CHARACTERIZATION OF THE DUFFY GENE PROMOTOR - EVIDENCE FOR TISSUE-SPECIFIC ABOLISHMENT OF EXPRESSION IN FY(A-B-) OF BLACK INDIVIDUALS

We have previously identified a novel first exon of Duffy gene and two inverse GATA motifs in the 600 bp 5' flanking region. The proximal GA TA is positioned downstream from the start position of endothelium and upstream from that of erythroid. One base substitution (-365T-->C) wa s found in the proximal GATA motif from three black Fy(a-b-) individua ls, and was regarded as a common polymorphic mutation in black Fy(a-b- ) individuals. The upstream sequence of the novel first exon was inser ted in the upstream of chloramphenicol acetyltransferase (CAT) gene an d transfected in human erythroleukemia cell line (HEL) and human micro vascular endothelial cells (HMvEC). The black type mutation abolished the CAT transcription in HEL cells but not in HMvEC. Deletion mutagene sis study revealed that the proximal GATA motif represent the erythroi d regulatory core region for Duffy gene. Gel shift assay showed that t he proximal GATA motif is the target sequence of GATA-1. These studies indicate that the black type mutation abolishes Duffy gene expression in erythroid but not in postcapillary venule endothelium, which is co mpatible with the Northern blot and immunohistochemical observation in black Fy(a-b-) individuals. (C) 1996 Academic Press, Inc.