RESUMEN
BACKGROUND: Nitric oxide synthase (NOS) activity, an enzyme potentially involved in the major depressive episodes (MDE), could be indirectly measured by the L-Citrulline/L-Arginine ratio (L-Cit/L-Arg). The aim of this study was: (1) to compare the NOS activity of patients with a MDE to that of healthy controls (HC); (2) to assess its change after antidepressant treatment. METHODS: A total of 460 patients with a current MDE in a context of major depressive disorder (MDD) were compared to 895 HC for NOS activity (L-Cit/L-Arg plasma ratio). L-Arg and L-Cit plasma levels were measured using a MS-based liquid chromatography method. Depressed patients were assessed at baseline, and after 3 and 6 months of antidepressant treatment for depression severity and clinical response. RESULTS: Depressed patients had a lower NOS activity than HC at baseline [0.31 ± 0.09 v. 0.38 ± 0.12; 95% confidence interval (CI) -0.084 to -0.062, p < 0.0001]. Lower NOS activity at baseline predicted a higher response rate [odds ratio (OR) = 29.20; 95% CI 1.58-536.37; p = 0.023]. NOS activity in depressed patients increased significantly up to 0.34 ± 0.08 after antidepressant treatment (Est = 0.0034; 95% CI 0.0002-0.0067; p = 0.03). CONCLUSIONS: Depressed patients have a decreased NOS activity that improves after antidepressant treatment and predicts drug response. NOS activity may be a promising biomarker for MDE in a context of MDD.
Asunto(s)
Trastorno Depresivo Mayor , Humanos , Trastorno Depresivo Mayor/tratamiento farmacológico , Antidepresivos/uso terapéutico , Citrulina/análisis , Citrulina/química , Arginina , Estudios de Casos y Controles , Óxido Nítrico SintasaRESUMEN
INTRODUCTION: The number of patients with depression in the world is 350 millions according to estimates. The search for new treatments, particularly in forms of resistant depression, is necessary given the growing number of patients experiencing treatment failure and resistance. Scopolamine, an anticholinergic antimuscarinic molecule, is one of the treatments under evaluation. It falls within the assumptions of cholinergic disruption of the pathophysiology of depression, at different levels (genetic, receptorial [muscarinic and glutamate receptors], hormonal, synaptic ). In 2006, a pilot study made to evaluate the role of the cholinergic system in cognitive symptoms of depression found unexpected results regarding the antidepressant effect of scopolamine in depressive patients. Since that time other studies have been conducted to evaluate the benefits of treatment with intravenous injections of scopolamine. OBJECTIVE: Our main objective was to evaluate the interest of scopolamine as an antidepressant treatment in depressed populations. METHODS: We conducted a literature review with the aim of assessing the effectiveness of treatment with scopolamine in uni- and bipolar patients with depressive symptoms. The protocol consisted of two injection blocks (each block consisting of three injections spaced fifteen minutes apart within three to five days) of active ingredient or placebo crossover. The selected patients were between 18 and 45years and had the DSM-IV major depressive disorder or bipolar disorder criteria. Regarding the methods of measurement, the primary endpoint was the reduction in scores of the Montgomery Asberg Depression Rating Scale (MADRS) with a total response defined by a decrease of more than 50 % of the score and remission corresponding to a MADRS score<10. Seven sessions of evaluations were performed. RESULTS: The published results are promising in terms of efficiency with rapid antidepressant effect, a total response rate ranging from 59-64% and a remission rate of between 37 and 55% in uni- and bipolar patients, which persists at least 15days. The treatment was well tolerated by patients with relatively mild and transient side effects the most common being the sensation of sleepiness that was also found in the placebo group. There were no serious side effects such as heart failure or confusion. In terms of mood, there was no becoming manic or hypomanic even for bipolar patients. CONCLUSION: The results are encouraging, but there is concern for the moment because of the few studies, so to date there is little data on the subject including medium and long term.
Asunto(s)
Trastorno Depresivo Mayor/tratamiento farmacológico , Trastorno Depresivo Resistente al Tratamiento/tratamiento farmacológico , Antagonistas Muscarínicos/uso terapéutico , Escopolamina/uso terapéutico , Adolescente , Adulto , Trastorno Bipolar/tratamiento farmacológico , Trastorno Depresivo Mayor/psicología , Trastorno Depresivo Resistente al Tratamiento/psicología , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
Several proteins of the Tol/Pal system are required for group A colicin import into Escherichia coli. Colicin A interacts with TolA and TolB via distinct regions of its N-terminal domain. Both interactions are required for colicin translocation. Using in vivo and in vitro approaches, we show in this study that colicin A also interacts with a third component of the Tol/Pal system required for colicin import, TolR. This interaction is specific to colicins dependent on TolR for their translocation, strongly suggesting a direct involvement of the interaction in the colicin translocation step. TolR is anchored to the inner membrane by a single transmembrane segment and protrudes into the periplasm. The interaction involves part of the periplasmic domain of TolR and a small region of the colicin A N-terminal domain. This region and the other regions responsible for the interaction with TolA and TolB have been mapped precisely within the colicin A N-terminal domain and appear to be arranged linearly in the colicin sequence. Multiple contacts with periplasmic-exposed Tol proteins are therefore a general principle required for group A colicin translocation.
Asunto(s)
Proteínas Bacterianas/metabolismo , Membrana Celular/metabolismo , Colicinas/metabolismo , Proteínas de Escherichia coli , Escherichia coli/citología , Escherichia coli/metabolismo , Periplasma/metabolismo , Proteínas Periplasmáticas , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Colicinas/química , Colicinas/genética , Reactivos de Enlaces Cruzados/metabolismo , Electroforesis en Gel de Poliacrilamida , Escherichia coli/genética , Formaldehído/metabolismo , Proteínas de la Membrana/metabolismo , Plásmidos/genética , Pruebas de Precipitina , Unión Proteica , Conformación Proteica , Estructura Terciaria de Proteína , Transporte de ProteínasRESUMEN
PURPOSE: To compare the contribution of various radiographic projections in the evaluation of impingement syndrome and rotator cuff tears. Materials and method. We realized a prospective study in 53 patients with suspected rotator cuff tear, evaluated by plain radiographs and arthrography (gold standard). 31 patients were men and 22 were women (mean age 51 years). In all patients, anteroposterior radiograph, strict anteroposterior straight-beam decubitus view and anteroposterior radiograph during Leclercq's maneuver of the affected shoulder were obtained. The population was divided into three groups: group 1: normal arthrography (n=19), group 2: isolated supraspinatus tendon tear (n=23), group 3: rupture of the supraspinatus and infraspinatus tendons (n=11). The acromio-humeral space was measured on all these views and differences between the three groups were statistically analyzed. RESULTS: There is a significant statistical difference between the height of the acromio-humeral space found in patients with isolated tear of the supraspinatus tendon and those with a tear extending to the infraspinatus tendon (p=0.0001). The ROC methodology showed a better accuracy of the strict anteroposterior straight-beam decubitus view in cases of wide ruptures of the rotator cuff, and this for a selected threshold value of 6 mm. CONCLUSION: Strict anteroposterior straight-beam decubitus view, seems to be easy to realize, cheap, reproducible and very powerful in the preoperative assessment of patients with suspected rotator cuff tendon tear. It allows an excellent visualization of the acromioclavicular joint.
Asunto(s)
Lesiones del Manguito de los Rotadores , Manguito de los Rotadores/diagnóstico por imagen , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Postura , Estudios Prospectivos , Radiografía/métodosRESUMEN
BACKGROUND: The periplasmic protein TolB from Escherichia coli is part of the Tol-PAL (peptidoglycan-associated lipoprotein) multiprotein complex used by group A colicins to penetrate and kill cells. TolB homologues are found in many gram-negative bacteria and the Tol-PAL system is thought to play a role in bacterial envelope integrity. TolB is required for lethal infection by Salmonella typhimurium in mice. RESULTS: The crystal structure of the selenomethionine-substituted TolB protein from E. coli was solved using multiwavelength anomalous dispersion methods and refined to 1. 95 A. TolB has a two-domain structure. The N-terminal domain consists of two alpha helices, a five-stranded beta-sheet floor and a long loop at the back of this floor. The C-terminal domain is a six-bladed beta propeller. The small, possibly mobile, contact area (430 A(2)) between the two domains involves residues from the two helices and the first and sixth blades of the beta propeller. All available genomic sequences were used to identify new TolB homologues in gram-negative bacteria. The TolB structure was then interpreted using the observed conservation pattern. CONCLUSIONS: The TolB beta-propeller C-terminal domain exhibits sequence similarities to numerous members of the prolyl oligopeptidase family and, to a lesser extent, to class B metallo-beta-lactamases. The alpha/beta N-terminal domain shares a structural similarity with the C-terminal domain of transfer RNA ligases. We suggest that the TolB protein might be part of a multiprotein complex involved in the recycling of peptidoglycan or in its covalent linking with lipoproteins.
Asunto(s)
Proteínas Bacterianas/química , Proteínas de Escherichia coli , Escherichia coli/química , Proteínas Periplasmáticas , Secuencia de Aminoácidos , Animales , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Sitios de Unión , Cristalografía por Rayos X , Escherichia coli/genética , Escherichia coli/patogenicidad , Ratones , Modelos Moleculares , Datos de Secuencia Molecular , Mutación , Conformación Proteica , Estructura Terciaria de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homología de Secuencia de AminoácidoRESUMEN
The Tol-peptidoglycan-associated lipoprotein (PAL) system of Escherichia coli is a multiprotein complex of the envelope involved in maintaining outer membrane integrity. PAL and the periplasmic protein TolB, two components of this complex, are interacting with each other, and they have also been reported to interact with OmpA and the major lipoprotein, two proteins interacting with the peptidoglycan. All these interactions suggest a role of the Tol-PAL system in anchoring the outer membrane to the peptidoglycan. Therefore, we were interested in better understanding the interaction between PAL and the peptidoglycan. We designed an in vitro interaction assay based on the property of purified peptidoglycan to be pelleted by ultracentrifugation. Using this assay, we showed that a purified PAL protein interacted in vitro with pure peptidoglycan. A peptide competition experiment further demonstrated that the region from residues 89 to 130 of PAL was sufficient to bind the peptidoglycan. Moreover, the fact that this same region of PAL was also binding to TolB suggested that these two interactions were exclusive. Indeed, the TolB-PAL complex appeared not to be associated with the peptidoglycan. This led us to the conclusion that PAL may exist in two forms in the cell envelope, one bound to TolB and the other bound to the peptidoglycan.
Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas de Escherichia coli , Lipoproteínas/metabolismo , Proteínas de la Membrana/metabolismo , Peptidoglicano/metabolismo , Proteínas Periplasmáticas , Proteoglicanos , Secuencia de Aminoácidos , Proteínas de la Membrana Bacteriana Externa/metabolismo , Sitios de Unión , Unión Competitiva , Membrana Celular/metabolismo , Pared Celular/metabolismo , Reactivos de Enlaces Cruzados , Escherichia coli , Haemophilus influenzae , Lipoproteínas/aislamiento & purificación , Datos de Secuencia Molecular , Fragmentos de Péptidos/metabolismo , Peptidoglicano/aislamiento & purificación , Periplasma/metabolismo , Unión ProteicaRESUMEN
The Tol-PAL system of Escherichia coli is a multiprotein system involved in maintaining the cell envelope integrity and is necessary for the import of some colicins and phage DNA into the bacterium. It is organized into two complexes, one near the outer membrane between TolB and PAL and one in the cytoplasmic membrane between TolA, TolQ, and TolR. In the cytoplasmic membrane, all of the Tol proteins have been shown to interact with each other. Cross-linking experiments have shown that the TolA transmembrane domain interacts with TolQ and TolR. Suppressor mutant analyses have localized the TolQ-TolA interaction to the first transmembrane domain of TolQ and have shown that the third transmembrane domain of TolQ interacts with the transmembrane domain of TolR. To get insights on the composition of the cytoplasmic membrane complex and its possible contacts with the outer membrane complex, we focused our attention on TolR. Cross-linking and immunoprecipitation experiments allowed the identification of Tol proteins interacting with TolR. The interactions of TolR with TolA and TolQ were confirmed, TolR was shown to dimerize, and the resulting dimer was shown to interact with TolQ. Deletion mutants of TolR were constructed, and they allowed us to determine the TolR domains involved in each interaction. The TolR transmembrane domain was shown to be involved in the TolA-TolR and TolQ-TolR interactions, while TolR central and C-terminal domains appeared to be involved in TolR dimerization. The role of the TolR C-terminal domain in the TolA-TolR interaction and its association with the membranes was also demonstrated. Furthermore, phenotypic studies clearly showed that the three TolR domains (N terminal, central, and C terminal) and the level of TolR production are important for colicin A import and for the maintenance of cell envelope integrity.
Asunto(s)
Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Proteínas de Escherichia coli , Escherichia coli/metabolismo , Proteínas Bacterianas/genética , Sitios de Unión , Membrana Celular/metabolismo , Colicinas/metabolismo , Colicinas/farmacología , Colifagos/metabolismo , Reactivos de Enlaces Cruzados , ADN Viral/metabolismo , Dimerización , Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Proteínas de la Membrana/metabolismo , Fragmentos de Péptidos/metabolismo , Fenotipo , Plásmidos , Unión Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismoRESUMEN
TolB from Escherichia coli is part of the Tol system used by the group A colicins to penetrate and kill cells. A TolB derivative tagged with six histidines was overexpressed, purified by chelation on a nickel affinity column and crystallized using the SAmBA software to define the optimal crystallization protocol. The crystals belong to the monoclinic system, space group P21 with unit-cell parameters a = 64.48, b = 41.06, c = 78.41 A, beta = 110.78 degrees. Frozen crystals diffract to 1.9 A resolution. Screening for heavy-atom derivatives both on the native TolB and various cysteine-substituted mutants is in progress. In addition, a selenomethionine-substituted protein is being produced in order to use the MAD method for structure determination.
Asunto(s)
Proteínas Bacterianas/química , Proteínas de Escherichia coli , Escherichia coli , Proteínas Periplasmáticas , Cristalización , Cristalografía por Rayos X , Recolección de Datos , Histidina/análisisRESUMEN
Group A colicins need proteins of the Escherichia coli envelope Tol complex (TolA, TolB, TolQ and TolR) to reach their cellular target. The N-terminal domain of colicins is involved in the import process. The N-terminal domains of colicins A and E1 have been shown to interact with TolA, and the N-terminal domain of colicin E3 has been shown to interact with TolB. We found that a pentapeptide conserved in the N-terminal domain of all group A colicins, the 'TolA box', was important for colicin A import but was not involved in the colicin A-TolA interaction. It was, however, involved in the colicin A-TolB interaction. The interactions of colicin A N-terminal domain deletion mutants with TolA and TolB were investigated. Random mutagenesis was performed on a construct allowing the colicin A N-terminal domain to be exported in the bacteria periplasm. This enabled us to select mutant protein domains unable to compete with the wild-type domain of the entire colicin A for import into the cells. Our results demonstrate that different regions of the colicin A N-terminal domain interact with TolA and TolB. The colicin A N-terminal domain was also shown to form a trimeric complex with TolA and TolB.
Asunto(s)
Proteínas Bacterianas/metabolismo , Colicinas/metabolismo , Proteínas de Escherichia coli , Escherichia coli/metabolismo , Proteínas Periplasmáticas , Western Blotting , Electroforesis en Gel de Poliacrilamida , Escherichia coli/genética , Proteínas de la Membrana/metabolismo , Mutagénesis , Fenotipo , Plásmidos/química , Reacción en Cadena de la PolimerasaRESUMEN
TolB is a periplasmic protein of the cell envelope Tol complex. It is partially membrane associated through an interaction with the outer membrane lipoprotein PAL (peptidoglycan-associated lipoprotein), which also belongs to the Tol system. The interaction of TolB with outer membrane porins of Escherichia coli was investigated with a purified TolB derivative harboring a six-histidine tag. TolB interacted with the trimeric porins OmpF, OmpC, PhoE, and LamB but not with their denatured monomeric forms or OmpA. These interactions took place both in the presence and in the absence of lipopolysaccharide. TolA, an inner membrane component of the Tol system, also interacts with the trimeric porins via its central periplasmic domain (R. Dérouiche, M. Gavioli, H. Bénédetti, A. Prilipov, C. Lazdunski, and R. Lloubès, EMBO J. 15:6408-6415, 1996). In the presence of the purified central domain of TolA (TolAIIHis), the TolB-porin complexes disappeared to form TolAIIHis-porin complexes. These results suggest that the interactions of TolA and TolB with porins might take place in vivo and might be concomitant events participating in porin assembly. They also suggest that the Tol system as a whole may be involved in porin assembly in the outer membrane.
Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas de Escherichia coli , Escherichia coli/fisiología , Proteínas Periplasmáticas , Porinas/metabolismo , Membrana Celular/metabolismo , Pruebas de Precipitina , Unión ProteicaRESUMEN
Colicins use two envelope multiprotein systems to reach their cellular target in susceptible cells of Escherichia coli: the Tol system for group A colicins and the TonB system for group B colicins. The N-terminal domain of colicins is involved in the translocation step. To determine whether it interacts in vivo with proteins of the translocation system, constructs were designed to produce and export to the cell periplasm the N-terminal domains of colicin E3 (group A) and colicin B (group B). Producing cells became specifically tolerant to entire extracellular colicins of the same group. The periplasmic N-terminal domains therefore compete with entire colicins for proteins of the translocation system and thus interact in situ with these proteins on the inner side of the outer membrane. In vivo cross-linking and co-immunoprecipitation experiments in cells producing the colicin E3 N-terminal domain demonstrated the existence of a 120 kDa complex containing the colicin domain and TolB. After in vitro cross-linking experiments with these two purified proteins, a 120 kDa complex was also obtained. This suggests that the complex obtained in vivo contains exclusively TolB and the colicin E3 domain. The N-terminal domain of a translocation-defective colicin E3 mutant was found to no longer interact with TolB. Hence, this interaction must play an important role in colicin E3 translocation.
Asunto(s)
Proteínas Bacterianas/genética , Colicinas/genética , Proteínas de Escherichia coli , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Periplasmáticas , Proteoglicanos , Fosfatasa Alcalina/metabolismo , Anticuerpos Antibacterianos/inmunología , Proteínas de la Membrana Bacteriana Externa/metabolismo , Proteínas de la Membrana Bacteriana Externa/fisiología , Proteínas Bacterianas/inmunología , Proteínas Bacterianas/aislamiento & purificación , Proteínas Bacterianas/metabolismo , Western Blotting , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Colicinas/inmunología , Colicinas/metabolismo , Citoplasma/metabolismo , Ácido Desoxicólico/farmacología , Electroforesis en Gel de Poliacrilamida , Formaldehído/metabolismo , Formaldehído/farmacología , Regulación Bacteriana de la Expresión Génica , Lipoproteínas/metabolismo , Microscopía Electrónica , Péptidos/aislamiento & purificación , Peptidoglicano/metabolismo , Plásmidos , Mutación Puntual , Pruebas de Precipitina , Recombinación Genética , Ribonucleasas/metabolismo , Dodecil Sulfato de Sodio/farmacología , Translocación Genética , beta-Lactamasas/metabolismoRESUMEN
The filamentous brush border glycocalyx forming the 'enteric surface coat' of the intestinal epithelium is composed in rabbits of a 400 kDa mucin-type glycoprotein, which was purified using the 3A4 monoclonal antibody. This monoclonal antibody recognizes a filamentous brush border glycocalyx-specific glycosidic structure containing an O-acetylated sialic acid, which is absent from all the other glycoproteins in the epithelium, with the exception of certain goblet cell mucins. Here we establish that only 50% of the rabbits tested synthesized this glycosidic structure. Upon immunolabeling surface epithelia and sections of jejunum from these rabbits, the carbohydrate epitope recognized by the 3A4 mAb was found to be present on the filamentous brush border glycocalyx of a variable number of enterocytes, which were patchily distributed over all the villi. This heterogeneous expression of 3A4 antigenicity, which was also observed in the crypts, suggests the existence of differences between the patterns of differentiation of enterocytes, which results in the expression of different pools of glycosyltransferases and/or acetyl transferases. In mature enterocytes, the 3A4 determinants were present only on the filamentous brush border glycocalyx, which is anchored solely to the membrane microdomain at the tip of brush border microvilli. However, expression of 3A4 antigenicity begins in the median third of crypts, in enterocytes with a short, thin brush border devoid of apical filamentous brush border glycocalyx. Here the 3A4 epitopes were present over the whole brush border membrane.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Expresión Génica , Glicoproteínas/biosíntesis , Mucosa Intestinal/metabolismo , Microvellosidades/metabolismo , Polisacáridos/biosíntesis , Animales , Anticuerpos Monoclonales , Diferenciación Celular , Células Epiteliales , Epitelio/metabolismo , Epitelio/ultraestructura , Epítopos/análisis , Técnica del Anticuerpo Fluorescente , Glicoproteínas/análisis , Glicosilación , Técnicas para Inmunoenzimas , Mucosa Intestinal/citología , Yeyuno , Microscopía Inmunoelectrónica , Microvellosidades/ultraestructura , Polisacáridos/análisis , Conejos , Ácidos Siálicos/análisisRESUMEN
TolA, -B, -Q, and -R proteins are involved in maintaining the cell envelope integrity of Escherichia coli; they have been parasitized by the group A colicins and the single strand DNA of some filamentous bacteriophages to permit them to enter the cells. TolA and TolR are anchored to the inner membrane by a single transmembrane domain, TolQ is an integral membrane protein with three transmembrane segments, and TolB has recently been found to be periplasmic although it is partially membrane-associated. The latter result suggests that TolB might interact with membrane proteins. Other lines of evidence favor the existence of a Tol complex. To further characterize this complex, we investigated which proteins interact with TolB. For this purpose, two different methods were used. First, we took advantage of the existence of a tagged TolB (TolBep) to perform immunoprecipitation under native conditions in order to preserve the putative associations of TolBep with other proteins. Secondly, in vivo cross-linking experiments with formaldehyde were performed. These two approaches led to the same result and demonstrated for the first time that a component of the Tol system, TolB, interacts with a protein located in the outer membrane, the peptidoglycan-associated lipoprotein.
Asunto(s)
Proteínas de la Membrana Bacteriana Externa , Proteínas Bacterianas/metabolismo , Proteínas de Escherichia coli , Escherichia coli/metabolismo , Lipoproteínas/metabolismo , Proteínas de la Membrana/metabolismo , Peptidoglicano/metabolismo , Proteínas Periplasmáticas , Proteoglicanos , Proteínas Bacterianas/aislamiento & purificación , Membrana Celular/metabolismo , Reactivos de Enlaces Cruzados , Escherichia coli/genética , Formaldehído , Genotipo , Immunoblotting , Lipoproteínas/aislamiento & purificación , Fusión de Membrana , Metionina/metabolismo , Peso Molecular , Peptidoglicano/aislamiento & purificación , Fenotipo , Plásmidos , Radioisótopos de AzufreRESUMEN
The tolB gene has been shown previously to encode two proteins of 47.5 kDa (TolB) and 43 kDa (TolB*). To explain the presence of these two forms, two hypotheses have been proposed: TolB might be posttranslationally processed to TolB*, or an internal in-frame translation initiation resulting in TolB* may occur (S. K. Levengood and R. E. Webster, J. Bacteriol. 171:6600-6609, 1989). To address this question, TolB was tagged by inserting in its C-terminal region an epitope recognized by monoclonal antibody 1C11 without altering the function of TolB. It was then demonstrated that the functional protein corresponded to TolB*, the mature periplasmic protein, and that TolB was its precursor form, which was observed only when the protein was overexpressed. These two forms were purified by immunoprecipitation, and their N-terminal sequences were determined. An antibody directed against TolB was raised, which confirmed the results obtained with the tagged TolB.
Asunto(s)
Proteínas Bacterianas/biosíntesis , Proteínas de Escherichia coli , Proteínas de la Membrana/biosíntesis , Proteínas Periplasmáticas , Procesamiento Proteico-Postraduccional , Secuencia de Aminoácidos , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Secuencia de Bases , Transporte Biológico , Compartimento Celular , Colicinas/metabolismo , Regulación Bacteriana de la Expresión Génica , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Precursores de Proteínas/química , Precursores de Proteínas/genética , Precursores de Proteínas/metabolismo , Análisis de SecuenciaRESUMEN
One monoclonal antibody (8A9) against the human sucrase-isomaltase complex and one (4H3) against the human dipeptidylpeptidase IV were produced in the rat and used to immunolabel thin frozen sections of human small intestine and colon. Both enzymes were found to be expressed in the poorly differentiated crypt cells of the small intestine as well as in the mature villous cells, and very low levels were found to be expressed in the colon. Homogeneous immunolabeling of the whole colonic epithelium with the monoclonal antibody 4H3 was often observed, whereas labeling with the monoclonal antibody 8A9, if any, was either restricted to a few crypts and plateaus. The two antibodies were used to perform specific immunoprecipitation of the corresponding antigen, the N-terminal sequence of which was determined after sodium dodecyl sulfate-polyacrylamide gel electrophoresis purification and electroblotting, and were compared with those of other species. In secretor blood group A humans, both the sucrase-isomaltase and the dipeptidylpeptidase IV have type 3 blood group A determinants.
Asunto(s)
Colon/enzimología , Dipeptidil-Peptidasas y Tripeptidil-Peptidasas/metabolismo , Intestino Delgado/enzimología , Complejo Sacarasa-Isomaltasa/metabolismo , Secuencia de Aminoácidos , Anticuerpos Monoclonales , Dipeptidil Peptidasa 4 , Dipeptidil-Peptidasas y Tripeptidil-Peptidasas/química , Técnica del Anticuerpo Fluorescente , Humanos , Microvellosidades/enzimología , Datos de Secuencia Molecular , Pruebas de Precipitina , Complejo Sacarasa-Isomaltasa/químicaRESUMEN
The results of immunoblot analysis performed with a specific monoclonal antibody showed that the intestinal mucosa, pancreas and liver are privileged tissues for the expression of annexin IV. Immunofluorescence labelling of thin frozen sections of these tissues showed a strong concentration of annexin IV along the basolateral domain of the plasma membrane of intestinal absorbing cells, hepatocytes and pancreatic acinar cells, whereas in intestinal mucous secreting cells and centro acinar pancreatic cells, annexin IV was found to be present throughout the cytoplasm.
Asunto(s)
Intestinos/química , Hígado/química , Páncreas/química , Proteínas Gestacionales/análisis , Animales , Anexinas , Epitelio/química , Técnica del Anticuerpo Fluorescente , Immunoblotting , ConejosRESUMEN
We previously characterized a dimeric, Mr = 115,000, developmentally regulated mouse T cell-activating molecule (THAM). We show in this report that the THAM-specific mAb H194-112 exhibits strong reactivity with several nonlymphoid tissues including polarized enterocytes from small intestine, kidney cortical tubuli, and liver bile ductuli, as well as kidney glomeruli and lung alveoloar pneumocytes. Both the tissue distribution and the structural features of THAM made it likely that this molecule belongs to the ectoenzyme family. This was confirmed by the following experimental evidence: 1) the H194-112+ molecules from enterocyte brush borders (BB) or M14.T thymoma cells were recognized by several antisera specific for intestinal aminopeptidase N (AP-N); 2) mAb H194-112 was found to immunodeplete the AP-N activity from both thymic or enterocyte BB detergent extracts; 3) the hydrophilic, Mr = 115,000 form obtained by papain treatment of thymoma or enterocyte BB could be immunopurified on H194-112 column and exhibited, after hypotonic elution, strong enzymatic activity on the AP-N substrates (i.e., leucyl or alanyl beta-derivatives); 4) mAb H194-112 was found to inhibit the AP-N activity when assayed on alanyl but not leucyl beta-naphthylamide substrate; and 5) preincubation of AP-N with mAb H194-112 prevented the inhibiting effects of bestatin and D,L-methionyl hydroxamate on AP-N activity. These data add a new member to the list of functional ectoenzymatic markers of lymphoid cells (i.e., CD10, CD13, CD26, CD55, and CD73). In view of the known immunomodulating properties of bestatin, one may speculate that the T cell-activating effects of mAb H194-112 is related to an impairment of a surface enzymatic function regulating lymphoid cell activation.
Asunto(s)
Aminopeptidasas/metabolismo , Factores Biológicos/metabolismo , Aminopeptidasas/inmunología , Animales , Anticuerpos Monoclonales/inmunología , Factores Biológicos/inmunología , Técnicas para Inmunoenzimas , Intestinos/enzimología , Activación de Linfocitos , Ratones , Peso Molecular , Pruebas de Precipitina , Especificidad por Sustrato , Linfocitos T/inmunología , Timo/citología , Timo/inmunología , Distribución TisularRESUMEN
Adenocarcinoma cells often form intracellular lumens and intercellular cysts. In order to study the structural relationships between these lumens and the apical domain of normal enterocytes, we have applied electron microscopy and confocal microscopy to a cloned cell line derived from the human colon adenocarcinoma cell line LoVo which express a high number of intracellular lumens and intercellular cysts. Microvilli reminiscent of those detected in the brush border of small intestinal cells are formed in the two types of compartments. By immunofluorescence, we found that a 135 kDa membrane glycoprotein characterized by a monoclonal Ab and normally associated with the brush-border of enterocytes is expressed at the surface of the intracellular lumens and intercellular cysts present in the adenocarcinoma cells. Comparison of fluorescence and reflection contrast micrographs obtained by confocal microscopy demonstrate the presence of spherical intracellular lumens in the juxtanuclear region of single cells, and of more complex shaped intercellular cysts located within clusters of cells. The later cells form junctional complexes limiting an apical plasma membrane domain in contact with the intercellular cyst. It is suggested that the intracellular lumens may represent the abortive form of an apical plasma membrane due to the lack of components required to establish epithelial cell contacts. As opposed to conventional fluorescence microscopy, confocal microscopy allows rapid inspection of the tridimensional organization of intracellular lumens and intercellular cysts even when they are located in cell multilayers.