Gene regulation function of the three specificity protein-1 (Sp1) within the human collectin placenta-1 proximal promoter

Abstract

Scavenger receptors including collection-placenta 1 (CL-P1) are cell surface glycoproteins capable of binding to oxidized low density lipoprotein (oxLDL), which are expressed on endothelial cells, macrophages, and smooth muscle cells. We cloned and characterized a 750 base-pair fragment containing the 5′-flanking region of the human CL-P1 gene using a human genomic library. The fragment obtained from the translational start site, which contained three specificity protein-1 (Sp1) sites upstream of transcriptional start site and putative binding sites for granulocyte chemotactic factor and early growth response factor-1, was ligated to the pGL4.10-basic vector, and promoter activity was confirmed by transfection studies. Luciferase and electrophoretic gel motility shift assays revealed that three Sp1 binding sites showed specific DNA-protein binding. Deletion and mutation analyses showed that the region comprising the three Sp1 sites was required for CL-P1 proximal promoter activity in human umbilical vein endothelial cells, Hs683 cells, and SK-LMS cells. Furthermore, the third Sp1 (−28/−20) binding site was regulated through some factor, not the Sp1 protein, by hydrogen peroxide stimulation.