Landsberger N, Wolffe A P
Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892-5431, USA.
EMBO J. 1997 Jul 16;16(14):4361-73. doi: 10.1093/emboj/16.14.4361.
Transcriptional repression occurs during meiotic maturation of Xenopus oocytes. Injection of a DNA template containing an hsp70 promoter into Xenopus oocytes, followed by progesterone-induced maturation has been used to demonstrate a dynamic competition between the assembly of transcription factor-containing nucleoprotein complexes and repressive nucleosomal arrays during the maturation process. In particular, it is shown that increased levels of injected heat shock protein, the transcriptional activator Gal4-VP16 or the DNA template itself all lead to reduced repression of transcription on maturation. Conversely, injection of additional histone increases repression. Repression of transcription is shown to be accompanied by the formation of a more regular array of nucleosomes and by an increase in the efficiency of nucleosome assembly on the injected plasmid. Meiotic maturation is therefore accompanied by replacement of transcription factor complexes by a repressive chromatin environment.
转录抑制发生在非洲爪蟾卵母细胞的减数分裂成熟过程中。将含有热休克蛋白70（hsp70）启动子的DNA模板注入非洲爪蟾卵母细胞，随后用孕酮诱导成熟，以此来证明在成熟过程中含转录因子的核蛋白复合物组装与抑制性核小体阵列之间存在动态竞争。具体而言，研究表明，注射的热休克蛋白、转录激活因子Gal4-VP16或DNA模板本身水平的增加，都会导致成熟过程中转录抑制的降低。相反，额外注射组蛋白会增强抑制作用。转录抑制伴随着更规则的核小体阵列的形成以及注射质粒上核小体组装效率的提高。因此，减数分裂成熟伴随着转录因子复合物被抑制性染色质环境所取代。
