Nuclear matrix proteins are crosslinked to transcriptionally active gene sequences by ionizing radiation.
Nuclear matrix proteins are crosslinked to transcriptionally active gene sequences by ionizing radiation.
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DOI：
10.2307/3576847
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发表时间：
1986-07
影响因子：
3.4
通讯作者：
S. Chiu;L. Friedman;N. M. Sokany;L. Xue;N. Oleinick
中科院分区：
文献类型：
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作者：
S. Chiu;L. Friedman;N. M. Sokany;L. Xue;N. Oleinick
未经辐照，呈指数增长的中国仓鼠细胞含有低水平（小于5%）的DNA与蛋白质紧密结合，通过过滤结合试验测量。这部分DNA在与聚（A+）RNA或核糖体RNA杂交的序列中高度富集。经过60 Gy γ辐照后，额外交联DNA的转录活性序列也比大量DNA丰富，而紫外线辐射交联DNA的活性序列频率不高于大量DNA。通过伽马辐射而不是紫外线与蛋白质交联的DNA在辐射后4小时内大量释放。在此期间，与蛋白质结合的DNA在活性序列中被耗尽；随后是在未辐照细胞中发现的活性基因富集蛋白复合体的明显恢复。当分离出核基质相关DNA时，发现活性DNA序列富集于基质相关DNA中，并且发现DNA-蛋白质交联的频率在基质部分高出10- 16倍。交联蛋白的凝胶电泳分析确定它们是核基质蛋白的子集。这些数据与已知的核基质性质一致，表明染色质结构在γ辐射诱导的DNA损伤的形成和修复中起着重要作用。
Unirradiated, exponentially growing Chinese hamster cells contain a low level (less than 5%) of their DNA firmly bound to protein, as measured by a filter-binding assay. That fraction of DNA is highly enriched in sequences which hybridize to poly(A+)RNA or ribosomal RNA. After 60 Gy gamma irradiation, the additional crosslinked DNA is also enriched in transcriptionally active sequences compared to bulk DNA, while DNA crosslinked by uv radiation has a frequency of active sequences which is no higher than the bulk DNA. DNA crosslinked to protein by gamma radiation but not by uv is largely released during a 4-h postirradiation incubation. The DNA which remains bound to protein during that period becomes depleted in active sequences; this is followed by an apparent restoration of the active gene-enriched protein complex found in unirradiated cells. When nuclear matrix-associated DNA was isolated free of the majority ("loop") DNA, an enrichment for active DNA sequences was found in the matrix-associated DNA, and the frequency of DNA-protein crosslinks was found to be 10- to 16-fold greater in the matrix fraction. Gel electrophoretic analysis of the crosslinking proteins identifies them as subset of proteins of the nuclear matrix. These data are consistent with known properties of the nuclear matrix and suggest that chromatin structure plays an important role in the formation and repair of gamma-radiation-induced DNA lesions.