Department of Immunology, Center of Biological Investigations, High Council of Scientific Investigations, Madrid, Spain.
Platelet endothelial cell adhesion molecule-1 (PECAM-1; CD31) is a cell adhesion molecule involved in transendothelial migration and expressed by hemopoietic and endothelial cells. To understand the mechanisms underlying its regulated expression, a genomic clone containing 1555 bp of the 5'-flanking region and the first exon of the human PECAM-1 gene has been isolated. The 5'-flanking region of the PECAM-1 gene lacks a consensus TATA box, but contains consensus motifs for Sp1, EGR1, ets, helix-loop-helix (HLH) box, GATA, AP-2, C/EBP, YY1, CCACC, LyF-1, imperfect octamer, heptamer, high mobility group proteins (HMG) box, and nuclear factor-kappaB, as well as shear stress-, retinoic acid-, glucocorticoid-, and acute phase-responsive elements, and an Alu sequence. Successive 5' to 3' or 3' to 5' deletions revealed tissue-specific promoter activity within the two contiguous 0.22-kb NheI/BglII and 0.44-kb BglII/PstI fragments. The transcriptional activity displayed by the 0.22-kb NheI/BglII fragment was specific for the myeloid lineage, whereas the promoter activity of the 0.44-kb BglII/PstI fragment was apparently restricted to endothelial cells. The transcriptional activity of the 0.22-kb NheI/BglII fragment was confirmed by 5' RACE (rapid amplification of 5' cDNA ends) and S1 nuclease protection experiments that revealed previously unidentified transcription start sites. The 0.22-kb NheI/BglII promoter exhibited PMA inducibility in myeloid cells and contained a PMA-responsive element recognized by Sp1 and EGR-1 transcription factors. Isolation and characterization of the human PECAM-1 promoter represent an initial step in elucidating the controlled expression of the PECAM-1 gene.