Preparation of a monospecific antibody to purified rabbit synovial fibroblast collagenase

In vivo collagen turnover following experimental balloon angioplasty injury and the role of matrix metalloproteinases

Extracellular matrix formation is the major component of the restenosis lesion that develops after balloon angioplasty. Although ex vivo studies have shown that the synthesis of collagen is stimulated early after balloon angioplasty, there is a delay in accumulation in the vessel wall. The objectives of this study were to assess collagen turnover and its possible regulation by matrix metalloproteinases (MMPs) in a double-injury iliac artery rabbit model of restenosis. Rabbits were killed at four time points (immediately and at 1, 4, and 12 weeks) after balloon angioplasty. In vivo collagen synthesis and collagen degradation were measured after a 24-hour incubation with [14C]proline. Arterial extracts were also run on gelatin zymograms to determine MMP (gelatinase) activity. Collagen turnover studies were repeated in a group of 1-week postangioplasty rabbits that were treated with daily subcutaneous injections of either a nonspecific MMP inhibitor, GM6001 (100 mg/kg per day), or placebo. Collagen synthesis and degradation showed similar temporal profiles, with significant increases in the balloon-injured iliac arteries compared with control nondilated contralateral iliac arteries immediately after angioplasty and at 1 and 4 weeks. Peak collagen synthesis and degradation occurred at 1 week and were increased (approximately four and three times control values, respectively). Gelatin zymography was consistent with the biochemical data by showing an increase of a 72-kD gelatinase (MMP-2) in the balloon-injured side immediately after the second injury, peaking at 1 week, and still detectable at 4 and 12 weeks (although at lower levels). In balloon-injured arteries, the MMP inhibitor reduced both collagen synthesis and degradation. Overall, at 1 week after balloon angioplasty, GM6001 resulted in a 33% reduction in collagen content in balloon-injured arteries compared with placebo (750 +/- 143 to 500 +/- 78 micrograms hydroxyproline per segment, P < .004), which was associated with a nonsignificant 25% reduction in intimal area. Our data suggest that degradation of newly synthesized collagen is an important mechanism regulating collagen accumulation and that MMPs have an integral role in collagen turnover after balloon angioplasty.

Collagenase production by immortalized human aortic endothelial cells infected with simian virus 40

Human aortic endothelial cells, isolated at autopsy from a 52-year-old male dying from lung cancer, were treated with simian virus 40 (SV40). One colony was isolated from the infected endothelial cell culture 4 weeks after infection. The cells expressed SV40 large T antigen and p53 protein (p53) in their nuclei but lacted the characteristics of a transformed phenotype. The cells grew well in a monolayer over the 97th passage and exhibited Factor VIII-related antigen, Ulex europaeus 1 agglutinin (UEA-1) as endothelial cell markers, and a well-developed fibronectin network. The amount of prostacyclin synthesized by the cells was less than the amount synthesized by normal aortic or umbilical cord vein endothelial cells. The cells produced relatively large amounts of procollagenase, and 12-o-tetradecanoyl-phorbol-13-acetate (TPA) augmented the ability of the cells to produce this enzyme. These immortalized human aortic endothelial cells, which have some characteristics of normal endothelial cells and, like capillary endothelial cells, have the ability to produce collagenase, will probably prove useful for studies of atherosclerosis and angiogenesis.

Proteolytic activity of first trimester human placenta: localization of interstitial collagenase in villous and extravillous trophoblast

In human placentation, events of implantation and early blastocyst development are mediated by fetal trophoblastic cells which penetrate into the maternal endometrium and myometrium. Although highly regulated in its biological behavior, trophoblast simulates a malignant neoplasm by virtue of invading the uterine wall and uterine spiral arteries and by embolizing throughout the systemic circulation. This process is at least in part dependant on the regulated production of proteolytic enzymes to degrade extracellular matrix. The most abundant extracellular protein is connective tissue type (interstitial) collagen. The uterine remodeling during the establishment of the embryo requires collagenase which catalyzes the initial step in the breakdown of collagen. This study demonstrates the presence of interstitial collagenase in villous and extravillous trophoblast of first trimester placenta using immunocytochemical methods on light microscopic and ultrastructural levels. Intracytoplasmic staining for interstitial collagenase was present in cyto- and syncytiotrophoblast covering the chorionic villi as well as in extravillous intermediate trophoblast invading spiral arteries in the placental bed. Furthermore, outgrowth cultures of chorionic villi were studied with the immunogold method. Gold labelling was associated with the cell surface of trophoblastic cells as well as with fibrillary collagen like proteins of newly synthesized extracellular matrix. We speculate that interstitial collagenase plays a role in the degradation of uterine collagen within the developing human placenta.

Crystallization and preliminary X-ray analysis of porcine synovial collagenase

Crystals of porcine synovial collagenase suitable for an X-ray structure analysis have been obtained. The crystals belong to space group I4, with unit cell dimensions a = b = 160.0 A, c = 53.1 A, with one molecule in the asymmetric unit. Diffraction extends beyond 3 A perpendicular to the c axis but along the 4-fold axis, the intensities are measurable only to 4 A.

Purification of the neutral proteoglycan-degrading metalloproteinase from human articular cartilage tissue and its identification as stromelysin matrix metalloproteinase-3

The 'neutral' proteoglycan-degrading metalloproteinase of human articular cartilage was purified 3,500-fold by use of an anti-(matrix metalloproteinase-3) immunoglobulin G affinity column. Molecular masses of the latent and multiple active forms and specificity of action on casein, transferrin, gelatin and fibronectin were identical with those of authentic stromelysin (matrix metalloproteinase-3) from cultured human rheumatoid synovial fibroblasts. The optimum pH of this proteinase on proteoglycan monomer was pH 5.5, and on Azocoll, 6.2; digestion of fibronectin and gelatin was more extensive at pH 5.5 than at 7.5.

The precursor of a metalloendopeptidase from human rheumatoid synovial fibroblasts. Purification and mechanisms of activation by endopeptidases and 4-aminophenylmercuric acetate

Two active forms (Mr 45,000 and 28,000) of a metalloendopeptidase that digest proteoglycans and other extracellular matrix components of connective tissues have previously been purified from rheumatoid synovial cells and characterized [Okada, Nagase & Harris (1986) J. Biol. Chem. 261, 14245-14255]. To study the mechanisms of activation the precursor of this metalloendopeptidase has now been purified. The final products are homogeneous on SDS/polyacrylamide-gel electrophoresis and identified as a set of zymogens of Mr 57,000 and 59,000, in which the latter form is probably the product of post-translational glycosylation of the Mr 57,000 zymogen, as it binds to concanavalin A. The zymogen can be activated by trypsin, chymotrypsin, plasma kallikrein, plasmin and thermolysin, but not by thrombin. Although the activated metalloendopeptidase is further degraded by trypsin, plasma kallikrein and thermolysin during a prolonged incubation, it is relatively stable against plasmin and chymotrypsin. Activation with 4-aminophenylmercuric acetate is dependent on its concentration. It requires the reaction with the zymogen, possibly through thiol groups, and the continued presence of the agent. During this treatment the zymogen undergoes a sequential processing; first it becomes active without changing its apparent molecular mass, and then it is processed to low-Mr species of Mr 46,000, 45,000 (HMM) and 28,000 (LMM). The rate of conversion of the precursor into an initial intermediate of Mr 46,000 follows first-order kinetics (t1/2 2.0 h with 1.5 mM-4-amino-phenylmercuric acetate at 37 degrees C) and is independent of the initial concentration of the zymogen or the presence of up to a 676-fold molar excess of substrate, whereas the generation of HMM and LMM species is affected by these parameters. These results indicate that activation of the prometalloendopeptidase by an organomercurial compound is initiated by the molecular perturbation of the zymogen that results in conversion into the 46,000-Mr intermediate by an intramolecular action; the subsequent processing of this intermediate in HMM and LMM species is a bimolecular reaction. In vivo it is probable that the precursor of this metalloendopeptidase is activated either by direct limited proteolysis by tissue or plasma endopeptidases, or, alternatively, by factors that cause certain conformational changes in the zymogen molecule.

Cloning of a complementary DNA for rabbit proactivator. A metalloproteinase that activates synovial cell collagenase, shares homology with stromelysin and transin, and is coordinately regulated with collagenase

Rabbit proactivator is a neutral metalloproteinase that activates another metalloproteinase, procollagenase, and degrades noncollagenous matrix. We describe the construction of an activator complementary DNA (cDNA) clone, which is 1.9 kb, that selects a 2.1-kb messenger RNA (mRNA) in Northern blot hybridizations. Nucleic acid sequence studies of the activator cDNA indicate 1) that it encodes protein Mr 53,881, 2) that this protein exhibits approximately 80% homology with rat transin, an oncogene-induced protein with a previously unknown function, and 3) that, in the first 172 residues, it is virtually identical to the rabbit metalloproteinase, stromelysin. Homology between rabbit activator and human skin collagenase is approximately 50%. Activator and collagenase mRNA are coordinately regulated; untreated cultures of rabbit synovial fibroblasts produce low levels of each protein, but addition of phorbol myristate acetate (10(-8)M) results in an increase in mRNA for both proteins by 2.5-5 hours. Adding all-trans-retinoic acid (10(-6)M) or dexamethasone (10(-7)M) to phorbol-stimulated cells coordinately suppresses both activator and collagenase mRNA. Our data suggest the existence of coordinately regulated metalloproteinases that are important in the modulation of connective tissue metabolism.

Use of lectin affinity chromatography for the purification of collagenase from human polymorphonuclear leukocytes

Polymorphonuclear leukocytes (PMNLs) store collagenase in an inactive form in secretory granules. The enzyme can be activated in vitro by limited proteolysis or by sulfhydryl-modifying agents such as N-ethylmaleimide (NEM). We have enriched NEM-activated collagenase 820-fold using granule isolation, gel filtration, and wheat germ agglutinin (WGA)-agarose chromatography. The use of WGA-agarose resulted in a 55-fold enrichment of collagenase in a single step with very little loss of activity. The chromatographic behavior of collagenase on other lectin matrices was explored and gave information about the type of complex asparagine-linked oligosaccharide found on collagenase isolated from PMNLs.

Induction of collagenase production in U937 cells by phorbol ester and partial purification of the induced enzyme

The U937 cell line is a monoblast-like cell line that can be induced to differentiate when treated with phorbol ester or a variety of other agents. Collagenase was detected in the media of U937 cell cultures after treatment with phorbol myristate acetate (PMA) at concentrations of 5 ng/mL or greater. In general, no collagenase was detected in the media of untreated cells. The induced collagenase cleaved native type I collagen into the 3/4 and 1/4-length fragments and showed the inhibition by ethylenediaminetetraacetic acid characteristic of the action of mammalian collagenases. Collagenase activity could be detected in the media of treated cells 12-18 h after the addition of PMA. Secretion of collagenase continued for 2-3 days after PMA addition. The production of collagenase by PMA-treated U937 cells was inhibited by actinomycin D and cycloheximide, suggesting that the induction of the enzyme is the result of de novo synthesis. The collagenase secreted by U937 cells induced with PMA has been purified 12-fold by using DEAE-Sephacel followed by wheat germ agglutinin-agarose chromatography. The apparent molecular mass of this U937 collagenase, determined by gel filtration chromatography on the partially purified enzyme, was 29-36 kilodaltons.

Proactivator-dependent activation of procollagenase induced by treatment with EGTA

A new mechanism for activation of the proactivator of procollagenase [Vater, Nagase & Harris (1983) J. Biol. Chem. 258, 9374-9382] has been found. Collagenolytic and other proteolytic enzyme activities in the medium of cultured rabbit synovial fibroblasts were found to be activated by a new mechanism: short-term incubation at 37 degrees C performed in the presence of EGTA followed by replacement of Ca2+ during enzyme assay. The crucial event in procollagenase activation is the production of a functional activator enzyme. Activation of procollagenase in the culture medium did not occur when proactivator was removed by immunoprecipitation. Proteolytic activity of proactivator was fully activated, whereas procollagenase alone could not be activated by the same sequence. EGTA treatment of the culture medium at 0 degrees C did not result in enzyme activation if Ca2+ was replaced before incubation at 37 degrees C. Certain other bivalent metal ions (e.g. Sn2+, Cd2+, Zn2+ and Mn2+) could substitute for Ca2+ to stabilize the proactivator as a zymogen and therefore prevent the appearance of proteolytic activity in culture medium. Isolation of proactivator and procollagenase from EGTA-treated radiolabelled culture medium by immunoprecipitation and subsequent analyses by fluorography revealed that a time-dependent proteolysis of both molecules occurred after replacement of Ca2+ and incubation at 37 degrees C. However, comparison of enzyme activity with fluorographic analyses showed that the maximal activation of both enzymes was achieved before any detectable decrease in Mr. The results suggest that the activation of proactivator and the subsequent activation of procollagenase may be initiated by conformational changes in structure of the proactivator molecule produced by removal of stabilizing bivalent metal ions.

Homology between exon-containing portions of rabbit genomic clones for synovial cell collagenase and human foreskin and synovial cell mRNAs

Portions of rabbit genomic clones containing exons cross-hybridize with human synovial cell and human foreskin fibroblast mRNAs. These cross-hybridizing genomic fragments have been subcloned into pBR328 and may be useful probes in isolating cDNA and genomic clones from human tissue, and perhaps from other species as well. In addition, DNA sequence data on a 530 bp cDNA clone for rabbit synovial-cell collagenase indicate that this clone is composed primarily of 3'-untranslated region. As such, it is probably not useful in cross-species hybridizations.

Autoregulation of collagenase production by a protein synthesized and secreted by synovial fibroblasts: cellular mechanism for control of collagen degradation

Conditioned medium taken from cultures of resting rabbit synovial fibroblasts contained a protein that prevented the synthesis of the neutral proteinase collagenase. Conditioned medium was concentrated 10-fold and placed on cultures of rabbit synovial fibroblasts along with an inducer of collagenase (phorbol myristate acetate or latex particles) and [3H]leucine. Collagenase production was measured by immunoprecipitation of culture medium with monospecific antibody. Gel filtration showed that the inhibitory factor had MrS of 12,500, 25,000-50,000, and 150,000, suggesting that the protein may exist as aggregates. Activity was destroyed by boiling, by trypsin, and by dithiothreitol. Production of the inhibitory protein was prevented by cycloheximide. Isoelectric focusing purified the protein 100- to 150-fold and revealed pIs in the range of 3.2-3.7. Glycosylation was demonstrated by binding to Con A-Sepharose. Our data indicate that rabbit synovial fibroblasts autoregulate collagenase production and suggest that the low levels of collagenase seen in resting cultures result from an active suppression of collagenase synthesis.

Isolation of a collagenase cDNA clone and measurement of changing collagenase mRNA levels during induction in rabbit synovial fibroblasts

To facilitate our studies on the mechanisms controlling collagenase production at a molecular level in rabbit synovial fibroblasts, we have constructed a cDNA library using mRNAs isolated from cells induced with crystals of monosodium urate monohydrate. We have screened this library with cDNA probes made from induced and control mRNA populations. From among 30 clones that hybridized preferentially to the induced-cell probe, 4 contained collagenase sequences. The largest, a clone of 650 base pairs, was identified by its ability to hybrid select a mRNA that could be translated in a cell-free system into a product that was precipitable with monospecific antibody to collagenase. Using this clone to probe blots of RNA from induced cells, we detected the appearance of a collagenase mRNA of 2.7 kilobases within 5 hr of addition of urate. The level of collagenase mRNA continued to increase for 35-40 hr, when it was 60 to 90 times more abundant in induced cells than in control cells. The increase in mRNA levels correlated with an increase in immunoreactive collagenase protein that was detectable in culture medium by 10 hr.

Biosynthesis and secretion of procollagenase by rabbit synovial fibroblasts. Inhibition of procollagenase secretion by monensin and evidence for glycosylation of procollagenase

Monolayer cultures of rabbit synovial fibroblasts stimulated with phorbol myristate acetate to produce large amounts of collagenase (EC 3.4.24.7) were used to study the biosynthesis and secretion of this enzyme. [3H]Leucine was added to cell cultures for pulse-chase and continuous-labelling experiments. The labelled procollagenase synthesized was identified by immunoprecipitation followed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and fluorography. The amounts of intracellular and extracellular proenzyme were quantified by measuring radioactivity incorporated into the proteins. procollagenase was synthesized as doublet proteins of Mr 57 000 and Mr 61 000. Immunoprecipitable proenzyme proteins were first detected in culture medium 35 min after [3H]leucine was added to the cells. Monensin treatment of the cells inhibited procollagenase secretion and led to intracellular accumulation of the proenzyme. Cells treated with tunicamycin produced only the 57 000-Mr form, indicating that in rabbit synovial cells the 61 000-Mr form was post-translationally modified by addition of oligosaccharides to asparagine residues. The ratios of glycosylated to unglycosylated forms in cell lysates and in culture medium were 0.22:1 and 0.07:1 respectively.

Increased level of translatable collagenase messenger ribonucleic acid in rabbit synovial fibroblasts treated with phorbol myristate acetate or crystals of monosodium urate monohydrate

We studied mechanisms governing production of the neutral proteinase collagenase by synovial cells. We used a model system of monolayer cultures of rabbit synovial fibroblasts stimulated to produce collagenase by treatment with phorbol myristate acetate or crystals of monosodium urate monohydrate. mRNAs from these and untreated cells were translated in a wheat germ cell-free system. Collagenase was not present in the culture medium or in the in vitro translation products of mRNA from untreated cells but was present in both the medium and translation products of stimulated cells, as analyzed by gel electrophoresis and immunoprecipitation with monospecific antibody. Induction of collagenase was prevented by treatment of the cells with alpha-amanitin (2 mug/ mL), an inhibitor of mRNA synthesis. We have concluded that the induction of collagenase synthesis by either phorbol myristate acetate or urate crystals is due to an increased level of translatable mRNA.

Effects of all-trans-retinoic acid (retinoic acid) and 4-hydroxyphenylretinamide on synovial cells and articular cartilage

We studied the effects of two retinoids, naturally occurring all-trans-retinoic acid (retinoic acid) and the synthetic 4-hydroxyphenylretinamide (4-OH-PRT) on monolayer cultures of rabbit synovial fibroblasts and on explants of rabbit articular cartilage. Treatment of fibroblasts with phorbol myristate acetate (PMA; 10(-8) M) induced the synthesis and secretion of large amounts of collagenase: this was inhibited if the cells were treated with retinoic acid (10(-6) M) or dexamethasone (10(-7 M). Combined treatment with retinoic acid and the steroid prednisolone, at concentrations as low as 19(-10) M, gave an additive inhibition of collagenase production. Both retinoids inhibited collagenase production, but only 4-OH-PRT prevented the increase in prostaglandin E2 (PGE2) induced by PMA. Levels of plasminogen activator were also increased by treatment with PMA, and concomitant addition of either retinoid further enhanced this stimulation. Possible toxicity was assessed by measuring release of glycosaminoglycans (GAG) from explants of articular cartilage. Treatment with retinoic acid induced release of 80% of the total GAG, whereas treatment with 4-OH-PRT resulted in release of 40% of the total, a finding similar to that seen with untreated samples. 4-OH-PRT inhibited production of collagenase and PGE2 by rabbit synovial fibroblasts but was not toxic to articular cartilage.