Identification of an adhesion factor for chondrocytes.

Earlier studies suggested that there is a specific activity in mammalian serum and plasma that supports epidermal (epithelial) cell movement. This activity was shown to be nondialyzable and heat labile. In the studies reported here, using standard biochemical procedures-i.e., ammonium sulfate fractionation, ion-exchange and gel filtration chromatography, isoelectric precipitation, and preparative polyacrylamide gel electrophoresis-we have purified a factor from human plasma that supports epidermal cell movement. The factor travels as an apparent single band on disc gel electrophoresis and corresponds to a glycosylated single-chain protein ofapproximately 65,000 ± 3,000 daltons. The purified fraction is necessary and sufficient for epithelial cell movement in three in vitro assays: (i) spreading of dissociated epidermal cells, (ii) outgrowth ofepithelial sheets from skdn explants, and (iii) epiboly, epithelial sheet movement over a floating skin explant. The purified fraction is active at a concentration of 1-2 pg/ml ofgrowth medium. It is destroyed by trypsin and its activity is augmented more than 10-fold by a second, as yet unpurified, fraction of plasma. These studies support the notion that a single protein ofplasma supports epidermal cell movement and that this protein may play an important role in wound closure. Because it supports epiboly, the most biologically relevant ofthe assays, it has been named epibolin

Section: Resultssupporting

confidence: 70%

Epibolin: a protein of human plasma that supports epithelial cell movement.

Stenn¹

1981

“…For example, chondrocytes attach to type II collagen by a serum factor, termed "chondronectin," which is distinct from fibronectin (32). The attachment ofepithelial and endothelial cells to type IV collagen is mediated by laminin (33).…”

mentioning

confidence: 99%

Attachment of smooth muscle cells to collagen and their migration toward platelet-derived growth factor.

Grotendorst¹,

Seppä²,

Kleinman³

et al. 1981

Self Cite

434

154

Smooth muscle cells use fibronectin to bind to type I and type Im collagens but bind to type V collagen by a trypsin-resistant intrinsic glycoconjugate. The binding site on type V collagen is located in the aA chain. By using collagen-coated filters in a modified Boyden chamber assay for chemotaxis, it was observed that the platelet-derived growth factor was chemotactic for smooth muscle cells but that several other growth factors were inactive. We suggest that the migration of smooth muscle cells from the media to the intima of a blood vessel, which leads to the formation of an atherosclerotic plaque, may be the result of a chemotactic migration of cells responsive to the platelet-derived growth factor.Smooth muscle cells are connective tissue cells that are present in blood vessels and other pulsatile tissues. These cells synthesize various matrix proteins including proteoglycan (1), elastin (2), and types I, III, and V collagen (3)(4)(5)(6). Because atherosclerotic plaques are composed in large part of smooth muscle cells and the extracellular products they produce (7), there is much interest in factors that regulate the growth and distribution of these cells.Current theories suggest that the formation of the atherosclerotic plaque is initiated at sites where endothelial cells are lost from the basement membrane (for reviews, see refs. 7-9), leading to an accumulation ofplatelets and other blood elements at those sites. Under such conditions, platelets release the platelet-derived growth factor (PDGF), a potent mitogen for smooth muscle but not for endothelial cells (10,11). It is assumed that PDGF causes the proliferation of smooth muscle cells beyond the basement membrane to the inner surface of the blood vessel. Interestingly, Benditt and Benditt (12) found that the cells in many plaques are monoclonal suggesting that a single cell or a single type of cell (13) proliferated to form a plaque.Recently, we and others have studied the attachment and migration of connective tissue cells. Fibroblasts, for example, are attracted to lymphokines (14), macrophage factors (15), activated serum (16), fibronectin (17), the cell binding fragment of fibronectin (18), and collagen fragments (19). Fibroblasts require a substrate of collagen of types I-IV for attachment and migration in the Boyden chamber assays for chemotaxis (14).Here, we confirm earlier work on smooth muscle cells that indicates that smooth muscle cells use fibronectin to attach to types I and III collagens (20). We have extended these studies to show that smooth muscle cells attach preferentially to type V collagen without a requirement for fibronectin. When attached to collagen, the cells migrate toward PDGF in the Boyden chamber assay for chemotaxis. The chemotactic activity of PDGF may be of importance in the early stages of atherosclerosis.MATERIALS AND METHODS Materials. Tissue culture media were purchased from GIBCO. Fetal calf serum and bovine serum albumin were obtained from Reheis Chemical (Kankakee, IL). Trypsin and elastase were fro...

“…For example, many cells of mesenchymal origin, such as fibroblasts, myoblasts, and smooth muscle cells, utilize fibronectin to bind to interstitial type I and type III collagens (1,4). Chondrocytes, which synthesize type II collagen, cartilage collagen, use another glycoprotein, chondronectin, to adhere to this collagen (5). Laminin, the major glycoprotein ofthe basement membranes, mediates the attachment of epithelial and neoplastic cells to type IV collagen (2,6,7).…”

mentioning

confidence: 99%

Laminin receptor on human breast carcinoma cells.

Terranova¹,

Rao²,

Kalebic³

et al. 1983

353

209

Human MCF-7 breast carcinoma cells possess a receptor-like moiety on their surface that has a high binding affinity (Kd = 2 nM) for laminin, a glycoprotein localized in basement membranes. Laminin preferentially stimulates (8-fold) MCF-7 cells to attach to type IV (basement membrane) collagen, whereas fibronectin stimulates attachment only 2-fold for these cells on type I collagen. The attachment properties of two other human breast carcinoma cell lines to type IV collagen were also studied. The attachment of ZR-75-1 cells was stimulated 4-fold by laminin and 5-fold by fibronectin, whereas T47-D cell attachment was stimulated 2-fold by laminin and 7-fold by fibronectin. By employing protease-derived fragments oflaminin, the major domains of the laminin molecule that participate in MCF-7 cell attachment to type IV collagen were identified. The whole laminin molecule has the configuration of a four-armed cross with three short arms and one long arm. A major cell-binding domain was found to reside near the intersection point of the short arms, and the type IV collagen-binding domain was associated with the globular end regions of the short arms. The receptor for laminin on the surface of these tumor cells may be involved in the initial interaction oftumor cells via laminin with the vascular basement membrane to facilitate invasion and subsequent promotion of metastasis.