Embelin ameliorated sepsis-induced disseminated intravascular coagulation intensities by simultaneously suppressing inflammation and thrombosis.

Disseminated intravascular coagulation (DIC), an acute syndrome of systemic thrombus formation in microvasculatures throughout the body, can be induced by severe infections, e.g. sepsis.

Suppression of Tumor Growth and Metastases by Targeted Intervention in Urokinase Activity with Cyclic Peptides.

Urokinase-type plasminogen activator (uPA) is a diagnostic marker for breast and prostate cancers recommended by American Society for Clinical Oncology and German Breast Cancer Society. Inhibition of uPA was proposed as an efficient strategy for cancer treatments. In this study, we report peptide-based uPA inhibitors with high potency and specificity comparable to monoclonal antibodies.

Origin and diversification of the plasminogen activation system among chordates.

Background: The plasminogen (PLG) activation system is composed by a series of serine proteases, inhibitors and several binding proteins, which together control the temporal and spatial generation of the active serine protease plasmin. As this proteolytic system plays a central role in human physiology and pathophysiology it has been extensively studied in mammals. The serine proteases of this system are believed to originate from an ancestral gene by gene duplications followed by domain gains and deletions.

Crystal structure of plasma kallikrein reveals the unusual flexibility of the S1 pocket triggered by Glu217.

Unlabelled: Serine proteases play important roles in numerous physiological and pathophysiological processes. Moreover, serine proteases are classical subjects for studies of catalytic and inhibitory mechanisms of enzymes. Here, we determined the crystal structures of a serine protease, murine plasma kallikrein (mPK), and its complex with a peptidic inhibitor.

Cleavage of peptidic inhibitors by target protease is caused by peptide conformational transition.

Some peptide sequences can behave as either substrates or inhibitors of serine proteases. Working with a cyclic peptidic inhibitor of the serine protease urokinase-type plasminogen activator (uPA), we have now demonstrated a new mechanism for an inhibitor-to-substrate switch. The peptide, CSWRGLENHAAC (upain-2), is a competitive inhibitor of human uPA, but is also slowly converted to a substrate in which the bond between Arg and Gly (the P1-P1' bond) is cleaved.

Ligand binding modulates the structural dynamics and activity of urokinase-type plasminogen activator: A possible mechanism of plasminogen activation.

The catalytic activity of trypsin-like serine proteases is in many cases regulated by conformational changes initiated by binding of physiological modulators to exosites located distantly from the active site. A trypsin-like serine protease of particular interest is urokinase-type plasminogen activator (uPA), which is involved in extracellular tissue remodeling processes. Herein, we used hydrogen/deuterium exchange mass spectrometry (HDXMS) to study regulation of activity in the catalytic domain of the murine version of uPA (muPA) by two muPA specific monoclonal antibodies.

Structural Principles in the Development of Cyclic Peptidic Enzyme Inhibitors.

This review summarizes our studies in the development of small cyclic peptides for specifically modulating enzyme activity. Serine proteases share highly similar active sites but perform diverse physiological and pathological functions. From a phage-display peptide library, we isolated two mono-cyclic peptides, upain-1 (CSWRGLENHRMC) and mupain-1 (CPAYSRYLDC), which inhibit the activity of human and murine urokinase-type plasminogen activators (huPA and muPA) with values in the micromolar or sub-micromolar range, respectively.

Multi-tissue RNA-seq and transcriptome characterisation of the spiny dogfish shark (Squalus acanthias) provides a molecular tool for biological research and reveals new genes involved in osmoregulation.

The spiny dogfish shark (Squalus acanthias) is one of the most commonly used cartilaginous fishes in biological research, especially in the fields of nitrogen metabolism, ion transporters and osmoregulation. Nonetheless, transcriptomic data for this organism is scarce. In the present study, a multi-tissue RNA-seq experiment and de novo transcriptome assembly was performed in four different spiny dogfish tissues (brain, liver, kidney and ovary), providing an annotated sequence resource.

Latency transition of plasminogen activator inhibitor type 1 is evolutionarily conserved.

Plasminogen activator inhibitor type 1 (PAI-1) is a central regulator of fibrinolysis and tissue remodelling. PAI-1 belongs to the serpin superfamily and unlike other inhibitory serpins undergoes a spontaneous inactivation process under physiological conditions, termed latency transition. During latency transition the solvent exposed reactive centre loop is inserted into the central β-sheet A of the molecule, and is no longer accessible to reaction with the protease.

Discovery of a novel conformational equilibrium in urokinase-type plasminogen activator.

Although trypsin-like serine proteases have flexible surface-exposed loops and are known to adopt higher and lower activity conformations, structural determinants for the different conformations have remained largely obscure. The trypsin-like serine protease, urokinase-type plasminogen activator (uPA), is central in tissue remodeling processes and also strongly implicated in tumor metastasis. We solved five X-ray crystal structures of murine uPA (muPA) in the absence and presence of allosteric molecules and/or substrate-like molecules.

A Conjugate of Two tPA-Binding RNA Aptamers Efficiently Inhibits Fibrinolysis.

Uncontrolled bleeding is a major cause of mortality. Lysine analogues are routinely used in the management of bleeding, but several studies indicate a risk of serious detrimental effects upon their administration. In this study, we report a bivalent conjugate "3218" of two RNA aptamers selected for binding to the serine protease tissue-type plasminogen activator (tPA), the principal initiator of fibrinolysis in mammals.

An RNA Aptamer Inhibits a Mutation-Induced Inactivating Misfolding of a Serpin.

Most serpins are fast and specific inhibitors of extracellular serine proteases controlling biological processes such as blood coagulation, fibrinolysis, tissue remodeling, and inflammation. The inhibitory activity of serpins is based on a conserved metastable structure and their conversion to a more stable state during reaction with the target protease. However, the metastable state also makes serpins vulnerable to mutations, resulting in disease caused by inactive and misfolded monomeric or polymeric forms ("serpinopathy").

A Camelid-derived Antibody Fragment Targeting the Active Site of a Serine Protease Balances between Inhibitor and Substrate Behavior.

A peptide segment that binds the active site of a serine protease in a substrate-like manner may behave like an inhibitor or a substrate. However, there is sparse information on which factors determine the behavior a particular peptide segment will exhibit. Here, we describe the first x-ray crystal structure of a nanobody in complex with a serine protease.

Crystal Structure of a Two-domain Fragment of Hepatocyte Growth Factor Activator Inhibitor-1: FUNCTIONAL INTERACTIONS BETWEEN THE KUNITZ-TYPE INHIBITOR DOMAIN-1 AND THE NEIGHBORING POLYCYSTIC KIDNEY DISEASE-LIKE DOMAIN.

Hepatocyte growth factor activator inhibitor-1 (HAI-1) is a type I transmembrane protein and inhibitor of several serine proteases, including hepatocyte growth factor activator and matriptase. The protein is essential for development as knock-out mice die in utero due to placental defects caused by misregulated extracellular proteolysis. HAI-1 contains two Kunitz-type inhibitor domains (Kunitz), which are generally thought of as a functionally self-contained protease inhibitor unit.

Urokinase links plasminogen activation and cell adhesion by cleavage of the RGD motif in vitronectin.

Components of the plasminogen activation system including urokinase (uPA), its inhibitor (PAI-1) and its cell surface receptor (uPAR) have been implicated in a wide variety of biological processes related to tissue homoeostasis. Firstly, the binding of uPA to uPAR favours extracellular proteolysis by enhancing cell surface plasminogen activation. Secondly, it promotes cell adhesion and signalling through binding of the provisional matrix protein vitronectin.

Expected and unexpected features of protein-binding RNA aptamers.

RNA molecules with high affinity to specific proteins can be isolated from libraries of up to 10 different RNA sequences by systematic evolution of ligands by exponential enrichment (SELEX). These so-called protein-binding RNA aptamers are often interesting, e.g.

Development of a specific affinity-matured exosite inhibitor to MT1-MMP that efficiently inhibits tumor cell invasion in vitro and metastasis in vivo.

The membrane-associated matrix metalloproteinase-14, MT1-MMP, has been implicated in pericellular proteolysis with an important role in cellular invasion of collagenous tissues. It is substantially upregulated in various cancers and rheumatoid arthritis, and has been considered as a potential therapeutic target. Here, we report the identification of antibody fragments to MT1-MMP that potently and specifically inhibit its cell surface functions.

Building a Molecular Trap for a Serine Protease from Aptamer and Peptide Modules.

In drug development, molecular intervention strategies are usually based on interference with a single protein function, such as enzyme activity or receptor binding. However, in many cases, protein drug targets are multifunctional, with several molecular functions contributing to their pathophysiological actions. Aptamers and peptides are interesting synthetic building blocks for the design of multivalent molecules capable of modulating multiple functions of a target protein.

Structural basis of specific inhibition of tissue-type plasminogen activator by plasminogen activators inhibitor-1.

Thrombosis is a leading cause of death worldwide [1]. Recombinant tissue-type plasminogen activator (tPA) is the FDA-approved thrombolytic drug for ischemic strokes, myocardial infarction and pulmonary embolism. tPA is a multi-domain serine protease of the trypsin-family [2] and catalyses the critical step in fibrinolysis [3], converting the zymogen plasminogen to the active serine protease plasmin, which degrades the fibrin network of thrombi and blood clots.

Insights into the serine protease mechanism based on structural observations of the conversion of a peptidyl serine protease inhibitor to a substrate.

Background: Serine proteases are one of the most studied group of enzymes. Despite the extensive mechanistic studies, some crucial details remain controversial, for example, how the cleaved product is released in the catalysis reaction. A cyclic peptidyl inhibitor (CSWRGLENHRMC, upain-1) of a serine protease, urokinase-type plasminogen activator (uPA), was found to become a slow substrate and cleaved slowly upon the replacement of single residue (W3A).

Design of Specific Serine Protease Inhibitors Based on a Versatile Peptide Scaffold: Conversion of a Urokinase Inhibitor to a Plasma Kallikrein Inhibitor.

All serine proteases hydrolyze peptide bonds by the same basic mechanism and have very similar active sites, in spite of the fact that individual proteases have different physiological functions. We here report a strategy for designing high-affinity and high-specificity serine protease inhibitors using a versatile peptide scaffold, a 10-mer peptide, mupain-1 (CPAYSRYLDC). Mupain-1 was previously reported as a specific inhibitor of murine urokinase-type plasminogen activator (Ki = 0.

Crystal Structure of the Michaelis Complex between Tissue-type Plasminogen Activator and Plasminogen Activators Inhibitor-1.

Thrombosis is a leading cause of death worldwide. Recombinant tissue-type plasminogen activator (tPA) is the Food and Drug Administration-approved thrombolytic drug. tPA is rapidly inactivated by endogenous plasminogen activator inhibitor-1 (PAI-1).

Selection of High-Affinity Peptidic Serine Protease Inhibitors with Increased Binding Entropy from a Back-Flip Library of Peptide-Protease Fusions.

We have developed a new concept for designing peptidic protein modulators, by recombinantly fusing the peptidic modulator, with randomized residues, directly to the target protein via a linker and screening for internal modulation of the activity of the protein. We tested the feasibility of the concept by fusing a 10-residue-long, disulfide-bond-constrained inhibitory peptide, randomized in selected positions, to the catalytic domain of the serine protease murine urokinase-type plasminogen activator. High-affinity inhibitory peptide variants were identified as those that conferred to the fusion protease the lowest activity for substrate hydrolysis.

Characterisation of aptamer-target interactions by branched selection and high-throughput sequencing of SELEX pools.

Nucleic acid aptamer selection by systematic evolution of ligands by exponential enrichment (SELEX) has shown great promise for use in the development of research tools, therapeutics and diagnostics. Typically, aptamers are identified from libraries containing up to 10(16) different RNA or DNA sequences by 5-10 rounds of affinity selection towards a target of interest. Such library screenings can result in complex pools of many target-binding aptamers.

Tissue-type plasminogen activator-binding RNA aptamers inhibiting low-density lipoprotein receptor family-mediated internalisation.

Recombinant tissue-type plasminogen activator (tPA, trade name Alteplase), currently the only drug approved by the US Food and Drug Administration and the European Medicines Agency for the treatment of cerebral ischaemic stroke, has been implicated in a number of adverse effects reportedly mediated by interactions with the low-density lipoprotein (LDL) family receptors, including neuronal cell death and an increased risk of cerebral haemorrhage. The tissue-type plasminogen activator is the principal initiator of thrombolysis in human physiology, an effect that is mediated directly via localised activation of the plasmin zymogen plasminogen at the surface of fibrin clots in the vascular lumen. Here, we sought to identify a ligand to tPA capable of inhibiting the relevant LDL family receptors without interfering with the fibrinolytic activity of tPA.