Presence of glucocorticoid responsive elements in the mitochondrial genome

Glucocorticoids rapidly affect nuclear RNA synthesis by binding, as hormone-receptor complexes, to Glucocorticoid Responsive Elements (GRE), differently positioned in glucocorticoid inducible genes. Glucocorticoids also affect, within minutes, mitochondrial RNA synthesis. We therefore searched for GREs in the mitochondrial genome of human (H), rat (R) and mouse (M) and found a number of such potential elements as follows: one within the 12s - rRNA gene (H1, R1 and M1) one within (H2), or at the start (R2, M2), of the presumptive protein 1 gene and three within the mouse cytochrome oxidase subunit 1 gene (COX1, COX2 and COX3). The nucleotide sequence of H1, R1 and M1 reveals the possibility of the formation of hairpin structures, stabilized by hydrogen bond formation, between three or four consecutive bases. The presence of potential GREs in the mitochondrial genome suggests an adjustment of mitochondrial metabolic control to the general control mechanisms of the cell.