The plasminogen (fibrinolytic) system.
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Animals↗
Biomedical subjects
D Collen
Publications and source records attributed to D Collen.
Matrix metalloproteinase system deficiencies and matrix degradation.
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Aneurysm↗
A role of plasminogen in atherosclerosis and restenosis models in mice.
In addition to its preeminent role in fibrinolysis, the plasminogen system is believed to play a key role in mediating cell migration. Leukocyte migration into the vessel wall is a key and early event in the development of the lesions of atherosclerosis and restenosis, pathologies which may be viewed as specific examples of vascular inflammatory responses. The development of mice in which the plasminogen gene has been inactivated affords an opportunity to test the contribution of plasminogen in leukocyte migration during in vivo. This article summarizes recent studies conducted in murine models of the inflammatory response, restenosis and atherosclerosis in which leukocyte migration, and in particular monocyte/macrophage migration, has been evaluated in plasminogen-deficient mice. Recruitment of these cells through the vessel wall in inflammatory response models and into the vessel wall in restenosis and transplant atherosclerosis models is substantially blunted. These data implicate plasminogen in the migration of leukocytes in these murine models. With the numerous correlations between components and/or activation of the plasminogen system in restenosis and atherosclerosis, these results also support a role of plasminogen in the corresponding human pathologies.
Animals↗
Reduced transplant arteriosclerosis in plasminogen-deficient mice.
Recent gene targeting studies indicate that the plasminogen system is implicated in cell migration and matrix degradation during arterial neointima formation and atherosclerotic aneurysm formation. This study examined whether plasmin proteolysis is involved in accelerated posttransplant arteriosclerosis (graft arterial disease). Donor carotid arteries from wild-type B10.A2R mice were transplanted into either plasminogen wild-type (Plg+/+) or homozygous plasminogen-deficient (Plg-/-) recipient mice with a genetic background of 75% C57BL/6 and 25% 129. Within 15 d after allograft transplantation, leukocytes and macrophages infiltrated the graft intima in Plg+/+ and Plg-/- recipient mice to a similar extent. In Plg+/+ recipients, the elastic laminae in the transplant media exhibited breaks through which macrophages infiltrated before smooth muscle cell proliferation, whereas in Plg-/- recipients, macrophages failed to infiltrate the transplant media which remained structurally more intact. After 45 d of transplantation, a multilayered smooth muscle cell-rich transplant neointima developed in Plg+/+ hosts, in contrast to Plg-/- recipients, in which the transplants contained a smaller intima, predominantly consisting of leukocytes, macrophages, and thrombus. Media necrosis, fragmentation of the elastic laminae, and adventitial remodeling were more pronounced in Plg+/+ than in Plg-/- recipient mice. Expression of the plasminogen activators (PA), urokinase-type PA (u-PA) and tissue-type PA (t-PA), and expression of the matrix metalloproteinases (MMPs), MMP-3, MMP-9, MMP-12, and MMP-13, were significantly increased within 15 d of transplantation when cells actively migrate. These data indicate that plasmin proteolysis plays a major role in allograft arteriosclerosis by mediating elastin degradation, macrophage infiltration, media remodeling, medial smooth muscle cell migration, and formation of a neointima.
Animals↗
Inactivation of the gene for anticoagulant protein C causes lethal perinatal consumptive coagulopathy in mice.
Matings of mice heterozygous for a protein C (PC) deficient allele, produced by targeted PC gene inactivation, yielded the expected Mendelian distribution of PC genotypes. Pups with a total deficiency of PC (PC-/-), obtained at embryonic day (E) 17.5 and at birth, appeared to develop normally macroscopically, but possessed obvious signs of bleeding and thrombosis and did not survive beyond 24 h after delivery. Microscopic examination of tissues and blood vessels of E17.5 PC-/- mice revealed their normal development, but scattered microvascular thrombosis in the brain combined with focal necrosis in the liver was observed. In addition, bleeding was noted in the brain near sites of fibrin deposition. The severity of these pathologies was exaggerated in PC-/- neonates. Plasma clottable fibrinogen was not detectable in coagulation assays in PC-/- neonatal mice, suggestive of fibrinogen depletion and secondary consumptive coagulopathy. Thus, while total PC deficiency did not affect the anatomic development of the embryo, severe perinatal consumptive coagulopathy occurred in the brain and liver of PC-/- mice, suggesting that a total PC deficiency is inconsistent with short-term survival.
Animals↗
Oxidized LDL and malondialdehyde-modified LDL in patients with acute coronary syndromes and stable coronary artery disease.
BACKGROUND: The association between oxidative modifications of LDL and coronary artery disease (CAD) is suspected but not established. Therefore, the association between plasma levels of oxidized LDL and malondialdehyde (MDA)-modified LDL and acute coronary syndromes and stable CAD was investigated. METHODS AND RESULTS: The study population contained 63 patients with acute coronary syndromes (45 with acute myocardial infarction and 18 with unstable angina pectoris), 35 nontransplanted patients with angiographically confirmed stable angina, 28 heart transplant patients with posttransplant CAD, 79 heart transplant patients without CAD, and 65 control subjects. After correction for age, sex, and LDL and HDL cholesterol, plasma levels of oxidized LDL and MDA-modified LDL were significantly higher in patients with CAD than in individuals without CAD (r2=0.57 and r2=0.26, respectively; both P=0.0001). Plasma levels of MDA-modified LDL were significantly higher in patients with acute coronary syndromes than in individuals with stable CAD (r2=0.65; P=0.0001) and were associated with increased levels of troponin I and C-reactive protein (r2=0.39 and r2=0.34, respectively; both P=0.0001). Plasma levels of oxidized LDL were not associated with increased levels of troponin I and C-reactive protein (r2=0.089 and r2=0.063, respectively). CONCLUSIONS: Elevated plasma levels of oxidized LDL are associated with CAD. Elevated plasma levels of MDA-modified LDL suggest plaque instability and may be useful for the identification of patients with acute coronary syndromes.
Aged↗
Development and disease in proteinase-deficient mice: role of the plasminogen, matrix metalloproteinase and coagulation system.
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Animals↗
High resolution mapping of the B cell epitopes of staphylokinase in humans using negative selection of a phage-displayed antigen library.
Staphylokinase (Sak), a 16-kDa protein secreted by Staphylococcus aureus, induces fibrin-specific thrombolysis in patients with thrombotic disorders. However, Sak also elicits high titers of neutralizing Abs that persist for several months and preclude its repeated use in humans. To identify the antigenic determinants of Sak recognized by humans, a phage-displayed library of Sak variants was selected for mutants that escape binding to an affinity matrix derivatized with patient-specific polyclonal anti-Sak Abs. Fifty-six escape Sak variants were identified after three selection cycles using human polyclonal anti-Sak IgGs obtained from four different patients. DNA sequencing revealed 213 amino acid substitutions, of which 73% were found at 25 positions clustered in eight discontinuous Sak antigenic segments. Although each antigenic segment was recognized to a variable extent by each patient antiserum, the main epitopes of Sak in all patients were roughly targeted to two large discontinuous areas covering 35% of the solvent-accessible surface of Sak. The antigenic area I comprises three segments centered on residues 66, 73, and 135, while the antigenic area II consists of four segments centered on positions 20, 95, 102, and 121. These results suggest that a secondary immune response against Sak can occur in patients, and confirm an initial site-directed mutagenesis study wherein amino acid Lys74 was shown to play a prominent antigenic role. Comprehensive mapping of the most relevant sites of Sak that are antigenic for humans will guide efforts to modulate the immunogenicity of this therapeutically important molecule.
Amino Acid Substitution↗
Local adenovirus-mediated transfer of human endothelial nitric oxide synthase reduces luminal narrowing after coronary angioplasty in pigs.
BACKGROUND: Nitric oxide, synthesized from L-arginine by nitric oxide synthase (NOS), is a vasodilator and inhibits vascular smooth muscle cell (SMC) proliferation and migration. The effects of local NOS gene transfer on restenosis after experimental balloon angioplasty were investigated. METHODS AND RESULTS: Left anterior descending coronary artery angioplasty was performed in 25 pigs. Animals received an intramural injection of adenovirus (1.5 x 10(9) pfu) carrying either the NOS cDNA (AdCMVceNOS) or no cDNA (AdRR5) via the Infiltrator. Local gene transfer efficiency and bioactivity of recombinant protein were assessed after 4 days. Indices of restenosis were evaluated by computerized planimetry on coronary artery sections prepared 28 days after angioplasty. Adenoviral vectors permitted efficient gene delivery to medial SMCs and adventitial cells of coronary arteries. Vascular cGMP levels were depressed after angioplasty from 1.30+/-0.42 to 0.33+/-0.20 pmol/mg protein (P<0.05) but were restored after constitutive endothelial (ce) NOS gene transfer to 1.82+/-0.98 pmol/mg (P<0.05 versus injured group and P=NS versus control). The ratio of the neointimal area to the internal elastic lamina fracture length, maximal neointimal thickness, and percent stenosis were all reduced in AdCMVceNOS- versus AdRR5-transduced pigs (0.59+/-0.14 versus 0.80+/-0.19 mm, P=0.02; 0.75+/-0.21 versus 1.04+/-0.25 mm, P=0.019; and 53+/-15% versus 75+/-11%, P=0.006, respectively). Lumen area was significantly larger (0.70+/-0.35 mm2 in AdCMVceNOS versus 0.32+/-0.18 mm2 in AdRR5, P=0.007). CONCLUSIONS: Percutaneous adenovirus-mediated NOS gene transfer resulted in efficient local overexpression of functional NOS after angioplasty in coronary arteries. Restored NO production in injured coronary arteries significantly reduced luminal narrowing, most likely through a combined effect on neointima formation and on vessel remodeling after angioplasty.
Adenoviridae↗
NH2-terminal structural motifs in staphylokinase required for plasminogen activation.
Staphylokinase (Sak) forms an inactive 1:1 stoichiometric complex with plasminogen which requires both conversion of plasminogen to plasmin and hydrolysis of the Lys10-Lys11 peptide bond of Sak to become a potent plasminogen activator (Schlott, B., Guhrs, K.-H., Hartmann, M., Rocker, A., and Collen, D. (1997) J. Biol. Chem. 272, 6067-6072). Exposure of a positively charged NH2-terminal amino acid after hydrolysis of Sak is a major determinant of the plasminogen-activating potential, but in itself is neither necessary nor sufficient. Here, the structural motifs of the NH2-terminal region Lys11-Gly-Asp-Asp-Ala-Ser16-Tyr-Phe-Glu of processed Sak, required for plasminogen activating potential, were studied by deletion and substitution mutagenesis. Expression in Escherichia coli of variants with deletion of 11, 14, 15, or 16 NH2-terminal amino acids yielded correctly processed but inactive molecules. Expression of their homologues with the NH2-terminal amino acid substituted with Lys-generated derivatives from which the NH2-terminal initiation Met was no longer removed, yielding inactive (</= 10%) Sak42DDeltaN11(M),G12K, active (>50%) Sak42DDeltaN14(M), A15K and Sak42DDeltaN15(M),S16K, and inactive Sak42DDeltaN16(M),Y17K. Lys variants without NH2-terminal Met, generated from fusion proteins in which a His6 tag and a factor Xa recognition sequence were linked to the NH2 terminus of the Sak variants, were indistinguishable from their NH2-terminal Met-containing counterparts. All variants studied had intact affinities for plasminogen as measured by biospecific interaction analysis. The activity of Sak42DDeltaN11(M),G12K could be restored by additional substitution of both Asp13 and Asp14 with Asn, yielding active Sak42DDeltaN11(M),G12K, D13N, D14N, whereas substitution in Sak42DDeltaN16(M),Y17K of Phe18 and Glu19 with Asn yielded inactive Sak42DDeltaN16(M),Y17K,F18N,E19N. These data, in combination with the recent finding that the 20 NH2-terminal amino acids of Sak lack secondary structure, suggest that the NH2-terminal region of Sak is not required for binding to plasmin/plasminogen, but that a positively charged amino acid in the ultimate or penultimate NH2-terminal position corresponding to amino acids 11-16 of this flexible region participates in the reconfiguration of the active site of the plasmin molecule to endow it with plasminogen-activating potential.
Amino Acid Sequence↗
Role of HIF-1alpha in hypoxia-mediated apoptosis, cell proliferation and tumour angiogenesis.
As a result of deprivation of oxygen (hypoxia) and nutrients, the growth and viability of cells is reduced. Hypoxia-inducible factor (HIF)-1alpha helps to restore oxygen homeostasis by inducing glycolysis, erythropoiesis and angiogenesis. Here we show that hypoxia and hypoglycaemia reduce proliferation and increase apoptosis in wild-type (HIF-1alpha+/+) embryonic stem (ES) cells, but not in ES cells with inactivated HIF-1alpha genes (HIF-1alpha-/-); however, a deficiency of HIF-1alpha does not affect apoptosis induced by cytokines. We find that hypoxia/hypoglycaemia-regulated genes involved in controlling the cell cycle are either HIF-1alpha-dependent (those encoding the proteins p53, p21, Bcl-2) or HIF-1alpha-independent (p27, GADD153), suggesting that there are at least two different adaptive responses to being deprived of oxygen and nutrients. Loss of HIF-1alpha reduces hypoxia-induced expression of vascular endothelial growth factor, prevents formation of large vessels in ES-derived tumours, and impairs vascular function, resulting in hypoxic microenvironments within the tumour mass. However, growth of HIF-1alpha tumours was not retarded but was accelerated, owing to decreased hypoxia-induced apoptosis and increased stress-induced proliferation. As hypoxic stress contributes to many (patho)biological disorders, this new role for HIF-1alpha in hypoxic control of cell growth and death may be of general pathophysiological importance.
Animals↗
Substitution of the carboxyl-terminal domain of apo AI with apo AII sequences restores the potential of HDL to reduce the progression of atherosclerosis in apo E knockout mice.
HDL metabolism and atherosclerosis were studied in apo E knockout (KO) mice overexpressing human apo AI, a des- (190-243)-apo AI carboxyl-terminal deletion mutant of human apo AI or an apo AI-(1-189)-apo AII-(12-77) chimera in which the carboxyl-terminal domain of apo AI was substituted with the pair of helices of apo AII. HDL cholesterol levels ranked: apo AI/apo E KO approximately apo AI-(1-189)-apo AII- (12-77)/apo E KO > > des-(190-243)-apo AI/apo E KO > apo E KO mice. Progression of atherosclerosis ranked: apo E KO > des-(190-243)-apo AI/apo E KO > > apo AI-(1-189)- apo AII-(12-77)/apo E KO approximately apo AI/apo E KO mice. Whereas the total capacity to induce cholesterol efflux from lipid-loaded THP-1 macrophages was higher for HDL of mice overexpressing human apo AI or the apo AI/apo AII chimera, the fractional cholesterol efflux rate, expressed in percent cholesterol efflux/microg apolipoprotein/h, for HDL of these mice was similar to that for HDL of mice overexpressing the deletion mutant and for HDL of apo E KO mice. This study demonstrates that the tertiary structure of apo AI, e.g., the number and organization of its helices, and not its amino sequence is essential for protection against atherosclerosis because it determines HDL cholesterol levels and not cholesterol efflux. Amino acid sequences of apo AII, which is considered to be less antiatherogenic, can be used to restore the structure of apo AI and thereby its antiatherogenicity.
Amino Acid Substitution↗
Proteolytic cleavage of urokinase-type plasminogen activator by stromelysin-1 (MMP-3).
Matrix metalloproteinase-3 (MMP-3, or stromelysin-1) specifically hydrolyzes the Glu143-Leu144 peptide bond in 45-kDa single-chain urokinase-type plasminogen activator (scu-PA) and in its two-chain (tcu-PA) derivative, yielding a 17-kDa NH2-terminal domain comprising the u-PA receptor (u-PAR) binding site and a 32-kDa COOH-terminal moiety containing the serine proteinase domain of u-PA. The conversion is completely abolished in the presence of the MMP inhibitors EDTA or 1,10-phenanthroline. Biospecific interaction analysis indicates that binding of MMP-3 occurs through the 32-kDa fragment. The 32-kDa fragment derived from scu-PA (scu-PA-32k) has a specific activity of </=500 IU/mg, but it can be activated with plasmin to a two-chain derivative (tcu-PA-32k) with a specific activity of 79 000 IU/mg. tcu-PA and tcu-PA-32k moieties derived from scu-PA-32k by plasmin or from tcu-PA by MMP-3 have comparable amidolytic activities toward the chromogenic substrate S-2444 (kcat/Km of 110 and 160 mM-1 s-1, respectively) and similar plasminogen activating activities in a coupled chromogenic substrate assay. Specific binding of the 17-kDa NH2-terminal domain to THP-1 monocytoid cells is completely abolished by competition with scu-PA but is not affected by scu-PA-32k (residual binding of 88 +/- 9% (mean +/- SEM; n = 3) with 25-fold molar excess). Thus, MMP-3 removes a functional NH2-terminal u-PAR-binding domain from u-PA without affecting its enzymatic properties.
Amino Acid Sequence↗
Arginine 719 in human plasminogen mediates formation of the staphylokinase:plasmin activator complex.
Staphylokinase (Sak), a 16-kDa bacterial protein, forms a 1:1 stoichiometric complex with the serine proteinase domain of human plasmin, which in turn converts other plasminogen molecules into plasmin. To identify amino acid residues critical for generating the Sak:plasmin activator complex, alanine-scanning mutagenesis was performed on phage-displayed micro-plasminogen (microPlg). Substitution of Arg719 with Ala [microPlg(R719A)] disrupted complex formation, although the sensitivity of phage-displayed microPlg(R719A) to activation by urokinase and the amidolytic activity of the micro-plasmin derivative [microPli(R719A)] remained unaffected. Likewise, the soluble microPlg(R719A) molecule did not generate a functional activator complex with Sak, whereas quantitative activation into plasmin was obtained upon incubation with either urokinase or the Sak:plasmin complex. Real-time biospecific affinity measurements revealed that the Arg --> Ala substitution at position 719 increased the equilibrium dissociation constant between microPlg(R719A) and Sak from 46 nM to 1 microM, primarily by reducing the association rate constant. Arg719 has recently also been implied in the functional complex formation between human plasmin and streptokinase [Dawson, K. M., Marshall, J. M., Raper, R. H., Gilbert, R. J., and Ponting, C. P. (1994) Biochemistry 33, 12042-12047.], suggesting that both bacterial cofactors may share common structural and/or mechanistic aspects for plasminogen activation.
Amino Acid Substitution↗
Generation of an angiostatin-like fragment from plasminogen by stromelysin-1 (MMP-3).
Matrix metalloproteinase-3 (MP-3 or stromelysin-1) specifically hydrolyzes the Glu59-Asn60, Pro447-Val448, and Pro544-Ser545 peptide bonds in plasminogen, yielding a 55 kDa NH2-terminal angiostatin-like domain (comprising kringles 1-4), a 14 kDa domain comprising kringle 5, and a 30 kDa domain comprising the serine proteinases domain. The conversion is completely abolished in the presence of the MMP inhibitors EDTA or 1,10-phenanthroline. Biospecific interactions analysis indicates that binding of proMMP-3 and MMP-3 to plasminogen occurs with comparable affinity (KA of 4.7 x 10(6) and 4.1 x 10(6) M-1, respectively) and is mediated via the miniplasminogen moiety (kringle 5 plus the proteinase domain) and via the catalytic domain of MMP-3. Thus, proteolytic cleavage of plasminogen by MMP-3 generates angiostatin-like fragments.
Angiostatins↗
Human endothelial nitric oxide synthase gene transfer inhibits vascular smooth muscle cell proliferation and neointima formation after balloon injury in rats.
BACKGROUND: Loss of endothelial NO production after arterial injury may contribute to restenosis, characterized by neointima formation and elastic recoil. Adenovirus-mediated transfer of the gene encoding NO synthase (NOS) in balloon-injured arteries may restore NO production and inhibit neointima formation. METHODS AND RESULTS: After balloon injury, rat carotid arteries were transduced with 3x10(10) pfu/mL recombinant adenovirus carrying the human endothelial constitutive NOS cDNA (AdCMVceNOS, n=8) or no cDNA (AdRR5, n=8). ceNOS expression was confirmed by immunoblot analysis of vascular extracts and was localized by immunostaining in 30% of medial smooth muscle cells (SMCs) and in the adventitia of AdCMVceNOS-transduced arteries. Vascular cGMP levels were reduced from 3.9 pmol/g wet wt in uninjured arteries to 0.7 pmol cGMP/g after AdRR5 but were restored after ceNOS gene transfer (3.8 pmol cGMP/g wet wt, P<.05 versus AdRR5). Intima-to-media ratio 2 weeks after injury was significantly reduced (0.19+/-0.02 in AdCMVceNOS-infected versus 0.69+/-0.07 in AdRR5-infected arteries, P<.05). In vitro, BrdU incorporation of AdCMVceNOS-infected SMCs was reduced by 28% compared with AdRR5-infected SMCs. Transduced cells from injured carotid arteries subjected to FACS sorting showed a significantly lower BrdU labeling index in ceNOS-infected rats (29+/-6% versus 43+/-5% and 45+/-4% in control, injured, and AdRR5-infected rats, respectively, P<.05). CONCLUSIONS: AdCMVceNOS gene transfer to balloon-injured rat carotid arteries restores vascular NO production and reduces neointima formation, at least in part because of an antiproliferative effect on medial SMCs. Adenovirus-mediated ceNOS gene transfer might reduce arterial restenosis after balloon angioplasty.
Adenoviridae↗
Plasminogen deficiency differentially affects recruitment of inflammatory cell populations in mice.
It is widely held that the plasminogen (Plg) system plays a role in inflammation through plasmin-mediated directional cell migration. However, substantial evidence for its involvement in the inflammatory response has been obtained from indirect studies and lacks firm biological confirmation. To directly characterize plasminogen's involvement in the inflammatory response, we used thioglycollate to induce a peritoneal inflammatory reaction in Plg(+/+), Plg(+/-), and Plg(-/-) mice. At 6 hours poststimulation, neutrophil recruitment into the peritoneum was maximal and similar between Plg(+/+), Plg(+/-), and Plg(-/-) mice. In contrast, monocyte recruitment was significantly diminished after 24 hours poststimulation in Plg(-/-) mice relative to Plg(+/+) mice. Lymphocyte recruitment also was blunted. Blood monocyte levels in these mice indicated that diminished recruitment into the peritoneum was not the result of a diminished source of cells in the circulation. Macrophage phagocytic function was similar between Plg(+/+) and Plg(-/-) mice. This study establishes a direct involvement of plasminogen in monocyte recruitment during a representative inflammatory response.
Animals↗
Stromelysin-1 (MMP-3)-independent gelatinase expression and activation in mice.
A potential physiological role of stromelysin-1 (MMP-3) in the expression or activation of gelatinase A (MMP-2) or gelatinase B (MMP-9) in the wall of injured arteries was studied with the use of homozygous MMP-3-deficient (MMP-3-/-) mice. One week after perivascular electric injury of the carotid or femoral artery in wild-type (MMP-3+/+) or MMP-3-/- mice, 70 kD and 65 kD proMMP-2 levels were enhanced by twofold to fourfold, with corresponding increases of 20- to 40-fold for active 61 kD and 58 kD MMP-2, and of 10- to 80-fold for 94 kD proMMP-9. Active MMP-2 species represented approximately one third of the total MMP-2 concentration for both MMP-3+/+ and MMP-3-/- mice. Active 83 kD MMP-9 was not detected in noninjured carotid or femoral arteries, whereas one week after injury its contribution to the total MMP-9 level was 11% to 18% for MMP-3+/+ and MMP-3-/- mice. Immunostaining of arterial sections confirmed enhanced expression of both MMP-2 and MMP-9 after vascular injury. Double immunostaining showed colocalization of MMP-9 with macrophages in the adventitia, whereas MMP-2 was also detected mainly in the adventitia but failed to colocalize with smooth muscle cells. Cell culture experiments confirmed comparable ratios of active versus latent MMP-2 in skin fibroblasts and smooth muscle cells derived from MMP-3+/+ and MMP-3-/- mice. Addition of plasmin(ogen) did not significantly affect activation of proMMP-2. In MMP-3+/+ and MMP-3-/- macrophages, comparable levels of 94 kD proMMP-9 were detected, and plasmin(ogen)-mediated conversion to 83 kD MMP-9 was obtained in both genotypes. These data thus indicate that proMMP-2 activation may occur via a plasmin- and MMP-3-independent mechanism, whereas plasmin can directly activate proMMP-9 via a MMP-3-independent mechanism.
Animals↗