Biosynthesis of collagenase by human skin fibroblasts in monolayer culture

The turnover and degradation of collagen

The interstitial collagens are degraded predominantly extracellularly, by specific collagenases (metalloproteinases) capable of cleaving the helical region across the three chains at a similar locus, solubilizing the cleaved products from the fibril. Other neutral proteinases may also function in this role by cleaving near cross-links in the fibril. Collagen type, molecular aggregation and small changes in temperature all markedly affect rates of collagenolysis in the fibril. Regulation of collagenolysis is also modulated at the levels of (1) cellular production of latent collagenase (procollagenase), (2) activation of latent collagenase, and (3) production of collagenase inhibitors. Fibroblastic cells and certain macrophages are probably the predominant sources of collagenases in inflammation; an enzyme in polymorphonuclear leucocytes (neutrophils) is distinct from the tissue enzyme. Molecules such as mononuclear cell factor (MCF), homologous with interleukin 1, which augment cellular collagenase production in inflammation, are derived from monocytes. The mechanisms of augmented collagenase production involve new protein synthesis and, if this augmentation is analogous to that produced by urate crystals, it is probably associated with increased levels of procollagenase mRNA. MCF production is itself controlled by products of lymphocytes as well as by interactions of monocytes with the Fc portion of immunoglobulins and components of the extracellular matrix. Activation of latent (pro)collagenase probably occurs in vivo through the action of neutral proteinases such as plasmin (through plasminogen activator). These effects may be indirect and exerted through proteolytic activation of a procollagenase activator. Tissue inhibitors act to regulate the active collagenase.

Analysis of TIMP expression and activity

This chapter provides practical information on the assay of tissue inhibitor of metalloproteinase (TIMP) activity and background information enabling meaningful interpretation of the data. Protocols are given for assessing the presence of TIMPs in biological samples by immunoblotting and by virtue of their ability to inhibit matrix metalloproteinase (MMP) hydrolysis of protein substrates (reverse zymography) and synthetic fluorogenic substrates.

Modulation by hypergravity of extracellular matrix macromolecules in in vitro human dermal fibroblasts

In vitro human dermal fibroblasts were submitted to normal gravity (1 g) or to chronic hypergravity (20 g) over a period of 8 days. Changes in organization of extracellular matrix molecules were seen by indirect immunofluorescence. In the fibronectin layer, bundles of fibrils were gathered together leading to a disorganisation of the normal parallel pattern of fibers seen in control cultures. Type I collagen fibrils appeared with wooly outlines in controls whereas thick fibers were closely packed in 20-g cultures. A moderate increase of type III collagen fibril density was observed. No elastic fibers were seen in control or in 20-g cultures. In the culture medium, the release of soluble elastin (ELISA) and type I and III collagens (RIA) was undisturbed. Assays of enzymes involved in the remodeling of extracellular matrix showed an increase of cellular elastase activity (10%) and a decrease of the spontaneously active collagenase. Nevertheless, the total collagenase activity, (activated by trypsin), was increased by up to 30%. These data show a significant rise of the latent collagenase activity and suggest that release of the tissue inhibitor of metalloproteinase (TIMP1) was enhanced by hypergravity.

Expression of interstitial collagenase is restricted to skeletal tissue during mouse embryogenesis

Collagenases are thought to be involved in physiological and pathological processes that require extracellular matrix remodeling. Using the in situ hybridization technique, we describe the expression of interstitial collagenase gene during mouse embryogenesis between E6.5 and E17. We demonstrate that interstitial collagenase expression is exclusively detected in one event, namely the onset of bone formation. Transcripts accumulate in hypertrophied chondrocytes, found in the mature cartilaginous matrix of long-bone growth plates or ribs, and in osteoblasts and/or in endothelial cells that have migrated into the shafts of developing long bones. The expression of the tissue inhibitor of metalloproteinases (TIMP-2) gene precedes the expression of interstitial collagenase in developing bones. These data suggest that interstitial collagenase plays a specific role in bone development and that the tight regulation of its activity during development is achieved not only by post-translational mechanisms with TIMPs, as previously suggested, but also at the transcriptional level.

Immunolocalization of collagenase and TIMP in healing human burn wounds

Degradative events in remodeling connective tissues are mediated through the actions of one or more members of the matrix metalloproteinase family. Conversely, members of the tissue inhibitors of metalloproteinase (TIMP) family act to attenuate proteolysis. Because collagenase and TIMP are rapidly secreted into the extracellular matrix following their biosynthesis and may not remain near their cell of origin, we undertook an immunohistochemical examination of human burn injuries to establish the distribution of these proteins during acute wound repair. Immunostaining for collagenase and TIMP was markedly increased within the wound bed but not in adjacent regions of histologically normal skin. Immunoreactive collagenase was first noted at the eschar-dermal interface by day 3 after injury and became very prominent in the dermis from day 5 to day 17. By day 5, focal patches of immunoreactive collagenase were found at the epidermal-dermal junctions at the wound margins. Within the wound bed, intense staining for collagenase was noted in the connective tissue surrounding the surviving epithelial appendages and around blood vessels. Immunoreactive TIMP was detected by day 2 both in the dermis and the overlying eschar but rapidly assumed the same interfacial pattern as described for collagenase. Staining for TIMP was only sporadically found at the dermal-epidermal margins and surrounding surviving epithelial appendages. Like collagenase, TIMP was prominently localized about vascular structures. These studies demonstrate that, in acute wounds, immunoreactive collagenase and TIMP are generally increased throughout the area of injury but particularly so at interface zones including eschar-dermis, epidermis-dermis, appendages-dermis, and around vascular structures.

Localization of mRNAs representing interstitial collagenase, 72-kda gelatinase, and TIMP in healing porcine burn wounds

The process of wound healing sets in motion a complex and dynamic series of events, which includes the remodeling of the extracellular matrix. Degradation of matrix macromolecules is mediated through the actions of the matrix metalloproteinase family. Conversely, the actions of this enzyme family are regulated by tissue inhibitors of metalloproteinases (TIMPs). In this study, we have developed riboprobes derived from human cDNAs representing collagenase, 72-kDa gelatinase, and TIMP and have found them to be sufficiently specific and sensitive for use in in situ hybridization studies of porcine burn wounds. Expression of these mRNAs, although not seen in uninjured skin, was found to be a predictable and locally distinct event in wound repair. Transcripts for collagenase and TIMP but not 72-kDa gelatinase were detected at the resurfacing epithelial margin; label was also detected in and around follicular epithelium within the wound bed. Transcripts for both metalloenzymes and TIMP were found throughout the viable dermis and subcutaneous tissues underlying the wound bed. However, expression of 72-kDa gelatinase was most prominent in the superficial dermis adjacent to the resurfacing epidermis at the wound margin. Collagenase and TIMP transcripts were particularly prominent in a perivascular pattern in the dermis and in the connective tissue network surrounding adipocytes in the subcutaneous zone. Numerous cell types appeared to be involved, including keratinocytes, fibroblasts, macrophages, and endothelial cells. Future exploitation of this porcine thermal injury model is likely to provide information about the spatial and temporal patterns of matrix metalloproteinase and TIMP expression in cutaneous wound healing.

Decreased collagenase expression in cultured systemic sclerosis fibroblasts

One cause of the excessive deposition of collagen in systemic sclerosis is thought to be abnormal functioning of fibroblasts. The purpose of this study is to determine whether there is decreased expression of collagenase in systemic sclerosis fibroblasts. In this study, we analyzed collagen and collagenase expression in dermal fibroblasts derived from eight patients with systemic sclerosis and compared the findings with those from nine sex- and age-matched healthy subjects. Increased collagen synthesis accompanying enhanced mRNA levels was observed in two of eight strains, whereas all eight strains showed remarkable decreases in collagenase activity and production. There were no differences in the levels of collagenase mRNA between the systemic sclerosis strains and the normal strains. Results suggest that decreased collagenase expression is a characteristic of systemic sclerosis fibroblasts, and both increased collagen expression and decreased collagenase expression in systemic sclerosis fibroblasts may result in the excessive accumulation of collagen in patients with systemic sclerosis. It is also suggested that decreased collagenase expression is altered at translational and/or post-translational levels.

Regulation of uterine collagenase gene expression: interactions between serotonin and progesterone

This report seeks to further define the requirements for the previously established induction of collagenase gene expression by serotonin and inhibition by progesterone in primary cultures of rat uterine smooth muscle cells. Detectable increases in collagenase production were observed after as little as 3 h exposure of cells to 5 microM serotonin, with maximal induction occurring after approximately 8 h of exposure. The apparent half-life of collagenase mRNA upon removal of serotonin was estimated to be approximately 12 h, and was not dependent on the duration of induction. Inhibition by either cycloheximide or progesterone showed similar half lives for collagenase mRNA, however a much shorter half-life (6 h) was obtained in the presence of actinomycin D. These experiments suggest that neither serotonin induction nor progesterone inhibition of collagenase synthesis represents a primary effect on collagenase gene transcription. Rather they appear to be secondary to changes that occur at one or more primary intermediate genes whose induction or decay must occur prior to changes in collagenase transcription. The progesterone receptor antagonist, RU-486, abrogates the ability of progesterone to inhibit serotonin-induced collagenase gene expression, indicating that the effects of progestins in this system likely are receptor-mediated. Finally, the present studies demonstrate that pretreatment of cells for times as long as 5 days with medroxyprogesterone in the absence of serotonin is unable to prevent subsequent serotonin-induced collagenase mRNA increases. These data suggest the possibility of a unique interaction between the molecular pathways of inducer and inhibitor, one in which serotonin may help mediate the progesterone-dependent repression of the levels of collagenase mRNA.

Immunohistochemical examination of skin wounds with antibodies against alpha-1-antichymotrypsin, alpha-2-macroglobulin and lysozyme

The distribution of the proteinase inhibitors alpha-1-antichymotrypsin (alpha 1-act), alpha-2-macroglobulin (alpha-2-m) and lysozyme was analysed immunohistochemically in 27 intravitally acquired wounds, 3 postmortem skin lacerations and 9 specimens of undamaged skin. Intravitally acquired wounds demonstrated distinct positive reactions for all antibodies examined (alpha-1-act 66.6%; alpha-2-m 51.9%; lysozyme 25.9%). However the undamaged skin margins opposite the wound margins also gave positive reactions (alpha-1-act 51.8%; alpha-2-m 37.0%; lysozyme 25.9%). Nearly half of the control cases (specimens of undamaged skin) exhibited weak positive reactions for all 3 antibodies. These could be easily distinguished from the strong positive reactions observed in intravitally acquired wounds. False positive reactions were observed due to contamination resulting from contact with serum components, in cases of advanced autolysis of specimens, and as a result of fixation and drying artefacts. Even though immunohistochemical studies of alpha-1-act, alpha-2-m and lysozyme give some indications concerning wound vitality, they cannot be considered as proof because irrefutable differentiation of true positive and false positive reactions is not possible in all cases.

On the mechanism of drug-induced gingival hyperplasia

Proposed mechanisms of the side effect of drug-induced gingival hyperplasia are reviewed. Hypotheses with regard to inflammation from bacterial plaque, increased sulfated glycosaminoglycans, immunoglobulins, gingival fibroblast phenotype population differences, epithelial growth factor, pharmacokinetics and tissuebinding, collagenase activation, disruption of fibroblast cellular sodium/calcium flux, folic acid and a combination hypothesis are evaluated.

Mechanisms of tubulointerstitial fibrosis

With regard to tubulointerstitial fibrogenesis we are left with a variety informational gaps regarding nearly all aspects of this clinically important process. Table 2 summarizes a generalized version of fibrogenesis based primarily on investigations in other organs. Extrapolation of data obtained with other fibrogenic systems is useful, but only in so far as it motivates us to adapt and test many of the experimental principles within in the context of the kidney. This begins with a comprehensive examination of the in vivo state, the establishment of adequate animal models, and the dissections of the process in vitro. Key areas for the future are the characterization of the signals involved, the cellular responses to these signals, and the variations in interactions produced by differing inciting fibrogenic conditions.

Reconstituted basement membrane matrix stimulates interstitial procollagenase synthesis by human fibroblasts in culture

Synthesis of interstitial collagenase by human fibroblasts was compared when cultured on plastic, in the presence or absence of soluble laminin, on a type I collagen gel and on a gel of basement membrane components (matrigel). Fibroblasts cultured on matrigel or on type I collagen gel displayed an increase in the steady-state levels of mRNA for interstitial procollagenase that was proportional to its enzymatic activity. Laminin, the main component of matrigel, had no effect on the interstitial collagenase synthesis by fibroblasts. We suggest that matrigel, which stimulates the interstitial collagenase production at a transcriptional step, could regulate the catabolic potential of fibroblasts.

Intracellular secretory pathway and ultrastructural localization of interstitial procollagenase in human gingival fibroblasts

Fibroblast-type collagenase, a neutral secretory metalloproteinase capable of cleaving interstitial collagen types I-III, is expressed by a number of different cell types including fibroblasts, macrophages, osteoblasts, and keratinoyctes. To elucidate the secretory pathway of this enzyme, we examined the ultrastructural localization of this metalloproteinase in cultured human gingival fibroblasts, particularly the routing of the enzyme from the Golgi cisternae to the cell surface utilizing rabbit polyclonal antibodies raised against human fibroblast (pro) collagenase. For this purpose, one percent glutaraldehyde followed by gentle permeabilization with saponin gave superior preservation of both cellular morphology and intracellular antigenicity. At the light microscopic level, the reacting antibodies visualized by immunofluorescence and immunoperoxidase staining were localized intracellularly in the perinuclear region reflecting the Golgi apparatus. Immunoelectronmicroscopy using the pre-embedding technique and peroxidase or immunogold staining revealed electron dense label in large vacuoles indicating extended cisternae of the Golgi field. Vesicles were noted leaving the plasma membrane in long extensions. Moreover, intact vesicle containing the antibody reaction product appeared outside the membrane. In addition, most extracellular vesicular structures appeared empty of label suggesting that the collagenase had been liberated into the extracellular space. The latter observation was supported by the fact that the label was found also on the extracellular surface of the cells indicating a (re)association of collagenase with the outer cell membrane. These data demonstrate that the pathway of interstitial collagenase in human gingival fibroblasts is similar to that of other secretory proteins.

Extraction of type-IV collagenase/gelatinase from plasma membranes of human cancer cells

Tumor proteinases are considered to be important in the process of cancer invasion and metastasis. We have proposed that the surface membrane localization of these proteinases places them in an optimal site to facilitate the invasion of surrounding extracellular matrix. In this study, we have used the organic solvent, n-butanol, and the detergent, n-octyl-glucoside, to sequentially extract metalloproteinases from crude plasma membranes of human RWP-I pancreatic cancer cells. Anion exchange chromatography and gel permeation chromatography were employed to further purify enzymes with the capacity to degrade gelatin, type-IV collagen, and carboxymethylated transferrin. Gelatin zymography was used to demonstrate proteinase bands of 92, 70 and 62-kDa. Immunoblotting of solubilized, partially purified pancreatic cancer plasma membrane proteins using polyclonal rabbit antibodies, which have specificity for type-IV collagenase/gelatinase, resulted in the recognition of a 70-kDa protein, but not the 92-kDa gelatinase. A type-IV collagenase/gelatinase of 68-kDa was similarly identified in A2058 human melanoma cancer cell plasma membranes.

Secretion and glycosylation of rabbit macrophage type V collagenase

Cultures of freshly isolated rabbit alveolar macrophages were used to study the synthesis, secretion, and glycosylation of type V collagenase. Cells were pulse-labeled with [35S-]methionine for 15 minutes followed by a chase with cold methionine for various time periods. Type V collagenase was identified in the culture supernatants and cell lysates by immunoprecipitation with a specific antiserum. Within 10 minutes of chase, an 82-kDa protein was found in the cell lysates. This protein was subsequently processed to a 92-kDa protein without identifiable intermediate forms. By 60 minutes of chase, intracellular radioactivity was no longer detectable. The larger protein could be detected within 20 minutes in the culture supernatants and accumulated in the medium for 60 minutes of chase time. Only the 92-kDa form was seen in the supernatants and the proteinase was secreted without intracellular storage or membrane association. Treatment of the 92-kDa proteinase with an enzyme which specifically removes N-linked carbohydrates resulted in an apparent reduction in molecular mass of approximately 10 kDa. Deglycosylation of the proteinase did not result in an apparent loss of activity. Thus, it was concluded that macrophage type V collagenase is synthesized as an 82-kDa polypeptide which is glycosylated by N-linkage and secreted.

Tumor necrosis factor-alpha induces mRNA for collagenase and TIMP in human skin fibroblasts

We demonstrated previously that growth promoting factors in general could induce the secretion of interstitial collagenase into the medium of human fibroblast cells (HF). In this study, the effect of tumor necrosis factor-alpha (TNF-alpha) on the induction of collagenase and tissue inhibitor of metalloproteinases (TIMP) was examined. Stimulation of quiescent HF cells with 10 ng/ml TNF-alpha induced the secretion of Mr 57,000, 52,000 procollagenases into the medium. The collagenase activity was elevated 2.8-fold after TNF-alpha treatment. Northern blot analysis of the steady-state mRNA indicated a tenfold elevation of collagenase transcript after 24 h treatment with 10 ng/ml TNF-alpha. The increase in collagenase mRNA was due to transcriptional activation of collagenase gene activity. TIMP mRNA level increased three-fold after TNF-alpha treatment. The activity of TNF-alpha on collagenase and TIMP induction may play an important role in tissue inflammatory, repair and remodeling processes after wound and injury.

Interstitial collagenase (MMP-1), gelatinase (MMP-2) and stromelysin (MMP-3) released by human fibroblasts cultured on acellular sarcoid granulomas (sarcoid matrix complex, SMC)

We studied collagenase, gelatinase and stromelysin syntheses by human fibroblasts cultured on three models of tridimensional matrix: native collagen sponge, native collagen complexed with glycosaminoglycans sponge, and acellular sarcoid matrix complex prepared from human sarcoid granulomas. Collagenase and stromelysin biosyntheses were differently stimulated according to culture conditions. Fibroblasts secreted a same amount of collagenase or stromelysin when cultured on collagen and collagen-glycosaminoglycans sponges, while collagenase and stromelysin secretions were widely amplified when cultured on sarcoid matrix complex. In contrast, gelatinase production was equally induced by the three culture conditions. In the different culture conditions on tridimensional matrix, the three matrix metalloproteinases were synthesized in a latent form. Thus, the sarcoid matrix complex stimulated the release of collagenase and stromelysin by fibroblast, but did not stimulate the release of gelatinase. This suggests that collagenase and stromelysin syntheses are co-regulated while gelatinase production is controlled by a distinct mechanism.

Plasminogen activator activity is associated with neural crest cell motility in tissue culture

We have examined the possibility that proteases such as plasminogen activator (PA) contribute to the extraordinary motile capability of neural crest cells. We show that trunk neural crest cells that migrate from isolated neural tubes in vitro produce PA and that the level of cell-associated PA increases dramatically after 8 days in culture. This increase is not the result of differentiation or time in culture, because neural crest cell clusters that form on top of the neural tube and differentiate into pigment cells but are immotile produce very low levels of PA. If these clusters are removed from the neural tube and replated on a plastic substratum where they migrate, the level of PA associated with the cells increases dramatically, suggesting that PA production is associated with motility. Inhibitors of PA/plasmin activity significantly reduce neural crest cell motility in vitro, further supporting the idea that proteases are important in neural crest cell migration.

Calmodulin regulates the interleukin 1-induced procollagenase production in human uterine cervical fibroblasts

Interleukin 1 (IL-1) stimulates the synthesis of collagenase in human uterine cervical fibroblasts. This inductive effect of IL-1 on collagenase production was augmented by N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), a specific inhibitor of calmodulin, in a dose-dependent manner. The apparent collagenase activity observed in the culture medium of the cells treated with IL-1 and 40 microM W-7 was about three times higher than that produced by the cells treated with IL-1 alone. The immunoblotting with the specific antibody against human collagenase showed that the increased collagenase activity resulted from the accelerated biosynthesis of collagenase. Another calmodulin inhibitor, trifluoperazine, enhanced the effect of IL-1 on collagenase production similarly. However, the effect of N-(6-aminohexyl)-1-naphthalenesulfonamide, the weakest inhibitor of calmodulin, was negligible. These results suggest that W-7 enhances the collagenase production by specifically inhibiting calmodulin and that calmodulin may act as a suppressor of the IL-1-induced collagenase production in human uterine cervical fibroblasts.

Differential stimulation of collagenase and chemotactic activity in fibroblasts derived from rat wound repair tissue and human skin by growth factors

Epidermal growth factor and cartilage-derived basic fibroblast growth factor (EGF and CD-bFGF) are mitogens shown to increase the rate of wound repair in animal models. In addition to being a mitogen for granulation tissue, CD-bFGF stimulates the recruitment of cells to the wound site. CD-bFGF and a closely-related chondrosarcoma-derived fibroblast growth factor stimulated chemotaxis of granulation tissue cells in vitro, each factor having a maximum activity at a concentration of 55 pM. Epidermal growth factor was also a potent chemoattractant for rat granulation tissue fibroblasts; however, maximum activity was obtained at 1.7 nM. Cells from all stages of wound repair were chemotactically responsive to these factors, but there was some attenuation of the response to bFGF in cells derived from fully-organized day 28 granulation tissue. Collagenase-catalyzed restructuring of collagen, an additional significant feature of wound repair, is probably critical to cell movement in an extracellular matrix. Cells derived from organizing (6-day old) sponge granulation tissue secreted latent collagenase constitutively in vitro. In the presence of serum, the production of collagenase was stimulated three-four fold by 1.8 nM bFGF derived either from cartilage or chondrosarcoma. When serum was present, as at a wound site, collagenase production was not enhanced by the addition of EGF. Cells from fully organized, day 21 sponge granulation tissue did not secrete latent collagenase constitutively and could not be stimulated to do so by the addition of EGF, bFGF, or phorbol ester. Human skin fibroblast collagenase production was also stimulated by bFGF and was refractory to EGF. While both classes of growth factor have the ability to promote wound healing, the varying responses they elicit in cell populations from the wound site emphasize the different pathways of cellular activation.

Fast increase of proteinase inhibitors in necrotic collagenous tissue

Using the PAP immunohistochemical technique, accumulation of two proteinase inhibitors, alpha-1-antichymotrypsin and alpha-2-macroglobulin, can be detected at the edges of collagenous fibers in the corium after slash wounds of the skin. This accumulation was observed within a survival time of 10-30 min. It, however, is not detectable in postmortally inflicted trauma.

Differential response of early and late passage fibroblasts to collagenase stimulatory factor in conditioned media

Comparison of the proteins secreted by early and late passage cultures of human fibroblasts reveals enhanced production of three proteins (Mr = 55,000, 58,000, and 61,000) in the late passage culture conditioned medium. The 55,000 and 58,000 Da proteins react with anticollagenase antibodies and are identified as procollagenase (Sottile, J. M. and Millis, A. J. T., J. Cell Biol. 106: 1518a, 1987). The production of immunoreactive collagenase was assayed using immunoprecipitation and immunofluorescence. Immunofluorescence microscopy revealed that each culture was heterogenous. The percentage of collagenase positive cells ranged from 1% (early passage) to 35% (late passage). Late passage cultures also secreted higher levels of immunoprecipitable collagenase into the culture medium than early passage cultures. High levels of collagenase production were also observed in fibroblasts cultured from donors with Werner's syndrome and from an aged donor. Media conditioned by the growth of human fibroblasts contained collagenase stimulating activity. In the presence of conditioned medium, the percentage of collagenase positive cells was increased to 10-20% (early passage) and 85% (late passage), indicating that each culture contains both responding and non-responding cells.

Immunolocalization of collagenase inhibitor in normal skin and basal cell carcinoma

Human collagenase inhibitor is a ubiquitous glycoprotein capable of blocking the action of several connective tissue metalloproteinases, including collagenase, gelatinase, and proteoglycanase. The action of this proteinase inhibitor may constitute a pivotal step in the control of connective tissue matrix degradation. Using monospecific antibody to collagenase inhibitor as an immunocytochemical probe, we determined its in vivo localization in normal human skin and in a pathologic state, the altered connective tissue stroma surrounding basal cell carcinoma. Collagenase inhibitor was localized diffusely throughout the dermis and appeared to be associated with the extracellular matrix components, both in normal skin and in basal cell carcinoma. Intense staining was present in the stroma surrounding islands of basal cell carcinoma. The increased amounts of collagenase inhibitor may be a result of its production by stromal fibroblasts stimulated by cytokines of tumor or inflammatory cell origin. These findings are similar to those previously described for dermal collagenase. Both collagenase inhibitor and collagenase itself appear to be normal components of the extracellular matrix, and amounts of both are increased in the altered stroma surrounding neoplastic cells. Thus we suggest that the balance of degradative proteinase(s) to specific inhibitor may be an important factor in determining the composition of the extracellular matrix.

Effect of tunicamycin on the biosynthesis of human fibroblast collagenase

It is generally accepted that collagenase from human fibroblast cultures consists of two proenzymes (Mr 60,000 and 55,000) and two active forms (Mr 50,000 and 43,000). We demonstrated previously that epidermal growth factor (EGF) as well as a number of other growth factors induced the secretion of procollagenase (Mr 60,000, Mr 55,000) into the medium of human fibroblast cultures (Chua et al., 1985). In the presence of tunicamycin and EGF, the secretion of the larger form of procollagenase was suppressed preferentially with concomitant appearance of a new band, Mr 40,000. This Mr 40,000 band could be specifically immunoprecipitated by antibody raised against human collagenase. By two-dimensional peptide mapping, the Mr 40,000 material appeared to have similar composition as the Mr 60,000 band. In a time course study, the Mr 55,000 procollagenase band was the earliest protein to appear in the medium after 1 hour labeling with [35S]-methionine. The Mr 60,000, 50,000 and 43,000 bands appeared after a 2 hour labeling period. Our results indicate that human collagenases are glycosylated proteins and are synthesized via the dolichol phosphate pathway.

Diminished response of Werner's syndrome fibroblasts to growth factors PDGF and FGF

Patients with Werner's syndrome, an autosomal recessive disorder, undergo an accelerated aging process that leads to premature death. Fibroblasts from such patients typically grow poorly in culture. Here it is shown that fibroblasts from a patient with Werner's syndrome have a markedly attenuated mitogenic response to platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF). In contrast, they have a full mitogenic response to fetal bovine serum. Both PDGF binding and receptor numbers per cell are unaltered. The Werner's syndrome cells express high constitutive levels of collagenase in vitro. Although PDGF enhances collagenase expression through increased levels of hybridizable collagenase messenger RNA in normal skin fibroblasts, no induction of collagenase occurs in the Werner's syndrome fibroblasts. Moreover, the failure to respond to this agonist effect of PDGF is not restored by fetal bovine serum. The data suggest that failure of one or more PDGF-mediated pathways in Werner's syndrome cells may contribute to the phenotypic expression of the disorder.

Elevated levels of human collagenase inhibitor in blister fluids of diverse etiology

Blister fluids from a variety of bullous disorders were examined for the presence of human collagenase inhibitor. A protein immunologically identical to the collagenase inhibitor produced by human skin fibroblasts was found in high concentrations within bullae of diverse etiologies. Levels of collagenase inhibitor in blister fluids ranged from 0.9-12.5 micrograms/ml, averaging 4.9 micrograms/ml. The mean values were 3- to 4-fold greater than those present in the sera of corresponding patients and exceeded plasma levels by 6- to 8-fold. The time course of collagenase inhibitor accumulation in blister fluid was studied using heat- and suction-induced bullae. The concentration in newly formed blisters was approximately 0.5 micrograms/ml, virtually identical to plasma inhibitor levels, and remained constant for approximately 4 h. Inhibitor concentrations then rose rapidly, reaching peak values of approximately 6 micrograms/ml after 48 h. We speculate that the role of this inhibitor in blister fluid involves the inhibitions of active proteinases within the bulla cavity and may occur to limit the extent of blister formation or to assist in wound repair.

Half-life of synovial cell collagenase mRNA is modulated by phorbol myristate acetate but not by all-trans-retinoic acid or dexamethasone

As part of our studies on the mechanisms controlling the synthesis of the neutral proteinase collagenase by rabbit synovial cells, we used a cDNA clone to measure total collagenase mRNA levels and to determine mRNA half-life. Phorbol myristate acetate was used to induce collagenase synthesis while all-trans-retinoic acid and dexamethasone were used to inhibit it. Cells stimulated with phorbol myristate acetate contained substantial amounts of collagenase mRNA, but cells treated with all-trans-retinoic acid or dexamethasone contained decreased amounts of collagenase mRNA which correlated well with levels of collagenase protein. Studies on mRNA half-life showed that the t1/2 for total poly(A+) RNA was about 25 h, while that of collagenase varied from as short as 12 h to as long as 36 h. The half-life was not affected by treatment with all-trans-retinoic acid or dexamethasone but was affected by the level of induction of collagenase mRNA: the greater the amount of collagenase mRNA induced, the longer the t1/2. We conclude that our data are consistent with the hypothesis that retinoic acid and dexamethasone act at the level of transcription to decrease collagenase production and the increased level of collagenase mRNA resulting from stimulation with phorbol esters is, in part, due to increased stability of the induced collagenase mRNA.

Age-related changes in collagenase expression in cultured embryonic and fetal human skin fibroblasts

Since skin collagenase is required for initiation of the degradation of types I and III collagens, the major collagens of the human dermis, we examined its expression during embryonic and fetal development. When using skin fibroblasts cultured from human embryos and fetuses, immunoreactive collagenase concentrations were strongly correlated with estimated gestational age (p less than 0.001), with levels at 7-8 weeks of gestation that were about one-twentieth of those in the 29-week cell cultures. In crude culture medium, the apparent catalytic efficiency (activity per unit immunoreactive protein) was variable, an observation attributable in part to variable expression of a collagenase-inhibitory protein. Following chromatographic purification, four of ten fetal collagenases were found to have greater than or equal to 4-fold decrease in specific activity, suggesting that these particular fetal collagenases may be structurally and/or catalytically altered. Since the decreased levels of immunoreactive protein suggested that decreased enzyme synthesis was the major mechanism, we examined collagenase synthesis in a cell-free translation system. Here, we quantitated collagenase expression in the culture medium of intact cells prior to harvesting mRNA. Compared with the intact adult cells, the fetal cells had 3-17 times less collagenase activity in the medium, while in cell-free translation there was a 2- to 3-fold decrease in collagenase synthesis. These data suggest that decreased in vitro expression is correlated with decreased levels of translatable collagenase mRNA but that other factors, such as the collagenase inhibitor and altered specific activity of the enzyme, may be important in modulating collagenase activity.

Coregulation of collagenase and collagenase inhibitor production by phorbol myristate acetate in human skin fibroblasts

Phorbol myristate acetate (PMA), a tumor promotor known to stimulate collagenase production in fibroblasts and endothelial cells, was examined with regard to its ability to regulate the expression of the collagenase inhibitor secreted by human skin fibroblasts. Confluent human skin fibroblasts were incubated with concentrations of PMA ranging from 10(-11) to 10(-7) M, and the conditioned medium was analyzed by enzyme-linked immunosorbent assay for both immunoreactive collagenase and collagenase inhibitor. PMA stimulated the production of both collagenase and collagenase inhibitor in several cell lines to maximal rates that were very similar, 300 to 350 vs 230 to 330 pmol 10 micrograms DNA-1 48 h-1, respectively. Due to differences in the basal levels of expression of these proteins, such rates reflected a two- to sevenfold stimulation in collagenase production, in comparison to a more uniform two- to threefold enhancement in inhibitor synthesis. Production of inhibitor was 50% of maximal at 7 X 10(-9) M and maximal at 10(-7) M phorbol. This concentration-dependent effect was very similar to that observed for collagenase expression. Total protein synthesis by the phorbol-conditioned cells, as studied by incorporation of [3H]leucine into newly synthesized protein, was not significantly increased, nor was cellular DNA content. The onset of the effect of PMA on inhibitor production occurred between 4 and 8 h, was maximal by 8 h, and continued undiminished for at least another 64 h. After the first 8 h, inhibitor production continued at a roughly constant rate of approximately 10 pmol 10 micrograms DNA-1 h-1. Interestingly, following the removal of phorbol from culture medium, such fibroblasts continued to produce increased quantities of inhibitor protein for at least 72 h. Metabolic labeling studies in which fibroblasts were exposed to [3H]leucine followed by immunoprecipitation using inhibitor-specific antibody suggested that stimulation of inhibitor production by PMA was mediated via an increased synthesis of new inhibitor protein. Therefore, in response to the tumor promoter, PMA collagenase and collagenase inhibitor expression by human skin fibroblasts appear to be coregulated.

Glucocorticoid modulation of collagenase expression in human skin fibroblast cultures. Evidence for pre-translational inhibition

Glucocorticoids inhibit collagenase accumulation in the medium of human skin explant cultures. To examine the mechanism for this process, skin fibroblasts were placed in serum-free medium containing various steroids. Dexamethasone produced a dose-dependent inhibition of trypsin-activatable collagenase in the culture medium with maximal inhibition of approx. 85% at 10(-6) M. Dexamethasone failed to inhibit collagenase activity directly. The decrease in activity in the medium was paralleled by a decrease in immunoreactive protein, suggesting inhibition of enzyme synthesis. The specificity of the effect was shown in two ways. At 10(-6) M steroid, only dexamethasone and hydrocortisone were inhibitory; estradiol, progesterone and testosterone produced less than 10% inhibition. In biosynthetic studies, exposure to 10(-7) M dexamethasone for 24 h produced approx. 50% inhibition of collagenase synthesis but caused no greater than 10% inhibition of total protein synthesis. The T1/2 for achieving the effect was approx. 16 h after initial exposure to dexamethasone. These kinetics were parallel to the inhibition caused by actinomycin D and cordycepin, two inhibitors of transcription, but were longer than that caused by cycloheximide (T 1/2 less than 3 h). To examine this process, cells were cultured in the presence or absence of 10(-6) M dexamethasone prior to harvesting mRNA for cell-free translation. In each case the inhibition or enzyme activity in the intact cells was paralleled by a reduction in translatable collagenase mRNA from the same cells. At the same time, there was no significant inhibition of total protein translation by the steroid. These data suggest that glucocorticoids regulate collagenase synthesis at a pre-translational level, possibly through inhibition of transcription.

Purification of gelatin-specific neutral protease from human skin by conventional and high-performance liquid chromatography

Human skin, maintained in serum-free organ culture, secretes a neutral metalloendopeptidase which is remarkably specific for gelatin. Because the product peptides from the action of collagenase on collagen become denatured into random coil polypeptides of 25000 and 75000 daltons at physiological temperature, it is thought that this "gelatinase" is the second, and possibly the only other enzyme in the pathway of extracellular collagen degradation. New types of high-performance liquid chromatography (HPLC) columns have enabled us to improve the yields of active gelatinase from skin culture medium. Raw medium, which has been dialyzed and lyophilized, is fractionated with ammonium sulfate, and applied to Pharmacia Blue Sepharose in a batch step. The 0.4 M sodium chloride eluate is then subjected to gel filtration on Sephacryl S-200, followed by gradient elution from Amicon Green Sepharose. The fractions with gelatinolytic activity are applied to a Bio-Rad TSK-Phenyl-5PW HPLC column for mild hydrophobic chromatography with a gradient of decreasing ammonium sulfate concentration. In the final step, the enzyme is applied to a Pharmacia Mono-Q FPLC column and eluted with a gradient of sodium chloride. At this point, the enzyme appears as two bands, corresponding to enzymatic activity zymograms on sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

The interaction of platelet proteins with three fibroblast-derived collagenases

Three collagenases were purified from the culture medium of human skin fibroblasts using ammonium sulfate fractionation, ion-exchange chromatography and gel filtration. The cationic collagenase had a molecular weight of 42,000; two anionic collagenases had molecular weights of 63,000 and 115,000. Preincubation of the individual collagenases with purified human and bovine platelet heparin binding proteins resulted in the inhibition of the two anionic activities, but only by bovine low heparin affinity platelet protein (beta-TG). Such inhibition was dose-dependent at the microgram level, was not antagonized by heparin, and persisted even when the collagenases had been transformed into their 53,000 and 105,000 forms through treatment with p-aminophenylmercuric acetate. Neither human nor bovine high heparin affinity platelet factors (PF-4) nor human low heparin affinity platelet protein (beta-TG) were inhibitory to any of the three collagenases studied. This suggests that the ability of platelet proteins to inhibit collagenase is specifically influenced by the ionic nature of the enzyme and this inhibition is specifically dependent upon the species and type of platelet protein.

Epithelial organoids and mononuclear phagocytes from DMBA-induced mammary tumors of the rat secrete collagenase in vitro

The production of collagenase has been examined in primary cultures of multicellular epithelial organoids and of stromal cells isolated from DMBA-induced mammary tumors of the rat. Plastic culture dishes and dishes coated with collagen fibrils were used to study the effect of such a substrate on collagenase release. Cultures of 51-micron epithelial organoids consisted of cuboidal cells and a myoepithelial-like cell type which formed a continuous layer under the cuboidal cells. A transient low production of collagenase with an apparent molecular weight (MW) of 72 kD was detected on both substrates. Upon separation by trypsin only cuboidal cells released collagenase. Cultures of 27-micron organoids contained only few myoepithelial-like cells. On plastic, they formed dense monolayers of cuboidal cells and released more collagenase than the greater aggregates. On collagen fibrils, these organoids formed cords and ridges and collagenase production was about 4- to 6-fold higher. These results indicate that collagenase release is influenced by the nature of the interaction of cuboidal cells with the substrate on which they grow. Similar organoids prepared from virgin mammary glands failed to secrete collagenase on either substrate. Primary cultures of stromal cells derived from tumor tissues comprised one basic cell type that expressed a series of properties characteristic for monocytes/macrophages. These cultures were capable of producing collagenase with an apparent MW of 56 kD. Collagenase with a similar size was detected in the extracts of 51 from 65 mammary tumors.

Human gingival fibroblast collagenase: purification and properties of precursor and active forms

Human gingival fibroblast procollagenase has been purified to apparent homogeneity from serum-free and serum-supplemented fibroblast culture medium by a combination of ammonium sulfate precipitation, CM-cellulose chromatography, and gel-filtration on Bio-Gel P-150. Sodium dodecylsulfate polyacrylamide gel electrophoretic studies suggests that the purified fibroblast proenzyme is comprised of two closely related zymogens with the estimated Mr of 57,000 and 52,000. Upon densitometric scanning of the gels, the ratio of the two proenzyme forms was about 1 : 4 (57 : 52 kdal). Limited proteolysis of the fibroblast procollagenase with trypsin resulted in the conversion of both proenzyme forms into active enzyme forms of Mr 48,000 and 44,000, respectively. Amino acid analysis of the active enzymes and proenzyme forms revealed that the active enzymes contained fewer basic amino acids than do the proenzyme forms. The purified trypsin-activated fibroblast collagenase hydrolyzed type I collagen fibrils, cleaved tropocollagen in solution at 24 degrees C into TCA and TCB fragments, and cleaved the synthetic peptide substrate, DNP-peptide III, at the Gly-Ile bond. The gingival fibroblast collagenase exhibited a pH optimum of 7.5, was completely inhibited by EDTA or dithioerythritol but was not inhibited by N-ethylmaleimide or phenylmethylsulfonyl fluoride, and appeared to cleave human type III collagen approximately 10-fold faster than homologous type I collagen. In addition, comparison of the biochemical properties of the precursor and active forms of human gingival fibroblast collagenase with the precursor and active forms of human skin fibroblast collagenase, previously characterized by Stricklin and co-workers (Biochemistry 17: 2331-2337, 1978), revealed that they were similar in Mr, amino acid composition, and substrate specificity. Furthermore, the human gingival and skin fibroblast procollagenases were immunologically identical.

Biological significance of interstitial collagenase in DMBA-induced mammary tumors of the rat

In this review the production of interstitial collagenase in DMBA-induced mammary tumors of the rat has been examined. Cell sorting and cell cultures have given us the opportunity to relate the release of collagenase to a specific cell type. By means of FITC-fluorescence and monospecific antibodies (S. Sakamoto, Harvard University, Boston) it was further possible to localize collagenase in vitro and in vivo. The most outstanding characteristic is that collagenase is produced both by cuboidal, epithelial cell and by macrophages in vitro but not by myoepithelial-like cells. On the other hand, synthesis of collagenase in vivo was detected in some stromal cells, possibly macrophages, but not in neoplastic cuboidal cells. This observation has been related to the inability of cuboidal cells to interact with stromal, fibrillar collagen in vivo since tumor cells are arranged in glandular-like structures bordered by myoepithelial cells and a basement membrane. In vitro, fibrillar rat tail tendon collagen was found to be a potent stimulator of collagenase production by cuboidal cells. Collagenase stimulation by interstitial collagen therefore suggests a plausible mechanism for the degradation of collagen fibrils during local invasion by mammary tumor cells.

Retinoic acid inhibition of collagenase and gelatinase expression in human skin fibroblast cultures. Evidence for a dual mechanism

Human skin fibroblast cultures have been employed to study the effects of a variety of vitamin A analogues (retinoids) on the expression of two enzymes involved in collagen degradation in the skin, collagenase and a gelatinolytic protease. In normal and recessive dystrophic epidermolysis bullosa fibroblast cultures, retinoic acid compounds were effective inhibitors of the accumulation of both enzymes in the culture medium with half-maximal inhibitions occurring at 0.25-1 microM for collagenase and at 3-6 microM for the gelatinolytic protease. Various retinoids exhibited differing degrees of inhibitory actions, so that at a 1 microM concentration, relative inhibitions were: 13-cis-retinoic acid greater than all-trans-retinoic acid greater than aromatic retinoid (Ro 10-9359) much greater than retinol. The retinoic acid-mediated decrease in collagenase activity was accompanied by a parallel decrease in immunoreactive collagenase protein, suggesting that the retinoic acids were acting to inhibit synthesis of the enzyme. However, an additional effect of these agents was encountered. Although the retinoids themselves had no direct collagenase inhibitory action, medium derived from cultures maintained in these retinoids showed direct inhibitory capacity which was dependent both on the concentration of retinoic acid and on the length of time in culture. The results suggest that the retinoic acids modulate collagenase in vitro by two mechanisms: by decreasing the synthesis of enzyme protein and by modulating the expression of an inhibitory molecule.

Enzyme-linked immunosorbent assay for human skin collagenase

A specific and sensitive indirect inhibition enzyme-linked immunosorbent assay (ELISA) was develop for human skin collagenase. Using an antiserum dilution of 1: 8000, the ELISA could detect 0.2 ng of enzyme, which was approximately 10 times more sensitive than the previously described radioimmunoassay for human skin collagenase. The assay was also highly reproducible. In comparative studies, bacterial, tadpole and crab collagenases did not react in the ELISA. Rat uterine collagenase and collagenases from bovine gingival explants and fibroblasts displayed approximately 0.1% of the reactivity found with human skin collagenase. Human synovial and gingival collagenases and collagenase from skin fibroblasts from patients with recessive dystrophic epidermolysis bullosa showed almost complete identity with the normal human skin fibroblast enzyme.

Human skin collagenase: assignment of the structural gene to chromosome 11 in both normal and recessive dystrophic epidermolysis bullosa cells using human-mouse somatic cell hybrids

Somatic cell hybrids between mouse cells and human normal skin and corneal fibroblasts and recessive dystrophic epidermolysis bullosa (RDEB) skin fibroblasts have been used to assign the structural gene for collagenase to its human chromosome. A total of 46 hybrid subclones from several hybridization events were isolated in hypoxanthine-aminopterin thymidine (HAT) selection medium and used to measure the production of human collagenase by a specific radioimmunoassay. We have found that both the normal and RDEB human collagenase gene maps to human chromosome 11. This indicates that the abnormal collagenase produced by RDEB cells is probably not a totally distinct form of the enzyme, but is a structural mutation of the normal collagenase enzyme.