OBJECTIVETo investigate the roles of protease-activated receptors (PARs) in thrombin-induced brain injury and neurogenesis in rats.

METHODSNinety male SD rats were randomly assigned to receive intra-hippocampus injection of NS, thrombin or specific agonists of 3 protease-activated receptors (PAR-1, PAR-3 and PAR-4), respectively. At 1,3 and 7 d after injection, the area of the hippocampus was determined with HE staining, the density and morphology of astrocyte were detected with GFAP staining, degenerated neurons were detected with Fluoro-Jade C staining, and the neurogenesis was examined with DCX staining.

RESULTSCompared to NS injection, the area of the hippocampus significantly increased at 1-3 d and decreased at 7 d after the injection of thrombin and PAR-1 agonist (P<0.05). In addition, injection of thrombin and PAR-1 agonist significantly increased the density of astrocyte and Fluoro-Jade C positive cells at 1-7 d after injection (P<0.05), and significantly increased the density of DCX positive cells at 3-7 d after injection(P<0.05). The injection of PAR-3 agonist and PAR-4 agonist had no affect on the area of the hippocampus, the density of astrocyte, Fluoro-Jade C positive cells and DCX positive cells.

CONCLUSIONThe activation of protease-activated receptor-1 may be related to the thrombin-induced brain injury and neurogenesis in rat hippocampus.

Animals ; Brain Injuries ; chemically induced ; metabolism ; pathology ; Hippocampus ; pathology ; Male ; Neurogenesis ; drug effects ; Rats ; Rats, Sprague-Dawley ; Receptor, PAR-1 ; agonists ; physiology ; Receptors, Thrombin ; agonists ; Thrombin ; toxicity

Coagulation factor 2 receptor (F2R), also well-known as a protease-activated receptor 1 (PAR1), is the first known thrombin receptor and plays a critical role in transmitting thrombin-mediated activation of intracellular signaling in many types of cells. It has been known that bacterial infections lead to activation of coagulation systems, and recent studies suggest that PAR1 may be critically involved not only in mediating bacteria-induced detrimental coagulation, but also in innate immune and inflammatory responses. Community-acquired pneumonia, which is frequently caused by Streptococcus pneumoniae (S. pneumoniae), is characterized as an intra-alveolar coagulation and an interstitial neutrophilic inflammation. Recently, the role of PAR1 in regulating pneumococcal infections has been proposed. However, the role of PAR1 in pneumococcal infections has not been clearly understood yet. In this review, recent findings on the role of PAR1 in pneumococcal infections and possible underlying molecular mechanisms by which S. pneumoniae regulates PAR1-mediated immune and inflammatory responses will be discussed.
Bacterial Infections ; Blood Coagulation Factors* ; Inflammation ; Negotiating ; Neutrophils ; Pneumococcal Infections* ; Pneumonia ; Receptor, PAR-1 ; Receptors, Thrombin ; Streptococcus pneumoniae

Aged ; Aged, 80 and over ; Blood Platelets ; chemistry ; Humans ; Receptor, PAR-1 ; blood ; Receptors, Thrombin ; blood ; Renal Dialysis ; Uremia ; blood ; therapy

OBJECTIVESTo investigate molecular mechanisms of PAR-1 regulation on intracellular Ca²(+) mobilization in lung giant cell carcinoma cells in vitro and its involvement in tumor metastasis.

METHODSFree intracellular Ca²(+) ([Ca²(+)]i) was measured in lung giant cell carcinoma PLA801C and PLA801D cells by confocal microscopy. Sense and anti-sense PAR-1 expression vectors were transfected into PLA801C (C+)and PLA801D(D-) cells, respectively. The effects of PAR-1 expression were investigated by thrombin and TRAP-induced mobilization of [Ca²(+)]i in the C+ and D-cells.

RESULTSThere were significant differences of the mean values of [Ca²(+)]i between PLA801D (59.55) and PLA801C cells (35.46, P < 0.01). The mean [Ca²(+)]i of C+ cells (45.77) was significantly higher than that of its control CV cells (35.46, P < 0.05), and the mean [Ca²(+)]i of D-cells (48.42) was significantly lower than that of its control DV cells (59.55, P < 0.05). The peaks of [Ca²(+)]i of C+ and CV cells were 48.19 ± 9.84 and 45.64 ± 9.87 (P < 0.05) respectively at 80 s and 100 s after thrombin treatment, but were 111.31 ± 25.00 and 52.93 ± 11.21 (P < 0.05) respectively at 60 s after TRAP treatment. The peaks of [Ca²(+)]i of D- and DV cells were 40.71 ± 5.89 and 61.07 ± 21.36 (P < 0.05) respectively at 60 s after thrombin treatment, but were 84.98 ± 11.23 and 102.58 ± 21.48 (P < 0.05) respectively at 40 s after TRAP treatment.

CONCLUSIONSThe high metastatic potential of PLA801D and PLA801C may be related to [Ca²(+)]i of the tumor cells. PAR-1 may play an important role in the metastasis of lung giant cell carcinoma cells by up-regulating the intracellular Ca²(+).

Calcium ; metabolism ; Calcium Signaling ; drug effects ; Carcinoma, Giant Cell ; metabolism ; pathology ; Cell Line, Tumor ; DNA, Antisense ; genetics ; Humans ; Lung Neoplasms ; metabolism ; pathology ; RNA, Messenger ; metabolism ; Receptor, PAR-1 ; genetics ; metabolism ; physiology ; Receptors, Thrombin ; metabolism ; Thrombin ; pharmacology ; Transfection ; Up-Regulation

This study was designed to compare the effects of protease-activated receptor 1 (PAR-1) and protease-activated receptor 4 (PAR-4) to the expression of platelet surface GPIbalpha and cytoskeleton reorganization, then to investigate the role of PARs in platelet signal transmission. PAR1 (25 micromol/L) and PAR4 (250 micromol/L) were used to stimulate platelet at different time points (0 - 60 minutes), and the platelet surface GPIbalpha, actin and myosin and P-selectin were detected with flow cytometry, the alteration of GPIbalpha, actin and myosin in cytoskeleton was compared by Western blot, the membrane cytoskeleton followed GPIbalpha immunoprecipitation was analyzed. The results showed that an increase of P-selectin and reversible decrease of GPIbalpha expression were obtained after platelet activation by PAR1 o r PAR4, and a different kinetics of redistribution of GPIbalpha was found for the two peptides all over the time course (P < 0.05). PAR1 acted more potently and rapidly than PAR4, but the effect of PAR4 persisted longer in the course of platelet activation. Meanwhile, there was a transient change of actin, myosin and GPIbalpha in cytoskeleton proteins. Similar redistribution was also found in GPIbalpha/myosin and GPIbalpha/actin association. It is concluded that PAR1 and PAR4 possess an important role in platelet signal transmission. Either of the receptors can mediate platelet activation and GPIbalpha redistribution, which is correlated with cytoskeleton reorganization. PAR1 acts more rapidly, and effect of PAR4 persists longer.
Cytoskeleton ; chemistry ; Flow Cytometry ; Humans ; Myosins ; analysis ; P-Selectin ; analysis ; Platelet Activation ; Platelet Glycoprotein GPIb-IX Complex ; Receptor, PAR-1 ; physiology ; Receptors, Thrombin ; physiology

Thrombomodulin (TM) is thrombin receptor present on the luminal surface of endothelial cells. Because the thrombin-TM complex acts as an anticoagulant, the functional variants or deficiency of TM may lead to increment of thrombotic tendency. In this study, we screened the genetic variants of the TM gene in patients with myocardial infarction (MI) and analyzed the genotype to elucidate the effects of genetic variations of TM gene on the development of the MI. We screened a promoter region and coding sequence of the TM gene using single strand conformation polymorphism-heteroduplex analysis and identified three common genetic variants: those were TM G-33A, TM Ala455Val, and TM C1922T. The genotype frequencies were investigated in the patients with MI (n=234) and control subjects (n=291) by the method of allele-specific oligomer hybridization. The frequencies of mutant genotypes (TM -33A, TM 455Val, and TM 1922T) were higher in patient group compared to the control subjects in males while there were no significant differences in females. In the multiple logistic regression analysis, TM 455Val and TM 1922T alleles were independent risk factors for MI (OR[95% CI: 1.799[1.125-2.878] p=0.014 and 5.624[1.019-31.025], p=0.048, respectively) in males. However, the genetic variations were not independent risk factors for MI in females. There were significant linkage disequilibriums among three genetic variants. These linkage disequilibriums explain the similar effects of three genetic variants on the development of MI. To investigate the effect of the TM G-33A mutation on TM promoter activity, the two TM promoter constructs (pTM-355 and pTM-125, bearing TM -33G or TM -33A) containing of firefly luciferase gene were transfected into HepG2, BAE, and CHO cells. The promoter activities were higher in the promoter constructs with TM -33G compared to the constructs with TM -33A in pTM-355. These results suggest the possibility of the positive predisposing effect of TM -33A allele on MI in males. The functional study for TM Ala455Val and TM C1922T should be followed to elucidate the genotype effects of these mutations on the development of MI. In this study, we identified three genetic variants of TM gene and showed the significant associations between genetic variants and MI in males. These results proposed that TM gene is an attractive candidate for genetic risk factor for MI in Koreans.
Alleles ; Animals ; CHO Cells ; Clinical Coding ; Cricetinae ; Endothelial Cells ; Female ; Fireflies ; Genetic Variation ; Genotype ; Humans ; Linkage Disequilibrium ; Logistic Models ; Luciferases ; Male ; Myocardial Infarction* ; Phenobarbital ; Promoter Regions, Genetic ; Receptors, Thrombin ; Risk Factors* ; Thrombomodulin

Animals ; Cardiovascular Diseases ; etiology ; metabolism ; Humans ; Inflammation ; metabolism ; Periodontitis ; complications ; metabolism ; microbiology ; Platelet Aggregation ; physiology ; Porphyromonas gingivalis ; pathogenicity ; RNA, Messenger ; metabolism ; Receptor, PAR-1 ; metabolism ; Receptor, PAR-2 ; genetics ; metabolism ; Receptors, Proteinase-Activated ; metabolism ; Receptors, Thrombin ; metabolism

OBJECTIVETo study the mechanism of restenosis after angioplasty and to clarify the effect of thrombin and its receptor on restenosis development.

METHODSBalloon catheter-induced injury was adopted to induce intimal hyperplasia of the carotid arteries in rats. Antisense thrombin receptor (ATR) cDNA was transfected by perfusing recombinant LXSN ATR plasmid/nanoparticle complex into the segment of the injured carotid artery.

RESULTSPCR result showed integration of the recombined gene. Dot blot showed the expression of antisense TR mediated by recombinant LXSN ATR plasmid/nanoparticle complex in the wall of common carotid arteries of the experimental group rats, which enabled to inhibit TR gene expression and intimal hyperplasia of the injured arteries.

CONCLUSIONSThrombin and its receptor play an important role in the formation of neointima after the injury, which provides a potential clue in developing a new approach for prevention and treatment of restenosis after angioplasty.

Animals ; Carotid Arteries ; Hyperplasia ; Rats ; Receptors, Thrombin ; metabolism ; Thrombin ; pharmacology ; Tunica Intima ; metabolism

Thrombin is a multifunctional serine protease that plays a key role in a variety of physiological and pathological conditions. In addition to the role in hemostasis and coagulation, thrombin has other numerous biological activities affecting inflammation, immune responses, tissue repair and wound healing. Apart from its physiological role thrombin activates the oncogenic potential of both normal and malignant cells and leads a metastatic phenotype. It is a potent mitogen for many tumor cells. It potentiates the proliferative response of tumor cells to some growth factors, increases the adhesive properties to the platelets and invasion processes of tumor cells to the extracellular matrix, enhances the metastatic capacity of tumor cells, activates angiogenesis and remodels the microenvironment of the tumor. The cellular biological effects of thrombin are mediated at least in part by a new subfamily of G-protein-coupled receptors designated proteinase-activited receptors (PARs). Thrombin has a bilateral effect on tumor cells:enhanced growth at low concentration, impaired growth/apoptosis at higher concentration. In this papers, the biological function of thrombin, thrombin and tumors, and thrombin receptors etc were reviewed.
Animals ; Humans ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Neoplasms ; enzymology ; pathology ; Receptors, Thrombin ; physiology ; Thrombin ; physiology

Thrombin is the most important factor in hemostasis. In recent years, it has been found that thrombin is a potent mitogen capable of inducing cellular functions. Therefore, it is proved to be of importance in promoting the growth, metastasis and angiogenesis of cancer. Anticoagulant therapy not only reduce the characteristic hypercoagulability of cancer, but also inhibits growth and metastasis of cancer, and alters the fundamental biology of cancer. In this paper thrombin and its receptor, relationship of thrombin and its receptor with cancer growth, metastasis and angiogenesis, the mechanisms of thrombin influence on cancer angiogenesis, as well as application prospects on anti-angiogenesis and anti-coagulation therapy were reviewed.
Angiogenesis Inhibitors ; therapeutic use ; Animals ; Anticoagulants ; therapeutic use ; Antithrombins ; therapeutic use ; Humans ; Neoplasms ; blood supply ; drug therapy ; Neovascularization, Pathologic ; Receptors, Thrombin ; physiology ; Thrombin ; physiology