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Memorias Do Instituto Oswaldo Cruz Aug 2011Enolase is the eighth enzyme in the glycolytic pathway, a reaction that generates ATP from phosphoenol pyruvate in cytosolic compartments. Enolase is essential,... (Review)
Review
Enolase is the eighth enzyme in the glycolytic pathway, a reaction that generates ATP from phosphoenol pyruvate in cytosolic compartments. Enolase is essential, especially for organisms devoid of the Krebs cycle that depend solely on glycolysis for energy. Interestingly, enolase appears to serve a separate function in some organisms, in that it is also exported to the cell surface via a poorly understood mechanism. In these organisms, surface enolase assists in the invasion of their host cells by binding plasminogen, an abundant plasma protease precursor. Binding is mediated by the interaction between a lysine motif of enolase with Kringle domains of plasminogen. The bound plasminogen is then cleaved by specific proteases to generate active plasmin. Plasmin is a potent serine protease that is thought to function in the degradation of the extracellular matrix surrounding the targeted host cell, thereby facilitating pathogen invasion. Recent work revealed that the malaria parasite Plasmodium also expresses surface enolase, and that this feature may be essential for completion of its life cycle. The therapeutic potential of targeting surface enolases of pathogens is discussed.
Topics: Animals; Cell Membrane; Fibrinolysin; Life Cycle Stages; Phosphopyruvate Hydratase; Plasminogen; Plasmodium
PubMed: 21881761
DOI: 10.1590/s0074-02762011000900011 -
Acta Neurologica Belgica Apr 2024Alzheimer's disease (AD) is the most common type of dementia associated with amyloid beta (Aβ) deposition. Dysfunction of the neuronal clearance pathway promotes the... (Review)
Review
Alzheimer's disease (AD) is the most common type of dementia associated with amyloid beta (Aβ) deposition. Dysfunction of the neuronal clearance pathway promotes the accumulation of Aβ. The plasminogen-activating system (PAS) is controlled by various enzymes like tissue plasminogen activators (tPA). Neuronal tPA enhances the conversion of plasminogen to plasmin, which cleaves Aβ; this function is controlled by many inhibitors of PAS, including a plasminogen-activating inhibitor (PAI-1) and neuroserpin. Therefore, the objective of the present narrative review was to explore the potential role of tPA/neuroserpin in the pathogenesis of AD. PAI-1 activity is increased in AD, which is involved in accumulating Aβ. Progressive increase of Aβ level during AD neuropathology is correlated with the over-production of PAI-1 with subsequent reduction of plasmin and tPA activities. Reducing plasmin and tPA activities promote Aβ by reducing Aβ clearance. Neuroserpin plays a critical role in the pathogenesis of AD as it regulates the expression and accumulation of Aβ. Higher expression of neuroserpin inhibits the neuroprotective tPA and the generation of plasmin with subsequent reduction in the clearance of Aβ. These observations raise conflicting evidence on whether neuroserpin is neuroprotective or involved in AD progression. Thus, neuroserpin over-expression with subsequent reduction of tPA may propagate AD neuropathology.
Topics: Humans; Alzheimer Disease; Tissue Plasminogen Activator; Amyloid beta-Peptides; Neuroserpin; Fibrinolysin; Plasminogen Activator Inhibitor 1; Plasminogen
PubMed: 37917293
DOI: 10.1007/s13760-023-02403-x -
Pacific Symposium on Biocomputing.... 2010Plasmin and urokinase-type plasminogen activator (uPA) are ubiquitous proteases regulating the extracellular environment. They can activate each other via proteolytic...
Plasmin and urokinase-type plasminogen activator (uPA) are ubiquitous proteases regulating the extracellular environment. They can activate each other via proteolytic cleavage, suggesting the potential for complex dynamic behaviors that could be elucidated by computational modeling. Ordinary differential equations are constructed to model the activation dynamics of plasminogen into plasmin, and single-chain uPA (scUPA) into two-chain uPA (tcUPA). Computational simulations and phase plane analysis reveal two stable steady states for the activation of each protein. Bifurcation analysis shows the in silico system to be bistable. Cell-free experiments verify the system to have ultrasensitive activation behavior, where scUPA is the stimulus and plasmin the output. Furthermore, two significantly different steady states could be seen in vitro for the same stimulus levels, depending on the initial activation level of the plasmin. The switch-like dynamics of the uPA-plasmin system could have potential relevance to many normal and disease processes including angiogenesis, migration and metastasis, wound healing and fibrosis.
Topics: Computational Biology; Computer Simulation; Enzyme Activation; Fibrinolysin; Humans; Kinetics; Models, Biological; Nonlinear Dynamics; Plasminogen; Urokinase-Type Plasminogen Activator
PubMed: 19908371
DOI: 10.1142/9789814295291_0021 -
Blood Nov 2015Coagulation factor XIIIa (FXIIIa) is a transglutaminase that covalently cross-links fibrin and other proteins to fibrin to stabilize blood clots and reduce blood loss. A...
Coagulation factor XIIIa (FXIIIa) is a transglutaminase that covalently cross-links fibrin and other proteins to fibrin to stabilize blood clots and reduce blood loss. A clear mechanism to describe the physiological inactivation of FXIIIa has been elusive. Here, we show that plasmin can cleave FXIIIa in purified systems and in blood. Whereas zymogen FXIII was not readily cleaved by plasmin, FXIIIa was rapidly cleaved and inactivated by plasmin in solution (catalytic efficiency = 8.3 × 10(3) M(-1)s(-1)). The primary cleavage site identified by mass spectrometry was between K468 and Q469. Both plasma- and platelet-derived FXIIIa were susceptible to plasmin-mediated degradation. Inactivation of FXIIIa occurred during clot lysis and was enhanced both in plasma deficient in fibrinogen and in plasma treated with therapeutic levels of tissue plasminogen activator. These results indicate that FXIIIa activity can be modulated by fibrinolytic enzymes, and suggest that changes in fibrinolytic activity may influence cross-linking of blood proteins.
Topics: Factor XIII; Fibrinolysin; Fibrinolysis; Humans; Proteolysis; Tissue Plasminogen Activator
PubMed: 26359437
DOI: 10.1182/blood-2015-07-650713 -
Journal of Bone and Mineral Research :... Feb 2017Extensive or persistent calcium phosphate deposition within soft tissues after severe traumatic injury or major orthopedic surgery can result in pain and loss of joint...
Extensive or persistent calcium phosphate deposition within soft tissues after severe traumatic injury or major orthopedic surgery can result in pain and loss of joint function. The pathophysiology of soft tissue calcification, including dystrophic calcification and heterotopic ossification (HO), is poorly understood; consequently, current treatments are suboptimal. Here, we show that plasmin protease activity prevents dystrophic calcification within injured skeletal muscle independent of its canonical fibrinolytic function. After muscle injury, dystrophic calcifications either can be resorbed during the process of tissue healing, persist, or become organized into mature bone (HO). Without sufficient plasmin activity, dystrophic calcifications persist after muscle injury and are sufficient to induce HO. Downregulating the primary inhibitor of plasmin (α2-antiplasmin) or treating with pyrophosphate analogues prevents dystrophic calcification and subsequent HO in vivo. Because plasmin also supports bone homeostasis and fracture repair, increasing plasmin activity represents the first pharmacologic strategy to prevent soft tissue calcification without adversely affecting systemic bone physiology or concurrent muscle and bone regeneration. © 2016 American Society for Bone and Mineral Research.
Topics: Animals; Calcinosis; Cardiotoxins; Diphosphates; Fibrinolysin; Fibrinolysis; Genetic Predisposition to Disease; Mice, Inbred C57BL; Muscle, Skeletal; Ossification, Heterotopic; Regeneration
PubMed: 27530373
DOI: 10.1002/jbmr.2973 -
The Journal of Trauma and Acute Care... Jun 2015Postinjury systemic fibrinolysis has been recognized as a biologic process for more than 200 years, but the specific mechanisms of regulation and their clinical... (Review)
Review
Postinjury systemic fibrinolysis has been recognized as a biologic process for more than 200 years, but the specific mechanisms of regulation and their clinical implications remain to be elucidated. By the 1950s, the plasminogen-plasmin-antiplasmin system was established as critical in preserving microvascular patency during blood clotting to maintain hemostasis. The challenges in modulating systemic fibrinolysis became evident soon thereafter. In the 1960s systemic fibrinolysis was identified by thrombelastography (TEG) during the anhepatic phase of liver transplantation, prompting the recommendation for intraoperative antifibrinolytics. But the administration of antifibrinolytic was associated with fatal postoperative pulmonary emboli. During the same period, there was experimental evidence that antifibrinolytics prevented irreversible hemorrhagic shock. More recently, a randomized trial indicated that plasmin inhibition during coronary artery bypass grafting was associated with increased mortality. The interest in antifibrinolytic therapy for trauma induced coagulopathy (TIC) is a relatively recent event, largely driven by the increasing use of viscoelastic hemostatic assays. The CRASH-2 trial, published in 2010, stimulated worldwide enthusiasm for tranexamic acid (TXA). However, the limitations of this study were soon acknowledged, raising concern for the unbridled use of TXA. Most recently, the documentation of fibrinolysis shutdown soon after injury has highlighted the potential adverse effects due to the untimely administration of TXA. A recent retrospective analysis in severely injured patients supports this hypothesis. But final clarity of this volatile topic awaits the completion of the current ongoing randomized clinical trials throughout the world.
Topics: Antifibrinolytic Agents; Blood Component Transfusion; Fibrinolysin; Fibrinolysis; Humans; Plasminogen Activator Inhibitor 1; Tranexamic Acid; Wounds and Injuries
PubMed: 26002266
DOI: 10.1097/TA.0000000000000634 -
British Journal of Cancer Mar 2019Dysregulation of pericellular proteolysis usually accounts for cancer cell invasion and metastasis. Isolation of a cell-surface protease system for lung cancer...
BACKGROUND
Dysregulation of pericellular proteolysis usually accounts for cancer cell invasion and metastasis. Isolation of a cell-surface protease system for lung cancer metastasis is an important issue for mechanistic studies and therapeutic target identification.
METHODS
Immunohistochemistry of a tissue array (n = 64) and TCGA database (n = 255) were employed to assess the correlation between serine protease inhibitors (SPIs) and lung adenocarcinoma progression. The role of SPI in cell motility was examined using transwell assays. Pulldown and LC/MS/MS were performed to identify the SPI-modulated novel protease(s). A xenografted mouse model was harnessed to demonstrate the role of the SPI in lung cancer metastasis.
RESULTS
Hepatocyte growth factor activator inhibitor-2 (HAI-2) was identified to be downregulated following lung cancer progression, which was related to poor survival and tumour invasion. We further isolated a serum-derived serine protease, plasmin, to be a novel target of HAI-2. Downregulation of HAI-2 promotes cell surface plasmin activity, EMT, and cell motility. HAI-2 can suppress plasmin-mediated activations of HGF and TGF-β1, EMT and cell invasion. In addition, downregulated HAI-2 increased metastasis of lung adenocarcinoma via upregulating plasmin activity.
CONCLUSION
HAI-2 functions as a novel inhibitor of plasmin to suppress lung cancer cell motility, EMT and metastasis.
Topics: A549 Cells; Adenocarcinoma of Lung; Animals; Cell Line, Tumor; Cell Movement; Disease Progression; Epithelial-Mesenchymal Transition; Fibrinolysin; Hepatocyte Growth Factor; Humans; Lung Neoplasms; Membrane Glycoproteins; Mice; Neoplasm Invasiveness; Neoplasm Metastasis; Neoplasm Transplantation; Transforming Growth Factor beta1
PubMed: 30765871
DOI: 10.1038/s41416-019-0400-2 -
The Journal of Clinical Investigation Sep 1977Six children aged 12-15 yr, deficient in endogenous growth hormone, were each treated, after a 7-day control period, for 7 days with 0.0168, 0.052, and 0.168 U/kg body...
Six children aged 12-15 yr, deficient in endogenous growth hormone, were each treated, after a 7-day control period, for 7 days with 0.0168, 0.052, and 0.168 U/kg body wt3/4 human growth (hGH) (doses A, B, and C, respectively) in separate metabolic balance studies. Doses B and C caused a dose-related retention of N, P, K, Na, and Cl in ratios of 1/0.069/4.5/7.5/5.6. These ratios indicate increments in masses of protoplasm/extracellular fluid (ECF)/bone in ratios of 1/2.0/ less than 0.001. Three of the children were also treated with doses A, B, and C of reduced and carbamidomethylated hGH (RCAM-hGH). Doses B and C caused 1.2-2.8 times as much retention of N, P, and K, and 0.3-0.5 times as much retention of Na and Cl, as did the corresponding doses of hGH. The plasmin digest of RCAM-hGH gave results generally similar to RCAM-hGH. For RCAM-hGH and its plasmin digest, N, P, K, Na, and Cl were retained in ratios of about 1/0.14/5.4/2.2/2.1, indicating increments of protoplasm/ECF/bone of about 1/0.8/0.05. These findings indicate that reduction and carbamidomethylation alter the anabolic actions of hGH in man in both quantitative and qualitative manner. RCAM-hGH is more potent in stimulating enlargement of protoplasm and bone, and less potent in stimulating expansion of ECF, than is the native hormone. The profile of anabolic actions of RCAM-hGH in man does not appear to be further altered by digestion with plasmin.
Topics: Adolescent; Child; Dose-Response Relationship, Drug; Female; Fibrinolysin; Growth Hormone; Humans; Male
PubMed: 142777
DOI: 10.1172/JCI108808 -
The Journal of Biological Chemistry Aug 1997Extracellular manipulation of protein disulfide bonds has been implied in diverse biological processes, including penetration of viruses and endotoxin into cells and...
Extracellular manipulation of protein disulfide bonds has been implied in diverse biological processes, including penetration of viruses and endotoxin into cells and activation of certain cytokine receptors. We now demonstrate reduction of one or more disulfide bonds in the serine proteinase, plasmin, by a reductase secreted by Chinese hamster ovary or HT1080 cells. Reduction of plasmin disulfide bond(s) triggered proteolysis of the enzyme, generating fragments with the domain structure of the angiogenesis inhibitor, angiostatin. Two of the known reductases secreted by cultured cells are protein disulfide isomerase and thioredoxin, and incubation of plasmin with these purified reductases resulted in angiostatin fragments comparable with those generated from plasmin in cell culture. Thioredoxin-derived angiostatin inhibited proliferation of human dermal microvascular endothelial cells with half-maximal effect at approximately 0.2 microg/ml. Angiostatin made by cells and by purified reductases contained free sulfhydryl group(s), and S-carbamidomethylation of these thiol group(s) ablated biological activity. Neither protein disulfide isomerase nor thioredoxin were the reductases used by cultured cells, because immunodepletion of conditioned medium of these proteins did not affect angiostatin generating activity. The plasmin reductase secreted by HT1080 cells required a small cofactor for activity, and physiologically relevant concentrations of reduced glutathione fulfilled this role. These results have consequences for plasmin activity and angiogenesis, particularly in the context of tumor growth and metastasis. Moreover, this is the first demonstration of extracellular reduction of a protein disulfide bond, which has general implications for cell biology.
Topics: Angiostatins; Animals; CHO Cells; Cricetinae; Fibrinolysin; Humans; Oxidation-Reduction; Oxidoreductases; Peptide Fragments; Plasminogen; Thioredoxins
PubMed: 9252380
DOI: 10.1074/jbc.272.33.20641 -
Molecules (Basel, Switzerland) Jan 2015Plasmin, a key serine protease, plays a major role in clot lysis and extracellular matrix remodeling. Heparin, a natural polydisperse sulfated glycosaminoglycan, is...
Plasmin, a key serine protease, plays a major role in clot lysis and extracellular matrix remodeling. Heparin, a natural polydisperse sulfated glycosaminoglycan, is known to allosterically modulate plasmin activity. No small allosteric inhibitor of plasmin has been discovered to date. We screened an in-house library of 55 sulfated, small glycosaminoglycan mimetics based on nine distinct scaffolds and varying number and positions of sulfate groups to discover several promising hits. Of these, a pentasulfated flavonoid-quinazolinone dimer 32 was found to be the most potent sulfated small inhibitor of plasmin (IC50 = 45 μM, efficacy = 100%). Michaelis-Menten kinetic studies revealed an allosteric inhibition of plasmin by these inhibitors. Studies also indicated that the most potent inhibitors are selective for plasmin over thrombin and factor Xa, two serine proteases in coagulation cascade. Interestingly, different inhibitors exhibited different levels of efficacy (40%-100%), an observation alluding to the unique advantage offered by an allosteric process. Overall, our work presents the first small, synthetic allosteric plasmin inhibitors for further rational design.
Topics: Allosteric Regulation; Blood Coagulation; Drug Evaluation, Preclinical; Factor Xa; Fibrinolysin; Humans; Hydrolysis; Kinetics; Serine Proteinase Inhibitors; Small Molecule Libraries; Structure-Activity Relationship; Sulfates
PubMed: 25569517
DOI: 10.3390/molecules20010608