Borbhuiya M A, Sharma R
Department of Biochemistry, North-Eastern Hill University, Umshing, Shillong, India.
Indian J Biochem Biophys. 1995 Jun;32(3):125-9.
The specific binding of [3H]dexamethasone to its receptor and the activation of the hormone-receptor complexes from the kidney of mice at various postnatal ages were investigated. The results indicated that the level (fmol/mg protein) of glucocorticoid receptors remained unaltered at 10-, 15- and 30-day, increased significantly at 45-day and thereafter declined to its earlier level in 60-day old mice. Scatchard analysis of binding data confirmed the increased level of receptors at 45-day compared to day 15, without any change in the hormone affinity to its receptor at these two ages. The extent of temperature- and salt-dependent activation of the receptor showed no marked differences in 10- and 60-day old mice, as determined by DNA-cellulose binding assays. However, the nuclear binding of temperature- and salt-activated glucocorticoid-receptor complexes was significantly higher in 10-day old mice. Cross-mixing experiments showed nuclear specificity in higher binding of thermally activated receptor at day 10 of postnatal age. Molybdate, tungstate and N-ethylmaleimide inhibited the temperature- and salt-dependent activation of glucocorticoid-receptor complexes similarly at both the ages studied. DNase I extraction of bound hormone-receptor complexes from nuclei showed higher extractability at day 10 (63%) compared to day 60 (43%). These findings indicated changes in glucocorticoid receptor concentration together with chromatin organization that might play an important role in glucocorticoid-mediated responses during postnatal development of mice.
研究了[3H]地塞米松与其受体的特异性结合以及不同出生后年龄小鼠肾脏中激素-受体复合物的激活情况。结果表明，糖皮质激素受体水平（fmol/mg蛋白）在10日龄、15日龄和30日龄时保持不变，在45日龄时显著增加，此后在60日龄小鼠中降至早期水平。对结合数据的Scatchard分析证实，与15日龄相比，45日龄时受体水平增加，且在这两个年龄阶段激素与其受体的亲和力没有变化。通过DNA-纤维素结合试验测定，10日龄和60日龄小鼠中受体的温度和盐依赖性激活程度没有明显差异。然而，10日龄小鼠中温度和盐激活的糖皮质激素-受体复合物的核结合显著更高。交叉混合实验表明，出生后10日龄时热激活受体的更高结合具有核特异性。钼酸盐、钨酸盐和N-乙基马来酰亚胺在两个研究年龄阶段对糖皮质激素-受体复合物的温度和盐依赖性激活的抑制作用相似。从细胞核中提取结合的激素-受体复合物的DNase I实验表明，与60日龄（43%）相比，10日龄时的提取率更高（63%）。这些发现表明糖皮质激素受体浓度的变化以及染色质组织的变化可能在小鼠出生后发育过程中糖皮质激素介导的反应中起重要作用。
