Increased expression of lectinlike oxidized low density lipoprotein receptor-1 in initial atherosclerotic lesions of Watanabe heritable hyperlipidemic rabbits

A novel lectinlike oxidized low density lipoprotein receptor-1 (LOX-1) was recently identified in bovine aortic endothelial cells. It is strongly suggested to have a potential role in the initiation and development of atherosclerosis. In this study, we have isolated cDNA clones encoding the rabbit homologue of LOX-1 by screening a rabbit placenta cDNA library. In amino acid sequence and domain structure organization, the rabbit LOX-1 is highly conserved with the human counterpart. Transfection of rabbit LOX-1 cDNA to HEK-293 cells confers on them the activity to bind and internalize oxidized low density lipoprotein. Rabbit LOX-1 was identified as a 45-kDa protein by Western blot analysis with a specific monoclonal antibody. Notably, analyses by reverse transcription-polymerase chain reaction and Western blot revealed that LOX-I was accumulated in 8-week-old Watanabe heritable hyperlipidemic rabbit aortas compared with normal rabbit aortas. Immunostaining confirmed that the augmented expression of LOX-I was primarily localized within the intima at the earliest stages of atherogenesis. The most prominent staining was in the endothelial cells of lesions. Furthermore, the distinctive staining of LOX-1 was identified in the endothelium of nonlesion areas of Watanabe heritable hyperlipidemic rabbit aortas. Taken together, these findings support the possibility that LOX-1 might be involved in the initiation of atherosclerosis.