Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Complex carbohydrates on the surfaces of eukaryotic cells are thought to participate in a wide variety of cell-cell interactions. A model system has therefore been developed to study these processes. In the present experiments, the ability of chicken hepatocytes to recognize and adhere to sugars covalently linked to polyacrylamide gels was investigated. The gels were snythesized by two methods. Type I gels were prepared from a co-polymer of an active ester of acrylic acid (N-succinimidyl acrylate), acrylamide, and bisacrylamide. The "activated" polyacrylamide gel was then treated with the desired ligand containing an amino group, such as 6-aminohexyl O- or S-glycoside. Type II gels were formed by treating similar ligands with acryloyl chloride, followed by co-polymerization of the resulting N-substituted acrylamide with acrylamide and N,N'-methylenebisacrylamide. These polyacrylamide derivatives offer many advantages for studies with intact cells. They are not toxic to any cell type studied, can be cast in any desired shape, are transparent and stable over a wide range of pH values, and contain no cationic and low to negligible levels of anionic charge (charged groups can be introduced if desired), and the polyacrylamide matrix is stable to common biological agents such as bacteria and enzymes. In addition, type I gels can be synthesized using a broad range of molecules containing amino groups, such as glycopeptides, proteins, etc. The hepatocytes were prepared by collagenase perfusion of intact chicken livers. The rate and extent of adhesion of the cells to the derivatized gels was determined by measuring lactate dehydrogenase in these cells. This enzyme was also used to assay viability and cell "leakiness." At 37 degrees C, 70 to 100% of the cells adhered within 60 min to gels derivatized with N-acetylglucosamine, i.e. gels derivatized with 6-aminohexyl 2-acetamido-2-deoxy-beta-D-glucopyranoside (or the corresponding thioglycoside). By contrast, less than 5% of the cells adhered to polyacrylamide or to gels derivatized with 6-aminohexanol or the 6-aminohexyl glycosides of beta-D-glucose, beta-D-galactose, alpha-D-mannose, beta-D-maltose, beta-D-melibiose, beta-D-cellobiose, and (alpha or beta)-D-lactose. Kinetic studies with the chicken hepatocytes and N-acetylglucosamine gels showed that cell-gel binding was dependent upon Ca2+ and was decreased at low temperatures. Binding was inhibited by N-acetylglucosamine or by glycosides of this sugar, the most effective inhibitor being orosomucoid (alpha1-acid glycoprotein) pretreated with sialidase and beta-galactosidase. The cell surface receptor(s) involved in this interaction is not known, but may be related or identical to the chicken liver binding protein described by Lunney and Ashwell (Lunney, J., and Ashwell, G. (1976) Proc. Natl. Acad. Sci. U. S. A. 73, 341--343). The present results suggest that this model system should prove useful in delineating cell surface interactions with carbohydrates.
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PMID:Adhesion of chicken hepatocytes to polyacrylamide gels derivatized with N-acetylglucosamine. 70 Dec 94

The urokinase-dependent plasminogen activating system is regulated not only by zymogen to enzyme conversion of pro-urokinase and inhibition of the active enzyme by plasminogen activator inhibitors, but also by regulated expression of urokinase receptors on the cell surface. Receptor-bound pro-urokinase in turn becomes activated and is capable of activating plasminogen probably bound site by site to urokinase to a cell surface receptor. Plasmin by itself or via activation of pro-collagenase to collagenase is capable of degrading the extracellular matrix, in turn mediating processes like invasion, metastasis and tumour growth. In addition, in some cell lines the urokinase-dependent system mediated via receptor-bound active urokinase is also capable of eliciting a mitogenic response of the cells. Therefore, the urokinase-dependent plasminogen activating system might not only be responsible for mediating extravascular proteolysis but might also be an autocrine mitogen for some cell lines.
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PMID:Influence of urokinase on cell proliferation and invasion. 196 99

Tumor cell motility and the passage of tumor cells through various tissue matrices, including basement membrane, are important components of the metastatic process. Proteolytic enzymes, including a type IV collagen-specific collagenase, have been demonstrated to play a significant role in extracellular matrix and basement membrane degradation. In addition, exogenous collagenase has been shown to enhance the motility of some tumor cells independent of its effect on collagen-containing material. Previous studies have also indicated that collagen fragments are chemotactic for many tumor cells. We therefore studied the effect of type I and type IV collagen-specific collagenases, other enzymes involved in collagenase activation and connective tissue degradation, and subsequent collagen degradation products on the directed migration of tumor cells. We report that type I and type IV collagen-specific mammalian collagenases were potent chemoattractants as were native type I and type IV collagens and collagen fragments. Collagenase inhibitor SC44483 inhibited the type IV collagenase-stimulated migration. Collagenase pretreatment of the tumor cells potentiated the migratory response of the tumor cells to collagen and collagen fragments. The plasminogen activator, urokinase, as well as plasminogen itself also enhanced the directed migration of tumor cells in concentrations that suggest involvement of the appropriate cell surface receptor. The chemotactic response of tumor cells to the proteases studied extends the prior report of a role for collagenases and other matrix-active enzymes in tumor cell behavior in addition to matrix degradation.
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PMID:Directed migration of murine and human tumor cells to collagenases and other proteases. 254 19

The present study was intended to examine the structure of the rat Leydig cell gonadotropin receptor. Leydig cell suspensions were prepared by either collagenase digestion or mechanical disruption of the testes. The cells were incubated with 125I-human chorionic gonadotropin (hCG) following which the bound 125I-hCG was covalently cross-linked to the cell surface receptor using a cleavable (dithiobis(succinimidyl propionate] and a noncleavable (disuccinimidyl suberate) cross-linking reagent. The extracted cross-linked membrane proteins were resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions and subjected to autoradiographic analysis. Under nonreducing conditions, three radiolabeled bands, in addition to intact hCG and its alpha-subunit, were detected with apparent molecular weights of 184,000, 136,000, and 103,000. However, under reducing conditions, three radiolabeled bands migrated on the gel corresponding to molecular weights of 144,000, 106,000, and 75,000. The binding of 125I-hCG to the receptor was inhibited by hCG and luteinizing hormone, but not by a number of other peptides or proteins. The radiolabeled bands were not detectable in hCG down-regulated Leydig cells. Furthermore, a similar autoradiographic pattern of 125I-hCG-linked complexes was seen when the 125I-linked receptor complex was subjected to immunoprecipitation with anti-hCG antibodies followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In addition, evidence was obtained indicating that these three labeled bands were derived from the same molecular species. The data suggests that the hCG receptor in Leydig cell is probably an oligomeric complex with a molecular weight of about 250,000, which is composed of three polypeptide chains of molecular weights 121,000, 83,000, and 52,000 held together through noncovalent forces. Additionally, collagenase treatment of Leydig cells does not appear to alter the autoradiographic pattern of the 125I-hCG-linked receptor.
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PMID:Characterization of rat Leydig cell gonadotropin receptor structure by affinity cross-linking. 333 12

We used affinity chromatography to isolate a specific laminin-binding protein from murine fibrosarcoma cells. These cells bind exogenous laminin to their surface with high affinity (Kd = 2 X 10(-9)M for laminin) with approximately 5 X 10(4) sites per cell. Laminin affinity chromatography of [35S]methionine-labeled cell extracts produced two distinct proteins. One was identified as Type IV (basement membrane) collagen based on its migration pattern on SDS gels and bacterial collagenase sensitivity. The other protein, which migrates as a single band or closely spaced doublet on reduced SDS gels, has a reduced molecular weight of 69,000. Using a nitrocellulose filter disk assay, we found that the latter protein specifically bound 125I-laminin with the same high affinity (Kd = 2 X 10(-9)M for laminin) as did intact fibrosarcoma cells. By iodinating intact cells, we demonstrated that this laminin-binding protein is on the cell surface. We conclude that this protein with reduced molecular weight of 69,000 is a subunit or component of a larger cell surface receptor protein for laminin in this fibrosarcoma model. This laminin receptor may mediate the interaction of the cell with its extracellular matrix.
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PMID:Isolation of a cell surface receptor protein for laminin from murine fibrosarcoma cells. 630 2

Proteolytic enzymes such as urokinase-type plasminogen activator (uPA), plasmin, and collagenase mediate proteolysis by a variety of tumor cells. uPA secreted by tumor cells can be bound to a cell surface receptor via a growth factor-like domain within the amino-terminal fragment (ATF) of the uPA molecule with high affinity. Urinary trypsin inhibitor (UTI) efficiently inhibits the soluble and the tumor cell-surface receptor-bound plasmin and subsequently reduces tumor cell invasion and the formation of metastasis. The anti-invasive effect is dependent on the anti-plasmin activity of the UTI molecule, domain II in particular. We synthesized a conjugate between ATF of human uPA and a native UTI molecule or domain II of UTI (HI-8). The effect of the conjugates (ATF.UTI or ATF.HI-8) on tumor cell invasion in vitro was investigated. ATF.UTI and ATF.HI-8 bound to U937 cells in a rapid, saturable, dose-dependent, and reversible manner. A large part of receptor-bound ATF-UTI and ATF.HI-8 remains on the cell surface for at least 5 h at 37 degrees C. Inhibition of tumor cell-surface receptor-bound plasmin by ATF.UTI and ATF.HI-8 was markedly enhanced when compared with tumor cells treated either with ATF, UTI, or HI-8. Results of a cell invasion assay showed that ATF.UTI and ATF.HI-8 is very effective at targeting HI-8 specifically to uPA receptor-expressing tumor cells, whereas tumor cells devoid of uPA receptor may be less affected by the conjugates. Our results indicate that cell surface uPA and plasmin activity is essential to the invasive process and that the conjugates exhibit plasmin inhibition to the close environment of the cell surface and subsequently inhibit the tumor cell invasion through Matrigel in an in vitro invasion assay.
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PMID:Inhibitory effect of a conjugate between human urokinase and urinary trypsin inhibitor on tumor cell invasion in vitro. 771 45

Surfactant protein A (SP-A), with a reduced denatured molecular mass of 26-38 kDa, is characterized by a collagen-like sequence in the N-terminal half of the protein. This protein forms an oligomeric structure which is dependent upon this collagenous domain. SP-A has been demonstrated to function as an inhibitor of phospholipid secretion by primary cultures of alveolar type II cells via a cell surface receptor for the protein. However, the receptor-binding domain of SP-A has not been identified. The purpose of the present study was to investigate the role of the C-terminal domain of SP-A in binding to type II cells and regulation of phospholipid secretion. A monoclonal antibody to human SP-A, whose epitope was localized at the C-terminal domain of the protein, abolished the inhibitory activity of human SP-A on lipid secretion by type II cells, and attenuated the ability of human SP-A to compete with 125I-(rat SP-A) for receptor binding. SP-A was then digested with collagenase and the collagenase-resistant fragment (CRF), which is the C-terminal domain of SP-A (thus lacking the N-terminal domain), was isolated. Gel filtration chromatography revealed that CRF exists as a monomer in solution containing Ca2+. CRF had the ability to inhibit phospholipid secretion, although at a higher concentration than for SP-A, and was also able to compete with 125I-(rat SP-A) for binding to type II cells. A direct binding study showed that CRF bound to type II cells in a concentration-dependent manner. The present study demonstrates that the non-collagenous, C-terminal, domain of SP-A is responsible for the protein's inhibitory effect on lipid secretion and its binding to type II cells.
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PMID:Role of the C-terminal domain of pulmonary surfactant protein A in binding to alveolar type II cells and regulation of phospholipid secretion. 847 Oct 56

The intriguing problem of metastasis requires the spreading of metastatic cells through the basement membrane barrier. The interaction of the basement membrane with the metastatic cell is a cell surface activity involving the function of integrin receptors. Integrins are a group of alpha,beta heterodimeric proteins responsible for transducing intracellular signals on binding to the extracellular matrix proteins present in the basement membrane. To understand the role of integrin receptors in tumor metastasis, the cell surface receptor functions were modulated by All Trans Retinoic Acid (ATRA) treatment in B16F10 tumor cells. Our experimental results clearly indicate that All Trans Retinoic Acid (ATRA) inhibit metastatic potential of highly metastatic B16F10 melanoma cells by 1) downregulating the cell surface integrin receptors against ECM proteins specially laminin and vitronectin and 2) by inhibiting the 72 kd collagenase activity.
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PMID:Effect of retinoic acid on integrin receptors of B16F10 melanoma cells. 1084 Sep 41

IL-6 mediates its activity through a cell surface receptor composed of a signal transducing protein, CD130, and a ligand-binding protein which exists in membrane-bound form (CD126) or in soluble form (sIL-6R alpha). Interestingly, sIL-6R alpha combined with IL-6 is able to interact with CD130 leading to the intracellular cascade of activation. In the present study, using flow cytometry, we show that stromal cells from human bone marrow (BMSC) express CD130 but not CD126. We demonstrate that BMSC are responsive to IL-6 only in the presence of exogenous sIL-6R alpha. Indeed, exogenous sIL-6R alpha induces in BMSC the production of its own ligand, IL-6, and of both MMP-1 and MMP-2, two matrix metalloproteinases involved in bone resorption and in tumour spreading, respectively. Since myeloma cells release sIL-6R alpha in the close vicinity of BMSC, these data suggest a role for this factor in the pathophysiology of multiple myeloma, a B-cell malignancy dependent on IL-6 for its growth and characterized by bone destruction.
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PMID:Soluble IL-6R alpha upregulated IL-6, MMP-1 and MMP-2 secretion in bone marrow stromal cells. 1097 8

Human skin is exposed to solar ultraviolet radiation. Ultraviolet radiation damages human skin and results in an old and wrinkled appearance, called photoaging. We have previously reported that molecular mechanisms by which ultraviolet light causes photoaging involve activation of growth factor and cytokine receptors in keratinocytes and dermal cells. They lead to downstream signal transduction through activation of mitogen-activated protein kinase (extracellular signal-regulated kinase, c-jun N-terminal protein kinase, and p38) pathways. These signaling pathways converge in the nucleus of cells to form an activated complex of transcription factor activator protein 1 (cFos/cJun), which induces matrix metalloproteinases that degrade skin connective tissue. In addition to cell surface receptor activation, generation of reactive oxygen species by ultraviolet radiation is believed to be critical in triggering mitogen-activated protein kinase pathways. We investigated the ability of (i) ultraviolet irradiation to generate reactive oxygen species in human skin in vivo; and (ii) genistein, which possesses both tyrosine kinase inhibitory and antioxidant activities, and n-acetyl cysteine, which can be converted into the endogenous antioxidant glutathione, to impair responses to ultraviolet light that eventuate in photoaging in human skin in vivo. Ultraviolet irradiation caused a rapid and significant increase in hydrogen peroxide levels in human skin in vivo. Pretreatment of human skin with genistein inhibited ultraviolet-induced epidermal growth factor receptor tyrosine kinase activity, whereas n-acetyl cysteine did not. Genistein inhibited ultraviolet induction of both extracellular signal-regulated kinase and cJun N-terminal protein kinase activities. n-Acetyl cysteine inhibited extracellular signal-regulated kinase but not cJun N-terminal protein kinase activation. Both genistein and n-acetyl cysteine prevented ultraviolet induction of cJun protein. Consistent with this, genistein and n-acetyl cysteine blocked ultraviolet induction of cJun-driven enzyme, collagenase. Neither genistein nor n-acetyl cysteine acted as sunscreens as they had no effect on ultraviolet-induced erythema. These data indicate that compounds similar to genistein and n-acetyl cysteine, which possess tyrosine kinase inhibitory and/or antioxidant activities, may prevent photoaging.
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PMID:Topical N-acetyl cysteine and genistein prevent ultraviolet-light-induced signaling that leads to photoaging in human skin in vivo. 1271 90


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