RESUMEN
Mangiferin is a natural xanthone glycoside with therapeutic potential. Herein, its cytotoxic properties were explored in a human cell model of breast adenocarcinoma. The results supported the multi-target nature of mangiferin action, as the inhibition of three enzymatic systems, namely HMG-CoA reductase, the proteasome and plasmin, respectively in charge of regulating cholesterol homeostasis, protein turnover and cell adhesion, was documented for the first time. Globally, mangiferin was able to selectively block breast cancer cell growth by inducing apoptosis and by arresting cell proliferation through a combined action on cholesterol and proteasome pathways, as well as to inhibit plasmin-mediated mechanisms of cell migration.
Asunto(s)
Apoptosis/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Ácido Mevalónico/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Xantonas/farmacología , Biomarcadores , Neoplasias de la Mama , Cadherinas/metabolismo , Adhesión Celular/efectos de los fármacos , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Colesterol/metabolismo , Relación Dosis-Respuesta a Droga , Femenino , Fibrinolisina , Humanos , Inhibidores de Proteasoma/administración & dosificación , Inhibidores de Proteasoma/farmacología , Xantonas/administración & dosificaciónRESUMEN
BACKGROUND: Tyrosine kinase inhibitors (TKI) such as sunitinib and pazopanib display their efficacy in a variety of solid tumours. However, their use in therapy is limited by the lack of evidence about the ability to induce cell death in cancer cells. Our aim was to evaluate cytotoxic effects induced by sunitinib and pazopanib in 5637 and J82 bladder cancer cell lines. METHODS: Cell viability was tested by MTT assay. Autophagy was evaluated by western blot using anti-LC3 and anti-p62 antibodies, acridine orange staining and FACS analysis. Oxygen radical generation and necrosis were determined by FACS analysis using DCFDA and PI staining. Cathepsin B activation was evaluated by western blot and fluorogenic Z-Arg-Arg-AMC peptide. Finally, gene expression was performed using RT-PCR Profiler array. RESULTS: We found that sunitinib treatment for 24 h triggers incomplete autophagy, impairs cathepsin B activation and stimulates a lysosomal-dependent necrosis. By contrast, treatment for 48 h with pazopanib induces cathepsin B activation and autophagic cell death, markedly reversed by CA074-Me and 3-MA, cathepsin B and autophagic inhibitors, respectively. Finally, pazopanib upregulates the α-glucosidase and downregulates the TP73 mRNA expression. CONCLUSION: Our results showing distinct cell death mechanisms activated by different TKIs, provide the biological basis for novel molecularly targeted approaches.
Asunto(s)
Antineoplásicos/farmacología , Autofagia/efectos de los fármacos , Indoles/farmacología , Necrosis/inducido químicamente , Pirimidinas/farmacología , Pirroles/farmacología , Sulfonamidas/farmacología , Carcinoma de Células Escamosas/patología , Carcinoma de Células Transicionales/patología , Muerte Celular/efectos de los fármacos , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Humanos , Indazoles , Concentración 50 Inhibidora , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Proteínas Tirosina Quinasas/antagonistas & inhibidores , Especies Reactivas de Oxígeno , Sunitinib , Neoplasias de la Vejiga Urinaria/patologíaRESUMEN
Aberrant cellular proliferation and compromised apoptotic pathways are hallmarks of cancer aggressiveness, and in this framework, the role of protein degradation machineries has been extensively dissected. Among proteases, the proteasome is unequivocally central in the intracellular regulation of both these processes, thus several proteasome-directed therapies have been investigated, aiming at controlling its activity and possibly restoring normal cell functions. Numerous studies reported proteasome inhibitors (both synthetic and natural occurring) to potently and selectively induce apoptosis in many types of cancer cells. In this review we discuss recent advances in proteasomal modulation by some natural occurring polyphenols, globally providing evidence of the proteasome role as therapeutic target in cancer treatment.
Asunto(s)
Antineoplásicos/uso terapéutico , Productos Biológicos/uso terapéutico , Neoplasias/tratamiento farmacológico , Inhibidores de Proteasas/uso terapéutico , Inhibidores de Proteasoma , Animales , Humanos , Neoplasias/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismoRESUMEN
Electromagnetic fields are an assessed cause of prolonging free radicals lifespan. This study was carried out to investigate the influence of extremely low frequency electromagnetic fields on protein oxidation and on the 20S proteasome functionality, the complex responsible for the degradation of oxidized proteins. Caco 2 cells were exposed, for 24-72 hours, to 1 mT, 50 Hz electromagnetic fields. The treatment induced a time-dependent increase both in cell growth and in protein oxidation, more evident in the presence of TPA, while no changes in cell viability were detected. Exposing the cells to 50 Hz electromagnetic fields caused a global activation of the 20S proteasome catalytic components, particularly evident at 72 hours exposure and in the presence of TPA. The finding that EGCG, a natural antioxidant compound, counteracted the field-related pro-oxidant effects demonstrates that the increased proteasome activity was due to an enhancement in intracellular free radicals.
Asunto(s)
Campos Electromagnéticos/efectos adversos , Neoplasias/metabolismo , Complejo de la Endopetidasa Proteasomal/efectos de la radiación , Carbonilación Proteica/efectos de la radiación , Análisis de Varianza , Células CACO-2 , Carcinógenos/farmacología , Catequina/análogos & derivados , Catequina/farmacología , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/efectos de la radiación , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , Relación Dosis-Respuesta en la Radiación , Humanos , Protectores contra Radiación/farmacología , Temperatura , Acetato de Tetradecanoilforbol/farmacologíaRESUMEN
Aflatoxins are highly hazardous contaminants of common food and feed. Aflatoxin B1 in particular, the most predominant among aflatoxins, was thoroughly demonstrated to be highly toxic, mutagenic, teratogenic and carcinogenic in many animal species. Besides its established targets and effects, this work investigates on the possible direct interaction between aflatoxin B1 and three major serine proteases, namely elastase, thrombin and trypsin. These proteases belongs to a class of structurally and functionally related proteins pivotal in both direct and indirect regulation of a number of cellular events. Additionally, several pathological processes, including cancer, inflammatory processes and thrombosis, rely upon the subtle equilibrium between these enzymes and their potential modulators: in fact, their misregulation, caused by foreign molecules, could facilitate (or be the cause for) the occurrence of these pathologies. Our results provide the evidence for a reversible binding between AFB1 and these enzymes, likely to have profound implications in the manifestation of aflatoxicosis. Precisely, the toxin behaved as a moderate competitive inhibitor toward the enzymatic activity of the serine proteases in the low micromolar range.
Asunto(s)
Aflatoxina B1/metabolismo , Venenos/metabolismo , Serina Endopeptidasas/metabolismo , Inhibidores de Serina Proteinasa/metabolismo , Aflatoxina B1/química , Aflatoxina B1/toxicidad , Animales , Sitios de Unión , Unión Competitiva , Bovinos , Humanos , Elastasa Pancreática/antagonistas & inhibidores , Elastasa Pancreática/química , Elastasa Pancreática/metabolismo , Farmacocinética , Venenos/química , Venenos/toxicidad , Unión Proteica , Serina Endopeptidasas/química , Inhibidores de Serina Proteinasa/química , Inhibidores de Serina Proteinasa/toxicidad , Porcinos , Trombina/antagonistas & inhibidores , Trombina/química , Trombina/metabolismo , Tripsina/química , Tripsina/metabolismoRESUMEN
Pomegranate (Punica granatum) is an important source of polyphenols with assessed antioxidant properties. The aims of this study were: (i) the characterization of the monomeric phenolic variability on each isolated fruit component (endocarp, mesocarp, aril); (ii) the study on the effect of pomegranate fruit components on human thrombin amidolytic activity. Collectively, our data show that pomegranate components contain bioactive metabolites (mainly ellagic acid) and suggest a potential role for the pomegranate extract in the regulation of a number of physio-pathological processes involving thrombin (or thrombin-like proteinase).
Asunto(s)
Lythraceae/química , Fenoles/farmacología , Extractos Vegetales/farmacología , Trombina/antagonistas & inhibidores , Antioxidantes/aislamiento & purificación , Antioxidantes/farmacología , Frutas , Humanos , Fenoles/aislamiento & purificación , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificaciónRESUMEN
Wheat sprouts contain a very high level of organic phosphates and a powerful cocktail of different molecules such as enzymes, reducing glycosides and polyphenols. The antioxidant properties of wheat sprouts have been widely documented and it has been shown that they are able to protect DNA against free-radicals mediated oxidative damage. Furthermore, we have recently reported on the effects of several polyphenols on 20S proteasomes, underlying the dual role of epigallocatechin-3-gallate as an antioxidant and a proteasome effector in cancer cells. The aim of this study was to investigate the effects of wheat sprout extracts on 20S proteasome functionality. Wheat sprout extracts have been analysed and characterized for their polyphenolic content using the Folin-Ciocalteau reagent and RP-HPLC technique. Comparing our data with a polyphenol standard mixture we identified five different polyphenols: gallic acid, epigallocatechin-3-gallate, epigallocatechin, epicatechin and catechin. The treatment of isolated 20S proteasomes with the extract induced a gradual inhibition of all the tested components, ChT-L, T-L, PGPH and BrAAP, in both the complexes. At low extract concentration a slight activation of the enzyme was evident only for the BrAAP component of the constitutive enzyme and the ChT-L activity of the immunoproteasome. beta-casein degradation rate decreased, particularly with the immunoproteasome. Human Colon adenocarcinoma (Caco) cells, stimulated with 12-O-tetradecanoylphorbol-13-acetate, showed activation of the 20S proteasome activities at short incubation times and an increase in intracellular oxidative proteins. Cells treatment with wheat sprout extract led to proteasome inhibition in unstimulated cells and attenuated the effects mediated by TPA. Finally, exposure to the extract affected the expression levels of pro-apoptotic proteins.
Asunto(s)
Complejo de la Endopetidasa Proteasomal/metabolismo , Triticum/enzimología , Western Blotting , Cromatografía Líquida de Alta PresiónRESUMEN
The effect of a group of natural flavonoids on human thrombin amidolytic activity was investigated using a spectrophotometric inhibition assay while information on the kinetics and thermodynamics was obtained using optical biosensor techniques. All the flavonoids tested acted as reversible inhibitors, and the quercetin-thrombin complex was found to be most stable at pH=7.5. Docking analysis indicated that quercetin's inhibitory behavior could be related to its planar structure and low steric hindrance, and to its ability to form a critical H-bond with thrombin His57.
Asunto(s)
Flavonoides/química , Flavonoides/farmacología , Relación Estructura-Actividad Cuantitativa , Trombina/antagonistas & inhibidores , Trombina/química , Amidohidrolasas/antagonistas & inhibidores , Amidohidrolasas/química , Arginina/análogos & derivados , Sitios de Unión/efectos de los fármacos , Unión Competitiva , Técnicas Biosensibles , Coagulación Sanguínea/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Estabilidad de Enzimas , Humanos , Cinética , Modelos Moleculares , Estructura Molecular , Ácidos Pipecólicos/química , Ácidos Pipecólicos/farmacología , SulfonamidasRESUMEN
Nitric oxide and prostaglandins are among the numerous substances released by activated glial cells. The aim of this study was to evaluate the effect of high-level aspirin on iNOS expression in cultured rat glial cells treated with lipopolysaccharide (LPS) as pathological stimulator. Using Western Blotting, we verified that aspirin enhanced LPS-induced iNOS expression and the presence of 15-deoxy-Delta(12,14)-prostaglandin (15d-PGJ2) suppressed this aspirin effect. However, the exposure of LPS-treated glial cells to aspirin resulted in a decrease of NO production. These results suggest that aspirin interferes with the cross-talk of prostaglandins and NO, blocking the endogenous negative control exerted by COX products on iNOS expression. On the other side, aspirin seems to act directly on iNOS reducing its activity, even if it does not completely block NO release by LPS-stimulated glial cells. Then aspirin could maintain homeostatic functions of NO, while it prevents toxic effects, corresponding to high NO concentrations.
Asunto(s)
Aspirina/administración & dosificación , Lipopolisacáridos/administración & dosificación , Neuroglía/efectos de los fármacos , Neuroglía/metabolismo , Óxido Nítrico Sintasa/biosíntesis , Óxido Nítrico/metabolismo , Prostaglandina D2/análogos & derivados , Prostaglandina D2/administración & dosificación , Animales , Animales Recién Nacidos , Células Cultivadas , Relación Dosis-Respuesta a Droga , Interacciones Farmacológicas , Óxido Nítrico Sintasa de Tipo II , Ratas , Ratas WistarRESUMEN
The effect of oxidative stress induced by neurotoxic metal ions on the properties of the brain 20S proteasome or multicatalytic proteinase complex (MPC) has been studied. Exposure of the 20S proteasome to increasing amounts of Fe(III), Fe(II), Cu(II) or Zn(II) affects its main hydrolytic activities: trypsin-like (T-L), chymotrypsin-like (ChT-L), peptidylglutamyl-peptide hydrolase (PGPH), branched-chain amino acid preferring (BrAAP) and caseinolytic activities, although in different ways. T-L activity showed gradual activation by both iron ions but inhibition by Cu(II) and Zn(II). ChT-L and PGPH activities were inhibited whereas BrAAP activity was widely activated by all the tested metal salts except for zinc ions. Moreover, the exposure to ferrous salt increased the degradation rate of casein. The functional effects appear to be linked to oxidation-induced modifications, as demonstrated by an increase of carbonyl groups following the exposure to metal ions. In addition, modifications induced by ferrous salt on the catalytic subunits were also supported by western blot analyses performed using anti-X, anti-Y and anti-Z antibodies. The results obtained clearly indicate that metal-catalyzed oxidation strongly affects the functions of the brain 20S proteasome, even though the catalytic subunits seem to be differently influenced by oxidative phenomena.
Asunto(s)
Química Encefálica/efectos de los fármacos , Cisteína Endopeptidasas/química , Endopeptidasas/química , Metales/química , Metales/toxicidad , Complejos Multienzimáticos/química , Enfermedad de Alzheimer/metabolismo , Animales , Western Blotting , Caseínas/química , Catálisis , Bovinos , Cisteína Endopeptidasas/efectos de los fármacos , Electroforesis en Gel de Poliacrilamida , Endopeptidasas/aislamiento & purificación , Depuradores de Radicales Libres/química , Complejos Multienzimáticos/efectos de los fármacos , Oxidación-Reducción , Estrés Oxidativo/fisiología , Complejo de la Endopetidasa Proteasomal , Superóxido Dismutasa/químicaRESUMEN
The proteasome and heat shock proteins have been found in the centrosome. The evidence of their copurification reported by several studies suggests that they form stable complex. In addition, Hsp90 is involved in the loading of proteasome-generated antigenic peptides to the class I major histocompatibility complex. In this article, we report a detailed thermodynamic and kinetic characterization of the Hsp90-20S proteasome interaction, using a surface plasmon resonance technique. The modulation exerted by protons in solution has been investigated, and the results have been discussed, taking into account structural motifs characterizing the binding interface between the two macromolecules.
Asunto(s)
Cisteína Endopeptidasas/metabolismo , Proteínas HSP90 de Choque Térmico/metabolismo , Complejos Multienzimáticos/metabolismo , Animales , Proteínas HSP90 de Choque Térmico/farmacología , Concentración de Iones de Hidrógeno , Cinética , Modelos Químicos , Complejo de la Endopetidasa Proteasomal , Resonancia por Plasmón de Superficie , TermodinámicaRESUMEN
The structure--function relationships occurring on the bovine thymus 20S proteasome, which exhibits the features of an immunoproteasome, have been studied. The investigation has been performed, essentially, using a fluorimetric approach, taking advantage either of the sensitivity of the complex to sodium dodecil sulfate and chaotropic agents (urea and guanidine hydrochloride) or of the presence, on the molecule, of a high number of tryptophan residues. The results obtained indicate that the perturbation or the oxidation of these residues affect the catalytic events taking place on the thymus proteasome and that the functional effects determined by SDS and chaotropic agents most likely occur through a series of progressive structural modifications leading to an inactive molecule. The presence of structural intermediates in the proteasome inactivation process suggests that thymus proteasome is a molecule characterized, at the same time, by structural flexibility (modulation of active sites) and structural stability (maintaining of the quaternary structure) in agreement with its crucial role in the cell life cycle.
Asunto(s)
Cisteína Endopeptidasas/metabolismo , Complejos Multienzimáticos/metabolismo , Animales , Bovinos , Cisteína Endopeptidasas/química , Fluorescencia , Fluorometría/métodos , Guanidina , Complejos Multienzimáticos/química , Complejo de la Endopetidasa Proteasomal , Desnaturalización Proteica , Dodecil Sulfato de Sodio , Relación Estructura-Actividad , Timo/enzimología , UreaRESUMEN
The multicatalytic proteinase complex (MPC or proteasome) from bovine thymus was isolated and purified to homogeneity applying a protocol utilizing ion exchange and gel permeation chromatography as major purification tools. The purified complex shows molecular properties that are common for proteasomal molecules (high molecular mass, multisubunit organization, and multiple proteolytic activities) even though a peculiar subunit composition and the presence of specific regulatory mechanisms affecting the assembled proteolytic activities suggest a specialized function for this complex. Thymus proteasome is characterized by the presence of LMP2, LMP7, and LMP10 (MECL1) subunits, which replace the X, Y, and Z subunits. Since a similar complex was previously isolated in bovine spleen, it appears that the proteasomal population containing the LMP subunits is characteristic for organs involved in immune response. Both the thymus and spleen proteasomes are characterized by a marked efficiency in cleaving peptide bonds after branched-chain and aromatic amino acids, indicating that this proteasomal population is most likely involved in intracellular processing of class I antigenic peptides and is an example of an "in vivo" functioning immunoproteasome. However, in spite of several similarities, the complexes isolated from the two lymphoid organs do not show superimposable functional properties, which suggests the presence of organ-specific regulatory mechanisms affecting each of the proteolytic components assembled in the complex.
Asunto(s)
Cisteína Endopeptidasas/química , Complejos Multienzimáticos/química , Timo/química , Animales , Western Blotting , Bovinos , Cumarinas/química , Inhibidores de Cisteína Proteinasa/química , Electroforesis en Gel Bidimensional , Isocumarinas , Complejo de la Endopetidasa Proteasomal , Bazo/químicaRESUMEN
The clotting activity of human fibrinogen was fully inhibited in vitro by peroxynitrite. The decrease of activity followed an exponential function and the concentration of peroxynitrite needed to inhibit 50% of fibrinogen clotting was 22 microM at 25 degrees C. The oxidative modification(s) induced by the peroxynitrite system (i.e. ONOO-, ONOOH and ONOOH*) appeared specifically to affect fibrin clot formation (through the inhibition of fibrinogen polymerization) since the interaction of peroxynitrite-modified fibrinogen with thrombin appeared to be unaffected. The addition of NaHCO3 decreased the peroxynitrite effect on fibrinogen clotting, suggesting that the reactive species formed by the reaction of CO2 with peroxynitrite are less efficient oxidants of peroxynitrite itself. Similar effects were observed after addition of bilirubin, which also exerted a significant protection against peroxynitrite-mediated modification of fibrinogen.
Asunto(s)
Coagulación Sanguínea/fisiología , Fibrinógeno/metabolismo , Nitratos/farmacología , Bilirrubina/farmacología , Coagulación Sanguínea/efectos de los fármacos , Dióxido de Carbono/farmacología , Relación Dosis-Respuesta a Droga , Humanos , Nitratos/metabolismo , Oxidación-Reducción , Trombina/farmacología , Factores de TiempoRESUMEN
Exposure to [14C]-3,4-dichloroisocoumarin (DCI) of multicatalytic proteinase complexes (MPC) isolated from bovine pituitary and spleen leads to label incorporation into several beta-type subunits, to rapid inactivation of the chymotrypsin-like (ChT-L) activity, and to a slower inactivation of other activities of the MPC. The pituitary and spleen MPCs differ in that the first contains almost exclusively the X, Y, and Z subunits, whereas in the latter these subunits are largely replaced by LMP2, LMP7, and MECL1. Preincubation with two peptidyl aledhyde inhibitors of the ChT-L activity protected the X subunit in the pituitary MPC and unexpectedly the LMP2 subunit in the spleen MPC from label incorporation, despite the greater amino acid sequence homology of the LMP7 subunit to that of the X subunit. Losses in the yield of amino acids in both subunits, shown by amino acid sequencing, and lability of the DCI-protein bond indicated formation of an acyl derivative by reaction of DCI with the threonine OH group. Brief exposure to [14C]-DCI led to preferential incorporation of label into the LMP2 and X subunits, consistent with the high inactivation rate constants of the ChT-L activity. Z-LLF-CHO, an inhibitor of ChT-L activity, but not Z-GPFL-CHO, an inhibitor of the branched chain amino acid preferring component, prevented incorporation of radioactivity into the X subunits, whereas both inhibitors prevented label incorporation into LMP2, indicating differences in susceptibility to inhibition between the two components. These and other data are consistent with involvement of the X and LMP2 subunits in expression of the ChT-L activity in the pituitary and spleen MPC, respectively, and suggest the catalytic functions of two other beta-subunits.
Asunto(s)
Cumarinas/metabolismo , Cisteína Endopeptidasas/metabolismo , Complejos Multienzimáticos/metabolismo , Hipófisis/enzimología , Inhibidores de Serina Proteinasa/metabolismo , Bazo/enzimología , Animales , Radioisótopos de Carbono , Catálisis , Bovinos , Isocumarinas , Complejo de la Endopetidasa Proteasomal , Proteínas/metabolismo , Proteínas de la Matriz Viral/metabolismoRESUMEN
Three molecular forms of granulins (also known as epithelins) were isolated, for the first time, in human urine. Their N-terminal sequences, which have also been determined, are identical to those of granulins A and B, previously isolated from human leukocytes, and of granulin F, never isolated before but whose primary structure is known on the basis of the cDNA sequence. The urinary molecules, which show a molecular weight of about 6.5 kDa, are most likely produced by a posttranslational proteolytic processing occurring at the level of the kidney, which appears to be the organ richest in granulin precursor mRNA. The molecular events underlying the precursor processing are unknown, even though the involvement of the protease kallikrein, an enzyme thought to be responsible for the processing of several polypeptidic growth factor precursors, could be hypothesized. Granulins, however, do not show antikallikrein activity. The presence in human urine of isoform F, previously not identified from other human sources, seems to support the hypothesis that mature forms of granulins are generated by an organ-specific precursor processing, on the basis of particular physiological requirements, and to suggest also that this isoform may play "in vivo" an important and specific role in the epithelial cells of the human kidney.
Asunto(s)
Inhibidores de Crecimiento/aislamiento & purificación , Inhibidores de Crecimiento/orina , Sustancias de Crecimiento/aislamiento & purificación , Sustancias de Crecimiento/orina , Péptidos y Proteínas de Señalización Intercelular , Péptidos/aislamiento & purificación , Péptidos/orina , Proteínas Virales/aislamiento & purificación , Secuencia de Aminoácidos , Western Blotting , Fraccionamiento Químico , Cromatografía , Cromatografía Líquida de Alta Presión , Electroforesis en Gel de Poliacrilamida , Granulinas , Humanos , Datos de Secuencia Molecular , Progranulinas , Análisis de Secuencia , Homología de Secuencia de Aminoácido , Proteínas Virales/orinaRESUMEN
Amino acid sequencing of subunits of the multicatalytic proteinase complex (MPC) isolated from bovine spleen showed an almost complete replacement of the X, Y, and Z subunits, constitutively expressed in most tissues, by the interferon-gamma-inducible LMP7, LMP2, and MECL1 subunits. A comparison with the pituitary MPC found a decreased chymotrypsin-like activity, a depressed peptidylglutamyl-peptide hydrolyzing activity, and a highly active component with properties similar to, but not identical with, that of the pituitary branched chain amino acid preferring (BrAAP) component. Unlike the pituitary BrAAP component, that of the spleen MPC exhibited a greatly decreased Km, a highly increased catalytic efficiency (kcat), and a 80-180 times greater specificity constant (kcat/Km) toward substrates with either branched chain or aromatic amino acid residues in the P1 position. Also, unlike the pituitary BrAAP component, that of the spleen was sensitive to inactivation by 3,4-dichloroisocoumarin and sensitive to inhibition by peptidyl-aldehydes with either phenylalaninal or leucinal residues. Several phenylalaninal peptidyl-aldehydes were identified which selectively inhibited components of the spleen but not of the pituitary MPC. Two of the inhibitors are dipeptidyl-aldehydes, two others are tetrapeptidyl-aldehydes with a Pro residue in the P3 position. The possibility is discussed that the properties and specificity of the spleen MPC are a consequence of the presence of the interferon-gamma-inducible subunits.
Asunto(s)
Cisteína Endopeptidasas/química , Cisteína Endopeptidasas/metabolismo , Complejos Multienzimáticos/química , Complejos Multienzimáticos/metabolismo , Proteínas/metabolismo , Bazo/enzimología , Proteínas de la Matriz Viral/metabolismo , Secuencia de Aminoácidos , Animales , Bovinos , Cisteína Endopeptidasas/biosíntesis , Cisteína Endopeptidasas/aislamiento & purificación , Inducción Enzimática , Interferón gamma/farmacología , Cinética , Pulmón/enzimología , Sustancias Macromoleculares , Datos de Secuencia Molecular , Complejos Multienzimáticos/aislamiento & purificación , Fragmentos de Péptidos/química , Hipófisis/enzimología , Complejo de la Endopetidasa Proteasomal , Biosíntesis de Proteínas , Especificidad por Sustrato , Proteínas de la Matriz Viral/biosíntesisRESUMEN
A comparative study of the levels of acid-stable proteinase inhibitors (kallikrein and trypsin inhibitors) in the urine of healthy and Alzheimer subjects, of both sexes, has been performed. A preliminary characterization of the purified inhibitors indicates that the urinary antitryptic activity is accounted for by the presence of the well known Urinary Trypsin Inhibitor (UTI) while an apparently new molecule appears to be responsible for the antikallikrein activity. The urinary levels of kallikrein inhibitors are very similar in healthy and sick subjects while the levels of trypsin inhibitors appear significatively increased in Alzheimer subjects of both sexes. The data presented here support the hypothesis that unpaired proteolytic processes could be involved in the pathogenesis of Alzheimer's disease and suggest that the levels of urinary acid-stable inhibitors may prove to be useful markers of the disease.
Asunto(s)
Enfermedad de Alzheimer/orina , Inhibidores de Serina Proteinasa/orina , Anciano , Anciano de 80 o más Años , Cromatografía Líquida de Alta Presión , Femenino , Humanos , MasculinoRESUMEN
Polyacrylamide gel electrophoresis and high performance liquid chromatography of multicatalytic proteinase complexes (MPC) isolated from bovine pituitary, lung, and liver showed marked differences in the pattern of subunits. The concentrations of LMP7 in the lung and liver were 10 and 5 times, respectively, greater than those in the pituitary, whereas the chymotrypsin-like activity and the amount of a subunit (BO2), necessary for its expression, were markedly decreased in the lung and moderately decreased in the liver. Lower trypsin-like, small neutral amino acid preferring, and peptidyl-glutamyl-peptide hydrolyzing activities were also found in the lung and liver. The activity of the branched chain amino acid preferring component (BrAAP), predominantly latent in the pituitary, was highly activated in the lung and liver, as evidenced by a greatly decreased Km and a 20-fold increase of the specificity constant Vmax/Km, indicating facilitated substrate access to its active site and increased affinity toward substrates with branched chain amino acids in the P1 position. It is suggested that overexpression of LMP7 in the lung is related to increased exposure of the airways to foreign antigens. The possible association between amounts of LMP7 and the activation of the BrAAP component needs further examination.
Asunto(s)
Cisteína Endopeptidasas/metabolismo , Hígado/enzimología , Pulmón/enzimología , Complejos Multienzimáticos/metabolismo , Hipófisis/enzimología , Proteínas/metabolismo , Secuencia de Aminoácidos , Animales , Catálisis , Bovinos , Quimotripsina , Cumarinas/farmacología , Cisteína Endopeptidasas/química , Isocumarinas , Datos de Secuencia Molecular , Complejos Multienzimáticos/química , Complejo de la Endopetidasa ProteasomalRESUMEN
Protein proteinase inhibitors belonging to the Kunitz family have been isolated and characterized in several fallow deer organs. In all the organs studied we found the basic pancreatic trypsin inhibitor (BPTI) while its isoforms, previously isolated and characterized in organs of other ruminant species (bovids and ovids), were absent. In the kidney, in addition to BPTI, active fragments of the inter-alpha-trypsin inhibitor were also isolated. The distribution of Kunitz-type inhibitors in different species of ruminants is compared and discussed on the basis of the expression of their encoding genes.