Regulation by thyroid hormone of the synthesis of a cytosolic thyroid hormone binding protein during liver regeneration.

To understand the regulation by thyroid hormone, 3,3',5-triiodo-L-thyronine (T3), of the synthesis of a cytosolic thyroid hormone binding protein (p58-M2) during liver regeneration, the synthesis of p58-M2 was evaluated. The synthesis of p58-M2 was measured by metabolic labeling of primary cultures derived from the regenerating liver of euthyroid, hypo- or hyperthyroid rats. During regeneration, the increase in the liver/body weight ratio is approximately 25% higher in hyper- than in hypothyroid rats. However, T3 has no effect on the rate of overall liver regeneration observed in four days. In mature liver, T3 increased the synthesis of p58-M2 by approximately 2.5-fold. During regeneration, however, the change in the synthesis of p58-M2 varied with the thyroid status. In euthyroid rats, the synthesis of p58-M2 continued to increase up to 2-fold during liver regeneration. In hyperthyroid rats, after an initial increase by 1.5-fold on day 1, the synthesis of p58-M2 subsequently declined during regeneration. In hypothyroid rats, the synthesis of p58-M2 remained virtually unchanged during regeneration. These results indicate that T3 regulates the synthesis of p58-M2 in mature and regenerating liver.