Kirov N, Djondjurov L, Tsanev R
J Mol Biol. 1984 Dec 15;180(3):601-14. doi: 10.1016/0022-2836(84)90029-9.
The association of the mouse alpha-globin gene with the nuclear matrix was studied when the gene was permanently repressed in Ehrlich ascites cells, potentially active in uninduced Friend cells or actively transcribed in induced Friend cells. Matrix-associated DNA was obtained by two methods, differing in the order of treatment of the nuclei with high salt and DNase I. By using a cloned alpha-globin probe, no enrichment in alpha-globin sequences was found in the matrix-associated DNA after DNase I digestion of high-salt treated nuclei from Ehrlich ascites and uninduced Friend cells. In induced Friend cells, a high enrichment (up to 20 times) of alpha-globin sequences was detected in the DNA left with the nuclear matrix structures. The size of the DNA fragments obtained by this procedure indicated a random attack and did not correspond to a progressive top-to-bottom cleavage model. No enrichment in alpha-globin sequences was found in induced Friend cells if nuclear matrices were obtained by DNase I digestion of the nuclei before the treatment with high salt. Our data suggest that the enrichment in actively transcribed genes of matrices from nuclei treated with high salt does not reflect a localization of these genes close to the attachment sites of the chromatin loops but rather their artefactual association with some high salt-insoluble proteins of the transcriptional complexes.
当小鼠α-珠蛋白基因在艾氏腹水细胞中永久抑制、在未诱导的Friend细胞中可能有活性或在诱导的Friend细胞中活跃转录时，研究了该基因与核基质的关联。通过两种方法获得与基质相关的DNA，这两种方法在高盐和DNase I处理细胞核的顺序上有所不同。使用克隆的α-珠蛋白探针，在对来自艾氏腹水细胞和未诱导的Friend细胞的高盐处理细胞核进行DNase I消化后，在与基质相关的DNA中未发现α-珠蛋白序列富集。在诱导的Friend细胞中，在与核基质结构保留的DNA中检测到α-珠蛋白序列高度富集（高达20倍）。通过该程序获得的DNA片段大小表明是随机切割，并不符合从顶部到底部的渐进切割模型。如果在用高盐处理之前通过对细胞核进行DNase I消化来获得核基质，则在诱导的Friend细胞中未发现α-珠蛋白序列富集。我们的数据表明，高盐处理细胞核的基质中活跃转录基因的富集并不反映这些基因定位在染色质环的附着位点附近，而是反映了它们与转录复合物中一些高盐不溶性蛋白质的人为关联。
