Characterization and Comparative Evaluation of a Novel PAI-1 Inhibitor

Gils, Ann; Stassen, Jean–Marie; Nar, H.; Kley, Jörg T.; Weikel, W.; Ries, Uwe J.; Declerck, Paul

doi:10.1055/s-0037-1613166

Cited by 33 publications

(26 citation statements)

References 47 publications

(48 reference statements)

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“…Consistent with studies showing that PAZ-417 directly inhibits PAI-1 in the brain, immunohistochemistry studies showed that PAI-1 protein levels are reduced in the hippocampus of transgenic AD mice after drug treatment (data not shown). This observation is consistent with studies demonstrating that the half-life of PAI-1 is significantly reduced when bound by smallmolecule inhibitors (32).…”

Section: Discussionsupporting

confidence: 92%

Enhanced clearance of Aβ in brain by sustaining the plasmin proteolysis cascade

Js¹,

Ta²,

Martone³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

129

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The amyloid hypothesis states that a variety of neurotoxic ␤-amyloid (A␤) species contribute to the pathogenesis of Alzheimer's disease. Accordingly, a key determinant of disease onset and progression is the appropriate balance between A␤ production and clearance. Enzymes responsible for the degradation of A␤ are not well understood, and, thus far, it has not been possible to enhance A␤ catabolism by pharmacological manipulation. We provide evidence that A␤ catabolism is increased after inhibition of plasminogen activator inhibitor-1 (PAI-1) and may constitute a viable therapeutic approach for lowering brain A␤ levels. PAI-1 inhibits the activity of tissue plasminogen activator (tPA), an enzyme that cleaves plasminogen to generate plasmin, a protease that degrades A␤ oligomers and monomers. Because tPA, plasminogen and PAI-1 are expressed in the brain, we tested the hypothesis that inhibitors of PAI-1 will enhance the proteolytic clearance of brain A␤. Our data demonstrate that PAI-1 inhibitors augment the activity of tPA and plasmin in hippocampus, significantly lower plasma and brain A␤ levels, restore long-term potentiation deficits in hippocampal slices from transgenic A␤-producing mice, and reverse cognitive deficits in these mice.Alzheimer ͉ plasminogen activator inhibitor ͉ tissue plasminogen activator A lzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the presence of intracellular neuronal tangles and extracellular parenchymal and vascular amyloid deposits containing ␤-amyloid peptide (A␤). A␤ is a 39-to 42-aa peptide derived from the proteolytic processing of the amyloid precursor protein (APP) (1). The ''amyloid hypothesis'' of AD postulates a central causal role for A␤ in AD pathogenesis and is supported by genetic and physiological evidence. All known early onset familial AD mutations result in enhanced levels of cytotoxic A␤ species, amyloid plaque deposition, and dementia. Furthermore, A␤ peptide is reported to be neurotoxic and synaptotoxic in vitro and in vivo, inhibiting long-term potentiation (LTP), a physiological correlate of memory (2). Based on these observations, a number of strategies to reduce brain A␤ levels are being pursued as therapeutic approaches to treat AD (3, 4).If the amyloid hypothesis of AD is correct and A␤ levels are pivotal to disease etiology, then the balance between A␤ production and catabolism is likely to be a key determinant of disease progression. It has been suggested that insufficient clearance of A␤ may account for elevated A␤ levels in the brain and the accumulation of pathogenic amyloid deposits in sporadic AD (5). A number of proteases have been implicated in the proteolytic clearance of A␤ from the CNS, including neprilysin, insulin-degrading enzyme, endothelin converting enzyme, and plasmin (3, 6-8). The relative contribution of these enzymes to A␤ catabolism remains unclear, but each protease may play a significant role in the degradation and clearance of A␤, resulting in a slowing of A␤ accumulation and aggregation and u...

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Section: Discussionsupporting

confidence: 92%

Enhanced clearance of Aβ in brain by sustaining the plasmin proteolysis cascade

Js¹,

Ta²,

Martone³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

129

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“…Synthetic Compounds-The IC 50 value obtained with 7 nM TA was ϳ1000-fold lower than our previously reported IC 50 value for the PAI-1 inactivator, PAI-039 (32), and is markedly lower than any previously reported small-molecule PAI-1 inactivating compound (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36). Likewise the IC 50 values obtained with EGCG and EGCDG were also significantly better than PAI-039 and most other PAI-1 inactivators, suggesting that galloyl-containing compounds may represent a potent new family of PAI-1 inactivating compounds.…”

Section: Resultsmentioning

confidence: 55%

“…The flexible structure of PAI-1, the lack of a rigid active site, and its multiple functions all contribute to the difficulties in identifying and designing small-molecule PAI-1 inactivators. Despite these obstacles, several small-molecule PAI-1 inhibitors have been described (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36); however, each has significant limitations that have reduced their potential for further drug development.…”

mentioning

confidence: 99%

Characterization of a Novel Class of Polyphenolic Inhibitors of Plasminogen Activator Inhibitor-1

Cale

Warnock

et al. 2010

Journal of Biological Chemistry

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Plasminogen activator inhibitor type 1, (PAI-1) the primary inhibitor of the tissue-type (tPA) and urokinase-type (uPA) plasminogen activators, has been implicated in a wide range of pathological processes, making it an attractive target for pharmacologic inhibition. Currently available small-molecule inhibitors of PAI-1 bind with relatively low affinity and do not inactivate PAI-1 in the presence of its cofactor, vitronectin. To search for novel PAI-1 inhibitors with improved potencies and new mechanisms of action, we screened a library selected to provide a range of biological activities and structural diversity. Five potential PAI-1 inhibitors were identified, and all were polyphenolic compounds including two related, naturally occurring plant polyphenols that were structurally similar to compounds previously shown to provide cardiovascular benefit in vivo. Unique second generation compounds were synthesized and characterized, and several showed IC 50 values for PAI-1 between 10 and 200 nM. This represents an enhanced potency of 10 -1000-fold over previously reported PAI-1 inactivators. Inhibition of PAI-1 by these compounds was reversible, and their primary mechanism of action was to block the initial association of PAI-1 with a protease. Consistent with this mechanism and in contrast to previously described PAI-1 inactivators, these compounds inactivate PAI-1 in the presence of vitronectin. Two of the compounds showed efficacy in ex vivo plasma and one blocked PAI-1 activity in vivo in mice. These data describe a novel family of high affinity PAI-1-inactivating compounds with improved characteristics and in vivo efficacy, and suggest that the known cardiovascular benefits of dietary polyphenols may derive in part from their inactivation of PAI-1. Plasminogen activator inhibitor type 1 (PAI-1)3 is the primary physiologic inhibitor of uPA and tPA with a well characterized role in fibrinolysis (1). PAI-1 also plays a role in many physiologic processes, including angiogenesis, wound healing, and cell migration (2-6), and has been implicated in fibrotic diseases of the kidney and lung, and in tumor metastasis (7-11). More recently, PAI-1 has been linked to obesity and metabolic syndrome (12-16), and to the development of vascular diseases such as venous thrombosis and atherosclerosis (17)(18)(19). The prospect that PAI-1 may play a direct role in the early development of a variety of diseases has made it an attractive target for drug development (20,21). However, the structural complexity of PAI-1 has made the identification and development of PAI-1 inhibitors challenging. This is due in part to the metastable structure of PAI-1, which can adopt several different conformations, including active, latent, cleaved, and protease complexed (1). These different forms of PAI-1 provide conformational control of PAI-1 interactions and dictate its localization to either matrix or the cell surface and control its activity in cell signaling events (22, 23).Active PAI-1 inhibits protease targets and is associated with vitron...

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“…Small-molecule synthetic antagonists of PAI-1 have been described previously (Charlton et al, 1996;Friederich et al, 1997;Neve et al, 1999;Gils et al, 2002;Einholm et al, 2003;Elokdah et al, 2004;Liang et al, 2005;Gorlatova et al, 2007). The metastable conformation of PAI-1 along with the intricacies of the pathway by which PAI-1 inhibits tPA affords numerous potential opportunities whereby a PAI-1 inhibitor could block PAI-1 activity.…”

mentioning

confidence: 99%

Neutralization of Plasminogen Activator Inhibitor I (PAI-1) by the Synthetic Antagonist PAI-749 via a Dual Mechanism of Action

Gardell¹,

Krueger²,

Antrilli³

et al. 2007

Mol Pharmacol

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PAI-749 is a potent and selective synthetic antagonist of plasminogen activator inhibitor 1 (PAI-1) that preserved tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) activities in the presence of PAI-1 (IC 50 values, 157 and 87 nM, respectively). The fluorescence (Fl) of fluorophore-tagged PAI-1 (PAI-NBD119) was quenched by PAI-749; the apparent K d (254 nM) was similar to the IC 50 (140 nM) for PAI-NBD119 inactivation. PAI-749 analogs displayed the same potency rank order for neutralizing PAI-1 activity and perturbing PAI-NBD119 Fl; hence, binding of PAI-749 to PAI-1 and inactivation of PAI-1 activity are tightly linked. Exposure of PAI-1 to PAI-749 for 5 min (sufficient for full inactivation) followed by PAI-749 sequestration with Tween 80 micelles yielded active PAI-1; thus, PAI-749 did not irreversibly inactivate PAI-1, a known metastable protein. Treatment of PAI-1 with a PAI-749 homolog (producing less assay interference) blocked the ability of PAI-1 to displace p-aminobenzamidine from the uPA active site. Consistent with this observation, PAI-749 abolished formation of the SDS-stable tPA/PAI-1 complex. PAI-749-mediated neutralization of PAI-1 was associated with induction of PAI-1 polymerization as assessed by native gel electrophoresis. PAI-749 did not turn PAI-1 into a substrate for tPA; however, PAI-749 promoted plasmin-mediated degradation of PAI-1. In conclusion, PAI-1 inactivation by PAI-749 using purified components can result from a dual mechanism of action. First, PAI-749 binds directly to PAI-1, blocks PAI-1 from accessing the active site of tPA, and abrogates formation of the SDS-stable tPA/PAI-1 complex. Second, binding of PAI-749 to PAI-1 renders PAI-1 vulnerable to plasmin-mediated proteolytic degradation.Plasminogen activator inhibitor 1 (PAI-1) is a rapidly acting inhibitor of tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) (Dellas and Loskutoff, 2005). PAI-1 is a member of the serpin class of serine protease inhibitors that characteristically produce SDS-stable complexes with their cognate protease targets (Silverman et al., 2001). Formation of the acyl-enzyme adduct between PAI-1 and the protease involves initial formation of a Michaelis-type noncovalent complex without significant conformational change, followed by reversible acylation and irreversible reactive loop conformational changes that trap the protease in a covalent complex (Olson et al., 2001). Two other conformation states of PAI-1 are known. First, the acyl-enzyme adduct between PAI-1 and tPA (or uPA) can be hydrolyzed to form cleaved (inactive) PAI-1 and regenerate active plasminogen activator (PA) (Declerck et al., 1992). Second, active PAI-1 can undergo a spontaneous large conformation change that gives rise to an inactive (latent) state of the inhibitor (Levin and Santell, 1987;Mottonen et al., 1992).PAI-1 plays a pivotal role in a myriad of physiological processes that involve activation of plasminogen (Dellas and Loskutoff, 2005). High ...

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Characterization and Comparative Evaluation of a Novel PAI-1 Inhibitor

Cited by 33 publications

References 47 publications

Enhanced clearance of Aβ in brain by sustaining the plasmin proteolysis cascade

Enhanced clearance of Aβ in brain by sustaining the plasmin proteolysis cascade

Characterization of a Novel Class of Polyphenolic Inhibitors of Plasminogen Activator Inhibitor-1

Neutralization of Plasminogen Activator Inhibitor I (PAI-1) by the Synthetic Antagonist PAI-749 via a Dual Mechanism of Action

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