Role of the elastin-laminin receptor in the cardiovascular system

Extracellular matrix (ECM)-cell interactions play a key role in regulating cell and organ functions, and many of them are mediated by receptors belonging to the integrin family. A nonintegrin ECM receptor has a 67 kDa perimembrane subunit that contains a high-affinity binding site for laminin and elastin peptides (Kd approximately nM), as well as a second lectin site whose occupation by galactoside-type carbohydrates results in release of the peptide bound to the first site and of the 67 kDa subunit from the cell membrane. This elastin-laminin receptor is involved in the regulation of several biological systems and in tumor cell invasion and metastasis. In the cardiovascular system, the 67 kDa receptor contributes to the modulation of circulating inflammatory cell activity and helps to regulate the adhesion, growth, or synthetic activity of cells starting in utero. The 67 kDa receptor is present on both adherent cardiovascular system cells and on circulating inflammatory cells. It is involved in balancing degradation processes initiated by inflammatory cells and in the response of adherent cells to alterations in surrounding ECM. These events may play a key role in the initiation and progression of atherosclerosis, as well as in the fibrotic processes secondary to myocardial infarction. The 67 kDa receptor may also contribute to vascular tone regulation by the endothelium, to attachment of circulating metastatic cells to the endothelium followed by tissue invasion, and to tumor neovascularization. Its multiple functions suggest that the elastin-laminin receptor may be pivotal in the pathophysiology of the cardiovascular system and other systems.