Retinoic acid receptor-related orphan receptor α (RORα) is a member of the nuclear receptor superfamily. Using RT-PCR, RORα mRNA was identified in human aortic smooth muscle cells (hASMC), endothelial cells (EC), as well as in human mammary arteries and atherosclerotic plaques. We found a predominant expression of RORα1 in hASMC, and RORα4 in EC. RORα2 and RORα3 were not detected. In arteries, RORα4 was predominant compared with RORα1. In atherosclerotic plaques, RORα expression was significantly decreased. In hASMC stimulated with cytokines, RORα expression was increased by 2.5-fold. RORα mRNA was also significantly increased (∼2-fold) in hASMC and EC cultured under hypoxia.
