Urokinase

Last updated
PLAU
Available structures
PDB Ortholog search: PDBe RCSB
Identifiers
Aliases PLAU , ATF, BDPLT5, QPD, UPA, URK, u-PA, plasminogen activator, urokinase
External IDs OMIM: 191840 MGI: 97611 HomoloGene: 55670 GeneCards: PLAU
Orthologs
SpeciesHumanMouse
Entrez

5328

18792

Ensembl

ENSG00000122861

ENSMUSG00000021822

UniProt

P00749

P06869

RefSeq (mRNA)

NM_001145031
NM_002658
NM_001319191

NM_008873

RefSeq (protein)

NP_001138503
NP_001306120
NP_002649

NP_032899

Location (UCSC) Chr 10: 73.91 – 73.92 Mb Chr 14: 20.89 – 20.89 Mb
PubMed search [3] [4]
Wikidata
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Urokinase
Clinical data
AHFS/Drugs.com Monograph
ATC code
Identifiers
CAS Number
DrugBank
ChemSpider
  • none
UNII
KEGG
ChEMBL
Chemical and physical data
Formula C1376H2145N383O406S18
Molar mass 31126.65 g·mol−1
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Urokinase, also known as urokinase-type plasminogen activator (uPA), is a serine protease present in humans and other animals. The human urokinase protein was discovered, but not named, by McFarlane and Pilling in 1947. [5] Urokinase was originally isolated from human urine, and it is also present in the blood and in the extracellular matrix of many tissues. The primary physiological substrate of this enzyme is plasminogen, which is an inactive form (zymogen) of the serine protease plasmin. Activation of plasmin triggers a proteolytic cascade that, depending on the physiological environment, participates in thrombolysis or extracellular matrix degradation. This cascade had been involved in vascular diseases and cancer progression. [6]

Urokinase is encoded in humans by the PLAU gene, which stands for "plasminogen activator, urokinase". [7] The same symbol represents the gene in other animal species.

Function

The PLAU gene encodes a serine protease (EC 3.4.21.73) involved in degradation of the extracellular matrix and possibly tumor cell migration and proliferation. A specific polymorphism in this gene may be associated with late-onset Alzheimer disease and also with decreased affinity for fibrin-binding. The protein encoded by this gene converts plasminogen to plasmin by specific cleavage of an Arg-Val bond in plasminogen. This gene's proprotein is cleaved at a Lys-Ile bond by plasmin to form a two-chain derivative in which a single disulfide bond connects the amino-terminal A-chain to the catalytically active, carboxy-terminal B-chain. This two-chain derivative is also called HMW-uPA (high molecular weight uPA). HMW-uPA can be further processed into LMW-uPA (low molecular weight uPA) by cleavage of chain A into a short chain A (A1) and an amino-terminal fragment. LMW-uPA is proteolytically active but does not bind to the uPA receptor. [8]

Structure

Urokinase is a 411-residue protein, consisting of three domains: the serine protease domain (consisting of residues 159-411), the kringle domain (consisting of residues 50-131), and the EGF-like domain (consisting of residues 1-49). The kringle domain and the serine protease domain are connected by an interdomain linker or connecting peptide (consisting of residues 132-158). Urokinase is synthesized as a zymogen form (prourokinase or single-chain urokinase), and is activated by proteolytic cleavage between Lys158 and Ile159. The two resulting chains are kept together by a disulfide bond between Cys148 and Cys279. [9]

In comparison to the mammalian system, zebrafish (Danio rerio) contains two orthologs of urokinase which have been characterised as zfuPA-a and zfuPA-b. zfuPA-a differs from the mammalian uPA by lacking an exon sequence encoding for the uPAR (urokinase receptor) binding domain; while the zfuPA-b lacks two cysteines of the epidermal growth factor-like domain. zfuPA-b also has no binding activity in fish white blood cells or fish cell lines. The uPAR binding in mammalian system is essential for the activity of urokinase and uPAR as it also functions as an adhesion receptor due to its affinity to vitronectin, integrins and other proteases like PAI-1. The lack of the uPAR binding region in zebrafish uPA, suggests that zebrafish uPA functions without uPAR binding. [10]

Interaction partners

The most important inhibitors of urokinase are the serpins plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2), which inhibit the protease activity irreversibly. In the extracellular matrix, urokinase is tethered to the cell membrane by its interaction to the urokinase receptor.

Fibrinolysis (simplified). Blue arrows denote stimulation, and red arrows inhibition. Fibrinolysis.svg
Fibrinolysis (simplified). Blue arrows denote stimulation, and red arrows inhibition.

uPa also interacts with protein C inhibitor. [11] [12]

zfuPA-a and zfuPA-b are poor activators of human plasminogen, while human uPA is a poor activator of salmon plasminogen. With the primary difference between the zebrafish uPA and human uPA being in the EGF domain. [10]

Urokinase and cancer

Elevated expression levels of urokinase and several other components of the plasminogen activation system are found to be correlated with tumor malignancy. It is believed that the tissue degradation following plasminogen activation facilitates tissue invasion and, thus, contributes to metastasis. [13] Urokinase-type plasminogen activator (uPA) is more commonly associated with cancer progression than tissue plasminogen activator (tPA). [14] This makes uPA an attractive drug target, and, so, inhibitors have been sought to be used as anticancer agents. [15] [16] However, incompatibilities between the human and murine systems hamper clinical evaluation of these agents. Moreover, urokinase is used by normal cells for tissue remodeling and vessel growth, which necessitates distinguishing cancer-associated urokinase features for specific targeting. [13]

uPA breakdown of the extracellular matrix is crucial for initiating the angiogenesis which is associated with cancer growth. [14]

uPA antigen is elevated in breast cancer tissue, which correlates with poor prognosis in breast cancer patients. [14] For this reason, uPA can be used as a diagnostic biomarker in breast cancer. [14]

Through its interaction with the urokinase receptor, urokinase affects several other aspects of cancer biology such as cell adhesion, migration, and cellular mitotic pathways.

As of December 7, 2012, Mesupron (upamostat), a small molecule serine protease inhibitor developed by the WILEX pharmaceutical company, has completed phase II trials. [17] Mesupron appears to be safe when combined with chemotherapeutic drug Capecitabine for the progression-free survival in human breast cancer. [18]

Clinical applications

Urokinase is effective for the restoration of flow to intravenous catheters blocked by clotted blood or fibrin (catheter clearance). Catheters are used extensively to administer treatments to patients for such purposes as dialysis, nutrition, antibiotic treatment and cancer treatment. Approximately 25% of catheters become blocked, meaning that affected patients cannot receive treatment until the catheter has been cleared or replaced. Urokinase is also used clinically as a thrombolytic agent in the treatment of severe or massive deep venous thrombosis, peripheral arterial occlusive disease, pulmonary embolism, acute myocardial infarction (AMI, heart attack), and occluded dialysis cannulas (catheter clearance). It is also administered intrapleurally to improve the drainage of complicated pleural effusions and empyemas. Urokinase is marketed as Kinlytic (formerly Abbokinase) and competes with recombinant tissue plasminogen activator (e.g., alteplase) as a thrombolytic drug.

All plasminogen activators (urokinase, tPA) catalyze the production of plasmin, which in turn leads to the breakdown of the fibrin mesh structure in blood clots.  While there are commonalities in the mode of action for urokinase and tPA, urokinase has some advantages for treatment of peripheral clots (Pulmonary Embolism, Deep Vein Thrombosis, Peripheral arterial occlusive disease).

Unlike tPA, which is activated by binding to the fibrin within clots, urokinase is not sequestered by fibrin and therefore does not specifically attack hemostatic clots.  This makes urokinase less likely to break down such hemostatic clots that are essential for ongoing blood vessel repair throughout the body.  Dissolution of these “good” clots can lead to serious adverse events through hemorrhagic bleeding.  Years of clinical study have confirmed the safety advantage of using urokinase. [19] [20] Consequently, urokinase has been preferentially used in deep venous thrombosis and peripheral arterial occlusive disease where it is administered directly to the site of the clot while tPA is preferred in AMI where peripheral bleeding is a secondary consideration.  

A revolutionary method for the production of urokinase was patented by Evelyn Nicol in 1976 (U.S. Patent No. 3,930,944). Nicol was believed to be the first African American woman to receive a molecular biology patent. [21]

Society and culture

The presence of a fibrinolytic enzyme in human urine was reported in 1947, without a name given for such an enzyme behind its effect. [22] In 1952 a purified form of the enzyme was extracted from human urine and named "urokinase" for "urinary kinase". [23] The full text for this article is lost, and the only citation points to the abstract of a list of papers read at a conference in the same journal. [24] A few other papers on the purification were published independently around the same time. By 1960, it was still unclear whether the activation of plasminogen has anything to do with a protease, but a kinase is thought to play a role regardless. [25]

Related Research Articles

<span class="mw-page-title-main">Coagulation</span> Process of formation of blood clots

Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism of coagulation involves activation, adhesion and aggregation of platelets, as well as deposition and maturation of fibrin.

<span class="mw-page-title-main">Disseminated intravascular coagulation</span> Medical condition where blood clots block small blood vessels

Disseminated intravascular coagulation (DIC) is a condition in which blood clots form throughout the body, blocking small blood vessels. Symptoms may include chest pain, shortness of breath, leg pain, problems speaking, or problems moving parts of the body. As clotting factors and platelets are used up, bleeding may occur. This may include blood in the urine, blood in the stool, or bleeding into the skin. Complications may include organ failure.

<span class="mw-page-title-main">Fibrinogen</span> Soluble protein complex in blood plasma and involved in clot formation

Fibrinogen is a glycoprotein complex, produced in the liver, that circulates in the blood of all vertebrates. During tissue and vascular injury, it is converted enzymatically by thrombin to fibrin and then to a fibrin-based blood clot. Fibrin clots function primarily to occlude blood vessels to stop bleeding. Fibrin also binds and reduces the activity of thrombin. This activity, sometimes referred to as antithrombin I, limits clotting. Fibrin also mediates blood platelet and endothelial cell spreading, tissue fibroblast proliferation, capillary tube formation, and angiogenesis and thereby promotes revascularization and wound healing.

<span class="mw-page-title-main">Thrombin</span> Enzyme involved in blood coagulation in humans

Thrombin is a serine protease, an enzyme that, in humans, is encoded by the F2 gene. During the clotting process, prothrombin is proteolytically cleaved by the prothrombinase enzyme complex to form thrombin. Thrombin in turn acts as a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalyzing many other coagulation-related reactions.

Fibrinolysis is a process that prevents blood clots from growing and becoming problematic. Primary fibrinolysis is a normal body process, while secondary fibrinolysis is the breakdown of clots due to a medicine, a medical disorder, or some other cause.

<span class="mw-page-title-main">Tissue-type plasminogen activator</span> Protein involved in the breakdown of blood clots

Tissue-type plasminogen activator, short name tPA, is a protein that facilitates the breakdown of blood clots. It acts as an enzyme to convert plasminogen into its active form plasmin, the major enzyme responsible for clot breakdown. It is a serine protease found on endothelial cells lining the blood vessels. Human tPA is encoded by the PLAT gene, and has a molecular weight of ~70 kDa in the single-chain form.

<span class="mw-page-title-main">Plasmin</span> Enzyme in human blood that degrades clots and other proteins

Plasmin is an important enzyme present in blood that degrades many blood plasma proteins, including fibrin clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein is encoded by the PLG gene.

<span class="mw-page-title-main">Alteplase</span> Thrombolytic medication

Alteplase, sold under the brand name Activase among others, is a biosynthetic form of human tissue-type plasminogen activator (t-PA). It is a thrombolytic medication used to treat acute ischemic stroke, acute ST-elevation myocardial infarction, pulmonary embolism associated with low blood pressure, and blocked central venous catheter. It is given by injection into a vein or artery. Alteplase is the same as the normal human plasminogen activator produced in vascular endothelial cells and is synthesized via recombinant DNA technology in Chinese hamster ovary cells (CHO). Alteplase causes the breakdown of a clot by inducing fibrinolysis.

<span class="mw-page-title-main">Alpha 2-antiplasmin</span> Protein-coding gene in the species Homo sapiens

Alpha 2-antiplasmin is a serine protease inhibitor (serpin) responsible for inactivating plasmin. Plasmin is an important enzyme that participates in fibrinolysis and degradation of various other proteins. This protein is encoded by the SERPINF2 gene.

<span class="mw-page-title-main">Plasminogen activator inhibitor-1</span> Human protein

Plasminogen activator inhibitor-1 (PAI-1) also known as endothelial plasminogen activator inhibitor is a protein that in humans is encoded by the SERPINE1 gene. Elevated PAI-1 is a risk factor for thrombosis and atherosclerosis.

Protease-activated receptors (PAR) are a subfamily of related G protein-coupled receptors that are activated by cleavage of part of their extracellular domain. They are highly expressed in platelets, and also on endothelial cells, fibroblasts, immune cells, myocytes, neurons, and tissues that line the gastrointestinal tract.

<span class="mw-page-title-main">Plasminogen activator</span> Type of protein

Plasminogen activators are serine proteases that catalyze the activation of plasmin via proteolytic cleavage of its zymogen form plasminogen. Plasmin is an important factor in fibrinolysis, the breakdown of fibrin polymers formed during blood clotting. There are two main plasminogen activators: urokinase (uPA) and tissue plasminogen activator (tPA). Tissue plasminogen activators are used to treat medical conditions related to blood clotting including embolic or thrombotic stroke, myocardial infarction, and pulmonary embolism.

<span class="mw-page-title-main">Tissue factor</span> Protein involved in blood coagulation

Tissue factor, also called platelet tissue factor, factor III, or CD142, is a protein encoded by the F3 gene, present in subendothelial tissue and leukocytes. Its role in the clotting process is the initiation of thrombin formation from the zymogen prothrombin. Thromboplastin defines the cascade that leads to the activation of factor X—the tissue factor pathway. In doing so, it has replaced the previously named extrinsic pathway in order to eliminate ambiguity.

<span class="mw-page-title-main">Urokinase receptor</span> Mammalian protein found in Homo sapiens

The Urokinase receptor, also known as urokinase plasminogen activator surface receptor (uPAR) or CD87, is a protein encoded in humans by the PLAUR gene. It is a multidomain glycoprotein tethered to the cell membrane with a glycosylphosphotidylinositol (GPI) anchor. uPAR was originally identified as a saturable binding site for urokinase on the cell surface.

<span class="mw-page-title-main">Plasminogen activator inhibitor-2</span> Coagulation factor protein found in humans

Plasminogen activator inhibitor-2, a serine protease inhibitor of the serpin superfamily, is a coagulation factor that inactivates tissue plasminogen activator and urokinase. It is present in most cells, especially monocytes/macrophages. PAI-2 exists in two forms, a 60-kDa extracellular glycosylated form and a 43-kDa intracellular form.

<span class="mw-page-title-main">Protein C inhibitor</span> Human protein

Protein C inhibitor is a serine protease inhibitor (serpin) that limits the activity of protein C.

<span class="mw-page-title-main">LRP1</span> Mammalian protein found in Homo sapiens

Low density lipoprotein receptor-related protein 1 (LRP1), also known as alpha-2-macroglobulin receptor (A2MR), apolipoprotein E receptor (APOER) or cluster of differentiation 91 (CD91), is a protein forming a receptor found in the plasma membrane of cells involved in receptor-mediated endocytosis. In humans, the LRP1 protein is encoded by the LRP1 gene. LRP1 is also a key signalling protein and, thus, involved in various biological processes, such as lipoprotein metabolism and cell motility, and diseases, such as neurodegenerative diseases, atherosclerosis, and cancer.

<span class="mw-page-title-main">ST14</span> Protein-coding gene in the species Homo sapiens

Suppressor of tumorigenicity 14 protein, also known as matriptase, is a protein that in humans is encoded by the ST14 gene. ST14 orthologs have been identified in most mammals for which complete genome data are available.

<span class="mw-page-title-main">HPN (gene)</span> Protein-coding gene in humans

Serine protease hepsin is an enzyme that in humans is encoded by the HPN gene.

Angiogenesis is the process of forming new blood vessels from existing blood vessels, formed in vasculogenesis. It is a highly complex process involving extensive interplay between cells, soluble factors, and the extracellular matrix (ECM). Angiogenesis is critical during normal physiological development, but it also occurs in adults during inflammation, wound healing, ischemia, and in pathological conditions such as rheumatoid arthritis, hemangioma, and tumor growth. Proteolysis has been indicated as one of the first and most sustained activities involved in the formation of new blood vessels. Numerous proteases including matrix metalloproteinases (MMPs), a disintegrin and metalloproteinase domain (ADAM), a disintegrin and metalloproteinase domain with throbospondin motifs (ADAMTS), and cysteine and serine proteases are involved in angiogenesis. This article focuses on the important and diverse roles that these proteases play in the regulation of angiogenesis.

References

  1. 1 2 3 GRCh38: Ensembl release 89: ENSG00000122861 - Ensembl, May 2017
  2. 1 2 3 GRCm38: Ensembl release 89: ENSMUSG00000021822 - Ensembl, May 2017
  3. ↑ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ↑ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ↑ Degryse B (1 June 2011). "The urokinase receptor system as strategic therapeutic target: challenges for the 21st century". Current Pharmaceutical Design. 17 (19): 1872–1873. doi:10.2174/138161211796718161. PMID   21711231.
  6. ↑ Tang L, Han X (March 2013). "The urokinase plasminogen activator system in breast cancer invasion and metastasis". Biomedicine & Pharmacotherapy. 67 (2): 179–182. doi:10.1016/j.biopha.2012.10.003. PMID   23201006.
  7. ↑ Nagai M, Hiramatsu R, Kanéda T, Hayasuke N, Arimura H, Nishida M, Suyama T (Dec 1985). "Molecular cloning of cDNA coding for human preprourokinase". Gene. 36 (1–2): 183–188. doi:10.1016/0378-1119(85)90084-8. PMID   2415429.
  8. ↑ "Entrez Gene: PLAU plasminogen activator, urokinase".
  9. ↑ Vincenza Carriero M, Franco P, Vocca I, Alfano D, Longanesi-Cattani I, Bifulco K, et al. (January 2009). "Structure, function and antagonists of urokinase-type plasminogen activator". Frontiers in Bioscience. 14 (10): 3782–3794. doi: 10.2741/3488 . PMID   19273310.
  10. 1 2 Bager R, Kristensen TK, Jensen JK, Szczur A, Christensen A, Andersen LM, et al. (August 2012). "Urokinase-type plasminogen activator-like proteases in teleosts lack genuine receptor-binding epidermal growth factor-like domains". The Journal of Biological Chemistry. 287 (33): 27526–27536. doi: 10.1074/jbc.M112.369207 . PMC   3431643 . PMID   22733817.
  11. ↑ Geiger M, Huber K, Wojta J, Stingl L, Espana F, Griffin JH, Binder BR (August 1989). "Complex formation between urokinase and plasma protein C inhibitor in vitro and in vivo". Blood. 74 (2): 722–728. doi: 10.1182/blood.V74.2.722.722 . PMID   2752144.
  12. ↑ España F, Berrettini M, Griffin JH (August 1989). "Purification and characterization of plasma protein C inhibitor". Thrombosis Research. 55 (3): 369–384. doi:10.1016/0049-3848(89)90069-8. PMID   2551064.
  13. 1 2 Madunić J (December 2018). "The Urokinase Plasminogen Activator System in Human Cancers: An Overview of Its Prognostic and Predictive Role". Thrombosis and Haemostasis. 118 (12): 2020–2036. doi: 10.1055/s-0038-1675399 . PMID   30419600.
  14. 1 2 3 4 Mahmood N, Mihalcioiu C, Rabbani SA (2018). "Multifaceted Role of the Urokinase-Type Plasminogen Activator (uPA) and Its Receptor (uPAR): Diagnostic, Prognostic, and Therapeutic Applications". Frontiers in Oncology. 8: 24. doi: 10.3389/fonc.2018.00024 . PMC   5816037 . PMID   29484286.
  15. ↑ Jankun J, Skrzypczak-Jankun E (July 1999). "Molecular basis of specific inhibition of urokinase plasminogen activator by amiloride". Cancer Biochemistry Biophysics. 17 (1–2): 109–123. PMID   10738907.
  16. ↑ Matthews H, Ranson M, Kelso MJ (November 2011). "Anti-tumour/metastasis effects of the potassium-sparing diuretic amiloride: an orally active anti-cancer drug waiting for its call-of-duty?". International Journal of Cancer. 129 (9): 2051–2061. doi:10.1002/ijc.26156. PMID   21544803. S2CID   205943879.
  17. ↑ "Gemcitabine With or Without WX-671 in Treating Patients With Locally Advanced Pancreatic Cancer That Cannot Be Removed By Surgery". ClinicalTrials.gov. 28 March 2012.
  18. ↑ "Fox Chase Cancer Center : New Small Molecule Inhibitor Could be a Safe and First-Line Treatment for Metastatic Breast Cancer". Press Release. Temple University Health System.
  19. ↑ Ouriel K, Gray B, Clair DG, Olin J (March 2000). "Complications associated with the use of urokinase and recombinant tissue plasminogen activator for catheter-directed peripheral arterial and venous thrombolysis". Journal of Vascular and Interventional Radiology. 11 (3): 295–298. doi:10.1016/S1051-0443(07)61420-1. PMID   10735422.
  20. ↑ Cinà CS, Goh RH, Chan J, Kenny B, Evans G, Rawlinson J, Gill G (November 1999). "Intraarterial catheter-directed thrombolysis: urokinase versus tissue plasminogen activator". Annals of Vascular Surgery. 13 (6): 571–575. doi:10.1007/s100169900300. PMID   10541608. S2CID   470599.
  21. ↑ "Evelyn Nicol 1930 - 2020 - Obituary". www.legacy.com. Retrieved 2020-08-28.
  22. ↑ Macfarlane RG, Pilling J (June 1947). "Fibrinolytic activity of normal urine". Nature. 159 (4049): 779. Bibcode:1947Natur.159Q.779M. doi: 10.1038/159779a0 . PMID   20241608. S2CID   4125748.
  23. ↑ Sobel GW, Mohler SR, Jones NW, Dowdy ABC, Guest MM. Urokinase: an activator of plasma profibrinolysin extracted from urine. Am J Physiol 1952; 171: 768-69.
  24. ↑ "Abstracts of Papers Read". American Journal of Physiology. Legacy Content. 171 (3): 704–781. 30 November 1952. doi:10.1152/ajplegacy.1952.171.3.704. Normal human and dog urine contains fibrinolysin (plasmin) and a potent activator of profibrinolysin (plasminogen). The activator, which we have designated urokinase, can be concentrated and partially purified by acetone or alcohol fractionation methods.
  25. ↑ Celander DR, Guest MM (August 1960). "The biochemistry and physiology of urokinase". The American Journal of Cardiology. 6 (2): 409–419. doi:10.1016/0002-9149(60)90333-7. PMID   13808740.

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