HYPOTHYROIDISM LEADS TO A DECREASED EXPRESSION OF MITOCHONDRIAL F0F1-ATP SYNTHASE IN RAT-LIVER

In liver mitochondria isolated from hypothyroid rats, the rate of ATP synthesis is lower than in mitochondria from normal rats. Oligomycin-s ensitive ATP hydrolase activity and passive proton permeability were s ignificantly lower in submitochondrial particles from hypothyroid rats compared to those isolated from normal rats. In mitochondria from hyp othyroid rats, the changes in catalytic activities of F0F1-ATP synthas e are accompanied by a decrease in the amount of immunodetected beta-F -1, F(0)1-PVP, and OSCP subunits of the complex. Northern blot hybridi zation shows a decrease in the relative cytosolic content of mRNA for beta-F-1 subunit in liver of hypothyroid rats. Administration of 3,5,3 '-triodo-L-thyronine to the hypothyroid rats tends to remedy the funct ional and structural defects of F0F1-ATP synthase observed in the hypo thyroid rats. The results obtained indicate that hypothyroidism leads to a decreased expression of F0F1-ATP synthase complex in liver mitoch ondria and this contributes to the decrease of the efficiency of oxida tive phosphorylation.