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). GABPα subunit binds the PEA3/Ets binding sites (EBS), while GABPβ contains a transcription activation domain and mediates αβ dimer and α 2 β 2 tetramer formation essential for activation of transcription. Here we report the cloning of 2449 bp of the mouse (m) GABPα promoter region including 201 bp of the 5′ end of the published mGABPα 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 mGABPα cDNA. A search of the non-redundant nucleotide database revealed a human genomic sequence derived from chromosome 21 (21q22) bearing significant homology to the mGABPα/ATPsynCF6 promoter region and encompassed the entire hGABPα and hATPsynCF6 genes. Primer extension analysis revealed multiple transcription start sites for both mGABPα and mATPsynCF6 mRNAs that mapped near the published cDNA 5′ ends. Sequence analysis identified several binding sites upstream of the GABPα cDNA sequence including sites for GABP (−86, −104, −169, −257, and −994), YY1 (−57), Sp1 (−242 and −226), and NRF1 (−5). No ‘TATA’ motif was identified near either the GABPα 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.