Synthesis of Collagen by Bovine Chondrocytes Cultured in Alginate; Posttranslational Modifications and Cell–Matrix Interaction☆

Beekman, B.; Verzijl, Nicole; Bank, Ruud A.; Mark, K von der; TeKoppele, J.M.

doi:10.1006/excr.1997.3771

Cited by 105 publications

(64 citation statements)

References 20 publications

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“…The similar effect, i.e. increased collagen synthesis by BAPN treatment of cells, was also reported in chondrocyte cultures (8,11). In addition, up-regulation of collagen mRNA was also seen in lathyritic animals during the early phase of bone fracture healing as well as TGF-␤1 mRNA expression (4).…”

Section: Discussionsupporting

confidence: 74%

Lysyl Oxidase Binds Transforming Growth Factor-; and Regulates Its Signaling via Amine Oxidase Activity

Atsawasuwan

Mochida

Katafuchi

et al. 2008

Journal of Biological Chemistry

119

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Lysyl oxidase (LOX), an amine oxidase critical for the initiation of collagen and elastin cross-linking, has recently been shown to regulate cellular activities possibly by modulating the functions of growth factors. In this study, we investigated the interaction between LOX and transforming growth factor-␤1 (TGF-␤1), a potent growth factor abundant in bone, the effect of LOX on TGF-␤1 signaling, and its potential mechanism. The specific binding between mature LOX and mature TGF-␤1 was demonstrated by immunoprecipitation and glutathione S-transferase pulldown assay in vitro. Both proteins were colocalized in the extracellular matrix in an osteoblastic cell culture system, and the binding complex was identified in the mineral-associated fraction of bone matrix. Furthermore, LOX suppressed TGF-␤1-induced Smad3 phosphorylation likely through its amine oxidase activity. The data indicate that LOX binds to mature TGF-␤1 and enzymatically regulates its signaling in bone and thus may play an important role in bone maintenance and remodeling. Lysyl oxidase (LOX)2 is a copper-dependent amine oxidase that initiates the process of covalent intra-and intermolecular cross-linking in collagen and elastin (1). The critical role of LOX in tissue stability is well exemplified by "lathyrism," the condition where deleterious effects in connective tissues are caused by lathyrogens such as ␤-aminopropionitrile (BAPN) (2). In lathyritic animals, bone is one of the most severely affected tissues revealing kyphoscoliosis, bone deformities, weakening of tendons and ligament attachments, dislocation of joints, impaired bone fracture healing, and ectopic bone exostoses (3, 4). BAPN is a potent and irreversible inhibitor of LOX catalytic activity and thus prevents cross-linking of immature collagen and elastin into mature, stable, and insoluble fibers. Therefore, it has been thought that the phenotypes seen in lathyritic animals are due primarily to the lack of collagen/elastin cross-linking.Recent reports, however, have revealed novel functions for LOX, including the regulation of gene transcription and cellular functions. Although the mechanisms are still not clear, those functions could be associated with its ability to oxidize substrates, other than collagen and elastin, such as basic fibroblast growth factor (5) as well as histone H1 and H2 (6, 7). Thus, lathyritic phenotypes could be due in part to the loss of LOX control of cellular functions. Indeed, several studies have reported that collagen synthesis/expression significantly increased when osteoblasts or chondrocytes were cultured in the presence of BAPN (8 -11), which is suggestive of such functions.In bone, there are several major growth factors, including transforming growth factor-␤ (TGF-␤), bone morphogenetic proteins (BMPs), insulin-like growth factor and platelet-derived growth factor, tumor necrosis factor-␣, and basic fibroblast growth factor. Among those factors, TGF-␤s and BMPs are a group of growth factors that are basic in nature (theoretical pI Ͼ 8.5) and up-regula...

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Section: Discussionsupporting

confidence: 74%

Lysyl Oxidase Binds Transforming Growth Factor-; and Regulates Its Signaling via Amine Oxidase Activity

Atsawasuwan

Mochida

Katafuchi

et al. 2008

Journal of Biological Chemistry

119

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“…The results of the adhesion studies were consistent with a basal level of integrin-mediated adhesion which could be blocked in a dose-dependent fashion by the RGD containing peptide GRGDSP. Although the RGD motif has been associated primarily with FN and laminin, RGD has been reported to have a role in collagen binding as well (Beekman et al 1997, Vitale et al 1997, Grzesik et al 1998. Loss of adhesive function in culture was associated with the loss of integrin expression.…”

Section: Discussionmentioning

confidence: 86%

Maintenance of beta-cell function and survival following islet isolation requires re-establishment of the islet-matrix relationship

Rn¹,

Rosenberg²

1999

Journal of Endocrinology

300

295

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Islet transplantation is associated with a high rate of early graft failure, a problem that remains poorly understood. It is probable that the destruction of the islet microenvironment and loss of tropic support that occur during isolation lead to compromised survival. The purpose of this study was to determine the role of matrix-integrin interactions on beta-cell survival and function following islet isolation. Canine islets were obtained by conventional methods. Immediately after isolation, the peri-insular basement membrane (BM) was absent. The ability of islets maintained in suspension culture to attach to a collagen matrix declined progressively over 6 days. Attachment could be blocked by an arginine-glycine-aspartate (RGD) motif-presenting synthetic peptide, thereby implicating an integrin-mediated process. Characterization of cell surface integrins by immunocytochemistry (ICC) demonstrated that the expression of integrins 3, 5 and V diminished during the culture period. This change was coincident with both a decrease in beta-cell function (proinsulin gene expression, islet insulin content and stimulated insulin release) and a rise in beta-cell death from apoptosis, as determined by in situ cell death detection (TUNEL) assay. These adverse events were prevented or delayed by exposure of islets to matrix proteins. In conclusion, routine islet isolation disrupts the cell-matrix relationship leading to a variety of structural and functional abnormalities, including apoptotic cell death. These alterations can be diminished by restoration of a culture microenvironment that includes matrix proteins.

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“…Other researchers have found that the metabolic and morphologic changes could be reversed by the disruption of the cytoskeletal complex (12,13). The metabolic activity of isolated chondrocytes may be modulated by the matrix around the cells (8,14,15). Taken together, these findings indicate a possibility that the adhesion molecule(s) expressed on the chondrocytes plays a key role in the progression of dedifferentiation.…”

mentioning

confidence: 84%

αvβ5 Integrin promotes dedifferentiation of monolayer-cultured articular chondrocytes

Fukui¹,

Ikeda²,

Tanaka³

et al. 2011

Arthritis & Rheumatism

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Objective. When cultured in monolayers, articular chondrocytes undergo an obvious phenotypic change. Although the involvement of integrins has been suggested, the exact mechanisms of the change have not been determined. This study was undertaken to clarify the mechanisms underlying the loss of chondrocyte phenotype early after plating.Methods. Primary cultured human articular chondrocytes were used for the experiments. Involvement of respective integrins in the phenotypic change was investigated in RNA interference (RNAi) experiments. A signaling pathway involved in the change was identified in experiments using specific inhibitors and adenoviruses encoding mutated genes involved in the pathway. Adenoviruses carrying mutated GTPases were used to determine the involvement of small GTPases in the process.Results. In monolayer-cultured chondrocytes, suppression of ␣v or ␤5 integrin expression by RNAi inhibited morphologic changes in the cells and increased (or prevented a reduction in) the expression of various cartilage matrix genes. Consistent results were obtained in experiments using a blocking antibody and a synthetic inhibitor of ␣v␤5 integrin. The decrease in cartilage matrix gene expression in chondrocytes after plating was mediated by ERK signaling, which was promoted primarily by ␣v␤5 integrin. In articular chondrocytes, the affinity of ␣v␤5 integrin for ligands was regulated by the small GTPase R-Ras. R-Ras was gradually activated in monolayer-cultured chondrocytes after plating, which caused a gradual decline in cartilage matrix gene expression through enhanced ␣v␤5 integrin activation and the subsequent increase in ERK signaling.Conclusion. Our findings indicate that ␣v␤5 integrin may be involved in the change that occurs in monolayer-cultured chondrocytes after plating.

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Synthesis of Collagen by Bovine Chondrocytes Cultured in Alginate; Posttranslational Modifications and Cell–Matrix Interaction☆

Cited by 105 publications

References 20 publications

Lysyl Oxidase Binds Transforming Growth Factor-; and Regulates Its Signaling via Amine Oxidase Activity

Lysyl Oxidase Binds Transforming Growth Factor-; and Regulates Its Signaling via Amine Oxidase Activity

Maintenance of beta-cell function and survival following islet isolation requires re-establishment of the islet-matrix relationship

αvβ5 Integrin promotes dedifferentiation of monolayer-cultured articular chondrocytes

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