Isolation of a bi-directional promoter directing expression of the mouse GABPα and ATP synthase coupling factor 6 genes

The GA-binding protein (GABP) is a ubiquitous heteromeric transcription factor implicated in the regulation of several genes involved in mitochondrial energy metabolism including subunits of cytochrome c oxidase, ATP synthase, and mitochondrial transcription factor 1 (mtTF1). GABP alpha subunit binds the PEA3/Ets binding sites (EBS), while GABP beta contains a transcription activation domain and mediates alpha beta dimer and alpha (2)beta (2) tetramer formation essential for activation of transcription. Here we report the cloning of 2449 bp of the mouse (m) GABP alpha promoter region including 201 bp of the 5' end of the published mGABP alpha cDNA sequence. Surprisingly, sequences homologous to the 5'UTR of mouse, rat and human mitochondrial ATP synthase coupling factor 6 (ATPsynCF6) cDNAs were found165-240 bp upstream of the mGABP alpha cDNA. A search of the non-redundant nucleotide database revealed a human genomic sequence derived from chromosome 21 (21q22) bearing significant homology to the mGABP alpha /ATPsynCF6 promoter region and encompassed the entire hGABP alpha and hATP-synCF6 genes. Primer extension analysis revealed multiple transcription start sites for both mGABP alpha and mATPsynCF6 mRNAs that mapped near the published cDNA 5' ends. Sequence analysis identified several binding sites upstream of the GABP alpha cDNA sequence including sites for GABP (-86, -104, -169, -257, and -994), YY1 (-57), Spl (-242 and -226), and NRF1 (-5). No 'TATA' motif was identified near either the GABPa or ATPsynCF6 transcription start sites. The human and mouse promoters retain significant sequence identity including binding sites for several tissue-specific transcription factors. Transient transfection assays using Luciferase reporter constructs containing the intergenic region and flanking sequences confirmed that this region of DNA promotes transcription in both directions. (C) 2000 Elsevier Science B.V. All rights reserved.