Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To assess the direct effects of Bacteroides gingivalis on periodontal cells, human gingival fibroblasts were cultured in the presence of B. gingivalis extracts or a trypsinlike enzyme partially purified from the bacteria by chromatography on benzamidine-Sepharose and Sephacryl S-200. Analysis of cell surface glycoproteins by the periodate-[3H]borohydride labeling technique combined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-fluorography demonstrated that fibronectin and some other high-molecular-weight cell surface glycoproteins were degraded by a 35,000-Mr(35K) B. gingivalis protease. Immunostaining of the fibroblast cultures showed degradation of intercellular matrix fibronectin by the 35K protease. The pattern of fibronectin degradation was monitored by examining the reaction products with the SDS-PAGE-immunoblotting technique. The protease degraded fibronectin rapidly and more extensively than did corresponding amounts of pancreatic trypsin. Collagenase secretion by the fibroblasts was assayed by incubating cell culture medium with soluble type I [3H]collagen at 25 degrees C followed by SDS-PAGE-fluorography analysis of the reaction products. The medium was also assayed for plasminogen activator activity by using a casein-agarose diffusion plate assay. The fibroblasts cultured with the 35K protease secreted increased amounts of collagenase and plasminogen activator into the medium. The results suggest that periodontal infection by B. gingivalis causes proteolytic damage of the host cell surface structures. Concomitantly, B. gingivalis may induce the cells to degrade their pericellular matrix.
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PMID:A protease of Bacteroides gingivalis degrades cell surface and matrix glycoproteins of cultured gingival fibroblasts and induces secretion of collagenase and plasminogen activator. 253 33

To understand the mechanisms regulating osteoid removal by osteoblasts, mouse calvarial osteoblasts were grown on 14C-labelled type I collagen films and stimulated with 1,25-dihydroxyvitamin D-3 (2.5.10(-8) M) for 48-72 h. In the presence of 5% non-inhibitory rabbit serum this resulted in a 2-3-fold increase in collagen degradation and a dramatic change in osteoblast morphology, when compared with untreated osteoblasts. Collagenolysis was accompanied by increased synthesis and release of latent collagenase, gelatinase and stromelysin and a concomitant decrease in their specific inhibitor, TIMP (tissue inhibitor of metalloproteinases). In serum-free medium, osteoblasts failed to degrade collagen, but their ability to lyse collagen could be restored by adding plasminogen (5 micrograms/ml) to the cultures. Plasminogen-dependent collagenolysis was inhibited by human recombinant TIMP (5 units/ml), demonstrating that plasmin, derived from plasminogen, activated latent collagenase and did not itself degrade collagen. Plasminogen activator production was confirmed by culturing osteoblasts on 125I-labelled fibrin plates. Comparison with urokinase-type and tissue-type plasminogen activator standards suggested that osteoblast plasminogen activator was predominantly cell-associated and likely to be of the urokinase type. Immunocytochemistry indicated that osteoblasts also constitutively produce plasminogen activator inhibitor-1. These findings provide evidence for the involvement of a plasminogen-plasmin-latent metalloproteinase activation cascade in type I collagen degradation by osteoblasts, and for its regulation by TIMP and plasminogen activator inhibitor-1.
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PMID:Type I collagen degradation by mouse calvarial osteoblasts stimulated with 1,25-dihydroxyvitamin D-3: evidence for a plasminogen-plasmin-metalloproteinase activation cascade. 255 72

The sequence of events within the ovary during the process of ovulation discussed in this review is schematically represented in Fig. 1. It is obvious that LH, perhaps with some contribution from FSH, is the normal physiological trigger for the ovulatory sequence of events, and it appears from the available information that the effects of LH are mainly mediated via adenylate cyclase and increased cAMP levels. The cAMP in turn, via cAMP-dependent protein kinase, influences at least three distinct steps in the ovulatory process which seem to be of crucial importance, namely 1) the stimulation of steroidogenesis; 2) the stimulation of cyclooxygenase/lipooxygenase leading to increased prostaglandin/leukotriene synthesis; and 3) the stimulation of plasminogen activator which catalyzes the conversion of plasminogen to plasmin. A fourth crucial step in the ovulatory mechanism is the LH-induced increase in latent collagenase, but it remains to be determined if this step is mediated via cAMP. Concomitant with the increase in latent collagenase, there also appears to be an LH-dependent increase in collagenase inhibitors. The latent collagenase is then activated, and it appears that leukotrienes and prostaglandins, as well as plasmin, may be involved in this process. The active collagenase causes a digestion of the collagen in the follicle wall, and plasmin, as well as possibly other proteolytic enzymes such as proteoglycanases, may cause a further dissociation of the follicular wall. These processes of digestion of collagen and dissociation of the collagen fibers result in an opening in the follicular wall with the formation of the stigma and rupture. While the weakening of the follicular wall takes place throughout the entire wall, rupture remains for the most part a localized process at the apex of the follicle. This localization of the rupture may be explained on the basis of mechanical factors operating when the follicle wall thins and weakens. While it is clear that prostaglandins and leukotrienes can influence smooth muscle by causing contractions and that these compounds can cause vascular changes such as increased permeability, vasodilation, and vasoconstriction, it is not clear what the exact role of these latter processes are in ovulation. It appears that progesterone and not estrogen play an important role in the mechanism of LH-induced follicular rupture, but the locus of action of progesterone and its mechanism of action remains to be determined.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Mechanism of mammalian ovulation. 255 97

A meshwork of collagen over the apical region of the follicle must be breached to permit the ovum to escape. We propose that specific collagenase activity is responsible for collagen breakdown in this region. Immature rats are primed with pregnant mare serum gonadotropin (PMSG), followed at 48 h by hCG. At 8 h after hCG, collagenase activity, measured in extracts of ovarian tissue, is elevated about five-fold. Ovulation follows at 10-12 h. Ovaries from PMSG-primed rats are dissected at 48 h, placed in a perfusion apparatus, and perfused with luteinizing hormone and 3-isobutyl-1-methyl xanthine. The ovulations induced by this treatment can be blocked to the extent of 70% with a synthetic collagenase inhibitor. The activation of procollagenase is believed to involve plasminogen activator and plasmin. In support of this, we find that tranexamic acid at 1 mM inhibits ovulation about 70%. The inhibitor must be added within 3-4 h of LH to be effective. A specific plasmin inhibitor, D-Val-Phe-Lys-chloromethyl ketone, is similarly effective.
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PMID:Connective tissue breakdown in ovulation. 255 98

To assess the role of inhibitors of proteolytic enzymes, such as plasminogen activator (PA) and collagenase in the ovulatory process, inhibitor activity and mRNA levels were examined in periovulatory rat and human ovaries. In the rat, immature animals received 20 IU of pregnant mare serum gonadotropin (PMSG) followed 52 h later by 10 IU of hCG. Ovaries were removed at intervals from 0 to 20 h after human chorionic gonadotropin (hCG) administration. Inhibitor activity for metalloproteinases, such as collagenase, increased from 60.5 +/- 4.1 inhibitor units/ovary at 0 h (i.e., time of hCG treatment) to a maximum of 218.2 +/- 11.4 units/ovary at 8 h after hCG before decreasing at 12 h (time of ovulation) and 20 h (122.2 +/- 7.9 and 71.6 +/- 8.1 units/ovary, respectively). Human follicular fluid and granulosa cells were obtained from preovulatory follicles of patients in our in vitro fertilization program. Metalloproteinase inhibitor activity was evaluated in follicular fluid as well as the levels of PA and PA inhibitor (PAI) mRNA by Northern analysis. Increasing metalloproteinase inhibitor activity was positively correlated with follicular levels of estradiol (p less than 0.001) and progesterone (p less than 0.02, N = 26). Chromatographic separation of follicular fluid resulted in two peaks of metalloproteinase inhibitor activity. The large molecular weight (MW) inhibitor had an approximate size of 700 kilodaltons (kDa) and may represent alpha 2-macroglobulin, a serum-derived inhibitor. The small MW inhibitor shared many of the characteristics of tissue-derived inhibitors of metalloproteinases. Partial purification of the small MW inhibitor by Concanavalin A-Sepharose and Heparin-Sepharose chromatography demonstrated the inhibitor to be a glycoprotein with an approximate MW = 28-29 K. Northern analysis of human granulosa cell total RNA from preovulatory follicles showed little or no detectable tissue-type PA or urokinase-type PA mRNA. In contrast, two species of PA inhibitor type-1 mRNA were detected in relative abundance. The present findings demonstrate the presence of proteolytic inhibitors in periovulatory ovaries of the rat and human. These ovarian inhibitors may play a role in regulating connective tissue remodeling during follicular rupture.
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PMID:The role of ovarian proteases and their inhibitors in ovulation. 255 99

The secretion of elevated levels of proteinases is considered to be a distinct property of most transformed cells. The cellular and secreted levels of plasminogen activators and collagenases have been examined in the nonmalignant human osteosarcoma (HOS), the malignant Kirsten murine sarcoma virus transformed (KHOS/NP), the temperature sensitive revertant of virus transformed HOS (KHOS-240S) and N-methyl-N'-nitro-N-nitrosoguanidine transformed HOS (MNNG/HOS) clones. Virus and MNNG transformed clones exhibit 100- and 7-fold higher cellular and and 270- and 30-fold higher extracellular plasminogen activator (PA) activity as compared with untransformed HOS controls. The cellular PA activity of the revertant clone is similar to but the secreted level is slightly higher than the HOS controls. SDS-PAGE in the presence of casein and plasminogen is consistent with the major PA species of urinary type (u-PA) and with the absence of PA inhibitor in the parent and revertant clones. The cellular levels of active collagenase are low in all the clones. However, on activation by trypsin, the two active collagenase bands of similar intensity are observed for all the lines in SDS-PAGE in the presence of gelatin. While there appears to be some elevation of secreted collagenase prior to trypsin activation, the activated collagenases appear to have the same size and activity in all of the clones.
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PMID:Synthesis and secretion of plasminogen activators and collagenases in human cells transformed by Kirsten murine sarcoma virus and N-methyl-N'-nitro-N-nitrosoguanidine. 256 62

The sequence of ovarian events during the process of ovulation discussed in this review is schematically represented in Figure 1. It is obvious that LH, perhaps with some contribution from FSH, is the normal physiological trigger for the ovulatory sequence of events and it appears from the available information that LH's effects are mainly mediated via adenylate cyclase and increased cAMP. The cAMP in turn, via cAMP-dependent protein kinase, influences at least three distinct steps in the ovulatory process which seem to be of crucial importance, namely 1) the stimulation of steroidogenesis; 2) the stimulation of cyclooxygenase/lipooxygenase leading to increased prostaglandin/leukotriene synthesis; and 3) the stimulation of plasminogen activator which catalyzes the conversion of plasminogen to plasmin. A fourth crucial step in the ovulatory mechanism is the LH-induced increase in latent collagenase, but it remains to be determined if this step is mediated via cAMP. Concomitant with the increase in latent collagenase, there also appears to be an LH-dependent increase in collagenase inhibitors. The latent collagenase is then activated and it appears that leukotrienes and prostaglandins as well as plasmin may be involved in this process. The active collagenase causes a digestion of the collagen in the follicle wall. Plasmin as well as possibly other proteolytic enzymes such as proteoglycanases (Too et al., 1984) may cause a further dissociation of the follicular wall. These processes of digestion of collagen and dissociation of the collagen fibers result in an opening in the follicular wall with the formation of the stigma and rupture. While the weakening of the follicular wall takes place throughout the entire wall, rupture remains for the most part a localized process at the apex of the follicle. This localization of the rupture may be explained on the basis of mechanical factors operating when the follicle wall thins and weakens (Rodbard, 1984). While it is clear that prostaglandins and leukotrienes can influence smooth muscle by causing contractions and that these compounds can cause vascular changes such as increased permeability, vasodilatation and vasoconstriction, it is not clear what the exact role of these latter processes are in ovulation. It appears that progesterone and not estrogen play an important role in the mechanism of LH induced follicular rupture, but the locus of action of progesterone and its mechanism of action remains to be determined.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Mechanism of mammalian ovulation. 265 83

The early biochemical events that link interleukin-1 (IL-1) receptor occupancy to neutral proteinase production in synovial cells were studied. Addition of human r-IL-1 to human synovial cells in culture stimulated phospholipase A2 (PLA2) activity, inositol triphosphate production and plasminogen activator (PA) activity in a dose dependent manner with similar EC50 values (0.1-0.5 nM). These results, coupled with time courses and other studies, suggest that the IL-1 modulation of PA involves both products of PLA2 and phospholipase C (PLC) activation. On the other hand, the IL-1 induction of collagenase may primarily involve PLC and protein kinase C activation.
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PMID:Interleukin-1 mediated signal transduction associated with synovial cell activation. 267 53

Previous studies of alkali burns have provided evidence for an important role of the plasminogen activator (PA)/plasmin system in corneal ulceration. Current studies have utilized a sensitive, plasminogen-dependent fluorescent assay to demonstrate that PA is present mostly in a latent (trypsin- or plasmin-activatable) form (proactivator) in cultures of rabbit corneal epithelial cells or normal corneas. Cultures of ulcerating corneas demonstrate only active PA early in organ culture, whereas, latent PA levels increase later in culture. Thus, ulceration is correlated with the apparent conversion of latent to active PA. Moreover, profiles of proactivator and latent collagenase and of active PA and active collagenase in vitro, respectively, are similar, suggesting that activator and collagenase are under coordinate control. Cultures of normal epithelial cells and nonulcerating corneas contain PA molecular weight species of 72,000 and 46,000 MW, and ulcer corneas, species of 72,000, 46,000, and 35,000 MW. Double-diffusion analysis indicates that rabbit epithelial cells, fibroblasts, and ulcer corneas produce urokinase (UK)-like PA; and human cornea extracts and tears also contain PA immunoreactive with anti-UK antibodies. The existence of PA in a latent form identifies another level of regulation in the cascades that lead to stromal ulceration.
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PMID:Latent and active plasminogen activator in corneal ulceration. 298 39

The crucial role of non-plasminogen dependent serine proteinases is tissue invasive and cytolytic functions of Walker 256 cancer cells has been documented using a rat urinary bladder invasion and a 125I-labelled fibroblast cytolysis assay. The invasive capacity of these cancer cells was abrogated by non toxic concentrations of the serine proteinase inhibitors, diisopropylfluorophosphate and phenylmethylsulfonylfluoride, but not by metallo or cysteine proteinase inhibitors. Although tumour cell collagenase activity and plasminogen activator were demonstrated, these proteolytic enzymes were not essential in these in vitro assays. These results suggest that different categories of proteinases play specific roles in the complicated process of cancer invasion.
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PMID:Role for different cell proteinases in cancer invasion and cytolysis. 299 66


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