Smirnov V G, Kir'ianov G I, Vaniushin B F
Biokhimiia. 1978 Oct;43(10):1845-53.
The content of hydrocortisone in rat liver nuclei reaches its maximum in 1 hour after its intravenous injection and remains stable for another hour. In three hours after introduction it falls to the initial level (15 min after the injection of [3H]hydrocortisone). The accumulation of the hormone in nuclei completely coincides with kinetics of reversible DNA supermethylation and correlates with the induction of transcription. No free [3H]hydrocortisone was found in nuclei, in isolated nuclei it is found in the fraction of nuclear membranes, nucleoplasma, nucleolus and chromatin. Specific radioactivity of [3H]hydrocortisone (d. p. m. per 1 mg of DNA) in active chromatin is 10--50-fold as high as in condensed chromatin and is 10--15-fold as high as in nucleolus. It is suggested that there are at least two types of binding hormonereceptor complexes with chromatin. The initial binding of these complexes with condensed chromatin may result in its structural rearrangement (euchromatization), in the appearance of more specific secondary sites for binding hormone-receptor complexes with chromatin DNA, and also in the appearance of methylation and transcription initiation sites in DNA.
大鼠肝细胞核中氢化可的松的含量在静脉注射后1小时达到最高值，并在接下来的1小时内保持稳定。注射后3小时，其含量降至初始水平（注射[3H]氢化可的松15分钟后）。激素在细胞核中的积累与可逆性DNA超甲基化的动力学完全一致，并与转录诱导相关。在细胞核中未发现游离的[3H]氢化可的松，在分离的细胞核中，它存在于核膜、核质、核仁和染色质部分。活性染色质中[3H]氢化可的松的比放射性（每1毫克DNA的每分钟衰变数）比浓缩染色质高10至50倍，比核仁高10至15倍。有人提出，至少存在两种与染色质结合的激素受体复合物类型。这些复合物与浓缩染色质的初始结合可能导致其结构重排（常染色质化），出现更多与染色质DNA结合激素受体复合物的特异性二级位点，以及DNA中甲基化和转录起始位点的出现。
