Inhibition of vascular endothelial cell prostacyclin synthesis by plasmin

Schafer, Andrew I.; Rodríguez, R. Bustamante; Loscalzo, Joseph; Gimbrone, Michael A.

doi:10.1182/blood.v74.3.1015.1015

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…Other proteases including cathepsin G (21,31), aminopeptidase M (5), tryptase (30), granzyme A (43), and elastase (12,21) have also been hypothesized to be involved in attenuation of the thrombin response in platelets (33) and endothelial cells (3,39). The large number of potential targets and accessory binding proteins on the surfaces of these cells, including PAR1-4, makes it more difficult to interpret whole cell proteolysis experiments.…”

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confidence: 99%

Plasmin Desensitization of the PAR1 Thrombin Receptor: Kinetics, Sites of Truncation, and Implications for Thrombolytic Therapy

et al. 1999

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It has been hypothesized that protease-activated receptors may be activated and attenuated by more than one protease. Here, we explore a desensitization mechanism of the PAR1 thrombin receptor by anticoagulant proteases and provide an explanation to the enigma of why plasmin/tissue plasminogen activator (t-PA) can both activate and deactivate platelets prior to thrombin treatment. By using a soluble N-terminal exodomain (TR78) as a model for the full-length receptor, we were able to unambiguously compare cleavage rates and specificities among the serum proteases. Thrombin cleaves TR78 at the R41-S42 peptide bond with a kcat of 120 s-1 and a KM of 16 microM to produce TR62 (residues 42-103). We found that, of the anticoagulant proteases, only plasmin can rapidly truncate the soluble exodomain at the R70/K76/K82 sites located on a linker region that tethers the ligand to the body of the receptor. Plasmin cleavage of the TR78 exodomain is nearly equivalent to that of thrombin cleavage at R41 with similar rates (kcat = 30 s-1) and affinity (KM = 18 microM). Specificity was demonstrated since there is no observed cleavage at the five other potential plasmin-cleavage sites. Plasmin also cleaves the TR78 exodomain at the R41 thrombin-cleavage site generating transiently activated exodomain. We directly demonstrated that plasmin cleaves these same sites in full-length membrane-embedded receptor expressed in yeast and COS7 fibroblasts. The rate of plasmin truncation is similar between the extensively glycosylated COS7-expressed receptor and the nonglycosylated yeast-produced receptor. Mutation of the R70/K76/K82 sites to A70/A76/A82 eliminates plasmin truncation and desensitization of thrombin-dependent Ca2+ signaling and converts PAR1 into a plasmin-activated receptor with full agonist activity for plasmin. Plasmin does not desensitize the Ca2+ response of platelets or COS7 cells to SFLLRN consistent with intermolecular ligand-binding sites being located to the C-terminal side of K82. Truncation of the wild-type receptor at the C-terminal plasmin-cleavage sites removes the N-terminal tethered ligand or preligand, thereby providing an effective pathway for PAR1 desensitization in vivo.

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confidence: 99%

Plasmin Desensitization of the PAR1 Thrombin Receptor: Kinetics, Sites of Truncation, and Implications for Thrombolytic Therapy

et al. 1999

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“…A direct effect of PDGF-C on endothelial cells was also reported by several former studies [50,51,53]. A possible explanation for the preferential activation of PDGFR-α in the cells that line blood vessels might be that the proteases that cleave the latent PDGF-C pro-form [36,52,54,55,56,57,58] are provided by the blood stream or by endothelial cells themselves [59,60].…”

Section: Discussionmentioning

confidence: 53%

PHD3 Acts as Tumor Suppressor in Mouse Osteosarcoma and Influences Tumor Vascularization via PDGF-C Signaling

Egners

Rezaei

Kuzmanov

et al. 2018

Cancers

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Cancer cell proliferation and insufficient blood supply can lead to the development of hypoxic areas in the tumor tissue. The adaptation to the hypoxic environment is mediated by a transcriptional complex called hypoxia-inducible factor (HIF). HIF protein levels are tightly controlled by oxygen-dependent prolyl hydroxylase domain proteins (PHDs). However, the precise roles of these enzymes in tumor progression and their downstream signaling pathways are not fully characterized. Here, we study PHD3 function in murine experimental osteosarcoma. Unexpectedly, PHD3 silencing in LM8 cells affects neither HIF-1α protein levels, nor the expression of various HIF-1 target genes. Subcutaneous injection of PHD3-silenced tumor cells accelerated tumor progression and was accompanied by dramatic phenotypic changes in the tumor vasculature. Blood vessels in advanced PHD3-silenced tumors were enlarged whereas their density was greatly reduced. Examination of the molecular pathways underlying these alterations revealed that platelet-derived growth factor (PDGF)-C signaling is activated in the vasculature of PHD3-deficient tumors. Silencing of PDGF-C depleted tumor growth, increased vessel density and reduced vessel size. Our data show that PHD3 controls tumor growth and vessel architecture in LM8 osteosarcoma by regulating the PDGF-C pathway, and support the hypothesis that different members of the PHD family exert unique functions in tumors.

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“…Plasmin has also been shown to have effects on the vascular endothelium, another essential cellular component of hemostasis. Treatment of cultured vascular endothelial cells with plasmin resulted in a reduction in the thromboresistant properties of the vascular endothelial cells as demonstrated by decreased tPA synthesis and release, increased plasminogen activator inhibitor-1 synthesis, decreased thrombomodulin activity, and increased vascular permeability (71)(72)(73). Pretreatment of the endothelial cells with aprotinin (200 KIU/mL) attenuated these plasmin-induced effects (72).…”

Section: Plasminmentioning

confidence: 99%

Biochemistry of Serine Protease Inhibitors and Their Mechanisms of Action: A Review

Wegner

2003

J Extra Corpor Technol

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Cardiopulmonary bypass (CPB) activates and disrupts the hemostatic and inflammatory systems, which, in turn, makes an impact on the clinical outcome of patients. Postoperative bleeding is one common complication of CPB. Many techniques have been used to reduce post-operative bleeding, and pharmacological agents have demonstrated the greatest efficacy. In particular, the serine protease inhibitor, aprotinin, consistently reduces post-operative bleeding. The hemostatic mechanism of action of aprotinin; however, remains to be elucidated fully. The purpose of this review is to discuss the probable mechanisms of aprotinin action from the perspective of its interactions within the hemostatic and inflammatory pathways.

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Inhibition of vascular endothelial cell prostacyclin synthesis by plasmin

Cited by 5 publications

References 24 publications

Plasmin Desensitization of the PAR1 Thrombin Receptor: Kinetics, Sites of Truncation, and Implications for Thrombolytic Therapy

Plasmin Desensitization of the PAR1 Thrombin Receptor: Kinetics, Sites of Truncation, and Implications for Thrombolytic Therapy

PHD3 Acts as Tumor Suppressor in Mouse Osteosarcoma and Influences Tumor Vascularization via PDGF-C Signaling

Biochemistry of Serine Protease Inhibitors and Their Mechanisms of Action: A Review

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