Identification of Tissue-Specific Protein Binding Domains in the 5′-Proximal Regulatory Region of the Rat Mitochondrial Brown Fat Uncoupling Protein Gene

Abstract

The 5′ proximal region of the rat uncoupling protein gene, extending from −611 to +110, contains cis-acting elements involved in cell-specificity and cAMP regulation of transcription. DNAse I footprinting of this region was performed using protein extracts from brown adipose tissue and liver nuclei. Nine protein binding domains were observed using nuclear proteins from both tissues. They include the elements for basal promoter activity (TATA and CCAAT elements), a cAMP-responsive element, two C/EBP binding sites and three unidentified DNA-protein binding domains sharing a common GCCCCT sequence. A purine rich region at −402/−362 was observed to bind proteins abundant in liver but scarce in brown adipose tissue nuclei. A single region at −512/−487 was identified as the only element that binds nuclear proteins present in brown adipose tissue but absent in liver. This putative tissue-specific element in the uncoupling protein gene contains a sequence identical to mammalian or viral gene elements that bind members of the ETS family of transcription factors.