The effect of thyroid hormone treatment on the gene expression and enzyme activity of rat liver sodium-potassium dependent adenosine triphosphatase.
The effects of thyroid hormone (T3) treatment on liver Na,K-adenosine triphosphatase (Na,K-ATPase) at the levels of subunit messenger RNA (mRNA), enzymatic activity, and enzyme content were studied in euthyroid rats injected for 5 consecutive days with T3. Northern and slot blot analyses of polyadenylated mRNA revealed that T3 treatment coordinately increases the level of mRNA encoding the alpha 1- and beta 1-subunits, approximately 4- and 3-fold, respectively, above basal levels. To determine whether this increase in the subunit mRNA consequently results in an increase in the synthesis of the enzyme, a modified liver cell fractionation procedure was developed, and the subcellular fractions from control and T3-treated livers were examined biochemically. Western blot analysis and Na,K-ATPase assay demonstrated that T3 treatment resulted in a 2-fold increase in both the amount and activity of the enzyme. Furthermore, the Western blot analysis of endoglycosidase-H-treated membrane fractions revealed an increase in the amount of the precursor beta-subunit in the T3-treated liver rough microsomal fraction, suggesting that an increase in subunit synthesis contributes at least partially to the increase in the rat liver Na,K-ATPase by T3 treatment.
Department of Cell Biology, New York University School of Medicine, New York 10016.
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V
Desai-Yajnik
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Zeng
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Omori
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J
Sherman
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Morimoto
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D005786:Gene Expression Regulation; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014284:Triiodothyronine / Q000494:pharmacology*
D012333:RNA, Messenger; D014284:Triiodothyronine; D000254:Sodium-Potassium-Exchanging ATPase