Differential regulation of the uncoupling protein 1 gene

Abstract

The mouse uncoupling protein 1 gene (Ucpl) is expressed specifically in brown adipose tissue and its transcription is increased by cold exposure. We have analyzed the transcriptional control of this gene through deletion analysis of the upstream untranslated regions of Ucpl. Mutated minigene constructs were microinjected into mouse pronuclei to generate transgenic mice. Positive transgenic founders were crossed with Balb/cByJ +/+ mice to generate F₁ offspring heterozygous for the transgene, which were then examined for tissue-specific and cold inducible expression of the minigenes by northern analysis. Protein-DNA interactions at putative regulatory sites were also explored through in vitro gel shift assays of the promoter and enhancer regions. We found that the sequence between -2,581 and -2,335 bp of the enhancer region is critical for the expression of Ucpl. We also discovered that the region located between -991 and -230 bp does not play a major role in Ucpl expression. We found that nuclear factor-1 does not play a regulatory role at -166 bp in the promoter region. It was observed that CCAAT enhancer binding protein does not interact with the 5' flanking region at -2,450 to -2,411 bp.