipocytes differentiated from either mesenchymal stem cells or a preadipocyte cell line. As observed by time-lapse microscopy, flow, and laser-scanning cytometry, macrophages phagocytosed bites of adipocytes (trogocytosis), which led to their de novo, phagocytosis and NF-κB-dependent synthesis, then release of interleukin (IL)-6 and monocyte chemoattractant protein (MCP)-1. IL-6 secretion was not accompanied by secretion of other proinflammatory cytokines, such as tumor necrosis factor (TNF)-α and IL-8, except MCP-1. LPS-induced release of TNF-α, IL-8 and MCP-1 was decreased in the presence of the differentiated adipocytes but the IL-6 level did not subside suggesting that phagocytosis-dependent IL-6 secretion may have significant regulatory function in the inflamed adipose tissue.
Asunto(s)
Adipocitos/citología , Comunicación Celular , Diferenciación Celular , Interleucina-6/metabolismo , Macrófagos/citología , Fagocitosis , Adipocitos/efectos de los fármacos , Adipocitos/metabolismo , Brefeldino A/farmacología , Comunicación Celular/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Técnicas de Cocultivo , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Mediadores de Inflamación/metabolismo , Lipopolisacáridos/farmacología , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , FN-kappa B/metabolismo , Fagocitosis/efectos de los fármacosRESUMEN
The clearance of apoptotic cells has an important role in the maintenance of tissue homeostasis and in the protection of tissues from the inflammatory and immunogenic contents of dying cells. A defect in the recognition and phagocytosis of apoptotic cells contributes to the development of chronic inflammation and autoimmune disorders. We have observed that compared with healthy donors, differentiated macrophages from patients with untreated systemic lupus erythematosus (SLE) showed decreased phagocytosis of apoptotic neutrophils. A TaqMan Low Density Array was designed to determine the mRNA expression levels of 95 apopto-phagocytic genes in differentiated non-phagocytosing and phagocytosing macrophages. In the macrophages of clinically and immunoserologically active SLE patients, 39 genes were expressed at lower levels than in the control macrophages. When inactive patients were compared with those with minor immunoserological abnormalities or patients in an immunoserologically active state, a relationship was observed between the altered gene expression profile and the disease state. In the macrophages of patients with engulfing apoptotic cells, an upregulation of genes involved in inflammation, autophagy, and signaling was observed. These results indicate that novel immune-pathological pathways are involved in SLE and suggest targets for potential therapeutic modulation.
Asunto(s)
Apoptosis/genética , Lupus Eritematoso Sistémico/genética , Lupus Eritematoso Sistémico/inmunología , Macrófagos/inmunología , Macrófagos/patología , Fagocitosis/genética , Adulto , Antígenos de Superficie/genética , Estudios de Casos y Controles , Diferenciación Celular , Regulación hacia Abajo , Femenino , Humanos , Cadenas beta de Integrinas/genética , Lupus Eritematoso Sistémico/patología , Masculino , Persona de Mediana Edad , Proteínas de la Leche/genética , Monocitos/inmunología , Monocitos/patología , Neutrófilos/inmunología , Neutrófilos/patología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transcriptoma , Regulación hacia Arriba , Adulto JovenRESUMEN
Glucocorticoid-induced apoptosis of thymocytes is one of the first recognized forms of programmed cell death. It was shown to require gene activation induced by the glucocorticoid receptor (GR) translocated into the nucleus following ligand binding. In addition, the necessity of the glucocorticoid-induced, but transcription-independent phosphorylation of phosphatidylinositol-specific phospholipase C (PI-PLC) has also been shown. Here we report that retinoic acids, physiological ligands for the nuclear retinoid receptors, enhance glucocorticoid-induced death of mouse thymocytes both in vitro and in vivo. The effect is mediated by retinoic acid receptor (RAR) alpha/retinoid X receptor (RXR) heterodimers, and occurs when both RARα and RXR are ligated by retinoic acids. We show that the ligated RARα/RXR interacts with the ligated GR, resulting in an enhanced transcriptional activity of the GR. The mechanism through which this interaction promotes GR-mediated transcription does not require DNA binding of the retinoid receptors and does not alter the phosphorylation status of Ser232, known to regulate the transcriptional activity of GR. Phosphorylation of PI-PLC was not affected. Besides thymocytes, retinoids also promoted glucocorticoid-induced apoptosis of various T-cell lines, suggesting that they could be used in the therapy of glucocorticoid-sensitive T-cell malignancies.
Asunto(s)
Apoptosis/efectos de los fármacos , Glucocorticoides/farmacología , Receptores de Glucocorticoides/metabolismo , Retinoides/farmacología , Linfocitos T/efectos de los fármacos , Alitretinoína , Animales , Células Cultivadas , Fragmentación del ADN , Dexametasona/efectos adversos , Eliminación de Gen , Humanos , Inmunoprecipitación , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Compuestos Orgánicos/farmacología , Fosfoinositido Fosfolipasa C/metabolismo , Fosforilación , Multimerización de Proteína/efectos de los fármacos , Receptores de Ácido Retinoico/genética , Receptores de Ácido Retinoico/metabolismo , Receptor alfa de Ácido Retinoico , Receptores X Retinoide/agonistas , Receptores X Retinoide/metabolismo , Linfocitos T/fisiología , Factores de Transcripción/metabolismo , Transcripción Genética , Activación Transcripcional , Tretinoina/farmacología , Técnicas del Sistema de Dos HíbridosRESUMEN
Relationships among GH genotype (AluI polymorphism), parity, metritis and interval from calving to first ovulation, milk production and body condition score (BCS) loss were determined in dairy cows (n=307) on four large-scale farms in Hungary. Cows with systemic signs of puerperal metritis or mastitis were excluded. Time of the first postpartum (PP) ovulation was obtained from milk progesterone profiles. Based on GH genotype determination, groups of leucine homozygous cows (n=246) and valine allele carriers (n=61) were formed. All animals became cyclic during the study period. The average interval to first ovulation was 27.6+/-0.69-d PP (mean+/-S.D.). Genotype had no effect on the commencement of ovarian cyclicity. First ovulation occurred sooner after calving in pluriparous than in primiparous cows. The greater BCS loss cows had during the first 30-d PP, the longer they took to resume cyclic ovarian function. The interval from calving to first ovulation was substantially affected by farm, but not by mild cases of puerperal metritis. Genotype was not related to cumulative 30-d milk yield or BCS loss after calving. Primiparous cows had lower milk yield than pluriparous ones. Cows with metritis lost more body condition than healthy individuals in the first month postpartum. We concluded that, under field conditions, AluI polymorphism of the bovine GH gene had no effect on the interval from calving to first ovulation and could not be directly related to differences in milk yield and to the extent of BCS loss during the first month after calving in Holstein-Friesian cows.
Asunto(s)
Composición Corporal/genética , Bovinos/genética , Ciclo Estral/genética , Hormona del Crecimiento/genética , Lactancia/genética , Leche/fisiología , Animales , Femenino , Lactancia/fisiología , Parto , Polimorfismo Genético , EmbarazoRESUMEN
Transglutaminase 2 (TG2) is an inducible transamidating acyltransferase that catalyzes Ca(2+)-dependent protein modifications. It acts as a G protein in transmembrane signaling and as a cell surface adhesion mediator, this distinguishes it from other members of the transglutaminase family. The sequence motifs and domains revealed in the TG2 structure, can each be assigned distinct cellular functions, including the regulation of cytoskeleton, cell adhesion, and cell death. Though many biological functions of the enzyme have already been described or proposed previously, studies of TG2 null mice by our laboratory during the past years revealed several novel in vivo roles of the protein. In this review we will discuss these novel roles in their biological context.
Asunto(s)
Proteínas de Unión al GTP/deficiencia , Proteínas de Unión al GTP/metabolismo , Transglutaminasas/deficiencia , Transglutaminasas/metabolismo , Animales , Secuencia Conservada , Proteínas de Unión al GTP/química , Ratones , Ratones Noqueados , Proteína Glutamina Gamma Glutamiltransferasa 2 , Estructura Terciaria de Proteína , Transglutaminasas/químicaAsunto(s)
Apoptosis/efectos de los fármacos , Calcio/farmacología , Calpaína/metabolismo , Eritrocitos/patología , Proteínas de Unión al GTP/metabolismo , Fosfatidilserinas/metabolismo , Transglutaminasas/metabolismo , Animales , Eritrocitos/efectos de los fármacos , Eritrocitos/metabolismo , Proteínas de Unión al GTP/genética , Humanos , Ratones , Ratones Transgénicos , Proteína Glutamina Gamma Glutamiltransferasa 2 , Transglutaminasas/genéticaRESUMEN
MCF-7 cells undergo autophagic death upon tamoxifen treatment. Plated on non-adhesive substratum these cells died by anoikis while inducing autophagy as revealed by monodansylcadaverine staining, elevated light-chain-3 expression and electron microscopy. Both de novo and anoikis-derived autophagic dying cells were engulfed by human macrophages and MCF-7 cells. Inhibition of autophagy by 3-methyladenine abolished engulfment of cells dying through de novo autophagy, but not those dying through anoikis. Blocking exposure of phosphatidylserine (PS) on both dying cell types inhibited phagocytosis by MCF-7 but not by macrophages. Gene expression profiling showed that though both types of phagocytes expressed full repertoire of the PS recognition and signaling pathway, macrophages could evolve during engulfment of de novo autophagic cells the potential of calreticulin-mediated processes as well. Our data suggest that cells dying through autophagy and those committing anoikis with autophagy may engage in overlapping but distinct sets of clearance mechanisms in professional and non-professional phagocytes.
Asunto(s)
Autofagia/fisiología , Macrófagos/fisiología , Fagocitos/fisiología , Anoicis/efectos de los fármacos , Anoicis/fisiología , Autofagia/efectos de los fármacos , Autofagia/genética , Muerte Celular/efectos de los fármacos , Muerte Celular/genética , Muerte Celular/fisiología , Línea Celular Tumoral , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Células Epiteliales/ultraestructura , Humanos , Immunoblotting , Macrófagos/citología , Macrófagos/metabolismo , Microscopía Confocal , Microscopía Electrónica de Transmisión , Fagocitos/citología , Fagocitos/metabolismo , Fagocitosis/efectos de los fármacos , Fosfatidilserinas/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Tamoxifeno/farmacología , Transcripción GenéticaRESUMEN
The effect of the porcine myogenin (Myog) 3' polymorphism on birth weight, growth rate, carcass weight, lean weight, lean meat percentage and back-fat thickness has been investigated in Hungarian Large White pigs. MYOG genotypes were determined by PCR-RFLP assay. The obtained MYOGA frequency value was 0.6275. Due to the small number of BB piglets the effect of the MYOG genotypes on birth weight was not significant; however, an increasing tendency was observed from genotype AA to BB. The growth rate difference between MYOG genotypes was significant: BB animals showed the highest growth rate values during the fattening period. Since few results are available on the possible use of MYOG gene polymorphism in selection to improve carcass and growth traits, by this study the authors hope to provide additional data on this particular subject.
Asunto(s)
Peso Corporal/genética , Miogenina/genética , Polimorfismo Genético , Porcinos/crecimiento & desarrollo , Porcinos/genética , Animales , Peso al Nacer , Femenino , Frecuencia de los Genes , Genotipo , MasculinoAsunto(s)
Adenosina Trifosfato/biosíntesis , Proteínas de Unión al GTP/metabolismo , Daño por Reperfusión Miocárdica/prevención & control , Miocitos Cardíacos/metabolismo , Transglutaminasas/metabolismo , Animales , Proteínas de Unión al GTP/deficiencia , Proteínas de Unión al GTP/genética , Técnicas In Vitro , Masculino , Potenciales de la Membrana , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mitocondrias Cardíacas/metabolismo , Daño por Reperfusión Miocárdica/metabolismo , Miocitos Cardíacos/citología , Proteína Glutamina Gamma Glutamiltransferasa 2 , Receptores Adrenérgicos alfa 1/deficiencia , Receptores Adrenérgicos alfa 1/genética , Receptores Adrenérgicos alfa 1/metabolismo , Transducción de Señal , Transglutaminasas/deficiencia , Transglutaminasas/genéticaRESUMEN
BACKGROUND: Immunoglobulin A class transglutaminase autoantibodies are highly predictive markers of active coeliac disease, a disorder difficult to recognize solely on clinical grounds. AIMS: To develop and evaluate a simple rapid test for point-of-care detection of coeliac autoantibodies. METHODS: The novel whole blood test utilizes the patient's endogenous transglutaminase in red blood cells for detection of transglutaminase-specific immunoglobulin A antibodies present in the blood sample, with normal plasma immunoglobulin A detection as positive test control. We evaluated 284 patients under suspicion of coeliac disease and undergoing jejunal biopsy, and 263 coeliac patients on a gluten-free diet, 383 being tested prospectively in a point-of-care setting. Results were compared with histology, conventional serum autoantibody results and dietary adherence. RESULTS: The rapid test showed 97% sensitivity and 97% specificity for untreated coeliac disease, and identified all immunoglobulin A-deficient samples. Point-of-care testing found new coeliac cases as efficiently as antibody tests in laboratory. Coeliac autoantibodies were detected onsite in 21% of treated patients, while endomysial and transglutaminase antibodies were positive in 20% and 19%, respectively. The positivity rate correlated with dietary lapses and decreased on intensified dietary advice given upon positive point-of-care test results. CONCLUSIONS: Point-of-care testing was accurate in finding new coeliac cases and helped to identify and decrease dietary non-compliance.
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Enfermedad Celíaca/dietoterapia , Enfermedad Celíaca/diagnóstico , Adolescente , Adulto , Anciano , Autoanticuerpos/sangre , Niño , Preescolar , Glútenes/administración & dosificación , Humanos , Inmunoensayo/instrumentación , Inmunoensayo/métodos , Inmunoglobulina A/sangre , Lactante , Persona de Mediana Edad , Cooperación del Paciente , Sistemas de Atención de Punto , Estudios Prospectivos , Juego de Reactivos para Diagnóstico , Sensibilidad y Especificidad , Transglutaminasas/inmunologíaRESUMEN
Two F2 generations of an intercross between Hampshire boars and Hungarian Large White sows were produced to estimate the effects of the porcine KIT genotypes (II, Ii and ii) on quantitative and qualitative haematological indices, on piglet birth weight and growth performance until weaning. Piglets carrying the I allele had significantly fewer lymphocytes (p = 0.041) than the ii homozygotes, heterozygotes had measures between the two homozygotes. KIT genotypes did not influence white blood cells, red blood cells, haemoglobin and haematocrite. II genotype piglets were significantly lighter at birth than the ones carrying the recessive i allele, the effect of KIT genotypes on gain until weaning was not significant, but II piglets tended to gain less. The results of this study support the hypothesis of M. Johansson, H. Ellegren, L. Marklund, U. Gustavsson, E. Ringmar-Cederberg, K. Andersson, I. Edfors-Lilja and L. Andersson [(1992) Genomics, 14, 965] that the pleiotrophic effect of the porcine KIT mutations on haematopoietic cells must be mild.
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Peso al Nacer , Color del Cabello/genética , Sus scrofa/sangre , Sus scrofa/crecimiento & desarrollo , Sus scrofa/genética , Animales , Recuento de Células Sanguíneas/veterinaria , Peso Corporal , Cruzamientos Genéticos , Genotipo , Hematócrito/veterinaria , Hemoglobinas/metabolismo , Modelos LinealesRESUMEN
A total of 869 litter records of 226 Hungarian Large White sows have been analysed to investigate the possible use of the oestrogen receptor gene (ESR) as marker to improve litter size. First, second and later parities have been evaluated separately. Frequencies of A = 0.55 and B = 0.45 have been calculated for the two ESR alleles and the observed/ expected number of the three genotypes were as follows: AA: 71/69.1, AB: 108/111.8 and BB: 47/45.1. BB type first and later parity sows were superior to AB and AA sows for number born alive (NBA), total number of born (TNB) and the corrected number of weaned piglets (CNW), respectively.
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Tamaño de la Camada/genética , Receptores de Estrógenos/genética , Porcinos/genética , Alelos , Animales , Femenino , Ligamiento Genético , Marcadores Genéticos , Genotipo , Polimorfismo Genético , Sitios de Carácter CuantitativoRESUMEN
Earlier, we found that three protein disulfide isomerases (PDI) from Giardia lamblia (gPDI) also have transglutaminase (TGase) activity in vitro. We now show that differentiating Giardia cells contain isopeptide bonds (epsilon(gamma-glutamyl)lysine), the biological product of TGase activity that results in irreversible crosslinking of proteins in vivo. HPLC analyses showed the highest isopeptide bond content in cells encysting for 21 h, indicating an important role for TGase early in encystation. We were not able to detect isopeptide bonds in water-resistant cysts, possibly because they could not be extracted. One of the hallmarks of early encystation is the formation of encystation secretory vesicles (ESV) that transport nascent cyst wall proteins (CWPs) to the outer cell surface. ImmunoEM and live-cell immunofluorescence assays of encysting parasites revealed that gPDIs 1-3 are located in ESV and that gPDI-2 is also novel in that it is localized on the cell surface. Cystamine, a widely used TGase inhibitor, caused a dose-dependent inhibition of ESV formation by 21 h, thereby preventing development of trophozoites into cysts. Since cystamine (0.5-1 mM) inhibited the TGase activity of recombinant gPDIs 1-3 in vitro, PDIs appear to be the physiologic targets of cystamine. We found that when parasites were treated with cystamine, CWPs were not processed normally. These data suggest that TGase-catalyzed reactions may be needed for either the machinery that processes CWP precursors or their recruitment to ESV.
Asunto(s)
Giardia lamblia/enzimología , Giardia lamblia/crecimiento & desarrollo , Transglutaminasas/metabolismo , Animales , Secuencia de Bases , Cistamina/farmacología , ADN Protozoario/genética , Inhibidores Enzimáticos/farmacología , Giardia lamblia/efectos de los fármacos , Giardia lamblia/genética , Microscopía Inmunoelectrónica , Proteína Disulfuro Isomerasas/genética , Proteína Disulfuro Isomerasas/metabolismo , Proteínas Recombinantes/antagonistas & inhibidores , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transglutaminasas/antagonistas & inhibidores , Transglutaminasas/genéticaRESUMEN
According to recent results both protein disulphide isomerase (PDI) and thioredoxin (Trx) enzymes have transglutaminase activity which can be linked to the thioredoxin box found in these proteins. Analysis of known protein disulphide isomerase and thioredoxin sequences has revealed the presence of conserved Cys, His and Asp residues required for transglutaminases to catalyze the incorporation of primary amines into protein-bound glutamine residues. The available 3D structures of PDIs and Trxs show that these residues are in close proximity to achieve transglutamylation of substrate proteins. The shared activities of the members of the large protein disulphide isomerase, thioredoxin and transglutaminase enzyme families reviewed here may have general biological significance in the regulation of cellular and tissue processes.
Asunto(s)
Proteína Disulfuro Isomerasas/química , Tiorredoxinas/química , Transglutaminasas/química , Secuencia de Aminoácidos , Animales , Ácido Aspártico/química , Caenorhabditis elegans , Catálisis , Dicroismo Circular , Cisteína/química , Escherichia coli/metabolismo , Histidina/química , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Conformación Proteica , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Homología de Secuencia de Aminoácido , Programas Informáticos , EspectrofotometríaRESUMEN
The accumulation of misfolded proteins in intracellular inclusions is a generic feature of neurodegenerative disorders. Although heavily ubiquitylated, the aggregated proteins are not degraded by the proteasomes. A possible reason for this phenomenon may be a modification of deposited proteins by transglutaminases forming gamma-glutamyl-epsilon-lysine (GGEL) cross-links between distinct proteins. Here, we show that the frequency of GGEL cross-links is an order of magnitude higher in Alzheimer's brain cortex than in age-matched or younger controls. This difference is due to the accumulation of GGEL cross-links in ubiquitin-immunopositive protein particles present in both Alzheimer's brains and those from aged individuals. The highly cross-linked protein aggregates show immunoreactivity to antibodies against tau and neurofilament proteins, and partially also to alpha-synuclein, indicating that these structures are inherent in Alzheimer's neurofibrillary tangles and Lewy bodies. Using mass sequence analysis, we identified the same six pairs of peptide sequences cross-linked in both senile and Alzheimer's specimens: Gln31 and Gln190 of HSP27 protein are cross-linked with Lys29 and Lys48 of ubiquitin and HSP27 therefore may cross-link two (poly)ubiquitin chains. One lysine residue of parkin and one of alpha-synuclein were also found to be cross-linked. The data suggest that cross-linking of (poly)ubiquitin moieties via HSP27 may have a role in the stabilization of the intraneuronal protein aggregates by interference with the proteasomal elimination of unfolded proteins.
Asunto(s)
Enfermedad de Alzheimer/metabolismo , Química Encefálica , Dipéptidos/análisis , Proteínas de Choque Térmico/química , Proteínas de Neoplasias/química , Proteínas del Tejido Nervioso/química , Ovillos Neurofibrilares/química , Placa Amiloide/química , Ubiquitina-Proteína Ligasas/química , Ubiquitina/química , Adulto , Anciano , Anciano de 80 o más Años , Corteza Cerebral/química , Corteza Cerebral/ultraestructura , Cromatografía Líquida de Alta Presión , Ensayo de Inmunoadsorción Enzimática , Femenino , Glutamina/química , Proteínas de Choque Térmico HSP27 , Proteínas de Choque Térmico/aislamiento & purificación , Hipocampo/química , Hipocampo/ultraestructura , Humanos , Cuerpos de Inclusión/química , Lisina/química , Sustancias Macromoleculares , Masculino , Chaperonas Moleculares , Proteínas de Neoplasias/aislamiento & purificación , Proteínas del Tejido Nervioso/aislamiento & purificación , Proteínas de Neurofilamentos/análisis , Complejo de la Endopetidasa Proteasomal/metabolismo , Solubilidad , Sinucleínas , Ubiquitina/aislamiento & purificación , Ubiquitina-Proteína Ligasas/aislamiento & purificación , alfa-Sinucleína , Proteínas tau/análisisRESUMEN
BACKGROUND: IgA class serum autoantibodies against type 2 (tissue) transglutaminase (TG2) bind to both intestinal and extraintestinal normal tissue sections in vitro, eliciting endomysial, reticulin, and jejunal antibody reactions. It is not known whether similar binding also occurs in coeliac patients in vivo, and may thereby contribute to disease manifestations. AIMS: To investigate intestinal and extraintestinal coeliac tissues for the presence of in vivo bound TG2 specific IgA and its relation to small intestinal mucosal atrophy. PATIENTS: We investigated jejunal samples with normal villous morphology from 10 patients with developing coeliac disease who subsequently progressed to a flat lesion, from 11 patients with dermatitis herpetiformis, and from 12 non-coeliac controls. Six extrajejunal biopsy samples (liver, lymph node, muscle, appendix), obtained based on independent clinical indications from patients with active coeliac disease, were also studied. METHODS: Double colour immunofluorescent studies for in situ IgA, TG2, and laminin were performed. IgA was eluted from tissue sections and tested for TG2 specificity by enzyme linked immunosorbent assay and indirect immunofluorescence. RESULTS: IgA (in one IgA deficient case IgG) deposition on extracellularly located TG2 was detected in jejunal and extrajejunal specimens of all coeliac patients, and also in seven of 11 dermatitis herpetiformis patients, of whom two had no circulating endomysial antibodies. IgA eluted from extraintestinal coeliac tissues was targeted against TG2. CONCLUSIONS: Coeliac IgA targets jejunal TG2 early in disease development even when endomysial antibodies are not present in the circulation. Extraintestinal target sites of coeliac IgA further indicate that humoral immunity may have a pathogenetic role.