BINDING OF MITOCHONDRIAL AND NUCLEAR PROTEINS FROM MOUSE AND HUMAN-CELLS TO GRE-LIKE ELEMENTS OF MOUSE MITOCHONDRIAL-DNA

In the context of the hypothesis that the mitochondria represent primary sites of steroid hormone action we have evaluated the possible role of two nucleotide sequences partially homologous to Glucocorticoid Responsive Elements (GREs) present in the cytochrome oxidase subunit I gene of mouse and human mitochondrial DNA, as binding sites for mitochondrial and nuclear regulatory protein(s). Using a gel retardation assay, we examined whether proteins contained in mitochondrial and nuclear extracts from untreated and dexamethasone treated MCF7 and LATK- cell lines bind to these oligonucleotides. Both the mitochondrial and nuclear extracts from these cell lines contain protein(s) that bind to the oligonucleotides, as well as to the GRE of the human metallothionein II(A) promoter, binding which was considerably enhanced when the extracts were derived from cells previously treated with dexamethasone.