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Blood Sep 2014Endothelial cell protein C receptor (EPCR) was first identified and isolated as a cellular receptor for protein C on endothelial cells. EPCR plays a crucial role in the... (Review)
Review
Endothelial cell protein C receptor (EPCR) was first identified and isolated as a cellular receptor for protein C on endothelial cells. EPCR plays a crucial role in the protein C anticoagulant pathway by promoting protein C activation. In the last decade, EPCR has received wide attention after it was discovered to play a key role in mediating activated protein C (APC)-induced cytoprotective effects, including antiapoptotic, anti-inflammatory, and barrier stabilization. APC elicits cytoprotective signaling through activation of protease activated receptor-1 (PAR1). Understanding how EPCR-APC induces cytoprotective effects through activation of PAR1, whose activation by thrombin is known to induce a proinflammatory response, has become a major research focus in the field. Recent studies also discovered additional ligands for EPCR, which include factor VIIa, Plasmodium falciparum erythrocyte membrane protein, and a specific variant of the T-cell receptor. These observations open unsuspected new roles for EPCR in hemostasis, malaria pathogenesis, innate immunity, and cancer. Future research on these new discoveries will undoubtedly expand our understanding of the role of EPCR in normal physiology and disease, as well as provide novel insights into mechanisms for EPCR multifunctionality. Comprehensive understanding of EPCR may lead to development of novel therapeutic modalities in treating hemophilia, inflammation, cerebral malaria, and cancer.
Topics: Amino Acid Sequence; Animals; Antigens, CD; Endothelial Protein C Receptor; Hemostasis; Humans; Inflammation; Ligands; Models, Molecular; Molecular Sequence Data; Protein Structure, Tertiary; Receptors, Cell Surface; Sequence Homology, Amino Acid
PubMed: 25049281
DOI: 10.1182/blood-2014-05-578328 -
Thrombosis Research May 2016Activated protein C (APC) is a plasma serine protease that is capable of antithrombotic, anti-inflammatory, anti-apoptotic, and cell-signaling activities. Animal injury... (Review)
Review
Activated protein C (APC) is a plasma serine protease that is capable of antithrombotic, anti-inflammatory, anti-apoptotic, and cell-signaling activities. Animal injury studies show that recombinant APC and some of its mutants are remarkably therapeutic for a wide range of injuries. In particular, for neurologic injuries, APC reduces damage caused by ischemia/reperfusion in the brain, by acute brain trauma, and by chronic neurodegenerative conditions. For these neuroprotective effects, APC requires endothelial cell protein C receptor. APC activates cell signaling networks with alterations in gene expression profiles by activating protease activated receptors 1 and 3. To minimize APC-induced bleeding risk, APC variants were engineered to lack > 90% anticoagulant activity but retain normal cell signaling. The neuroprotective APC mutant, 3K3A-APC which has Lys191-193 mutated to Ala191-193, is very neuroprotective and it is currently in clinical trials for ischemic stroke.
Topics: Animals; Anticoagulants; Brain; Brain Injuries, Traumatic; Humans; Neurogenesis; Neuroprotection; Neuroprotective Agents; Protein C; Recombinant Proteins; Signal Transduction; Stroke
PubMed: 27207428
DOI: 10.1016/S0049-3848(16)30368-1 -
Anales de Pediatria May 2023The objective of the study was to establish the normal range for the levels of antithrombin (AT), protein C (PC), and protein S (PS) in the first week post birth in...
INTRODUCTION
The objective of the study was to establish the normal range for the levels of antithrombin (AT), protein C (PC), and protein S (PS) in the first week post birth in mother-infant pairings, adjusting for obstetric and perinatal factors, based on 2 different laboratory methods.
METHODS
Determinations were carried out in 83 healthy term neonates and their mothers, establishing 3 postpartum age groups: 1-2 days, 3 days, and 4-7 days.
RESULTS
There were no differences in the levels of any of the proteins between the different age groups in neonates or mothers in the first week post birth. The adjusted analysis found no association with obstetric or perinatal factors. The AT and PC levels were higher in mothers compared to infants (P < .001), while the PS levels were similar in both. Overall, the correlation of maternal and infant protein values was poor, except for the levels of free PS in the first 2 days after delivery. Although we found no differences based on which of the 2 laboratory methods was applied, the absolute values did differ.
Topics: Child, Preschool; Female; Humans; Infant; Infant, Newborn; Pregnancy; Mothers; Postpartum Period; Protein C; Thrombin; Protein S; Antithrombins
PubMed: 37076369
DOI: 10.1016/j.anpede.2023.03.005 -
International Journal of Molecular... Sep 2022Platelet and coagulation activation are highly reciprocal processes driven by multi-molecular interactions. Activated platelets secrete several coagulation factors and...
Platelet and coagulation activation are highly reciprocal processes driven by multi-molecular interactions. Activated platelets secrete several coagulation factors and expose phosphatidylserine, which supports the activation of coagulation factor proteins. On the other hand, the coagulation cascade generates known ligands for platelet receptors, such as thrombin and fibrin. Coagulation factor (F)Xa, (F)XIIIa and activated protein C (APC) can also bind to platelets, but the functional consequences are unclear. Here, we investigated the effects of the activated (anti)coagulation factors on platelets, other than thrombin. Multicolor flow cytometry and aggregation experiments revealed that the 'supernatant of (hirudin-treated) coagulated plasma' (SCP) enhanced CRP-XL-induced platelet responses, i.e., integrin αβ activation, P-selectin exposure and aggregate formation. We demonstrated that FXIIIa in combination with APC enhanced platelet activation in solution, and separately immobilized FXIIIa and APC resulted in platelet spreading. Platelet activation by FXIIIa was inhibited by molecular blockade of glycoprotein VI (GPVI) or Syk kinase. In contrast, platelet spreading on immobilized APC was inhibited by PAR1 blockade. Immobilized, but not soluble, FXIIIa and APC also enhanced in vitro adhesion and aggregation under flow. In conclusion, in coagulation, factors other than thrombin or fibrin can induce platelet activation via GPVI and PAR receptors.
Topics: Blood Platelets; Factor XIIIa; Fibrin; Hirudins; P-Selectin; Phosphatidylserines; Platelet Activation; Platelet Aggregation; Platelet Glycoprotein GPIIb-IIIa Complex; Platelet Membrane Glycoproteins; Protein C; Receptor, PAR-1; Syk Kinase; Thrombin
PubMed: 36142125
DOI: 10.3390/ijms231810203 -
The Journal of Biological Chemistry Nov 2020Activated protein C is a trypsin-like protease with anticoagulant and cytoprotective properties that is generated by thrombin from the zymogen precursor protein C in a...
Activated protein C is a trypsin-like protease with anticoagulant and cytoprotective properties that is generated by thrombin from the zymogen precursor protein C in a reaction greatly accelerated by the cofactor thrombomodulin. The molecular details of this activation remain elusive due to the lack of structural information. We now fill this gap by providing information on the overall structural organization of these proteins using single molecule FRET and small angle X-ray scattering. Under physiological conditions, both zymogen and protease adopt a conformation with all domains vertically aligned along an axis 76 Å long and maximal particle size of 120 Å. This conformation is stabilized by binding of Ca to the Gla domain and is affected minimally by interaction with thrombin. Hence, the zymogen protein C likely interacts with the thrombin-thrombomodulin complex through a rigid body association that produces a protease with essentially the same structural architecture. This scenario stands in contrast to an analogous reaction in the coagulation cascade where conversion of the zymogen prothrombin to the protease meizothrombin by the prothrombinase complex is linked to a large conformational transition of the entire protein. The presence of rigid epidermal growth factor domains in protein C as opposed to kringles in prothrombin likely accounts for the different conformational plasticity of the two zymogens. The new structural features reported here for protein C have general relevance to vitamin K-dependent clotting factors containing epidermal growth factor domains, such as factors VII, IX, and X.
Topics: Enzyme Precursors; Fluorescence Resonance Energy Transfer; Humans; Particle Size; Protein C; Protein Conformation; Scattering, Small Angle; X-Ray Diffraction
PubMed: 32855236
DOI: 10.1074/jbc.RA120.014789 -
Current Opinion in Hematology Sep 2017Hemophilia is a debilitating disease, marked by frequent, painful bleeding events, joint deterioration and early death. All current treatments consist of i.v. infusions... (Review)
Review
PURPOSE OF REVIEW
Hemophilia is a debilitating disease, marked by frequent, painful bleeding events, joint deterioration and early death. All current treatments consist of i.v. infusions of replacement factor or other procoagulant factors, and are incompletely effective, due in part to the short half-lives of the proteins. An alternative approach is to rebalance hemostasis by inhibiting natural anticoagulant mechanisms. In this article, we explain why activated protein C (APC) is an appropriate and safe target for the treatment of hemophilia.
RECENT FINDINGS
A serpin (serine protease inhibitor) was engineered to specifically inhibit APC and was found to rescue hemostasis in a hemophilia mouse model, even after a severe tail clip injury. However, APC is also anti-inflammatory and has cytoprotective activities, raising safety concerns over the use of an APC inhibitor to treat hemophilia. We summarize the molecular basis of the anticoagulant and signaling activities of APC to assess the potential impact of targeting APC.
SUMMARY
We conclude that the signaling and anticoagulant functions of APC are in spatially and kinetically distinct compartments, and that it is possible to specifically inhibit the anticoagulant activity of APC. Targeting APC with a serpin is remarkably effective and may be safe for long-term prophylactic use in the treatment of hemophilia.
Topics: Animals; Disease Models, Animal; Drug Delivery Systems; Hemophilia A; Humans; Mice; Protein C; Serpins
PubMed: 28632502
DOI: 10.1097/MOH.0000000000000364 -
Lipids in Health and Disease Jun 2023Population-based studies investigating the association between blood coagulation markers and non-alcoholic fatty liver disease (NAFLD) are rare. Thus, we aimed to...
BACKGROUND
Population-based studies investigating the association between blood coagulation markers and non-alcoholic fatty liver disease (NAFLD) are rare. Thus, we aimed to investigate the relationship between the Fatty Liver Index (FLI) as a measure of hepatic steatosis and plasma concentrations of antithrombin III, D-dimer, fibrinogen D, protein C, protein S, factor VIII, activated partial thromboplastin time (aPTT), quick value and international thromboplastin time (INR) in the general population.
METHODS
After the exclusion of participants with anticoagulative treatment, 776 participants (420 women and 356 men, aged 54-74 years) of the population-based KORA Fit study with analytic data on hemostatic factors were included in the present analysis. Linear regression models were used to explore the associations between FLI and hemostatic markers, adjusted for sex, age, alcohol consumption, education, smoking status, and physical activity. In a second model, additional adjustments were made for the history of stroke, hypertension, myocardial infarction, serum non-HDL cholesterol levels, and diabetes status. In addition, analyses were stratified by diabetes status.
RESULTS
In the multivariable models (with or without health conditions), significantly positive associations with FLI were obtained for plasma concentrations of D-dimers, factor VIII, fibrinogen D, protein C, protein S, and quick value, while INR and antithrombin III were inversely associated. These associations were weaker in pre-diabetic subjects and largely disappeared in diabetic patients.
CONCLUSION
In this population-based study, an increased FLI is clearly related to changes in the blood coagulation system, possibly increasing the risk of thrombotic events. Due to a generally more pro-coagulative profile of hemostatic factors, such an association is not visible in diabetic subjects.
Topics: Male; Humans; Female; Factor VIII; Antithrombin III; Protein S; Protein C; Blood Coagulation; Hemostatics; Anticoagulants; Fibrinogen
PubMed: 37386502
DOI: 10.1186/s12944-023-01854-8 -
Chinese Journal of Traumatology =... 2015Acute coagulopathy of trauma-shock (ACoTS) occurs in 25% of patients with severe trauma in the early phase, and the mortality of those patients is four-fold higher than... (Review)
Review
Acute coagulopathy of trauma-shock (ACoTS) occurs in 25% of patients with severe trauma in the early phase, and the mortality of those patients is four-fold higher than patients without coagulopathy. The pathophysiology of this complicated phenomenon has been focused on in recent years. Tissue injury and hypoperfusion, activated protein C and Complements play important roles in the early phase after trauma. While the use of blood products, hypothermia, acidosis and inflammation are the main mechanism in late phase. Supplementing coagulation factors and platelets to improve ACoTS are inefficient. Only positive resuscitation from shock and improving tissue hypoperfusion have expected benefits.
Topics: Blood Coagulation Disorders; Complement System Proteins; Disseminated Intravascular Coagulation; Humans; Hypothermia; Inflammation; Protein C; Shock, Traumatic
PubMed: 26511301
DOI: 10.1016/j.cjtee.2015.01.003 -
Chinese Journal of Traumatology =... Dec 2018Trauma-induced coagulopathy is classified into primary and secondary coagulopathy, with the former elicited by trauma and traumatic shock itself and the latter being... (Review)
Review
Trauma-induced coagulopathy is classified into primary and secondary coagulopathy, with the former elicited by trauma and traumatic shock itself and the latter being acquired coagulopathy induced by anemia, hypothermia, acidosis, and dilution. Primary coagulopathy consists of disseminated intravascular coagulation and acute coagulopathy of trauma shock (ACOTS). The pathophysiology of ACOTS is the suppression of thrombin generation and neutralization of plasminogen activator inhibitor-1 mediated by activated protein C that leads to hypocoagulation and hyperfibrinolysis in the circulation. This review tried to clarify the validity of activated protein C hypothesis that constitutes the main pathophysiology of the ACOTS in experimental trauma models.
Topics: Acute Disease; Animals; Blood Coagulation Disorders; Disease Models, Animal; Disseminated Intravascular Coagulation; Humans; Mice; Plasminogen Activator Inhibitor 1; Protein C; Thrombin; Wounds and Injuries
PubMed: 30594428
DOI: 10.1016/j.cjtee.2018.07.005 -
Journal of Thrombosis and Haemostasis :... Jan 2021Essentials Activated protein C (APC) is a serine protease with anticoagulant and cytoprotective effects. We tested whether APC or non-canonical PAR-derived peptides...
Essentials Activated protein C (APC) is a serine protease with anticoagulant and cytoprotective effects. We tested whether APC or non-canonical PAR-derived peptides suppress inflammasome activity. APC or PAR1- and PAR3-derived peptides restrict inflammasome-dependent caspase-1 activity. Combined PAR1-derived and PAR3-derived peptides synergistically suppress caspase-1 activity. ABSTRACT: Background Activated protein C (APC) has been shown to restrict murine inflammasome activity. However, whether APC can exert anti-inflammatory activity in part through suppression of inflammasome activation in human systems is unknown. Objectives Studies were made to determine whether either APC or protease activated receptor (PAR)-derived peptides can reduce NLRP3 inflammasome activity in differentiated human THP-1 macrophage-like cells or in primary human monocytes stimulated to activate the inflammasome. Methods Human THP-1 cells or primary human monocytes were differentiated, treated with APC or PAR-derived peptides, and then stimulated with lipopolysaccharide and ATP to induce caspase-1 activity, a product of inflammasome activation. Results Activated protein C or noncanonical PAR1-derived or PAR3-derived peptides significantly reduced caspase-1 activity, detection of fluorescent NLRP3, and IL-1β release from THP-1 cells. At low concentrations where no effect was observed for each individual peptide, combinations of the PAR1-derived peptide and the PAR3-derived peptide resulted in a significant synergistic decrease in caspase-1 and IL-1β release. Caspase-1 activity was also reduced in primary human monocytes. Studies using blocking antibodies and small molecule PAR1 inhibitors suggest that EPCR, PAR1, and PAR3 each play roles in the observed anti-inflammatory effects. Several shortened versions of the PAR1- and PAR3-derived peptide reduced caspase-1 activity and exhibited synergistic anti-inflammatory effects. Conclusions The results indicate that both APC and certain PAR1- and PAR3-derived peptides, which are biased agonists for PAR1 or PAR3, can reduce inflammasome activity in stimulated human monocytes as measured by caspase-1 activity and IL-1β release and that PAR-derived biased peptide agonist combinations are synergistically anti-inflammatory.
Topics: Adaptor Proteins, Signal Transducing; Anti-Inflammatory Agents; Caspase 1; Cell Cycle Proteins; Endothelial Protein C Receptor; Humans; Inflammasomes; Interleukin-1beta; Macrophages; NLR Family, Pyrin Domain-Containing 3 Protein; Peptides; Protein C; Receptor, PAR-1; Signal Transduction; THP-1 Cells
PubMed: 33049092
DOI: 10.1111/jth.15133