The expression of β1 integrins in human coronary artery

The beta 1 integrin adhesion receptors mediate the binding of cells to extracellular matrices, facilitating their growth, migration, and capacity to deposit matrix proteins: important factors in arterial restenosis and atherosclerosis. The expression of integrins in human coronary artery is, however, unexplored. The aim of the current study was, therefore, to define the expression of beta 1 integrins by cultured human coronary artery vascular smooth muscle cells (hCAVSMC) and in normal human coronary artery; confirming whether or not this differs from the repertoire found in other species and human vessels. The expression of beta 1 integrins by hCAVSMC was assessed by immuno-precipitation and the alkaline phosphatase anti-alkaline phosphatase (APAAP) immunochemical technique. In addition, mRNA expression was defined by reverse transcription polymerase chain reaction (RT-PCR). Normal adult human coronary arteries (n = 4) were also stained by the APAAP method. In vitro hCAVSMC express alpha 2 beta 1 (a collagen and occasional laminin receptor) and alpha 5 beta 1 (a fibronectin receptor) with lesser expression of alpha 3 beta 1 (a multifunctional receptor). They do, however, possess mRNA for several other integrins. Cells within the media of human coronary artery wall express alpha 3 beta 1 and alpha 5 beta 1 but not alpha 2 beta 1: instead the alternative collagen/laminin receptor, alpha 1 beta 1, is expressed in vivo. This pattern of expression differs subtly from that described in rats though it closely parallels that found in other human arteries.