THE EXPRESSION OF BETA-1 INTEGRINS IN HUMAN CORONARY-ARTERY

The beta 1 integrin adhesion receptors mediate the binding of cells to extracellular matrices, facilitating their growth, migration, and cap acity to deposit matrix proteins: important factors in arterial resten osis and atherosclerosis. The expression of integrins in human coronar y artery is, however, unexplored. The aim of the current study was, th erefore, to define the expression of beta 1 integrins by cultured huma n coronary artery vascular smooth muscle cells (hCAVSMC) and in normal human coronary artery; confirming whether or not this differs from th e repertoire found in other species and human vessels. The expression of beta 1 integrins by hCAVSMC was assessed by immuno-precipitation an d the alkaline phosphatase anti-alkaline phosphatase (APAAP) immunoche mical technique. In addition, mRNA expression was defined by reverse t ranscription polymerase chain reaction (RT-PCR). Normal adult human co ronary arteries (n = 4) were also stained by the APAAP method. In vitr o hCAVSMC express alpha 2 beta 1 (a collagen and occasional laminin re ceptor) and alpha 5 beta 1 (a fibronectin receptor) with lesser expres sion of alpha 3 beta 1 (a multifunctional receptor). They do, however, possess mRNA for several other integrins. Cells within the media of h uman coronary artery wall express alpha 3 beta 1 and alpha 5 beta 1 bu t not alpha 2 beta 1: instead the alternative collagen/laminin recepto r, alpha 1 beta 1, is expressed in vivo. This pattern of expression di ffers subtly from that described in rats though it closely parallels t hat found in other human arteries.