Nakashima K, Ohtsuka A, Hayashi K
Department of Biochemical Science and Technology, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890, Japan.
Biochem Biophys Res Commun. 1998 Oct 20;251(2):442-8. doi: 10.1006/bbrc.1998.9483.
Primary chick muscle cells were treated with physiological level of thyroxine (T4) or triiodothyronine (T3) to examine the effects of the hormones on growth, protein turnover, and apoptosis of the cells. Creatine kinase activity, as an index of differentiation, was increased by both T4 and T3. Even when the conversion from T4 to T3 was blocked by iopanoic acid, T4 increased creatine kinase activity. The rate of protein degradation estimated from [3H] tyrosine release was increased by T3 but not by T4. DNA cleavage and fragmentation, as indices of apoptosis, were induced by T3 but not by T4. These results show that T4 stimulates cell differentiation but not protein degradation and apoptosis in primary chick muscle cells, while all events are stimulated by T3.
用生理水平的甲状腺素（T4）或三碘甲状腺原氨酸（T3）处理原代鸡肌肉细胞，以研究这些激素对细胞生长、蛋白质周转和凋亡的影响。作为分化指标的肌酸激酶活性，在T4和T3处理下均增加。即使碘番酸阻断了T4向T3的转化，T4仍能增加肌酸激酶活性。根据[3H]酪氨酸释放估计的蛋白质降解率在T3处理下增加，而在T4处理下未增加。作为凋亡指标的DNA切割和片段化在T3处理下诱导产生，而在T4处理下未诱导产生。这些结果表明，T4刺激原代鸡肌肉细胞的细胞分化，但不刺激蛋白质降解和凋亡，而T3则刺激所有这些事件。
