GENE STRUCTURE, PROMOTER CHARACTERIZATION, AND BASIS FOR ALTERNATIVE MESSENGER-RNA SPLICING OF THE HUMAN CD58 GENE

The 60-kDa lymphocyte function-associated Ag-3 (LFA-3/CD58), a highly glycosylated adhesion molecule that serves as ligand for the T cell-re stricted glycoprotein CD2, is encoded by a gene at the human chromosom e locus 1p13, We have elucidated the exon-intron organization of the e ntire human CD58 gene, including similar to 2.5 kilobases (kb) of 5'-f lanking DNA, Four overlapping genomic clones, spanning similar to 65 k b, contained the entire similar to 1-kb coding sequence of CD58 and co nsisted of six separate exons, which varied from 72 to 294 bp in size, At least two different CD58 mRNA precursors can he generated from the human gene as a result of alternative choice of one of the two accept or splice sites located within exon 5, DNA sequence analysis of about 2.5 kb of 5'-flanking sequence of the CD58 gene indicated the absence of a CAAT box, However, potential binding sites for the transcriptiona l activators AP-2, GATA, PU.1, and Sp-1 are present. Two consensus TAT AA elements, located similar to 2.4 kb upstream of the transcriptional start site, have been identified, The 2.5-kb CD58 promoter sequence d isplayed functional activity in transient transfection assays in the h epatocellular carcinoma cell Line HepG2, Comparing the response of CD5 8 promoter-driven luciferase plasmids to several cytokines and other a gents suggests that the CD58 promoter is regulated by up-regulatory, e nhancer-like and down-regulatory, silencer-like elements, Further anal ysis of this region should allow researchers to gain insight into the molecular mechanisms by which this gene is regulated, e.g., during inf lammatory responses.