Inducible adhesion of mesenchymal cells to elastic fibers: elastonectin.

Abstract

The addition of highly purified elastic fibers to confluent human skin fibroblast or porcine aorta smooth muscle cell cultures resulted in a time-dependent, strong adhesion of the fibrils to the cell surface. The kinetics of adhesion was studied by video/time-lapse cinematography. After a 0.5-1 hr lag period, adhesion progressed to a maximum amount in 3-6 hr in the described conditions. Adhesion is strongly accelerated by the prior addition of soluble elastin peptides (K-elastin) to the cultures. Cycloheximide inhibits this induced adhesion. Adherent elastic fibers can be detached by treatment with elastase and trypsin but not with collagenase. The radioactive proteins adhering to elastic fibers, after a 6-hr incubation of the induced cultures in presence of [35S]methionine, were extracted and analyzed by NaDodSO4/PAGE. The proteins strongly adhering to the elastic fibers had apparent molecular sizes of about 120, 67, 60, and 45 kDa. Only the 120-kDa protein band showed a significant increase of its associated radioactivity in the induced cultures as compared to the noninduced cultures. We propose that the 120-kDa protein is responsible for the induced adhesion of mesenchymal cells to elastic fibers and designate it "elastonectin."In the past years, specific adhesive proteins that mediate cell attachment to the extracellular matrix have been identified and characterized. Fibronectin ensures the adhesion of mesenchymal cells to interstitial collagens and to some proteoglycans (1-4). Laminin is involved in the interaction between epithelial cells and basement membrane components, such as collagen type IV (5, 6). Elastin was originally considered to be an isotropic and inert constituent, but physicochemical studies have pointed to a more dynamic structure and to possible interactions with other connective tissue proteins (7,8). Elastin peptides were also shown to be able to interact with several other cell types (9, 10). Mecham et al. (11) studied the acquisition of chemotactic responsiveness to elastin peptides and the expression of the elastin phenotype by fetal bovine ligamentum fibroblasts during cell differentiation and showed that they were closely related events. Therefore, the investigation of whether specific protein(s) could mediate the adhesion of mesenchymal cells to elastic fibers was undertaken.In the present report, we have investigated the interactions between purified bovine ligamentum nuchae elastic fibers and human skin fibroblasts or pig aorta smooth muscle cells in culture and show that elastic fibers adhere strongly to both cell types. Fibronectin has been shown not to be involved in this process. Biosynthetic experiments carried out with human skin fibroblasts cultured in presence or absence of elastic fibers enabled us to carry out preliminary identification of an inducible protein closely associated with the added elastic fibers. We have designated this adhesive protein "elastonectin."MATERIAL AND METHODS Fibroblasts and smooth muscle cells were obtained from human dermis and porci...

Characterization of an <i>in vitro</i> Model of Calcification in Retinal Pigmented Epithelial Cells

“…We have reported that tropoelastin downregulates the induction of calcification via the elastin receptor (manuscript in submission), although the pathway of the inhibitory reaction by TE on calcification presents several candidate reactions such as the activation of signal transduction via the elastin receptor (33) and the binding of calcium by tropoelastin molecule (6,7). Moreover, it has been reported that TE has a variety of biological effects which are mediated by the elastin receptor, chemotactic cell migration, modulation of ion flux, adhesion of cells to elastin fibers, tumor cellmatrix interaction, elastase synthesis and release, free radical production, endothelium and nitric oxide-mediated vasorelaxation, chaperon for elastogenesis, lymphocyte proliferation, apoptotic cell death (34)(35)(36)(37)(38) as well as properties as a major elastic fiber component. In this study, we revealed a new candidate function of the TE molecule.…”

Elastic extracellular matrix of the embryonic chick heart: An immunohistological study using laser confocal microscopy

“…Elastin and fibrillin have been found to be present during the embryonic stages of heart development (Rosenquist et al, 1988;Gallagher et al, 1993). In addition, since elastin has been found to interact with neighboring cells by means of specific receptors (Hornebeck et al, 1986;Hinek et al, 1988), it may provide a structural link required for the generation of mechanical forces which are important during the morphogenesis of the heart.…”

Aortic smooth muscle cells in a three-dimensional collagen lattice culture. Evidence for posttranslational regulation of collagen synthesis.

“…41 Hornebeck et al 41 propose that the loss of the cell-elastin interaction leads to the modulation of the contractile to the synthetic phenotype of SMCs characteristic of the atherosclerotic vessel. To what degree this and other extracellular matrix components, such as proteoglycans organized in the type I collagen lattice, 742 may regulate biosynthetic activity by direct interaction or by influ- encing the effect of various growth factors 4344 remains to be elucidated.…”