THE HUMAN LGALS3 (GALECTIN-3) GENE - DETERMINATION OF THE GENE STRUCTURE AND FUNCTIONAL-CHARACTERIZATION OF THE PROMOTER

Galectin-3 is a beta-galactoside-specific lectin that is a pre-mRNA sp licing factor. Here we report the genomic organization of the human LG ALS3 (galectin-3) gene and functional characterization of the promoter . Southern blot analysis of genomic DNA revealed that galectin-3 is co ded by a single gene in the human genome, The gene is composed of six exons and five introns, spanning a total of similar to 17 kilobases (k b), Based on primer extension and ribonuclease protection analyses, th ere are two transcription initiation sites located 52 and 50 nucleotid es (nt) upstream of the exon I-intron 1 border, and defined here as 1a and + 1b, respectively. The translation start site is in exon II, T he ribonucleoprotein like N-terminal domain, containing the proline-gl ycine-alanine-tyrosine (PGAY) repeat motif, is found entirely within e xon III. The carbohydrate recognition sequence is found entirely withi n exon V. Genomic fragments encompassing -836 to +141 nt (relative to +1a) have significant promoter activity when linked to the luciferase reporter gene and transiently transfected into HeLa cells or human dip loid fibroblasts, Quiescent fibroblasts have low promoter activity but the activity increases 100-fold following serum addition, Serum respo nsive activation regions in the promoter are located between -513 and -339 nt and between -339 and -229 nt; an additional activation region may be located between -105 and -15 nt, Because galectin-3 is an immed iate-early gene whose expression is dependent on the proliferative sta te of the cell, this study provides the basis for determining the mole cular mechanisms of transcriptional regulation in neoplasia or cellula r senescence. (C) 1998 Academic Press.