n-Butyrate Enhances Induction of Thyroid Hormone- Responsive Nuclear Protein

抄録

Effects of n-butyrate on nuclear thyroid hormone receptors and on thyroid hormone-responsive nuclear protein were investigated by means of a perfusion system in rat liver. Treatment with 5mM n-butyrate resulted in an increase (150%) in the maximal binding capacity of 3, 5, 3'-L-triiodothyronine (T₃) nuclear receptors without altering the affinity of receptor for T₃. However, further perfusion for 4h decreased the number of the receptors to the control level. n-Butyrate increased the amount of acetylated histone H4. The ability of nuclear T₃ receptors to bind to core histones was diminished by acetylation of the core histones. Thyroid hormone-responsive nuclear protein (n protein) was increased by T₃. The induction of the n protein by T₃ was augmented by n-butyrate. These results suggested that n-butyrate modulates thyroid hormone-responsive gene expression in rat liver via the increased number of nuclear receptors or changes in the chromatin constitution.