Expression of a disintegrin-like protein in cultured human vascular cells and in vivo

Metalloproteinase-like, disintegrin-like, and cysteine-rich proteins (MDCs) are potential novel regulators of cell-cell and cell-matrix interactions, as well as of matrix degradation. We have asked whether MDCs are expressed in cultured diploid vascular cells, and have identified MDC 15 in human aortic smooth muscle (SMC) and umbilical vein endothelium (HUVEC). MDC 15 mRNA is expressed at higher levels in HUVECs than in SMCs. In cultured SMCs, MDC 15 mRNA levels are not regulated by PDGF or IGF-I or by adherence to different extracellular matrices. Nor is regulation of MDC 15 mRNA levels observed in HUVEC monolayers at different cell densities, after multi-scratch wounding, or after treatment with TNF-alpha, LPS, or thrombin. However, differences in proteolytic processing of MDC 15 are observed in different HUVEC strains. In contrast to cultured arterial cells, MDC 15 protein is not expressed in vivo in normal vessels, but is up-regulated in lesions of atherosclerosis. These findings suggest that MDC 15 may be a potential regulator of vascular cell function and may be involved in the development of lesions of atherosclerosis.