Academic literature on the topic 'Extracellular matrix fragments'
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Journal articles on the topic "Extracellular matrix fragments"
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McKeown-Longo, P. J., and D. F. Mosher. "Interaction of the 70,000-mol-wt amino-terminal fragment of fibronectin with the matrix-assembly receptor of fibroblasts." Journal of Cell Biology 100, no. 2 (February 1, 1985): 364–74. http://dx.doi.org/10.1083/jcb.100.2.364.
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Plasma fibronectin binds saturably and reversibly to substrate-attached fibroblasts and is subsequently incorporated into the extracellular matrix (McKeown-Longo, P.J., and D. F. Mosher, 1983, J. Cell Biol., 97:466-472). We examined whether fragments of fibronectin are processed in a similar way. The amino-terminal 70,000-mol-wt catheptic D fragment of fibronectin bound reversibly to cell surfaces with the same affinity as intact fibronectin but did not become incorporated into extracellular matrix. The 70,000-mol-wt fragment blocked binding of intact fibronectin to cell surfaces and incorporation of intact fibronectin into extracellular matrix. Binding of the 70,000-mol-wt fragment to cells was partially abolished by cleavage into 27,000-mol-wt heparin-binding and 40,000-mol-wt gelatin-binding fragments and more completely abolished by reduction and alkylation of disulfide bonds. Binding of the 70,000-mol-wt fragment to cells was not blocked by gelatin or heparin. When coated onto plastic, the 70,000-mol-wt fragment did not mediate attachment and spreading of suspended fibroblasts. Conversely, fibronectin fragments that had attachment and spreading activity did not block binding of exogenous fibronectin to substrate-attached cells. These results indicate that there is a cell binding site in the 70,000-mol-wt fragment that is distinct from the previously described cell attachment site and is required for assembly of exogenous fibronectin into extracellular matrix.
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Unsold, C., M. Hyytiainen, L. Bruckner-Tuderman, and J. Keski-Oja. "Latent TGF-beta binding protein LTBP-1 contains three potential extracellular matrix interacting domains." Journal of Cell Science 114, no. 1 (January 1, 2001): 187–97. http://dx.doi.org/10.1242/jcs.114.1.187.
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Latent TGF-beta binding proteins (LTBPs) are components of the extracellular matrix (ECM). They belong to the fibrillin/LTBP-superfamily, and are high molecular weight glycoproteins characterized by EGF-like repeats and 8-Cys repeats. Most LTBPs associate with the small latent forms of TGF-beta. Their roles include to facilitate the secretion of latent TGF-beta and to target it to the ECM. In order to identify new matrix-binding domains of LTBP-1 and to characterize their association with the extracellular matrix, we have produced (in a mammalian expression system) partly overlapping recombinant fragments of its shorter form, LTBP-1S, and analyzed the binding of the purified fusion proteins to extracellular matrices of cultured human dermal and lung fibroblasts. Recombinant fragments from three different regions of the N- and C-termini showed affinity to the matrix. These interacting regions contain either the first (hybrid), second or fourth 8-Cys domains of the LTBP-1S molecule. They bound independently to the matrix. Each of them had an ability to inhibit the association of native exogenous LTBP-1 with fibroblast extracellular matrix. The interactions of the LTBP-1 fragments with the extracellular matrix resisted treatment with sodium deoxycholate, suggesting strong, possibly covalent binding. The binding occurred in a time- and dose-dependent fashion. The N-terminal fragments bound more readily to the matrices. With all fragments the binding took place both with intact fibroblast matrices and with matrices isolated by sodium deoxycholate. When using CHO cell layers, which form sparse matrices, only the N-terminal fragment of LTBP-1 was efficiently incorporated. The association of the binding fragments with isolated matrices was enhanced by soluble, cell-derived factors. The current data suggest that LTBP-1 contains three different domains with an ability to associate with the extracellular matrix.
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Schedin, P., R. Strange, T. Mitrenga, P. Wolfe, and M. Kaeck. "Fibronectin fragments induce MMP activity in mouse mammary epithelial cells: evidence for a role in mammary tissue remodeling." Journal of Cell Science 113, no. 5 (March 1, 2000): 795–806. http://dx.doi.org/10.1242/jcs.113.5.795.
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Mammary gland form and function are regulated by interactions between epithelium and extracellular matrix. Major glycoprotein components of extracellular matrix have been identified that give survival, proliferation and differentiation signals to mammary epithelial cells. We provide evidence that proteolytic fragments of the extracellular matrix glycoprotein, fibronectin, suppress growth and can promote apoptosis of mouse mammary epithelial cells. During mammary gland involution, total fibronectin and fibronectin fragment levels are increased. The peak levels of fibronectin protein and fragments are observed 4–6 days post-weaning, coincident with the peak in epithelial cell death. Using a model for hormone withdrawal-induced death of mammary epithelium, elevated levels of fibronectin proteolytic fragments were associated with apoptosis in TM-6 cells, a tumorigenic mouse mammary epithelial cell line. Treatment of TM-6 cells with exogenous fibronectin fragments (FN120) reduced cell number, and induced apoptosis and matrix degrading protease activity. Inhibition of matrix protease activity rescued TM-6 cell viability, indicating that FN120-induced cell loss is mediated through matrix protease activity. In a three-dimensional model for mammary gland development, FN120 reduced alveolar-like and promoted ductal-like development by a matrix protease-dependent mechanism. These data suggest that during post-lactational involution, fibronectin fragments may contribute to epithelial cell loss and dissolution of mammary alveoli by inducing matrix degrading proteinases.
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Olmo, N., J. Turnay, G. Risse, R. Deutzmann, K. von der Mark, and M. A. Lizarbe. "Modulation of 5′-nucleotidase activity in plasma membranes and intact cells by the extracellular matrix proteins laminin and fibronectin." Biochemical Journal 282, no. 1 (February 15, 1992): 181–88. http://dx.doi.org/10.1042/bj2820181.
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Modulation of 5′-nucleotidase activity by the extracellular matrix proteins fibronectin, laminin and their fragments has been studied in plasma membrane preparations as well as in intact BCS-TC2 and Rugli cells. The ectoenzyme on plasma membranes is activated by laminin; fibronectin inhibits the AMPase activity on BCS-TC2 plasma membranes but no inhibitory effect is found in plasma membrane preparations from Rugli cells. These effects are dependent on the preincubation time and protein concentration. When the effect of the extracellular matrix proteins is studied on intact cells, both BCS-TC2 and Rugli cells show similar behaviour. A decrease in the enzyme activity is observed in the presence of fibronectin. The AMPase inhibitory activity is located on its 40 kDa fragment. No inhibitory activity is found in other fibronectin fragments, including the 140 kDa fragment which contains the RGDS cell-adhesion sequence. Laminin and its E1-4 and E8 fragments are able to activate the ecto-5′-nucleotidase activity of both BCS-TC2 and Rugli cells. The effect of the E1-4 fragment on intact cells is greater than that observed for the E8 fragment and uncleaved laminin. Our results suggest a bifunctional role for 5′-nucleotidase as ectoenzyme and cell receptor for extracellular matrix proteins.
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Bekaert, Sandrine, Marianne Fillet, Benoit Detry, Muriel Pichavant, Raphael Marée, Agnes Noel, Natacha Rocks, and Didier Cataldo. "Inflammation-Generated Extracellular Matrix Fragments Drive Lung Metastasis." Cancer Growth and Metastasis 10 (January 1, 2017): 117906441774553. http://dx.doi.org/10.1177/1179064417745539.
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Mechanisms explaining the propensity of a primary tumor to metastasize to a specific site still need to be unveiled, and clinical studies support a link between chronic inflammation and cancer dissemination to specific tissues. Using different mouse models, we demonstrate the role of inflammation-generated extracellular matrix fragments ac-PGP ( N-acetyl-proline-glycine-proline) on tumor cells dissemination to lung parenchyma. In mice exposed to cigarette smoke or lipopolysaccharide, lung neutrophilic inflammation produces increased levels of MMP-9 (matrix metalloproteinase 9) that contributes to collagen breakdown and allows the release of ac-PGP tripeptides. By silencing CXCR2 gene expression in tumor cells, we show that these generated ac-PGP tripeptides exert a chemotactic activity on tumor cells in vivo by binding CXCR2.
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ADAIRKIRK, T., and R. SENIOR. "Fragments of extracellular matrix as mediators of inflammation." International Journal of Biochemistry & Cell Biology 40, no. 6-7 (June 2008): 1101–10. http://dx.doi.org/10.1016/j.biocel.2007.12.005.
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WAGA, SHINOBU, KAZUHIKO SUGIMOTO, HIROSHI TANAKA, TATSUO ITO, TOHRU NAKAHATA, TAKASHI TATEYAMA, YOSHIKI KAKIZAKI, and MASARU YOKOYAMA. "IgA Interaction with Carboxy-Terminal 43-kD Fragment of Fibronectin in IgA Nephropathy." Journal of the American Society of Nephrology 10, no. 2 (February 1999): 256–63. http://dx.doi.org/10.1681/asn.v102256.
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Abstract. IgA deposition in the glomerular mesangial matrix is a prerequisite for the diagnosis of IgA nephropathy, and circulating IgA-containing complex has been implicated in this process. Since fibronectin is known to be involved in the assembly of extracellular matrix, this study was conducted to investigate whether fibronectin and its fragments are present in sera of patients and are capable of binding IgA1. Sera from patients with IgA nephropathy were purified by heparin-affinity chromatography, and column eluate were analyzed for the presence of fibronectin using Western blot and a set of anti-fibronectin monoclonal antibodies. Native fibronectin was digested with cathepsin D to obtain fragments similar to those of serum fibronectin. The capacity of fibronectin to bind IgA was examined with a mixture of purified IgA1 and cathepsin D-digested fibronectin fragments. A 43-kD carboxy-terminal fragment of fibronectin was detected in samples derived from sera of patients with IgA nephropathy but not in healthy control subjects. A similar-sized fragment was generated by cathepsin D digestion of the native molecule and was shown to bind to IgA1 in vitro. Since the carboxy-terminal domain is known to be critical in assembling exogenous fibronectin into the extracellular matrix, the affinity to IgA1 to a fragment found in patients may have pathogenic potential to mediate extracellular IgA deposition in IgA nephropathy.
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Christopher, R. A., S. R. Judge, P. A. Vincent, P. J. Higgins, and P. J. McKeown-Longo. "The amino-terminal matrix assembly domain of fibronectin stabilizes cell shape and prevents cell cycle progression." Journal of Cell Science 112, no. 19 (October 1, 1999): 3225–35. http://dx.doi.org/10.1242/jcs.112.19.3225.
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Adhesion to the extracellular matrix modulates the cellular response to growth factors and is critical for cell cycle progression. The present study was designed to address the relationship between fibronectin matrix assembly and cell shape or shape dependent cellular processes. The binding of fibronectin's amino-terminal matrix assembly domain to adherent cells represents the initial step in the assembly of exogenous fibronectin into the extracellular matrix. When added to monolayers of pulmonary artery endothelial cells, the 70 kDa fragment of fibronectin (which contains the matrix assembly domain) stabilized both the extracellular fibronectin matrix as well as the actin cytoskeleton against cytochalasin D-mediated structural reorganization. This activity appeared to require specific fibronectin sequences as fibronectin fragments containing the cell adhesion domain as well as purified vitronectin were ineffective inhibitors of cytochalasin D-induced cytoarchitectural restructuring. Such pronounced morphologic consequences associated with exposure to the 70 kDa fragment suggested that this region of the fibronectin molecule may affect specific growth traits known to be influenced by cell shape. To assess this possibility, the 70 kDa fragment was added to scrape-wounded monolayers of bovine microvessel endothelium and the effects on two shape-dependent processes (i.e. migration and proliferation) were measured as a function of time after injury and location from the wound. The addition of amino-terminal fragments of fibronectin to the monolayer significantly inhibited (by >50%) wound closure. Staining of wounded monolayers with BrdU, moreover, indicated that either the 70 kDa or 25 kDa amino-terminal fragments of fibronectin, but not the 40 kDa collagen binding fragment, also inhibited cell cycle progression. These results suggest that the binding of fibronectin's amino-terminal region to endothelial cell layers inhibits cell cycle progression by stabilizing cell shape.
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Chakraborty, Abir, Natasha Marie-Eraine Boel, and Adrienne Lesley Edkins. "HSP90 Interacts with the Fibronectin N-terminal Domains and Increases Matrix Formation." Cells 9, no. 2 (January 22, 2020): 272. http://dx.doi.org/10.3390/cells9020272.
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Heat shock protein 90 (HSP90) is an evolutionarily conserved chaperone protein that controls the function and stability of a wide range of cellular client proteins. Fibronectin (FN) is an extracellular client protein of HSP90, and exogenous HSP90 or inhibitors of HSP90 alter the morphology of the extracellular matrix. Here, we further characterized the HSP90 and FN interaction. FN bound to the M domain of HSP90 and interacted with both the open and closed HSP90 conformations; and the interaction was reduced in the presence of sodium molybdate. HSP90 interacted with the N-terminal regions of FN, which are known to be important for matrix assembly. The highest affinity interaction was with the 30-kDa (heparin-binding) FN fragment, which also showed the greatest colocalization in cells and accommodated both HSP90 and heparin in the complex. The strength of interaction with HSP90 was influenced by the inherent stability of the FN fragments, together with the type of motif, where HSP90 preferentially bound the type-I FN repeat over the type-II repeat. Exogenous extracellular HSP90 led to increased incorporation of both full-length and 70-kDa fragments of FN into fibrils. Together, our data suggested that HSP90 may regulate FN matrix assembly through its interaction with N-terminal FN fragments.
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Gaggar, Amit, and Nathaniel Weathington. "Bioactive extracellular matrix fragments in lung health and disease." Journal of Clinical Investigation 126, no. 9 (September 1, 2016): 3176–84. http://dx.doi.org/10.1172/jci83147.
Full textDissertations / Theses on the topic "Extracellular matrix fragments"
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Muir, Paula Louise. "Age-related changes and the effect of fibronectin fragments on the composition of the extracellular matrix of the meniscus." Thesis, Royal Veterinary College (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406036.
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Vallet, Sylvain D. "Structure et interactions de la lysyl oxydase et de fragments de la matrice extracellulaire." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1296.
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La matrice extracellulaire est un réseau tridimensionnel complexe qui joue le rôle de support aux cellules ainsi que de réservoir de molécules bioactives régulant le comportement cellulaire. Elle est composée de 1027 protéines chez l’Homme (Naba et al., Matrix Biol. 2016), 274 protéines constituant le matrisome et 753 associées (facteurs de croissance et protéines régulatrices de la matrice extracellulaire) et de 6 glycosaminoglycanes dont 5 sulfatés. La matrice extracellulaire est impliquée dans de nombreuses pathologies (Bonnans et al., Nat. Rev. Mol. Cell Biol. 2014). La lysyl oxydase, responsable de la réticulation des collagènes et de l’élastine est impliquée dans de nombreux cancers. La matrice extracellulaire est un réservoir de fragments bioactifs, nommés matricryptines, qui sont libérés par protéolyse des biomolécules de la matrice et régulent de nombreux processus biologiques tels que l’angiogenèse et l’adipogenèse (Ricard-Blum et Vallet Matrix Biol. 2017). Nous avons exprimé en cellules humaines plusieurs matricryptines dont les ectodomaines des collagènes membranaires XIII, XVII, XXIII et XXV et identifié leurs partenaires extracellulaires. Nous avons caractérisé le propeptide de la lysyl oxydase par SEC-MALS, diffusion dynamique de la lumière et par SAXS et avons modélisé à partir des données de SAXS sa structure tridimensionnelle. Nous avons identifié 17 nouveaux partenaires de ce fragment et analysé le mutant Arg158Gln dépourvu d’activité biologique. Cette mutation identifiée chez l’Homme inhibe les activités anti-prolifératives du propeptide et est associée à un risque accru de cancer du sein (Min et al., Cancer Res. 2009). Nous avons exprimé la lysyl oxydase mature et modélisé sa structure tridimensionnelle en utilisant toutes les données disponibles. Les interactions identifiées au cours de ce travail ont été associées à celles obtenues par curation manuelle de la littérature pour construire la première version de l’interactome extracellulaire humainThe extracellular matrix is an intricate tridimensional network supporting cells and a bioactive molecule reservoir involved in the regulation of cell behavior. It is composed of 1027 proteins in humans (Naba et al., Matrix Biol. 2016), including 274 of the core matrisome and 753 associated proteins (growth factors and extracellular matrix regulators) and 6 glycosaminoglycans including 5 sulfated. The extracellular matrix is altered in numerous pathologies (Bonnans et al., Nat. Rev. Mol. Cell Biol. 2014). The lysyl oxidase is responsible for the cross-linking of collagens and elastin and is involved in many cancers. The extracellular matrix is a reservoir of bioactive fragments named matricryptins which are released by proteolysis of extracellular matrix proteins and regulate numerous biological processes like angiogenesis and adipogenesis (Ricard-Blum et Vallet, Matrix Biol. 2017). We have expressed under a recombinant form in human cells some matricryptins including the ectodomains of the membrane collagens XIII, XVII, XXIII and XXV and have identified their extracellular partners. We have characterized the propeptide of lysyl oxidase by SEC-MALS, dynamic light scattering, and SAXS and have built a coarse-grained 3D model by SAXS-derived constraints. We have identified 17 new partners of this fragment and analyzed the mutant Arg158Gln which has no biological activity. This mutation has been identified in humans and inhibits the propeptide anti-proliferative properties. It is associated to an increased risk of breast cancer (Min et al., Cancer Res. 2009). We have expressed the mature lysyl oxidase and modelled its tridimensional structure using available data. All the interactions identified in this study were associated to manually curated interactions described in the literature to build the first version of the human extracellular interactions network
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Lai, Andrew. "Towards the development of novel bispecific antibodies to inhibit key cell surface receptors integral for the growth and migration of tumour cells." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/101339/1/Andrew_Lai_Thesis.pdf.
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This project describes the development of antibody fragments against key cell surface receptors as potential metastatic breast cancer therapeutics. As a product of an iterative screening process, an antibody fragment candidate was demonstrated to be functionally active in the inhibition of cancer cell growth and migration. This study provides a promising platform for further development of the characterised antibody fragment with the goal of generating an effective treatment for the inhibition of cancer cell survival and metastasis.
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Manuel, Rachel. "Propriétés anti-angiogéniques d'un fragment dérivé du collagène V : mécanismes moléculaires et perspectives thérapeutiques." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10001.
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La matrice extracellulaire joue un rôle très important dans la régulation de l’angiogenèse en procurant un support dans la formation des vaisseaux, en délivrant des facteurs endogènes pro- ou anti-angiogéniques. Nous avons montré que l’hypoxie induit une surexpression du gène COL5A1 dans les cellules endothéliales. Le laboratoire a identifié un fragment issu du collagène V, noté HEPV, qui contient un site de liaison à l’héparine, et qui montre des propriétés anti-angiogéniques remarquables. En effet, ce fragment est capable d’inhiber la prolifération et la migration des cellules endothéliales vasculaires et leur maturation en tubes endothéliaux. Les résultats obtenus montrent qu’HEPV est capable d’empêcher la phosphorylation de ERK1/2 et de Akt induite par le FGF-2 et donc la réponse aux stimuli mitogènes induits par FGF-2. De plus, une étude transcriptomique réalisée sur des cellules endothéliales traitées ou non par HEPV a révélé que HEPV est capable d’induire l’expression de COL4A1 et COL18A, gènes codant pour des collagènes qui peuvent aussi être clivés et libérer des facteurs anti-angiogéniques. Finalement, nous avons utilisé un modèle d’angiogenèse murin afin de valider in vivo l’activité anti-angiogénique d’HEPV. Ces expériences montrent que le peptide injecté en intraveineuse s’accumule au site d’angiogenèse en se fixant sur les vaisseaux en formation, et est capable d’inhiber l’angiogenèse induite par le FGF-2, alors qu’un peptide contrôle muté sur le site de liaison à l’héparine n’a aucun effet. Ce peptide est capable également d’inhiber efficacement l’angiogenèse tumorale, une inhibition qui se traduit par un ralentissement de la croissance de la tumeurThe basement membrane plays an important role in angiogenesis by providing support necessary for blood vessel formation and supplying endogenous pro- and anti-angiogenic factors that condition the endothelial cells behavior. CoLV is present at the vicinity of endothelial cell basement membrane? We previously showed that a fragment derived from COLV a1, named HEPV, contains a functional heparin binding site, inhibits specifically endothelial cell proliferation and migration and disrupts endothelial tube formation. Prolonged treatment with HEPV results in the activation of collagen IV a1 and collagene XVIII a1 expression, the parental molecules of the anti-angiogenic fragments arresten and endostatin respectively. Heparin binding sites have been involved in the regulation of FGF2-induced angiogenesis. Soluble HEPV significantly inhibits phosphorylation of ERK1/2 and AKT in FGF2-stimuled endothelial cells. Moreover, in vivo experimentation using the mouse angiogenesis subcutaneous sponge assay shows that HEPV accumulates at angiogenic sites and inhibits FGF-2-induced angiogenesis. HEPV also significantly lowers intra-tumoral angiogenesis and tumor xenograft growth in nude mice. We also showed that hypoxia, the major angiogenesis-inducing factor, induces Collagen V production by endothelial cells and the release of a fragment encompassing HEPV into the culture medium. Finally, the released of HEPV-containing fragments in vivo was attested by the immunodetection of the fragment with specific antibodies in human breast cancer in which collagen V is overexpressed. Collectively, our results qualify HEPV as a new endogenous regulator angiogenesis with possible application in cancer therapy
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Carvalho, Eduardo George Baptista de. "Integração de fragmento de fascia lata enxertado na lamina propria de prega vocal de cães : estudo histologico." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/313720.
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Orientador: Agricio Nubiato CrespoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
Made available in DSpace on 2018-08-06T13:38:08Z (GMT). No. of bitstreams: 1 Carvalho_EduardoGeorgeBaptistade_M.pdf: 6583260 bytes, checksum: c2467f978ca8069f79000308c237d538 (MD5) Previous issue date: 2006
Resumo: A correção de alterações da lâmina própria nas pregas vocais, como sulcos, cicatrizes e degenerações senis, ainda é um desafio à fonocirurgia. Materiais implantáveis e métodos de implantação são continuamente investigados. Este trabalho avaliou a utilização de enxerto de fragmento da faseia lata na lâmina própria da prega vocal de cães, estudando as alterações histológicas conseqüentes, quanto à reação inflamatória aguda e crônica, à fibrose e ã neovascularização. Doze cães adultos foram submetidos à enxertia de um fragmento de 0,3 X 0,3 cm da faseia lata na lâmina própria da prega vocal direita. Na prega vocal esquerda, o mesmo acesso cirúrgico foi reproduzido, sem colocação do enxerto. Após dois e seis meses, os animais foram sacrificados e suas pregas vocais estudadas histologicamente. A faseia não induziu resposta inflamatória, aguda ou crônica, em qualquer animal, nem desencadeou fibrose além da conseqüente ao procedimento cirúrgico, como observado no lado controle. Em todos os casos, identificou-se o tecido enxertado sem evidências de reabsorção e com aumento da neovascularização, demontrando que a faseia lata apresenta integração tecidual boa na camada superficial da lâmina própria de prega vocal de cão
Abstract: Satisfactory corrective treatment for sulcus, scar and senile alterations in the lamina propria of vocal folds is still under development. This study assessed the utilization of a fascia lata graft in the vocal fold lamina propria of dogs by analyzing the histological alterations induced by acute and chronic inflammatory reactions as well as the fibrosis triggered by graft procedure and persistence. A fragment measuring 0.3 X 0.3 cm of the fascia lata was grafted in the right vocal old lamina propria of 12 adult dogs. Identical surgical access in the left vocal fold was reproduced without introducing the graft. After periods of two and six months, the animals were sacrificed and a histological study of their vocal cords was performed. Besides the reactions resulting from the surgical procedure in the control side, the fascia did not induce an acute or chronic inflammatory reaction or trigger fibrosis in any of the animals. In all the cases, the grafted tissue did not show evidence of resorption, demonstrating that the superficial layer of the lamina propria in dogs presents good tolerance to fascia lata grafting
Mestrado
Otorrinolaringologia
Mestre em Ciências Médicas
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Asselot-Chapel, Catherine. "Biosynthèse des macromolécules de la matrice extracellulaire par les cellules mésenchymateuses : régulation transcriptionnelle, modifications dans le diabète et modulation pharmacologique par des fragments d'héparine." Paris 12, 1991. http://www.theses.fr/1991PA120030.
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En culture de cellules musculaires lisses d'aorte de porc, les fragments d'heparine cy222 inhibent de maniere specifique la biosynthese du collagene de type iii, au niveau meme de la transcription du gene. Ils inhibent, en outre, l'exportation de la fibronectine vers la matrice extracellulaire. Par contre, a partir de cultures de fibroblastes de derme humain, le cy222 diminue egalement la biosynthese de la fibronectine. L'action du tgf beta, au contraire, regule positivement la biosynthese de la fibronectine, sans toutefois en modifier sa repartition entre les differents compartiments cellulaires. Nous avons montre, qu'il existe au cours du diabete, une deregulation des biosyntheses de certaines macromolecules de la matrice extracellulaire: augmentation specifique des biosyntheses de la fibronectine, du collagene iii et de la laminine. Par contre, les biosyntheses de collagene iv (au niveau transcriptionnel), et des proteoglycannes des lames basales sont diminuees. Les fragments d'heparine cy222 corrigent les alterations metaboliques observees: le cy222 diminue les biosyntheses de la fibronectine, du collagene de type iii et de la laminine (au niveau meme de sa transcription), ils augmentent par ailleurs, les biosyntheses du collagene de type iv et des proteoglycannes. L'ensemble de ces resultats suggere que le cy222 pourrait representer in vivo un des elements cles de la regulation de la matrice extracellulaire, et etre utilise dans le traitement complementaire des alterations pathologiques liees au diabete et a l'atherosclerose
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Soulez, Mathilde. "Le fragment LG3 du perlécan : un nouveau régulateur de remodelage vasculaire en transplantation." Thèse, 2012. http://hdl.handle.net/1866/9130.
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L’apoptose endothéliale initie le processus menant au remodelage vasculaire et au développement de la néointima dans la vasculopathie du greffon. La formation de néointima résulte de l’accumulation de leucocytes, de matrice extracellulaire et de cellules positives pour l’actine musculaire lisse alpha (αSMA+) dans l’intima des artères, artérioles et capillaires du greffon. Les cellules αSMA+ dans la néointima sont des cellules musculaires lisses vasculaires (CMLV) dérivées du donneur ainsi que des cellules souches dérivées du receveur, dont des cellules souches mésenchymateuses (CSM). L’acquisition d’un phénotype anti-apoptotique chez ces cellules est déterminante pour le développement de la néointima. Le laboratoire de Dre Hébert a démontré que les cellules endothéliales (CE) apoptotiques libèrent des médiateurs induisant une résistance à l’apoptose chez les CMLV et les fibroblastes. Notamment, les CE apoptotiques relâchent la cathepsine L qui clive le perlécan et ainsi libère un fragment C-terminal correspondant au troisième motif laminine G du domaine V du perlécan (LG3). Le LG3 est anti-apoptotique pour les fibroblastes. Nous avons donc émis l’hypothèse que le LG3 est un des médiateurs clés libéré par les CE apoptotiques favorisant le développement de la néointima via l’induction d’un phénotype anti-apoptotique chez les cellules néointimales αSMA+.
Nous avons démontré que les médiateurs libérés par les CE apoptotiques induisent un phénotype anti-apoptotique chez les CSM dépendant de l’activation de la voie ERK1/2. De plus, le LG3 active la voie ERK1/2 via son interaction avec les intégrines beta 1 et induit une réponse anti-apoptotique chez ces cellules. Cependant l’activation de ERK1/2 par le LG3 est plus faible en comparaison de son activation par le milieu conditionné par des CE apoptotiques. Nos résultats suggèrent que les CE apoptotiques libèrent aussi de l’EGF qui agit de façon paracrine sur les CSM en coopération avec le LG3 pour induire un phénotype anti-apoptotique chez les CSM.
Nous avons poursuivi l’étude de l’effet du LG3 in vivo sur le remodelage vasculaire en transplantation. Nous avons pour cela développé un modèle murin de rejet vasculaire qui consiste en une transplantation aortique entre des souris alloincompatibles. Nous avons ensuite injecté du LG3 chez les souris receveuses en post-transplantation. Nous avons observé dans ce modèle que des niveaux augmentés de LG3 sérique augmentent la formation de néointima, favorisent l’accumulation de cellules néointimales αSMA+ et diminuent le nombre de cellules CD31+ au niveau du greffon aortique. Parallèlement nous avons vérifié que le LG3 induit aussi un phénotype anti-apoptotique chez les CMLV et nous avons démontré un nouvel effet du LG3, soit une activité pro-migratoire, qui dépend de l’activation de la voie ERK1/2 chez les CMLV. Nous avons complété cette étude par l’analyse des niveaux de LG3 sérique dans une cohorte de patients receveurs d’allogreffe rénale. Nous avons observé chez ces patients, une association entre des niveaux élevés de LG3 sérique et un rejet vasculaire.
Le LG3 contribue à la formation de néointima par son activité pro-migratoire et pro-survie chez les cellules néointimales et aussi de par son activité angiostatique. Nos résultats suggèrent que le LG3 est un nouveau médiateur important dans le remodelage vasculaire en transplantationIn allogeneic transplanted organs, endothelial apoptosis is associated with vascular remodeling and neointima formation which in turn leads to allograft vasculopathy, a maladaptive form of vascular repair. In allograft vasculopathy, neointima results from the accumulation of leukocytes, extracellular matrix and alpha-smooth muscle actin positive (αSMA+) cells in the intima of allogeneic arteries, arterioles and capillaries. Neointimal αSMA+ cells comprise vascular smooth muscle cells (VSMC) derived from the donor and stem cells derived from the recipient, including mesenchymal stem cells (MSC). Acquisition of an anti-apoptotic phenotype of neointimal cells is central to the development of vascular obliterative changes. Dr Hébert’s team demonstrated that apoptotic endothelial cells release mediators which in turn induce a state of resistance to apoptosis of VMSC and fibroblasts. Apoptotic endothelial cells release cathepsin-L which cleaves perlecan therefore releasing a C-terminal fragment harbouring a laminin G motif and referred to as LG3. LG3 is anti-apoptotic for fibroblasts. We hypothesized that LG3 is a key mediator produced by endothelial apoptosis of importance in favoring neointima formation via the induction of an anti-apoptotic phenotype in αSMA+ neointimal cells We demonstrated that mediators released by endothelial apoptosis induce an ERK1/2-dependent anti-apoptotic phenotype in MSC. We identified LG3 as one of the mediators implicated in the induction of this anti-apoptotic response. Interactions between LG3 and beta 1 integrins expressed on MSC trigger ERK1/2 activation albeit to a lesser degree than medium conditioned by apoptotic endothelial cells. We showed that apoptotic endothelial cells also release EGF which cooperates with LG3 to induce an anti-apoptotic phenotype on MSC through cross-talk between EGF receptor and integrin-dependent pathways. Next, we characterized the impact of LG3 on allogeneic vascular remodeling in vivo. We developed a murine model of vascular rejection based on orthotopic transplantation of an aortic segment between two fully MHC-incompatible mice in absence of immunosuppression. Recombinant LG3 was injected intravenously post-transplantation in recipients resulting in higher circulating levels of LG3. In LG3-injected mice, accumulation of αSMA+ neointimal cells was enhanced resulting in significantly increased intima/media ratios in the allogeneic aortic graft. Aortic grafts of LG3-injected allografts also showed decreased CD31+ cells. We also demonstrated, using cell-based approaches, that LG3 exerts a pro-migratory activity on VSMC through beta 1-integrin and ERK1/2 -dependent pathways. In line with these observations we also reported augmented serum LG3 in human renal transplant patients in association with acute vascular rejection episodes. Collectively these results suggest that the pro-migratory, pro-survival and angiostatic activities of LG3 contribute to neointima formation. Our results suggest that LG3 is a novel mediator of importance in the development of obliterative vascular remodeling associated with rejection of allogeneic organs.
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Labelle, Andrée. "Clonage du domaine V du perlécan et étude de son activité biologique." Thèse, 2005. http://hdl.handle.net/1866/15586.
Full textBook chapters on the topic "Extracellular matrix fragments"
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Chalikias, Georgios K., and Dimitrios N. Tziakas. "Biomarkers of the Extracellular Matrix and of Collagen Fragments." In Biomarkers in Cardiovascular Disease, 87–124. Dordrecht: Springer Netherlands, 2016. http://dx.doi.org/10.1007/978-94-007-7678-4_5.
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Chalikias, Georgios K., and Dimitrios N. Tziakas. "Biomarkers of the Extracellular Matrix and of Collagen Fragments." In Biomarkers in Cardiovascular Disease, 1–38. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-007-7741-5_5-1.
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Evans, John Spencer, and Sunney I. Chan. "The N-terminal fragment of bovine phosphophoryn, an extracellular mineral matrix protein, shares sequence homology with viral, bacterial and eukaryotic transcriptional and post-translational regulatory proteins." In Proteins, 251–59. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-010-9063-6_35.
Full textConference papers on the topic "Extracellular matrix fragments"
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Edgar, Lowell T., Steve A. Maas, James E. Guilkey, and Jeffrey A. Weiss. "A Continuous-Discrete Finite Element Model of Angiogenesis That Couples Vessel Growth With Matrix Deformation." In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14327.
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Recent developments in tissue engineering have created demand for the ability to create microvascular networks with specific topologies in vitro. During angiogenesis, sprouting endothelial cells apply traction forces and migrate along components of the extracellular matrix (ECM), resulting in neovessel elongation [1]. The fibrillar structure of the ECM serves as the major pathway for mechanotransduction between contact-dependent cells. Using a three-dimensional (3D) organ culture model of microvessel fragments within a type-I collagen gel, we have shown that subjecting the culture to different boundary conditions during angiogenesis can lead to drastically different vascular topologies [2]. Fragments cultured in a rectangular gel that were free to contract grew into a randomly oriented network [3, 4]. When the long-axis of the gel was constrained as to prevent contraction, microvessels and collagen fibers were found aligned along the constrained axis (Fig. 1) [4].
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de Groot, Philip G., Jan A. van Mourik, and Jan J. Sixma. "PRIMARY BINDING SITE OF VON WILLEBRAND FACTOR IN THE SUBENDOTHELIUM WHICH MEDIATES PLATELET ADHESION IS NOT COLLAGEN." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643587.
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We have studies the binding of von Willebrand factor (vWF) to extracellular matrices of endothelial cells and smooth muscle cells and to the vessel wall of human umbilical arteries in relation to its function in supporting platelet adhesion at high shear rates. CLB-RAg 38, a monoclonal antibody directed against vWF inhibits the binding of 125I-vWF extracellular matrices completely. The binding of 125I-vWF to subendothelium is not inhibited, because there are many different binding sites. CLB-RAg 38 inhibits platelet adhesion to extracellular matrices and subendothelium, in sofar as it is dependent on plasma vWF. CLB-RAg 38 has no effect on adhesion depending on vWF already bound to the matrix or subendothelium. CLB-RAg 38 does not inhibit binding of vWF to collagen type I and type III. Another monoclonal antibody against vWF, CLB-RAg 201, completely inhibits binding of vWF to collagen type I and type III. CLB-RAg 201 does not inhibit binding of 125I-vWF ot the extracellular matrices. CLB-RAg 201 partly inhibits platelet adhesion but this inhibition is also present when the adhesion depends on vWF already present in matrix or subendothelium, indicating that CLB-RAg 201 also inhibits the adhesion of platelets directly, this in contrast to CLB-RAg 38. The epitopes for CLB-RAg 201 and 38 were found on different tryptic fragments of vWF. These data indicate that vWF binds to subendothelium and to matrices of cultured cells by mechanism that is different from binding to collagen.
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Wasi, S., S. Juodvalkis, P. Alles, and J. E. Aubin. "STUDIES ON THE DIRECT PROTEOLYTIC ACTION OF HUMAN TISSUE PLASMINOGEN ACTIVATOR ON HUMAN FIBRONECTIN AND VITRONECTIN." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644376.
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The ability of cells to make or break specific attachments to extracellular matrix (ECM) and other cells is important in cell migration, proliferation and wound repair. Specific attachment proteins believed to be involved in mediating these interactions comprise functional domains joined by protease sensitive segments. Proteases can conceivably modulate cellular interactions by releasing functional domains from parent molecules. Tissue plasminogen activator (t-pA) is known to participate in various pathophysiological processes. That t-pA may also act directly on structural proteins has not been investigated. We have studied the direct proteolytic action of melanoma t-pA on fibronectin (FN), vitronectin (VN) and laminin (LN). These were incubated with t-pA for 0 to 48 h in 50 mM Tris HCi, pH 7.4. The cleavage products were separated on polyacrylamide slab gels and blotted onto nitrocellulose strips. FN and VN fragments with cell attachment properties were identified by incubating the strips with human gingiva fibroblasts and staining with Amido black. Monoclonal antibodies to FN were used to identify heparin, cell and gelatin binding fragments. VN was converted to a major 55 Kd product as a function of time. Lower molecular weight species migrating at 45 Kd, 30 Kd and 15 Kd positions were also identified. Most of these fragments possessed cell attachment properties. LN became susceptible to t-pA digestion after dénaturation with H2O2. The catalytic activity of t-pA could be inhibited in the presence of nitrophenyl-p-guinidino benzoate (a synthetic inhibitor of plasminogen activator), whereas O-phenanthroline (a metalloprotease inhibitor), α 2-antiplasmin and trasylol had no effect. A monoclonal IgG preparation (HI 72 A1, kindly provided by Dr. David J. Loskutoff) that specifically inhibits t-pA also inhibited the protelyotic action of t-pA on FN. These data suggest that direct proteolytic action of t-pA on adhesive proteins may modulate cellular behaviour in various normal and pathological conditions which involve dynamic interactions between cells and ECM and where plasminogen activator levels are elevated either transiently or permanently, for example during tissue remodelling, wound-related repair and thrombolytic therapy.
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Beneckv, M. J., C. G. Kolvenbach, D. L. Amrani, and M. W. Mosesson. "EVIDENCE THAT THE C-TERMINAL HEPARIN BINDING DOMAIN ("HEP II") DOMINATES HEPARIN-FIBRONECTIN INTERACTIONS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643631.
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The interaction of glycosaminoglycans with plasma fibronectin (PFn) may play a role in the conversion of PFn from an “inert” dimeric circulating form to an “activated” multimeric form deposited on the cell surface or in the extracellular matrix. We carried out a quantitative comparison of heparin affinity for PFn and its proteolytic fragments in order to assess the relative importance of heparin interactions with PFn’s various reported heparin-binding domains. We employed affinity chromatography on PFn-sepharose to prepare a subset of fluorescein-labelled heparin molecules with high affinity for PFn, and confirmed that heparin binding to PFn is very sensitive to ionic strength. This suggests that the PFn-sepharose column selectively binds a fraction of highly sulfated heparin molecules. We quantified PFn-heparin affinity in the fluid-phase by monitoring a fluorescence polarization change that occurred as a consequence of the decrease in the rotational diffusion rate of fluorescently-labelled heparin molecules (13.8 kD) as they became “immobilized” by binding to PFn. Scatchard analysis of the heparin fluorescence polarization data obtained for PFn in Tris-buffered saline yielded a biphasic curve with Kd’s estimated at 5 and 130 nM, respectively A 190 kD thrombin fragment, containing the C-terminal "Hep II" domain but lacking the 29 kD N-terminal “Hep I” domain, yielded a linear plot displaying a single class of heparin-binding sites with a Kd of 130 nM Similar results were obtained for the C-terminal 150 kD Fn fragment which also contained the “Hep II” domain. In contrast, the 29 kD N-terminal “Hep I” Fn fragment bound heparin weakly (Kd =25 μM). The nature of the “high affinity (Kd= 5 nM) heparin binding component is uncertain; it may reflect heparin interaction with soluble multimers present in our PFn preparations Our observations suggest that the Kd=130 nM heparin binding component corresponds to heparin interaction with the C-terminal “Hep II” domain We conclude that the N-terminal “Hep I” domain does not participate significantly in heparin binding to soluble dimeric Fn under physiological conditions, whereas the C-terminal “Hep II” domain dominates such interactions
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Eldor, A., M. Bar-Ner, L. Wasserman, Y. matzner, Z. Fuks, and I. Viodavsky. "HEPARIN AND NON-ANTICOAGULANT HEPARINS INHIBIT HEPARANASE ACTIVITY IN NORMAL AND MALIGNANT CELLS:POSSIBLE THERAPEUTIC USE IN PREVENTION OF EXTRAVASATION AND DISSEMINATION OF BLOOD BORNE CELLS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643664.
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Degradation of vascular subendothelium occurs in_vivo during the process of inflammation and tumor invasion. Various observations suggest that the capacity of some blood-borne cells to extravasate may depend in part on their ability to express hepara-nase activity. Incubation of human platelets, human nc-utrophils, or highly metastatic mouse lymphoma cells with sulfate-labeled extracellular matrix (ECM) results in heparanase mediated release of labeled heparan sulfate cleavage fragments (0.5<Kav<0.85 on Sepharose 5B) (J. Clin.Invest. 74: 1842 and 76: 1306; Cancer Res. 43: 2704). The present study was undertaken to test the heparanase inhibitory effect of heparin and non-anticoagulant species of heparin that might havea potential therapeutic use in preventing heparanase mediated extravasation ofblood-borne cells. We prepared totallyor N-desulfated heparins which were either left with their N-position exposed or were subsequently N-acetylated or N-resulfated. These heparins exhibited less than 5% of the anticoagulant activityof native heparin. It was found that total desulfation of heparin abolished its heparanase inhibitory activity whether desulfation was followed by N-acetylation or not. Inhibitory effect was restored by resulfation of the N-position. When only the N-sulfate group was desulfated, inhibitory activity was lost but could be restored by acetylation of the N-position. These results indicate that N-sulfate groups of heparin are necessary for its heparanase inhibitory activity but can be substituted by an acetyl group provided that the 0-sulfate groups are retained. Low Mr heparins (main Mr species of 2500 and 4500 daltons) and heparin fragments as small as the tetrasaccharide inhibited degradation of heparan sulfate in the ECM, albeit to a lower extent than native heparin. Similar effects of the different heparins were observed with heparanase activities from platelets, neutrophils and lymphoma cells. Preliminary in vivo experiments suggest that non-anticoagulant heparins interfere with tumor metastasis and experimental autoimmune diseases (some heparins were kindly provided by Inst. Choay, Paris and Kabi Vitrum, Stockholm).
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Schleuning, W. D. "THE BIOCHEMISTRY AND CELL BIOLOGY OF SINGLE CHAIN UROKINASE TYPE PLASMINOGEN ACTIVATOR." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642956.
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Urokinase was discovered in the late nineteenth century, as an enzymatic principle in urine, that initiates the dissolution of blood clots. The basis of this phenomenon was recognized more than fifty years ago as the activation of plasminogen, the precursor of a tryptic protease, then known as profibrinolysin. Despite this long history, detailed data on the biochemistry of plasminogen activation have only become available recently. Urokinase (now designated urokinase-type plasminogen activator : u-PA) is synthesized and secreted as a single chain polypeptide (Mr-: 53,000) by many cell types. Single chain u-PA (scu-PA) is with equal justification called prourokinase (pro-u-PA), notwithstanding its low catalytic activity for synthetic peptide substrates and plasminogen, as most proenzymes of proteases display a certain degree of activity. The structure of pro-u-PA has been elucidated by protein and cDNA sequencing. It consists of three domains, exhibiting characteristic homology to other proteins: a serine protease domain, homologous to trypsin, chymotrypsin and elastase; a kringle domain, likewise found in prothrombin, plasminogen, tissue-type plasminogen activator (t-PA) and Factor XII; and an epidermal growth factor (EGF)-like domain, found in many other proteins, including certain clotting factors. Pro-u-PA is activated by the cleavage of its LYS158-Ile159 h1 bY either plasmin or kallikrein. This cleavage leads to a high increase of Kcat values with respect to both plasminogen and synthetic peptide substrates, but apparently to a reduction of its affinity to plasminogen. Thrartoin inactivates pro-u-PA irreversibly by the cleavage of the Arg156-Phe157 bond. U-PA but not pro-u-PA rapidly forms ccnplexes with plasminogen activator inhibitors (PAI)-l and PAI-2: second order rate constants Kass are respectively > 107 and 0.9xl06 (M-11sec-1). Unknown enzymes process pro-u-PA and u-PA to low molecular weight (LMW) pro-u-PA and LMW u-PA (Mr: 33,000) by cutting off a fragment consisting of the kr ingle and the EGF—like region. Pro—u—PA mediated plasminogen activation is fibrin dependent in vivo, and to a certain degree in vitro. Hie biochemical basis of this fibrin specificity is at present uncertain, although there are reports indicating that it may require polyvalent cations. Through its EGF-like region HMW pro-u-PA and HMW u-PA are capable of binding to specific membrane protein receptors which are found on many cells. Thus, u-PA activity may be restricted to the cell surface. According to a recent report, binding of u—PA to the receptor may also mediate signal transduction in auto- or paracrine growth control. In cells permissive for the respective pathways, pro-u-PA gene transcription is stimulated by mechanisms of signal transduction, that include the cAMP, the tyrosine specific kinase and the protein kinase C dependent pathways. Glucocorticoid hormones downregulate pro-u-PA gene transcription in cells where the gene is canstitutively expressed. Although different cells vary greatly in their response to agents that stimulate urokinase biosynthesis, growth factors and other mitogens are in many cases effective inducers. Significantly elevated levels of u-PA are also found in many malignant tissues. These findings and many others suggest that plasminogen activation by u-PA provides localized extracellular matrix degradation which is required for invasive growth, cell migration and other forms of tissue remodelling. Fibrin represents in this view only a variant of an extracellular matrix, which is provided through the clotting system in the case of an emergency.
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Kruithof, E. KO, W. D. Schleuning, and F. Bachman. "PLASMINOGEN ACTIVATOR INHIBITOR BIOCHEMICAL AND CLINICAL ASPECTS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644764.
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Plasminogen activator (PAs) are enzymes that convert the zymogen plasminogen into the trypsin-like protease plasmin, which degrades extracellular matrix proteins and fibrin in the course of fibrinolysis, embryogenesis, tissue remodeling and in tumor metastasis. Plasminogen activator inhibitors (PAIs) are important modulators of PA activity. Several proteins have been identified which inhibit at fast rates urokinase (u-PA) and tissue-type PA (t-PA). In the order of inhibition rate constants these are: a) PAI-1, present in human plasma and platelet extracts and purified from human endothelial cell, fibrosarcoma cell and melanoma cell conditioned media; b) PAI-2, first identified in extracts of human placenta and later also in extracts and conditioned media of human granulocytes and monocytes; and c) protease nexin, a broad specificity protease inhibitor that was first identified and purified from human fibroblasts. We have chosen to use phorbol myristate acetate (30 ng/ml) stimulated histiocytic lymphoma cells (U-937) for the purification of PAI-2. The concentration of PAI-2 in the conditioned media after three days culture in the absence of fetal calf serum is 5 mg/1 and PAI-2 represents 3% of total protein. PAI-2 was purified by a two step procedure consisting of isoelectric focusing and affinity chromatography on Cibacron-Blue agarose. Two forms of PAI-2 were identified: a 47 kDa, nonglycosylated, pi 5.0 form and a 60 kDa glycosylated, pi 4.4 form. Immunctolot analysis and in vivo protein labeling studies under culture conditions that assure 100% viability of the cells showed that the glycosylated Torn is secreted, whereas the 47 kDa, nonglycosylated form remains intracellular. The glycosylation does not affect the activity of the inhibitors since both forms of PAI-2 react with the same rate with u-PA. PAI-2 is a fast inhibitor of u-PA (kl=9×l05M−1s−1) and two-chain t-PA (kl=2×l05) and a rather slow inhibitor of one chain t-PA (kl=l×l02) and of plasmin (kl×l02), but does not inhibit glandular and plasma kallikrein or thrombin. The inhibition spectrum and the kinetics of inhibition clearly distinguish PAI-2 from PAI-1 (kl of reaction with u-PA and two and one chain t-PA above 107) and from protease nexin, that is an efficient inhibitor also of thrombin and plasmin.We have cloned a 1880 Ip fragment of PAI-2 cDNA and determined its nucleotide sequence. The derived acid sequence reveals that PAI-2 is like PAI-1 and protease nexin a member of the serpin family of proteins and contains arginine at its putative active site. In an attenpt to identify parts of the inhibitor proteins that are responsible for conferring PA specificity to PAI-1 and PAI-2 we have compared the primary structures of PAI-1 and PAI-2 with each other and with antithrombin III (AT III). Surprisingly, PAI-2 exhibits no homology with PAI-1 in the region close to the active site except for the active site arginine, whereas, in that region, AT III showed three and seven conserved aminoacids when compared to PAI-1 and PAI-2, respectively. This finding suggests that other regions than those close to the active site contribute to the specificity of PAIs.Plasma concentrations of PAI-2 were measured by a specific radioimmunoassay in over 50 healthy individuals, PAI-2 levels were below detection limit (15 ng/ml) in half of the saitples. Maximal concentrations encountered were in the 30 ng/ml range. PAI-2 measurements in over 300 hospitalized patients demonstrated significantly elevated PAI-2 concentrations only in pregnant women. Measurements in various stages of pregnancy showed a steady increase of PAI-2 from below detection limit in nonpregnant women to values of 250 ng/ml at term and of PAI-1 frcm 25 ng/ml to 150 ng/ml. Unlike to PAI-1 concentrations that normalize rapidly after delivery, PAI-2 concentrations remain significantly elevated for several days.
Reports on the topic "Extracellular matrix fragments"
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Pines, Mark, Arieh Bar, David A. Carrino, Arnold I. Caplan, and James A. Dennis. Extracellular Matrix Molecules of the Eggshell as Related to Eggshell Quality. United States Department of Agriculture, 1997. http://dx.doi.org/10.32747/1997.7575270.bard.
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The extracellular matrix of the mineralizing eggshell contains molecules hypothesized to be regulators biomineralization. To study eggshell matrix molecules, a bank of monoclonal antibodies was generated that bound demineralized eggshell matrix or localized to oviduct epithelium. Immunofluorescence staining revealed several staining patterns for antibodies that recognized secretory cells: staining for a majority of columnar lining cells, staining for a minor sub-set of columnar lining cells, intensified staining within epithelial crypts, and staining of the entire tubular gland. Western blotting with the antibody Epi2 on eggshell matrix showed binding to molecules with the apparent molecular weight of eggshell matrix dermatan sulfate proteoglycan (eggshell DSPG) (Carrino, et al., 1997). Immunoblots of cyanogen bromide-cleaved eggshell DSPG revealed broad band of reactivity that shifted to 25 kDa after chondroitinase digestion; indicating that the Epi2 binding site is located on a fragment which contains dermatan sulfate side chains. Immunogold labeling showed that Epi2 binds to secretory vesicles within the non-ciliated cells of the columnar epithelium, while the antibodies Tg1 and Tg2 bind to secretory vesicles of tubular gland cells. Immunogold labeling of demineralized shell matrix showed binding of Epi2, Tg1, and Tg2 to the matrix of the palisades layer, and showed little reactivity to other regions of the shell matrix. Quantification of the immunogold particles within the eggshell matrix revealed that antibodies Epi2 and Tg1 bind all calcified regions equally while antibody Tg2 has a greater affinity for the baseplate region of the calcium reserve assembly.