Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tissue factor (TF) is the high affinity transmembrane receptor and cofactor for cellular initiation of the plasma coagulation protease cascades by factor VIIa. We describe the synthesis of recombinant huTF by stably transfected CHO cell lines carrying integrated huTF DNA, and the isolation of huTF glycoprotein with specific functional activity equivalent to natural huTF. The expression vector (pCDM8), carrying the cytomegalovirus promoter to drive transcription of a partial cDNA construct encoding the complete huTF protein chain, was cotransfected with a plasmid containing the neomycin resistance gene for selection. These clones were further selected for level of expression of huTF protein. Optimal expression compatible with stability and cell growth was approximately 13.5 x 10(6) molecules per cell. To our knowledge, this is one of the highest levels of expression described for a recombinant transmembrane receptor in mammalian cells. Recombinant huTF protein was obtained by single-step immuno-affinity purification, and exhibits heterogeneity due to N-linked glycosylation. The protein was indistinguishable from natural huTF based on functional properties of the glycoprotein reconstituted in lipid vesicles, and expression of conformational epitopes. Large scale production of recombinant huTF is feasible to permit basic studies of protein structure as well as for design of huTF thromboplastin reagents.
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PMID:High level expression of recombinant human tissue factor in Chinese hamster ovary cells as a human thromboplastin. 187 13

Effector cell protease receptor-1 (EPR-1) is a transmembrane glycoprotein receptor for factor Xa that contributes to cell surface assembly of proteolytic activities and leukocyte mitogenesis. It is now shown that membrane expression of EPR-1 is dynamically modulated by mRNA splicing. Northern hybridization analysis of EPR-1-expressing cells and genetically engineered transfectants demonstrates that this mechanism involves removal of a 451 bp intervening sequence retained in 70-90% of mature mRNA, as quantitated by polymerase chain reaction amplification and ribonuclease protection studies. Splicing of the intervening sequence occurs in a cell type-specific fashion, as judged by the constitutive membrane overexpression of EPR-1 in certain leukemic B lymphocytes and monocytic cells. Furthermore, phenotypic analysis of cell lines stably transfected with functionally spliced or unspliced EPR-1 constructs suggests a potential role of intron cis-acting sequence(s) in splicing regulation. Instead of a transmembrane receptor for factor Xa (EPR-1a), the most prevalent unspliced EPR-1 transcript generates a novel truncated protein of 110 amino acids (EPR-1b), in which a unique intron-encoded -COOH terminus carries a potential nuclear targeting signal PPQHRAKS. An antibody generated against the intron-encoded sequence of EPR-1b demonstrates prominent nuclear localization of this variant isoform in indirect immunofluorescence staining of permeabilized cells. These findings provide evidence for a novel mechanism based on high efficiency intron retention modulating factor Xa-dependent cellular effector functions.
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PMID:Splicing of effector cell protease receptor-1 mRNA is modulated by an unusual retained intron. 794 93

Pleural inflammation underlies many pleural diseases, but its pathogenesis remains unclear. Proteinase-activated receptor-2 (PAR(2)) is a novel seven-transmembrane receptor with immunoregulatory roles. We hypothesized that PAR(2) is present on mesothelial cells and can induce pleural inflammation. PAR(2) was detected by immunohistochemistry in all (19 parietal and 11 visceral) human pleural biopsies examined. In cultured murine mesothelial cells, a specific PAR(2)-activating peptide (SLIGRL-NH(2)) at 10, 100, and 1,000 muM stimulated a 3-, 42-, and 1,330-fold increase of macrophage inflammatory protein (MIP)-2 release relative to medium control, respectively (P < 0.05 all) and a 2-, 32-, and 75-fold rise over the control peptide (LSIGRL-NH(2), P < 0.05 all). A similar pattern was seen for TNF-alpha release. Known physiological activators of PAR(2), tryptase, trypsin, and coagulation factor Xa, also stimulated dose-dependent MIP-2 release from mesothelial cells in vitro. Dexamethasone inhibited the PAR(2)-mediated MIP-2 release in a dose-dependent manner. In vivo, pleural fluid MIP-2 levels in C57BL/6 mice injected intrapleurally with SLIGRL-NH(2) (10 mg/kg) were significantly higher than in mice injected with LSIGRL-NH(2) or PBS (2,710 +/- 165 vs. 880 +/- 357 vs. 88 +/- 46 pg/ml, respectively; P < 0.001). Pleural fluid neutrophil counts were higher in SLIGRL-NH(2) group than in the LSIGRL-NH(2) and PBS groups (by 40- and 26-fold, respectively; P < 0.05). This study establishes that activation of mesothelial cell PAR(2) potently induces the release of inflammatory cytokines in vitro and neutrophil recruitment into the pleural cavity in vivo.
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PMID:Activation of proteinase-activated receptor-2 in mesothelial cells induces pleural inflammation. 1559 15

The transmembrane receptor tissue factor is a prominent protein expressed at macrophages and smooth muscle cells within human atherosclerotic lesions. While many coagulation proteins are detectable in atherosclerosis, a locally active thrombin and fibrin generating molecular machinery may be instrumental in manipulating cellular functions involved in atherogenesis. These include inflammation, angiogenesis and cell proliferation. Indeed, many experimental studies in mice show a correlation between hypercoagulability and increased atherosclerosis. In mice, the amount of atherosclerosis and/or the plaque phenotype, appear to be modifiable by specific anticoagulant interventions. While attempts to vary tissue factor level in the vasculature does not directly reduce plaque burden, the overexpression of tissue factor pathway inhibitor attenuates thrombogenicity and neo intima formation in mice. Moreover, inhibition of factor Xa or thrombin with novel selective agents, including rivaroxaban and dabigatran, inhibits inflammation associated with atherosclerosis in apoE(-/-) mice. The potential to modify a complex chronic disease like atherosclerosis with novel selective anticoagulants merits further clinical study.
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PMID:Tissue factor-driven thrombin generation and inflammation in atherosclerosis. 2239 11

Tissue factor (TF) is a transmembrane receptor for coagulation factor VII/VIIa and is frequently overexpressed by cancer cells. The TF/VIIa complex acts as the main initiator of the clotting cascade in blood and a trigger of intracellular signaling that changes gene expression and the cellular phenotype. However, pathways mediating these changes are still poorly characterized and especially the impact of TF signals on regulatory microRNA (miR) networks in cancer remains unknown. We show that the monoclonal antibody that selectively neutralises the signaling (but not coagulant) function of human TF (CNTO 2559) inhibits progression of MDA-MB-231 breast cancer xenografts in mice and prolongs animal survival. CNTO 2559 blocks FVIIa-induced expression of interleukin 8 (IL-8) by cancer cells without impacting factor Xa (FXa) generation. Notably, acute exposure of MDA-MB-231 tumour xenografts to CNTO 2559 systemic injections triggers wide spread changes in the tumour miR profile including alterations in 75 miRs (55 downregulated) and impacting several miR-regulated and cancer-related pathways. These results suggest that TF signaling in the tumour microenvironment may provoke vast changes in the miR profile of cancer cells, affect disease biology, and reflect tumour interaction with the coagulation system, thereby presenting itself as a possible biomarker.
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PMID:Inhibition of tissue factor signaling in breast tumour xenografts induces widespread changes in the microRNA expression profile. 2911 25

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel envelope virus that causes coronavirus disease 2019 (COVID-19). Hallmarks of COVID-19 are a puzzling form of thrombophilia that has elevated D-dimer but only modest effects on other parameters of coagulopathy. This is combined with severe inflammation, often leading to acute respiratory distress and possible lethality. Coagulopathy and inflammation are interconnected by the transmembrane receptor, tissue factor (TF), which initiates blood clotting as a cofactor for factor VIIa (FVIIa)-mediated factor Xa (FXa) generation. TF also functions from within the nascent TF/FVIIa/FXa complex to trigger profound changes via protease-activated receptors (PARs) in many cell types, including SARS-CoV-2-trophic cells. Therefore, aberrant expression of TF may be the underlying basis of COVID-19 symptoms. Evidence suggests a correlation between infection with many virus types and development of clotting-related symptoms, ranging from heart disease to bleeding, depending on the virus. Since numerous cell types express TF and can act as sites for virus replication, a model envelope virus, herpes simplex virus type 1 (HSV1), has been used to investigate the uptake of TF into the envelope. Indeed, HSV1 and other viruses harbor surface TF antigen, which retains clotting and PAR signaling function. Strikingly, envelope TF is essential for HSV1 infection in mice, and the FXa-directed oral anticoagulant apixaban had remarkable antiviral efficacy. SARS-CoV-2 replicates in TF-bearing epithelial and endothelial cells and may stimulate and integrate host cell TF, like HSV1 and other known coagulopathic viruses. Combined with this possibility, the features of COVID-19 suggest that it is a TFopathy, and the TF/FVIIa/FXa complex is a feasible therapeutic target.
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PMID:Antiviral anticoagulation. 3268 86