Navegando por Palavras-chave "chymase"

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    Discriminating between the activities of human cathepsin G and chymase using fluorogenic substrates
    (Wiley-Blackwell, 2011-08-01) Korkmaz, Brice; Jegot, Gwenhael; Lau, Laurie C.; Thorpe, Michael; Pitois, Elodie; Juliano, Luiz [UNIFESP]; Walls, Andrew F.; Hellman, Lars; Gauthier, Francis; Univ Tours; Southampton Gen Hosp; Uppsala Univ; Universidade Federal de São Paulo (UNIFESP)
    Cathepsin G (CG) (EC 3.4.21.20) and chymase (EC 3.4.21.39) are two closely-related chymotrypsin-like proteases that are released from cytoplasmic granules of activated mast cells and/or neutrophils. We investigated the potential for their substrate-binding subsites to discriminate between their substrate specificities, aiming to better understand their respective role during the progression of inflammatory diseases. in addition to their preference for large aromatic residues at P1, both preferentially accommodate small hydrophilic residues at the S1' subsite. Despite significant structural differences in the S2' subsite, both prefer an acidic residue at that position. the Ala226/Glu substitution at the bottom of the CG S1 pocket, which allows CG but not chymase to accommodate a Lys residue at P1, is the main structural difference, allowing discrimination between the activities of these two proteases. However, a Lys at P1 is accommodated much less efficiently than a Phe, and the corresponding substrate is cleaved by beta 2-tryptase (EC 3.4.21.59). We optimized a P1 Lys-containing substrate to enhance sensitivity towards CG and prevent cleavage by chymase and beta 2-tryptase. the resulting substrate (ABZ-GIEPKSDPMPEQ-EDDnp) [ where ABZ is O-aminobenzoic acid and EDDnp is N-(2,4-dinitrophenyl)-ethylenediamine] was cleaved by CG but not by chymase and tryptase, with a specificity constant of 190 mM(-1).s(-1). This allows the quantification of active CG in cells or tissue extracts where it may be present together with chymase and tryptase, as we have shown using a HMC-1 cell homogenate and a sputum sample from a patient with severe asthma.
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    Diversity of pathways for intracellular angiotensin II synthesis
    (Lippincott Williams & Wilkins, 2009-01-01) Kumar, Rajesh; Boim, Mirian A. [UNIFESP]; Texas A&M Hlth Sci Ctr; Scott & White Mem Hosp & Clin; Cent Texas Vet Healthcare Syst; Universidade Federal de São Paulo (UNIFESP)
    Purpose of reviewThe renin-angiotensin system (RAS) has undergone continuous advancement since the initial identification of renin as a pressor agent. Traditionally considered a circulatory system, the RAS is now known to exist as a tissue system as well. Recently, the tissue RAS has been further categorized as intracellular and extracellular. Owing to the unique location, the intracellular RAS encompasses new components, such as cathepsin D and chymase, which participate in intracellular angiotensin (Ang) II synthesis. in this review, evidence of the intracellular RAS and the mechanism of Ang II synthesis in various cell types will be discussed.Recent findingsA physiological role for intracellular Ang II in vascular and cardiac cells has recently been demonstrated. Evidence of intracellular Ang II generation has been shown in several cell types, particularly cardiac, renal, and vascular. Importantly, intracellular synthesis of Ang II is more prominent in hyperglycemic conditions and generally involves angiotensin-converting enzyme-dependent and angiotensin-converting enzyme-independent mechanisms,SummaryThere is significant diversity in the mechanism of intracellular synthesis of Ang II in various cell types and pathological conditions. These observations suggest that a therapeutic intervention to block the RAS should take into consideration the nature of the disorder and the cell type involved.
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    Polycationic peptides as inhibitors of mast cell serine proteases
    (Elsevier B.V., 2003-04-01) Lundequist, A.; Juliano, M. A.; Juliano, L.; Pejler, G.; Swedish Univ Agr Sci; Universidade Federal de São Paulo (UNIFESP)
    When mast cells are activated, e.g. during allergic responses, they secrete the serine proteases chymase and tryptase, which both are complex-bound to heparin proteoglycan in vivo. Previous reports have demonstrated potent pro-inflammatory effects of both tryptase and chymase in different animal models, suggesting that these serine proteases may be relevant targets for therapeutic intervention. Recent investigations have shown that heparin-binding compounds can cause tryptase inhibition and it has been suggested that the inhibitory activity of such compounds is due to interference with the binding of heparin to tryptase. Here we tested various polycationic peptides for their ability to inhibit heparin-free human recombinant betaI-tryptase. We demonstrate powerful direct inhibition of tryptase (IC50 values similar to 1-100 nM) by poly-Arg and poly-Lys of different molecular weights. Poly-Arg and poly-Lys showed predominantely competitive inhibition kinetics, although decreases in the k(cat) values for the chromogenic substrate S-2288 were also observed. Peptides built up from heparin-binding motifs were also inhibitors of tryptase, albeit of lower efficiency than poly-Arg/Lys. Tryptase inhibition was strongly dependent on the size of the polycationic peptides. the various polycationic peptides were also inhibitory for heparin-dependent activities of chymase. the tryptase inhibition caused by the polycationic peptides could be reversed by adding heparin. After heparin-induced rescue of tryptase activity, the major part of the tryptase activity was sensitive to inhibition by bovine pancreatic trypsin inhibitor, whereas tryptase before addition of polycationic peptide was completely resistant. Taken together, our findings indicate that polycationic peptides can be used as powerful agents for combined inhibition of mast cell tryptase and chymase. (C) 2003 Elsevier Science Inc. All rights reserved.
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    Role of chymase in diabetic nephropathy
    (Royal Soc Medicine Press Ltd, 2012-08-01) Cristovam, Priscila C. [UNIFESP]; Carmona, Adriana K. [UNIFESP]; Arnoni, Carine P. [UNIFESP]; Maquigussa, Edgar [UNIFESP]; Pereira, Luciana G. [UNIFESP]; Boim, Mirian A. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Chymase is an alternative pathway for angiotensin-converting enzyme in angiotensin II (Ang II) formation, and its expression is increased in human diabetic kidneys and in human mesangial cells (MCs) stimulated with high glucose. in addition, chymase activates transforming growth factor (TGF-beta 1) via an Ang II-independent pathway. the aim of this study was to evaluate the role of chymase on TGF-beta 1 activation in diabetic rats and in rat MCs (RMCs) stimulated with high glucose (HG). Diabetes was induced in male Wistar rats by streptozotocin (60 mg/kg, intravenous). After 30 (D30) or 60 (D60) days, chymase activity and the expression of profibrotic markers were evaluated. RMCs were stimulated with HG in the presence or absence of 50 mu mol/L chymostatin, a chymase inhibitor, or 100 nmol/L of losartan, an Ang II antagonist. Chymase activity and expression increased in 060 kidneys, with increased expression of fibronectin, type I and III collagen, TGF-beta 1 and Smad 3 and with no change in Smad 7 expression. RMCs exposed to HG presented increases in chymase activity and expression, together with upregulation in fibrosis markers and in the TGF-beta 1 signaling pathway. All these effects were reversed by chymostatin and by losartan, but type 1 angiotensin II receptor blockade did not interfere with the Smad 3 and 7 pathway. Similar to HG-stimulated RMCs, control RMCs treated with chymase responded with increased expression of TGF-beta 1, Smad 3 and fibrosis markers. These effects were reversed by chymostatin but not by losartan. the results indicate an important role for chymase in inducing fibrosis through TGF-beta 1 activation, parallel with Ang II effects.