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J Travis

Publications and source records attributed to J Travis.

At least 73 records · Page 4Linked to original sources
PubMed1998

Oncostatin M and the interleukin-6 and soluble interleukin-6 receptor complex regulate alpha1-antichymotrypsin expression in human cortical astrocytes.

alpha1-Antichymotrypsin (ACT) is an acute phase protein expressed in the brain which specifically colocalizes with amyloid-beta during Alzheimer's disease. We analyzed ACT synthesis in cultured human cortical astrocytes in response to various cytokines and growth factors. Oncostatin M (OSM) and interleukin (IL)-1beta were potent stimulators of ACT mRNA expression, whereas tumor necrosis factor-alpha had modest activity, and IL-6 and leukemia inhibitory factor (LIF) were ineffective. The finding that OSM, but not LIF or IL-6, stimulated ACT expression suggests that human astrocytes express a "specific" OSM receptor, but not IL-6 or LIF receptors. However, cotreatment of human astrocytes with soluble IL-6 receptor (sIL-6R).IL-6 complex did result in potent stimulation of ACT expression. When the human ACT gene was cloned, two elements binding STAT1 and STAT3 (signal transducer and activator of transcription) in response to OSM or IL-6.sIL-6R complexes could be identified and characterized. Taken together, these findings indicate that OSM or IL-6.sIL-6 complexes may regulate ACT expression in human astrocytes and thus directly or indirectly contribute to the pathogenesis of Alzheimer's disease.

Acute-Phase Proteins↗
PubMed1998

Oncostatin M, leukaemia-inhibitory factor and interleukin 6 trigger different effects on alpha1-proteinase inhibitor synthesis in human lung-derived epithelial cells.

Interleukin 6 (IL-6), oncostatin M (OSM) and leukaemia-inhibitory factor (LIF) share a common signal-transducing subunit in each of their receptors and thus mediate an overlapping spectrum of biological activities. Although all of these cytokines stimulate the production of alpha1-proteinase inhibitor (alpha1-PI) in hepatocyte-derived cells, only OSM is able to up-regulate levels of this inhibitor in epithelial cells originating from the lung. In this study we characterized human lung-derived epithelial-like HTB58 cells for their ability to synthesize alpha1-PI after treatment with IL-6, OSM and LIF. The results demonstrate that the resistance of HTB58 cells to the effects of IL-6 and LIF was not because of a lack of their individual functional receptors and suggest that OSM utilizes two different receptors, gp130/LIF receptor and gp130/OSM receptor, in lung-derived epithelial cells.

Blotting, Northern↗
PubMed1998

Crystallization and preliminary X-ray diffraction analysis of gingipain R2 from Porphyromonas gingivalis in complex with H-D-Phe-Phe-Arg-chloromethylketone.

Gingipain R2 is a 50 kDa proteinase from the oral pathogenic bacterium Porphyromonas gingivalis. This proteinase, which displays no significant sequence homology to any protein previously analyzed by X-ray crystallography, has been crystallized using the vapor diffusion method. Two different crystal forms were obtained from a solution containing polyethylene glycol (MW 8,000) (space group P2(1)2(1)2(1)) or magnesium sulfate (space group R3) as precipitating agent. Complete diffraction data sets have been collected up to 2.0 and 2.9 A resolution, respectively. Cell dimensions are a = 51.9 A, b = 79.9 A, and c = 99.6 A (P2(1)2(1)2(1)), and a = b = 176.6 A, and c = 143.4 A (R3). Considerations of the possible values of Vm accounts for the presence of one monomer per asymmetric unit in the case of the orthorhombic crystal form, whereas the rhombohedral crystal form, together with the analysis of the self-rotation function, could accommodate a tetramer in the asymmetric unit.

Adhesins, Bacterial↗
PubMed1998

Ragweed pollen proteolytic enzymes: possible roles in allergies and asthma.

Extracts from ragweed pollen grains contain novel trypsin and chymotrypsin-like serine peptidases which are described in this report. The molecular mass of the chymotrypsin-like enzyme was 82 kDa, had a pH optimum near 9.0, and its activity was unaffected by chelating or reducing agents. It was inhibited by diisopropyl fluorophosphate (DFP), a general serine class inhibitor, and more specifically N-p-tosyl-L-phenylalanine chloromethyl ketone (TPCK), a chymotrypsin-like proteinase inhibitor. In addition to various synthetic substrates, the neuropeptides, vasoactive intestinal peptide (VIP) and substance P, which are required for normalized lung functions, were also rapidly hydrolysed. Activity toward protein substrates was not detected with the exception of the inactivation of alpha-1-proteinase inhibitor (alpha-1-PI) which occurred through cleavage within the reactive site loop. The 'trypsin-like' enzyme has a molecular mass near 80 kDa, a blocked N-terminus, a pH optimum near 9.0, and requires Ca++ for stability and activity, but not reducing agents. It is inhibited by DFP, and more specifically the trypsin-like proteinase inhibitor, N-p-tosyl-L-lysine chloromethyl ketone (TLCK). Again, activity toward protein substrates was not detected, but various synthetic substrates and biologically active peptides were efficiently cleaved. Significantly, atrial natriuretic peptide (ANP) and angiotensin 2 (ATII), whose degradation would amplify kinin activity and influence inflammatory diseases of the respiratory tract and nasal passages, were also rapidly hydrolyzed.

Allergens↗
PubMed1998

Effect of oxidation of beta-amyloid precursor protein on its beta-secretase cleavage. A model study with synthetic peptides and candidate beta-secretases.

As the amyloidogenic processing of beta-amyloid precursor protein (betaAPP) proceeds under conditions of oxidative stress, the methionine-596 residue at the beta-secretase cleavage point is likely in an oxidized state. In the present work, possible consequences of the oxidation of Met-596 for the generation of the N-terminus of amyloid beta protein were modeled using synthetic peptide substrates, matching 587-606 sequence fragment of betaAPP and containing either intact methionine or methionine sulfoxide. Patterns and rates for the cleavage of these substrates by purified mast cell chymase, cathepsin G, cathepsin D, matrix metalloproteinase-3 and neutrophil elastase, were compared. Only the three first proteases, all previously suggested as candidate beta-secretases, preferentially cleaved the "intact" substrate after Met-596. For chymase and cathepsin G, the specificity of this cleavage increased upon a shift from optimal alkaline pH to acidic pH, which is also more compatible with the plausible intracellular localization of amyloidogenic betaAPP processing. The substitution of methionine sulfoxide for methionine in the substrate slowed down the cleavage rate for all the enzymes tested, by a factor of 6-15. This was associated with shifts of cleavage preferences to points of minor importance for the "intact" peptide, suggesting a specific resistance of the peptide bond after MetSO-596 against proteolysis.

Amyloid Precursor Protein Secretases↗
PubMed1998

A relationship between proteinase activity and clinical parameters in the treatment of periodontal disease.

The objective of this research was to determine the effectiveness of a biochemical assay which measures proteolytic enzyme activity in gingival crevicular fluid (GCF) and to relate this enzyme activity to clinical parameters traditionally utilized for periodontitis detection. A clinical trial was conducted on 8 periodontitis subjects with > or =4 sites exhibiting a loss of attachment of > or =5 mm and probing depths of > or =5 mm with bleeding on probing. On each subject, a plaque index was performed, followed by GCF sampling at those sites which exhibited a loss of attachment and probing depths. GCF was analyzed for activity against benzoyl-L-arginine-p-nitroanilide in the presence (BAPNA w/gly-gly) and the absence (BAPNA w/o gly-gly) of glycyl-glycine and against MeOSuc-Ala-Ala-Pro-Val-pNA and Suc-Ala-Ala-Pro-Phe-pNA for neutrophil serine proteinases activity (elastase and cathepsin G, respectively). Subsequently, a gingival index was performed, attachment levels and probing depths were recorded using a constant force probe with bleeding on probing being noted. A split-mouth design was employed and half mouths were randomly assigned to the following treatment groups: group A, half of the mouth received scaling/root planing and polishing: group B, half of the mouth received no treatment (control). Subjects were treated, then instructed on toothbrushing and interdental cleaning. After 4 weeks, subjects returned to receive a plaque index; GCF sampling, gingival index, attachment levels, probing depths and bleeding on probing as described above. Using a paired Student t-test, the findings suggest that BAPNA w/gly-gly was significantly less in treatment sites than in non-treated control sites (p=0.05). No such correlation was found for other activities, including neutrophil serine proteinases which were shown to occur in GCF in free, proteolytically active forms. In addition, significant treatment effects were detected for probing depths (p= 0.03) which reduced by 1.3 mm and attachment levels (p=0.02) which gained 0.7 mm. The reduction of P. gingivalis from treated periodontitis sites as detected by a significant decrease in BAPNA w/ gly-gly may prove to be a valuable marker for periodontal disease activity.

Benzoylarginine Nitroanilide↗
PubMed1998

A peptide domain on gingipain R which confers immunity against Porphyromonas gingivalis infection in mice.

The cysteine proteinases referred to as gingipains R (gingipain R1 and gingipain R2) and gingipain K produced by Porphyromonas gingivalis are virulence factors of this periodontal pathogen which likely act by interrupting host defense mechanisms and by participating in the penetration and destruction of host connective tissue. To examine the effect of immunization with gingipains R on the ability of P. gingivalis to colonize and invade in the mouse chamber model, BALB/c mice were immunized intraperitoneally with the 95-kDa gingipain R1, the 50-kDa gingipain R2, or multiple antigenic peptide (MAP)-conjugated gingipain R-derived peptides and then challenged with P. gingivalis. Immunization of mice with the 95-kDa gingipain R1, the 50-kDa gingipain R2, or a peptide derived from the N-terminal sequence of the catalytic domain of gingipains R (peptide A) followed by challenge with P. gingivalis A7436 resulted in protection from P. gingivalis invasion. In contrast, immunization with peptides corresponding to either a sequence encompassing the catalytic cysteine residue of gingipains R (peptide B) or an identical sequence within the catalytic domains of gingipain R1 and gingipain K (peptide C), followed by challenge with P. gingivalis, did not protect animals, nor did immunization with a peptide corresponding to sequences within the adhesion/hemagglutinin domain of gingipain R1 (peptide D) which have been shown to be directly involved in the hemagglutinin activity of gingipain R1. However, the immunoglobulin G (IgG) titer obtained following immunization with peptide D was comparable to that obtained following immunization with the N-terminal peptide (peptide A). Competitive enzyme-linked immunosorbent assays, using either the 95-kDa gingipain R1 or gingipain K as the competing soluble antigen, indicated that 42 and 53% of the antibodies induced by immunization with heat-killed bacteria recognize gingipain R1 and gingipain K, respectively; however, even at very high concentrations, the 50-kDa gingipain R2 did not hinder IgG binding to P. gingivalis. These results indicate that antibodies directed to the amino-terminal region of the catalytic domain of gingipains R are capable of inducing a protective immune response against P. gingivalis infection in the mouse chamber model.

Adhesins, Bacterial↗
PubMed1998

Purification and characterization of an arginine-specific peptidase from ragweed (Ambrosia artemisiifolia) pollen.

Ragweed (Ambrosia artemisiifolia) is clinically the most important source of seasonal aeroallergens, as it is responsible for the majority and most severe cases of hay fever (allergic rhinitis). Extracts from pollen grains have been shown to contain numerous proteins with various functions, including a novel serine proteolytic enzyme with chymotrypsin-like specificity that has been previously described (J. Biol. Chem. 1996; 271:26227-26232). We now report the isolation and properties of a second, trypsin-like enzyme with a molecular mass near 80 kD, from ragweed pollen extracts. This enzyme has a blocked N-terminus, a pH optimum near 9.0, and requires Ca2+ for stability and activity, but not reducing agents. The enzyme is inhibited by diisopropyl fluorophosphate, a general serine class proteinase inhibitor, and more specifically by N-p-tosyl-L-lysine chloromethyl ketone. Activity toward protein substrates was not detected, but various synthetic substrates and small biologically active peptides were efficiently cleaved, with a strong preference for Arg in the P1 position and either Arg or Gly in the P2 position. This specificity was confirmed through inhibition studies with both peptidyl chloromethyl ketone and organophosphate inhibitors. Significantly, atrial natriuretic peptide and angiotensin 2, whose degradation would amplify kinin activity and influence inflammatory diseases of the respiratory tract and nasal passages, were also rapidly hydrolyzed. Thus, the ragweed pollen endopeptidase may be involved in the inactivation of regulatory neuropeptides during pollen-initiated allergic reactions.

Amino Acid Sequence↗
PubMed1998

Genetic variation of Porphyromonas gingivalis genes encoding gingipains, cysteine proteinases with arginine or lysine specificity.

Porphyromonas gingivalis hemagglutinating cysteine proteinases (gingipains) are considered as important virulence factors in the development of adult periodontitis. Using Southern blot analysis it was determined that genes of three distinct but related gingipains (gingipain-R1, gingipain-R2 and gingipain-K) were present in all tested strains including HG66, ATCC 33277, W50, E-20-1, EM-3, 381, A7436, and IKG5, with a region encoding a part of the hemagglutinin domain of gingipain-R1 and gingipain-K showing considerable variability. In contrast, the loci encoding gingipain-R1 (rgp1) and gingipain-R2 (rgp2) were strongly conserved excluding the concurrent occurrence of other gingipain-R-like genes such as cpgR and agp. Significantly, no evidence could be found to support the expression of a gene coding for the putative proteinase porphypain, an enzyme suggested to have both gingipain-R and gingipain-K activity.

Adhesins, Bacterial↗
PubMed1997

Oncostatin M stimulates the expression and release of the IL-6 receptor in human hepatoma HepG2 cells.

Soluble IL-6R (sIL-6R), which lacks the transmembrane domain, has been suggested to be a potent immunomodulator of IL-6 biologic activity. In this study, the ability of cells of hepatic origin to generate the sIL-6R was investigated. It was found that oncostatin M alone or in combination with the glucocorticoid analogue dexamethasone significantly up-regulated IL-6R release. Oncostatin M appeared to generate the sIL-6R primarily through an alternative splicing mechanism. Since sIL-6R is able to form biologically active complexes with IL-6, the release of the sIL-6R from hepatocytes may be important to sensitize cells lacking the membrane-bound receptor, particularly during an acute phase reaction.

Alternative Splicing↗
PubMed1997

Anionic- and lipophilic-mediated surface binding inhibitors of human leukocyte elastase.

We report the synthesis of a series of diphenylmethane-based oligomers containing anionic and lipophilic functionalities that are potent inhibitors of human leukocyte elastase (HLE). The enzyme inhibition is regulated by the size of the oligomer, as well as, the number of charges. Lipophilicity is an important element in determining potency and specificity against other basic enzymes. Compounds whose scaffolds contain three phenoxyacetic acid groups and three alkyl ethers are competitive and specific inhibitors of HLE with Ki = 20 nM. The mechanism of action of this class of compounds is believed to involve multidendate interactions with the surface of HLE near the active site which prevents substrate access to the catalytic site.

Benzhydryl Compounds↗
PubMed1997

Heparin-dependent modification of the reactive center arginine of antithrombin and consequent increase in heparin binding affinity.

Antithrombin, the principal plasma inhibitor of coagulation proteinases, circulates in a form with low inhibitory activity due to partial insertion of its reactive site loop into the A-beta-sheet of the molecule. Recent crystallographic structures reveal the structural changes that occur when antithrombin is activated by the heparin pentasaccharide, with the exception of the final changes, which take place at the reactive center itself. Here we show that the side chain of the P1 Arg of alpha-antithrombin is only accessible to modification by the enzyme peptidylarginine deiminase on addition of the heparin pentasaccharide, thereby inactivating the inhibitor, whereas the natural P1 His variant, antithrombin Glasgow, is unaffected, indicating that only the P1 Arg becomes accessible. Furthermore, the deimination of P1 Arg converts antithrombin to a form with 4-fold higher affinity for the heparin pentasaccharide, similar to the affinity found for the P1 His variant, due to a lowered dissociation rate constant for the antithrombin-pentasaccharide complex. The results support the proposal that antithrombin circulates in a constrained conformation, which when released, in this study by perturbation of the bonding of P1 Arg to the body of the molecule, allows the reactive site loop to take up the active inhibitory conformation with exposure of the P1 Arg.

Antithrombin III↗
PubMed1997

Activation of blood coagulation factor X by arginine-specific cysteine proteinases (gingipain-Rs) from Porphyromonas gingivalis.

The effect of two arginine-specific cysteine proteinases (gingipain Rs) from Porphyromonas gingivalis, a causative bacterium of adult periodontitis, on human blood coagulation was investigated. Activated partial thromboplastin time and prothrombin time were shortened by these proteinases, with a 95-kDa gingipain R containing adhesin domains being 5-fold more efficient in comparison to a 50-kDa gingipain R containing the catalytic domain alone. The 50-kDa enzyme reduced each coagulation time in several plasmas deficient in various coagulation factors, while it was ineffective in factor X-deficient plasma unless reconstituted with this protein. Each proteinase activated factor X in a dose- and time-dependent manner, with Michaelis constants (Km) being found to be lower than the normal plasma factor X concentration, strongly suggesting that factor X activation by gingipain Rs, especially the 95-kDa form which is strongly activated by phospholipids, could occur in plasma. This is the first report of factor X activation by bacterial proteinases and indicates that the gingipain Rs could be responsible for the production of thrombin and, indirectly, with the generation of prostaglandins, interleukin-1, etc., which have been found to be associated with the development of periodontitis induced by P. gingivalis infections. Furthermore, the data support the hypothesis that induction of blood coagulation by bacterial proteinases may be a causative agent in the pathogenesis of disseminated intravascular coagulation in sepsis.

Adhesins, Bacterial↗
PubMed1997

Biosynthesis of alpha1-proteinase inhibitor by human lung-derived epithelial cells.

Destruction of components of the extracellular matrix of the lung by neutrophil elastase is believed to be a critical event in the development of obstructive lung disease. The local synthesis of alpha1-proteinase inhibitor, the controlling inhibitor of this enzyme, may provide a partial mechanism for neutrophil elastase regulation, especially during inflammation, when proteolytic enzymes are released from phagocytes. In this study, we show that lung-derived epithelial cells not only have the capacity to synthesize functional alpha1-PI but also to increase the rate of its production when stimulated by specific inflammatory mediators, including oncostatin M, interleukin-1, and the glucocorticoid analogue, dexamethasone.

Antineoplastic Agents↗
PubMed1997

Molecular cloning and characterization of Porphyromonas gingivalis lysine-specific gingipain. A new member of an emerging family of pathogenic bacterial cysteine proteinases.

The proteinases of Porphyromonas gingivalis are key virulence factors in the etiology and progression of periodontal disease. Previous work in our laboratories resulted in the purification of arginine- and lysine-specific cysteine proteinases, designated gingipains, that consist of several tightly associated protein subunits. Recent characterization of arginine-specific gingipain-1 (gingipain R1; RGP-1) revealed that the sequence is unique and that the protein subunits are initially translated as a polyprotein encoding a proteinase domain and multiple adhesin domains (Pavloff, N., Potempa, J., Pike, R. N., Prochazka, V., Kiefer, M. C., Travis, J., and Barr, P. J. (1995) J. Biol. Chem. 270, 1007-1010). We now show that the lysine-specific gingipain (gingipain K; KGP) is also biosynthesized as a polyprotein precursor that contains a proteinase domain that is 22% homologous to the proteinase domain of RGP-1 and multiple adhesin domains. This precursor is similarly processed at distinct sites to yield active KGP. The key catalytic residues in the proteinase domain of KGP are identical to those found in RGP-1, but there are significant differences elsewhere within this domain that likely contribute to the altered substrate specificity of KGP. Independent expression of the proteinase domain in insect cells has shown that KGP does not require the presence of the adhesin domains for correct folding to confer proteolytic activity.

Adhesins, Bacterial↗
PubMed1997

The mitogen-activated protein kinase and JAK-STAT signaling pathways are required for an oncostatin M-responsive element-mediated activation of matrix metalloproteinase 1 gene expression.

Both astrocytes in the central nervous system and fibroblasts in somatic tissues are not only the major sources of extracellular matrix components but also of matrix metalloproteinases (MMPs), a family of enzymes directly involved in extracellular matrix breakdown. We have analyzed the regulation of the expression of MMPs and TIMPs (tissue inhibitors of metalloproteinases) in human primary astrocytes stimulated with oncostatin M (OSM) and other extracellular mediators in comparison with normal human dermal fibroblasts. It was found that OSM induced/enhanced transcription of MMP-1 (interstitial collagenase) and MMP-3 (stromelysin 1) in astrocytes, and MMP-1, MMP-9 (gelatinase B), and TIMP-1 in fibroblasts. Analysis of the signal transduction leading to activation of the MMP-1 gene revealed the presence of an OSM-responsive element (OMRE) encompassing the AP-1 binding site and the signal transducer and activator of transcription (STAT) binding element, which mediate activation by OSM. OMRE is also present in the TIMP-1 gene promoter and, although there are some differences in these two motifs, both appear to be targets for the simultaneous action of OSM-induced nuclear effectors. The induced enhancement of transcription by synergistically acting AP-1 and STAT binding elements in response to OSM is Raf-dependent. Cross-talk between the mitogen-activated protein kinase and JAK-STAT pathways is required to achieve maximal induction of the OMRE-driven transcription by OSM.

Base Sequence↗
PubMed1997

The potential role of alpha 2-macroglobulin in the control of cysteine proteinases (gingipains) from Porphyromonas gingivalis.

Porphyromonas gingivalis is closely associated with the development of some forms of periodontitis. The major cysteine proteinases released by this bacterium hydrolyze peptide bonds only after arginyl (gingipain R) or lysyl residues (gingipain K). No target protein inhibitors have been identified for either enzyme, leading us to investigate their inhibition by human plasma alpha 2-macroglobulin (alpha 2M). Both 50- and 95 kDa gingipain R were efficiently inhibited by alpha 2M, whereas the catalytic activity of gingipain K could not be eliminated. All 3 enzymes were, however, inhibited by a homologous macroglobulin from rat plasma, alpha 1-inhibitor-3 (alpha 1I3). alpha-Macroglobulins must be cleaved in the so-called "bait region" in order to inhibit proteinases by a mechanism involving physical entrapment of the enzyme. A comparison of the amino acid sequences of the 2 macroglobulins indicates that the lack of lysyl residues within the bait region of alpha 2M protects Lys-specific proteinases from being trapped. On this basis, other highly specific proteinases might also not be inhibited by alpha 2M, possibly explaining the inability of the inhibitor to control proteolytic activity in some bacterially induced inflammatory states, despite its abundance (2-5 mg/ml) in vascular fluids.

Adhesins, Bacterial↗