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.
Obata
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T
Division of Biochemistry, Jikei University School of Medicine, Tokyo, Japan.
Cheng
S Y
SY
D000818:Animals; D001345:Autoradiography; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D006498:Hepatectomy; D006980:Hyperthyroidism / Q000201:enzymology / Q000503:physiopathology*; D007037:Hypothyroidism / Q000201:enzymology / Q000503:physiopathology*; D007527:Isoenzymes / Q000096:biosynthesis* / Q000302:isolation & purification; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D008713:Methimazole / Q000494:pharmacology; D008715:Methionine / Q000378:metabolism; D011770:Pyruvate Kinase / Q000096:biosynthesis* / Q000302:isolation & purification; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D013462:Sulfur Radioisotopes; D014284:Triiodothyronine / Q000494:pharmacology*
D007527:Isoenzymes; D013462:Sulfur Radioisotopes; D014284:Triiodothyronine; D008713:Methimazole; D008715:Methionine; D011770:Pyruvate Kinase