The Experts below are selected from a list of 2214 Experts worldwide ranked by ideXlab platform
Robert W Colman - One of the best experts on this subject based on the ideXlab platform.
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inhibition of angiogenesis by antibody blocking the action of proangiogenic high molecular weight Kininogen
Journal of Thrombosis and Haemostasis, 2003Co-Authors: Robert W Colman, Robin A Pixley, Irma Isordiasalas, James S Song, Irma M Sainz, S N Muhamed, J A Powell, Shaker A MousaAbstract:Previously we demonstrated that domain 5 (D5) of high-molecular-weight Kininogen (HK) inhibits neovascularization in the chicken chorioallantoic membrane (CAM) assay and further found that kallikrein cleaved HK (HKa) inhibited FGF2-and VEGF-induced neovascularization, and thus was antiangiogenic. In this study, we sought to demonstrate whether uncleaved HK stimulates neovascularization and thus is proangiogenic. The chick chorioallantoic membrane was used as an in ovo assay of angiogenesis. Low-Molecular-Weight Kininogen stimulates angiogenesis, indicating that D5 is not involved. Bradykinin stimulates neovascularization equally to HK and LK and is likely to be responsible for the effect of HK. A murine monoclonal antibody to HK (C11C1) also recognizes a similar component in chicken plasma as detected by surface plasmon resonance. Angiogenesis induced by FGF2 and VEGF is inhibited by this monoclonal antibody and is a more potent inhibitor of neovascularization induced by VEGF than an integrin alphavbeta3 antibody (LM 609). Our postulate that C11C1 inhibits the stimulation of angiogenesis by HK was confirmed when either C11C1 or D5 completely inhibited angiogenesis in the CAM induced by HK. Growth of human fibrosarcoma (HT-1080) on the CAM was inhibited by GST-D5 and C11C1. These results indicate HK is proangiogenic probably by releasing bradykinin and that a monoclonal antibody directed to HK could serve as an antiangiogenic agent with a potential for inhibiting tumor angiogenesis and other angiogenesis-mediated disorders.
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high molecular weight Kininogen binds to mac 1 on neutrophils by its heavy chain domain 3 and its light chain domain 5
Journal of Biological Chemistry, 1994Co-Authors: Y T Wachtfogel, R Dela A Cadena, Satya P Kunapuli, Leonard Rick, M Miller, R L Schultze, Dario C Altieri, Thomas S Edgington, Robert W ColmanAbstract:Abstract High molecular weight Kininogen (HK) binds specifically, saturably, and reversibly to neutrophils and also reciprocally inhibits the binding of fibrinogen to neutrophils. Since fibrinogen binds to the leukocyte integrin CD11b/18 (Mac-1, alpha M beta 2), we investigated whether HK bound to Mac-1 and whether the binding site was similar to that for factor X. We also examined whether one or both chains of cleaved HK (HKa) were involved. Two monoclonal antibodies, 2B5 (0.29 microM) to HK heavy chain domains 2 (D2) and 3 (D3), and C11C1 (0.26 microM) to HK light chain domain 5 (D5), inhibited by 99 and 93% the binding, respectively, of 125I-HK (8.3 nM) to neutrophils. To minimize steric hindrance, we further demonstrated that the Fab' fragments of 2B5 and C11C1 were able to inhibit the binding of this ligand to virtually the same extent as the intact antibody, indicating that, as in binding of HK to platelets and endothelial cells, both chains are involved. To directly demonstrate the involvement of each chain, we showed that the reduced alkylated light chain derived from HK and low molecular weight Kininogen, which contains the same heavy chain as HK, each markedly inhibited the binding of HK to neutrophils. We localized the domain responsible for the binding in each chain by showing that recombinant D3 and D5 decreased the binding of HK to neutrophils. To define the receptor for HK, we employed three monoclonal antibodies to Mac-1: OKM1 and OKM10 to epitopes on the alpha M subunit and IB4 to an epitope on the beta 2 chain. OKM1, which can inhibit fibrinogen binding to neutrophils, inhibited HK binding by 79%, whereas the other antibodies inhibited HK binding less than 25%. Coagulation factor X also binds to Mac-1 on monocytes at a similar site to C3bi. Synthetic peptides which define noncontiguous surface loops in factor X that interact with Mac-1, failed to inhibit 125I-HK binding to neutrophils. We conclude that HK binds, via domains on its heavy chain, D3, and light chain, D5, to Mac-1 on the neutrophil surface, and HK occupies a site overlapping with fibrinogen and different from factor X.
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purification and characterization of a potent 70 kda thiol lysyl proteinase lys gingivain from porphyromonas gingivalis that cleaves Kininogens and fibrinogen
Journal of Biological Chemistry, 1993Co-Authors: C F Scott, E J Whitaker, B F Hammond, Robert W ColmanAbstract:Abstract We isolated an enzyme from a major periodontal pathogen, Porphyromonas gingivalis (also called Bacteroides gingivalis), that is capable of initially increasing the coagulant activity of high molecular weight Kininogen (HK), releasing bradykinin from HK and low molecular weight Kininogen (LK), and destroying the light chain (coagulant portion) of HK. This enzyme, a membrane-bound thiol proteinase that preferentially cleaves the P1-Lys position of tripeptide substrates, is also able to rapidly render fibrinogen nonclottable. We will refer to this enzyme as lys-gingivain because of its origin from P. gingivalis, its classification as a thiol proteinase, and its action as a lysyl-amidase. The activity of lys-gingivain is enhanced by beta-mercaptoethanol, and the enzyme has a molecular mass of 68-70 kDa, a pH optimum of 7.4, and is not inactivated by plasma protease inhibitors. The second-order rate constant for the destruction of the coagulant activity of the HK light chain (surface-binding domain) at 23 degrees C is 2.3 x 10(7) M-1 s-1, and, for cleavages that render fibrinogen unclottable, is 2.05 x 10(6) M-1 s-1. These data suggest that lys-gingivain is a very potent proteinase that would be fully functional in anaerobic periodontal crevices and might participate in the pathogenesis of periodontitis. Lys-gingivain appears to be the most potent Kininogenase and fibrase to be described to date.
Julie Chao - One of the best experts on this subject based on the ideXlab platform.
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the tissue kallikrein kinin system protects against cardiovascular and renal diseases and ischemic stroke independently of blood pressure reduction
Biological Chemistry, 2006Co-Authors: Julie Chao, Grant Bledsoe, Hang Yin, L E E ChaoAbstract:Tissue kallikrein (hK1) cleaves Low-Molecular-Weight Kininogen to produce kinin peptide, which binds to kinin receptors and triggers a wide spectrum of biological effects. Tissue kallikrein levels are reduced in humans and in animal models with hypertension, cardiovascular and renal diseases. Transgenic mice or rats over-expressing human tissue kallikrein or kinin B2 receptor are permanently hypotensive, and somatic kallikrein gene delivery reduces blood pressure in several hypertensive rat models. Moreover, kallikrein gene delivery or kallikrein protein infusion can directly improve cardiac, renal and neurological function without blood pressure reduction. Kallikrein has pleiotropic effects in inhibiting apoptosis, inflammation, proliferation, hypertrophy and fibrosis, and promoting angiogenesis and neurogenesis in different experimental animal models. Kallikrein's effects can be blocked by kinin B2 receptor antagonists. Mechanistically, tissue kallikrein/kinin leads to increased nitric oxide levels and Akt activation, and reduced reactive oxygen species formation, TGF-beta1 expression, MAPK and nuclear factor-kappaB activation. Our studies indicate that tissue kallikrein, through the kinin B2 receptor and nitric oxide formation, can protect against oxidative damage in cardiovascular and renal diseases and ischemic stroke. These novel findings suggest that kallikrein/kinin may serve as new drug targets for the prevention and treatment of heart failure, renal disease and stroke in humans.
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postischemic brain injury is exacerbated in mice lacking the kinin b2 receptor
Hypertension, 2006Co-Authors: Robert S. Smith, L E E Chao, Cesario V. Borlongan, Zhirong Yang, Bo Shen, Julie ChaoAbstract:Kallikrein cleaves low molecular weight Kininogen to generate vasoactive kinins, which bind to the kinin B2 receptor, triggering a host of biological effects. Kallikrein gene delivery has been shown previously to reduce ischemia/reperfusion-induced cerebral infarction. In this study, we tested the hypothesis that the kinin B2 receptor plays a protective role in ischemic brain injury using kinin B2 receptor gene knockout (B2R-KO) mice subjected to middle cerebral artery occlusion (MCAO). The mortality rate and neurological deficit scores of B2R-KO mice (n=48) after MCAO were significantly increased compared with wild-type (WT) mice (n=40) when examined over a 14-day period. In addition, the infarct volume in B2R-KO mice was significantly larger than in WT mice at days 1 and 3 after MCAO. Similarly, apoptotic cells, detected by TUNEL labeling counterstained with propidium iodide, and caspase-3 activity in the ischemic brain increased significantly in B2R-KO mice at days 1 and 3 after MCAO. Furthermore, the accumulation of neutrophils in the ischemic brain of B2R-KO mice after MCAO increased when compared with WT mice and was associated with elevated tumor necrosis factor α expression. These alterations in B2R-KO mice correlated with decreased NO levels, Akt, and glycogen synthase kinase-3β phosphorylation and increased nicotinamide-adenine dinucleotide oxidase activity. These results indicate that the kinin B2 receptor promotes survival and protects against brain injury by suppression of apoptosis and inflammation induced by ischemic stroke.
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expression and cellular localization of tissue kallikrein kinin system in human adrenal gland
American Journal of Physiology-renal Physiology, 1996Co-Authors: Danzhao Wang, Q.i.n.g. Song, L E E Chao, Limei Chen, Julie ChaoAbstract:The tissue kallikrein-kinin system has been implicated in regulating blood pressure and electrolyte homeostasis. To understand the function of this system, we identified the expression and cellular localization of its components including tissue kallikrein, kallistatin, Kininogen, and bradykinin B1 and B2 receptors in human adrenal gland. Reverse transcription-polymerase chain reaction followed by Southern blot analysis showed that these five components of this system were all expressed in human adrenal gland. In situ hybridization histochemistry with respective digoxigenin-labeled antisense riboprobes revealed localization of kallikrein transcript throughout the adrenal cortex and medulla except the zona glomerulosa, whereas kallistatin mRNA was only localized in the zona fasciculata. Low-Molecular-Weight Kininogen and B2 receptor mRNAs were colocalized in the zona glomerulosa and zona fasciculata and also in the zona reticularis and chromaffin cells but to a lesser degree. The B1 receptor mRNA was stained in the zona fasciculata and medulla. These results show the expression and differential colocalization of the components of the tissue kallikrein-kinin system and reveal the potential action sites of this system in the adrenal gland.
L E E Chao - One of the best experts on this subject based on the ideXlab platform.
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the tissue kallikrein kinin system protects against cardiovascular and renal diseases and ischemic stroke independently of blood pressure reduction
Biological Chemistry, 2006Co-Authors: Julie Chao, Grant Bledsoe, Hang Yin, L E E ChaoAbstract:Tissue kallikrein (hK1) cleaves Low-Molecular-Weight Kininogen to produce kinin peptide, which binds to kinin receptors and triggers a wide spectrum of biological effects. Tissue kallikrein levels are reduced in humans and in animal models with hypertension, cardiovascular and renal diseases. Transgenic mice or rats over-expressing human tissue kallikrein or kinin B2 receptor are permanently hypotensive, and somatic kallikrein gene delivery reduces blood pressure in several hypertensive rat models. Moreover, kallikrein gene delivery or kallikrein protein infusion can directly improve cardiac, renal and neurological function without blood pressure reduction. Kallikrein has pleiotropic effects in inhibiting apoptosis, inflammation, proliferation, hypertrophy and fibrosis, and promoting angiogenesis and neurogenesis in different experimental animal models. Kallikrein's effects can be blocked by kinin B2 receptor antagonists. Mechanistically, tissue kallikrein/kinin leads to increased nitric oxide levels and Akt activation, and reduced reactive oxygen species formation, TGF-beta1 expression, MAPK and nuclear factor-kappaB activation. Our studies indicate that tissue kallikrein, through the kinin B2 receptor and nitric oxide formation, can protect against oxidative damage in cardiovascular and renal diseases and ischemic stroke. These novel findings suggest that kallikrein/kinin may serve as new drug targets for the prevention and treatment of heart failure, renal disease and stroke in humans.
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postischemic brain injury is exacerbated in mice lacking the kinin b2 receptor
Hypertension, 2006Co-Authors: Robert S. Smith, L E E Chao, Cesario V. Borlongan, Zhirong Yang, Bo Shen, Julie ChaoAbstract:Kallikrein cleaves low molecular weight Kininogen to generate vasoactive kinins, which bind to the kinin B2 receptor, triggering a host of biological effects. Kallikrein gene delivery has been shown previously to reduce ischemia/reperfusion-induced cerebral infarction. In this study, we tested the hypothesis that the kinin B2 receptor plays a protective role in ischemic brain injury using kinin B2 receptor gene knockout (B2R-KO) mice subjected to middle cerebral artery occlusion (MCAO). The mortality rate and neurological deficit scores of B2R-KO mice (n=48) after MCAO were significantly increased compared with wild-type (WT) mice (n=40) when examined over a 14-day period. In addition, the infarct volume in B2R-KO mice was significantly larger than in WT mice at days 1 and 3 after MCAO. Similarly, apoptotic cells, detected by TUNEL labeling counterstained with propidium iodide, and caspase-3 activity in the ischemic brain increased significantly in B2R-KO mice at days 1 and 3 after MCAO. Furthermore, the accumulation of neutrophils in the ischemic brain of B2R-KO mice after MCAO increased when compared with WT mice and was associated with elevated tumor necrosis factor α expression. These alterations in B2R-KO mice correlated with decreased NO levels, Akt, and glycogen synthase kinase-3β phosphorylation and increased nicotinamide-adenine dinucleotide oxidase activity. These results indicate that the kinin B2 receptor promotes survival and protects against brain injury by suppression of apoptosis and inflammation induced by ischemic stroke.
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expression and cellular localization of tissue kallikrein kinin system in human adrenal gland
American Journal of Physiology-renal Physiology, 1996Co-Authors: Danzhao Wang, Q.i.n.g. Song, L E E Chao, Limei Chen, Julie ChaoAbstract:The tissue kallikrein-kinin system has been implicated in regulating blood pressure and electrolyte homeostasis. To understand the function of this system, we identified the expression and cellular localization of its components including tissue kallikrein, kallistatin, Kininogen, and bradykinin B1 and B2 receptors in human adrenal gland. Reverse transcription-polymerase chain reaction followed by Southern blot analysis showed that these five components of this system were all expressed in human adrenal gland. In situ hybridization histochemistry with respective digoxigenin-labeled antisense riboprobes revealed localization of kallikrein transcript throughout the adrenal cortex and medulla except the zona glomerulosa, whereas kallistatin mRNA was only localized in the zona fasciculata. Low-Molecular-Weight Kininogen and B2 receptor mRNAs were colocalized in the zona glomerulosa and zona fasciculata and also in the zona reticularis and chromaffin cells but to a lesser degree. The B1 receptor mRNA was stained in the zona fasciculata and medulla. These results show the expression and differential colocalization of the components of the tissue kallikrein-kinin system and reveal the potential action sites of this system in the adrenal gland.
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Expression and cellular localization of the kallikrein-kinin system in human ocular tissues
Exp.Eye Res., 1996Co-Authors: J.x. Ma, Q.i.n.g. Song, H C Hatcher, L E E Chao, R K Crouch, J.u.l.i. ChaoAbstract:Tissue kallikrein is a serine proteinase which processes Kininogens to release bioactive kinins. Kinins mediate a variety of biological processes through the interaction with kinin receptors. Kinins are involved in the regulation of blood pressure and local blood flow, vasodilation, smooth muscle contraction and relaxation, production of pain and inflammation, and stimulation of cell proliferation. The tissue kallikrein- kinin system has been implicated in a number of pathophysiological processes such as hypertension, allergy and diabetes mellitus. In the present study, we have identified the expression and localization of components of the kallikrein-kinin system in the human eye by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analyses, and in situ hybridization histochemistry. RT-PCR and Southern blot analyses have detected mRNAs of the key components of the system including tissue kallikrein, low molecular weight Kininogen, and bradykinin B1 and B2 receptors at high levels in human retina, choroid and ciliary body, and relatively low levels in the optic nerve. In situ hybridization has identified cellular localization of these four mRNAs in ocular tissues. They are expressed in retinal neuronal cells including the outer nuclear layer, inner nuclear layer and ganglion cell layer. These mRNAs were also identified in endothelial cells of ocular blood vessels, ciliary muscle and lens epithelial cells. The sense riboprobes showed negative staining, which indicates the specificity of the antisense riboprobes. These results suggest that the tissue kallikrein- kinin system is produced endogenously in human ocular tissues. Similar expression patterns of kallikrein, Kininogen and kinin receptors indicate that the kallikrein-kinin system may function in an autocrine or paracrine fashion in the eye
J Rhebock - One of the best experts on this subject based on the ideXlab platform.
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high and low molecular weight Kininogen and plasma prekallikrein plasma kallikrein in villous capillaries of human term placenta
Placenta, 1996Co-Authors: A Hermann, P Buchinger, B Somlev, J RhebockAbstract:This study examined the expression and presence of components of the kallikrein-kinin system in human term placenta. Immunohistochemical studies localized H-Kininogen and plasma prekallikrein/plasma kallikrein to endothelial cells of placental villous capillaries. In larger placental blood vessels and umbilical cord, neither Kininogens nor kallikreins were detected. High (H) and low (L) molecular weight Kininogen, plasma prekallikrein and plasma kallikrein were detected by Western blot analysis in human term placenta and in maternal and fetal blood, whereas tissue kallikrein was not. Furthermore, mRNA of plasma prekallikrein was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in placental homogenates, while mRNA of H-Kininogen, L-Kininogen and tissue kallikrein was not. Because H-Kininogen and plasma prekallikrein circulate in a complexed form, we suggest that endothelial cells bind Kininogen and plasma prekallikrein in which they are secreted by the fetal liver from fetal blood. The co-localization of Kininogen and plasma prekallikrein/plasma kallikrein suggests that kinins could be generated locally in placental capillaries. When released, they may play a role in regulating placental blood flow and transplacental transport of substrates and metabolites.
Frank J. Meloni - One of the best experts on this subject based on the ideXlab platform.
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low molecular weight Kininogen binds to platelets to modulate thrombin induced platelet activation
Journal of Biological Chemistry, 1991Co-Authors: Frank J. MeloniAbstract:Abstract The Kininogens, high molecular weight Kininogen (HK) and low molecular weight Kininogen (LK), are multifunctional, single-gene products that contain bradykinin and identical amino-terminal heavy chains. Studies were performed to determine if LK would bind directly to platelets. 125I-LK specifically bound to gel-filtered platelets in the presence of 50 microM Zn2+. HK effectively competed with 125I-LK for the same binding site (Ki = 27 +/- 9 nM, n = 5). Similarly, the Ki for LK inhibition of 125I-LK binding was 12 +/- 1 nM (n = 3). Albumin, fibrinogen, factor XIII, and kallikrein did not inhibit 125I-LK binding to unstimulated platelets. 125I-LK (66 kDa) was not cleaved upon binding to platelets. The binding of 125I-LK to unstimulated platelets was found to be fully reversible by the addition of a 50 molar excess of unlabeled LK at both 10 and 20 min. LK binding to platelets was saturable with an apparent Kd of 27 +/- 2 nM (mean +/- S.E., n = 9) and 647 +/- 147 binding sites/platelet. Both LK and HK at plasma concentrations inhibited thrombin-induced platelet aggregation. LK and HK at about 5% of plasma concentration also inhibited thrombin-induced secretion of both stirred and unstirred platelets. Both Kininogens were found to be noncompetitive inhibitors of proteolytically active thrombin binding to platelets. The Kininogens did not inhibit D-phenylalanyl-prolyl-arginine chloromethyl ketone-treated thrombin from binding to platelets. These studies indicated that both Kininogens have a region on their heavy chain which allows them to bind to platelets. Further, Kininogen binding by its heavy chain modulates thrombin activation of platelets since it prevents proteolytically active thrombin from binding to its receptor.
