TGF-BETA-INDUCIBLE EARLY GENE (TIEG) ALSO CODES FOR EARLY GROWTH-RESPONSE-ALPHA (EGR-ALPHA) - EVIDENCE OF MULTIPLE TRANSCRIPTS FROM ALTERNATE PROMOTERS

TGF beta-inducible early gene (TIEG) and early growth response alpha ( EGR alpha) are putative transcription factors based on homology to kno wn zinc finger proteins SP1, EGR1, BTEB, and Wilm tumor. Here we repor t that TIEG and EGR alpha are expressed from alternative promoters of the same gene. The TIEG/EGR alpha gene spans 8 kb and contains five ex ons. Use of alternative first exons results in TIEG having 12 unique a mino acids on its N-terminus. Computer analysis of the 5' upstream reg ions of either TIEG (exon 1a) or EGR alpha (exon 1b) does not identify a TATA box or initiator sequence but shows consensus sequence similar ities to binding sites for several transcription factors including SP1 , JunB, and aromatic hydrocarbon/receptor-ligand complexes. Analysis o f constructs containing 5'-flanking regions show that both the TIEG an d the EGR alpha promoters have significant activity in human fetal ost eoblast cells. Northern analysis of mRNA from various human tissues an d several cell lines reveals that TIEG is the predominant transcript p roduced and regulated by growth factors from the TIEG/EGR alpha gene. (C) 1998 Academic Press