Navegando por Palavras-chave "Plasma Kallikrein"

Agora exibindo 1 - 3 de 3
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Ação De Calicreína Plasmática Humana Sobre A Resposta Da Agregação Plaquetária Induzida Por Doses Hipoagregantes De Adp
    (Universidade Federal de São Paulo (UNIFESP), 2017-09-28) Fontes, Tatiana Neves [UNIFESP]; Oliva, Maria Luiza Vilela [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Human plasma kallikreín (huPK) potentiates platelet responses to subthreshold doses of ADP, although huPK itself, does not índuce platelet aggregation. In the present investigation, we observe that huPK pretreatment of platelets , potentiates ADP-induced platelet actívation by prior proteolysis of the G-proteincoupled receptor PAR-1. The potentiation of ADP-induced platelet activation by huPK is mediated by the integrin allb~3 through interactions with the KGD/KGE sequence motif ín huPK. Integrin allbf33 is a cofactor for huPK binding to platelets to support PAR-1 hydrolysis that contributes to activation of the ADP signaling pathway. This activation pathway leads to phosphorylation of Src, AktS473, ERK1/2, and p38 MAPK, and to Ca2+ release. The effect of huPK is blocked by specific antagonists of PAR-1 (SCH 19197) and allb~3 (abciximab) and by synthetic peptides comprising the KGD and KGE sequence motifs of huPK. Further, recombinant plasma kallikrein ínhibítor, rBbKI, also blocks this entíre mechanism. These results suggest a new function for huPK. Formation of plasma kallikrein lowers the threshold for ADP~induced platelet activation. The present observatíons are consistent wíth the notion that plasma kallikrein promotes vascu!ar disease and thrombosis in the intravascular compartment.
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Influência dos glicosaminoglicanos na interação das proteínas do sistema calicreína-cinina plasmático na superfície celular
    (Universidade Federal de São Paulo (UNIFESP), 2006-02-22) Melo, Kátia Regina Brasil [UNIFESP]; Motta, Guacyara da [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The kallirein-kinin system comprises low and high molecular weight kininogens (LK and HK), tissue and plasma kallikreins, and was first recognized as a plasma and tissue proteolytic system responsible for bradykinin (BK) release. The main function of kininogens has been described as precursors of BK, a peptide which is not active unless it is released from kininogens. The plasma kallikrein-kinin system is related to vascular biology and it is involved and interacts with different systems such as coagulation, fibrinolysis, complement and renin-angiotensin systems. HK is a multidomain protein with antithrombin, antiadhesive and profibrinolytic activities. Recent studies have revealed that HK free from BK (HKa) inhibits angiogenesis while BK promotes angiogenesis. In blood and vascular cells some different proteins have been described as HK binding receptors: Mac-1 integrin (aMb-2 or CD11b/CD18) on granulocytes, the receptor that binds to the globular “heads” of C1q (p33/gC1qR), cytokeratin 1 (CK1) and urokinase plasminogen activator receptor (uPAR) on HUVECs, and glycoprotein Ib-IX-V and thrombospondin on platelets. More recently both heparan sulfate and chondroitin sulfate have been described as HK putative receptors. The aim of this work was to study the influence of glycosaminoglycans (GAGs) on HK binding to cell surface and lysates and its processing using two different Chinese hamster ovary cell lines, CHO-wild type (CHO-K1) and CHO-745 (mutant) which is deficient in the synthesis of proteoglycans (PGs) due to lack of activity of xylosyl transferase. Biotin-HK (b-HK) bound to CHO-K1 cell surface in Zn2+ dependent manner. The b-HK level of binding was much higher on cell surfaces comparing to lysates from both cell lines and this binding was not reversible by 20 fold molar excess of unlabeled HK at both CHO-K1 and CHO-745. At 37°C the Bmax values for both CHO-K1 and CHO-745 are very similar but the Kdap for HK binding to CHO-K1 is 4.4 times higher comparing to CHO-745 suggesting that the presence of PGs/GAGs impair HK interaction with other putative receptors on cell surface. Considering the Bmax determinations at 4°C on CHOFor K1 it is 3.0 times lower comparing to Bmax at 37°C and on CHO-745 the Bmax value at 4°C is 1.4 times lower comparing to Bmax at 37°C. The difference of Bmax values at both temperatures for each cell line suggests that HK is internalized and confocal microscopy experiments detected HK internalized only on CHO-K1. Plasma prekallikrein (PK) bound to both cell lines in the presence of HK; however, in the absence of HK PK also bound only to CHO-K1 cell surface suggesting that PGs/GAGs may interact with PK. Once HK/PK complex is assembled on cell surface and lysates of both cell lines PK turns to plasma kallikrein (huPK) and both prolylcarboxypeptidase (PRCP) and cathepsins may participate in this process. The intact HK assembled to cell surface and lysates of both cell lines and in the absence of PK/huPK is cleaved in one site and probably PRCP or tissue kallikrein may process HK in this circumstances. The cell membrane interaction of plasma kallikrein-kinin system proteins through binding and internalization can result in liberation of HK fragments and huPK pericellular activity which may influence in pathological and physiological process.
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    The plant-derived bauhinia bauhinioides kallikrein proteinase inhibitor (rbbki) attenuates elastase-induced emphysema in mice
    (Acta Cirurgica Brasileira, 2016) Martins-Olivera, Bruno Tadeu; Almeida-Reis, Rafael; Theodoro-Junior, Osmar Aparecido; Oliva, Leandro Vilela; dos Santos Nunes, Natalia Neto [UNIFESP]; Olivo, Clarice Rosa; de Brito, Marlon Vilela [UNIFESP]; Prado, Carla Maximo [UNIFESP]; Leick, Edna Aparecida; Martins, Milton de Arruda; Vilela Oliva, Maria Luiza [UNIFESP]; Righetti, Renato Fraga; Lopes Calvo Tiberio, Iolanda de Fatima
    Background. Elastase mediates important oxidative actions during the development of chronic obstructive pulmonary disease (COPD). However, few resources for the inhibition of elastase have been investigated. Our study evaluated the ability of the recombinant plant derived Bauhinia bauhinioides Kallikrein proteinase Inhibitor (rBbKI) to modulate elastase-induced pulmonary inflammation. Methods. C57Bl/6 mice were given intratracheal elastase (ELA group) or saline (SAL group) and were treated intraperitoneally with rBbKI (ELA-rBbKI and SAL-rBbKI groups). At day 28, the following analyses were performed: (I) lung mechanics, (II) exhaled nitric oxide (ENO), (III) bronchoalveolar lavage fluid (BALF), and (IV) lung immunohistochemical staining. Results. In addition to decreasing mechanical alterations and alveolar septum disruption, rBbKI reduced the number of cells in the BALF and decreased the cellular expression of TNF-alpha, MMP-9, MMP-12, TIMP-1, eNOS, and iNOS in airways and alveolar walls compared with the ELA group. rBbKI decreased the volume proportion of 8-iso-PGF2 alpha, collagen, and elastic fibers in the airways and alveolar walls compared with the ELA group. A reduction in the number of MUC-5-positive cells in the airway walls was also observed. Conclusion. rBbKI reduced elastase-induced pulmonary inflammation and extracellular matrix remodeling. rBbKI may be a potential pharmacological tool for COPD treatment.