Inhibition of RNA polymerase II transcription causes chromatin decondensation, loss of nucleolar structure, and dispersion of chromosomal domains
Inhibition of RNA polymerase II transcription causes chromatin decondensation, loss of nucleolar structure, and dispersion of chromosomal domains
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DOI：
10.1006/excr.1996.0124
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发表时间：
1996-04-10
影响因子：
3.7
通讯作者：
Ward, DC
中科院分区：
文献类型：
--
作者：
Haaf, T;Ward, DC
荧光原位杂交和免疫荧光已经被用来显示特定的基因组DNA序列和用转录抑制物处理的间期核中的蛋白质。腺苷类似物5，6-dichloro-beta-D-ribofuranosylbenzimidazole和α-Amanitin在低剂量下选择性地抑制RNA聚合酶II的转录，当接触DRb或α-Amanitin时，通常紧密的核仁的纤维成分解体成项链状结构，代表高度延伸的核糖体(R)RNA基因的线性阵列。类似地，重复的卫星DNA片段解离成延伸的串珠链。定位的(常染色质)染色体区域甚至整个染色体区域散布在整个核内部。用剂量阻断rRNA合成的放线菌素D(AMD)处理细胞，不会引起核仁、异染色质和间期染色体区域的显著解聚。有趣的是，α-Amanitin和AND都能使Colin与核仁区结合，在AMD处理的细胞中，Colin富含在靠近残留核仁的核仁帽中，在α-Amanitin处理后，Colin集中在与核仁项链中的单个rDNA转录单位密切相关的许多小球中，在暴露于无毒剂量的转录抑制剂的细胞培养中，高阶核结构的变化是可逆的。因此，可以得出结论，核地形组织依赖于核基因的持续转录，而不是rRNA基因的持续转录。(C)1996年学术出版社。
Fluorescence in situ hybridization and immunofluorescence have been used to visualize specific genomic DNA sequences and proteins in interphase nuclei treated with transcriptional inhibitors. The adenosine analog 5,6-dichloro-beta-D-ribofuranosylbenzimidazole (DRB) and alpha-amanitin selectively inhibit transcription by RNA polymerase II at low doses, Upon exposure to DRB or alpha-amanitin the fibrillar components of the normally compact nucleolus unravel into necklace-like structures which represent highly extended linear arrays of ribosomal (r)RNA genes. Similarly, blocks of tandemly repeated satellite DNAs dissociate into extended beaded strands. Localized (euchromatic) chromosome domains and even whole chromosome territories disperse throughout the nuclear interior. Treatment of cells with actinomycin D (AMD) at doses that block rRNA synthesis does not cause significant decondensation of nucleolar, heterochromatic, and interphase chromosome domains. Interestingly, both alpha-amanitin and ARID cause coilin to associate with the nucleolar domain, In AMD-treated cells, coilin is enriched in nucleolar caps abutting upon the residual nucleolus, After alpha-amanitin treatment, coilin is concentrated in numerous beads closely associated with individual rDNA transcription units within nucleolar necklaces, The changes in higher-order nuclear structure are reversible in cell cultures exposed to nontoxic doses of transcriptional inhibitors. It therefore may be concluded that nuclear topographic organization is dependent on a continued transcription of nuclear genes, but not of the rRNA genes. (C) 1996 Academic Press, Inc.