Khodarev N N, Bennett T, Shearing N, Sokolova I, Koudelik J, Walter S, Villalobos M, Vaughan A T
Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois 60637, USA.
J Cell Biochem. 2000 Sep 7;79(3):486-95.
Using a directional cloning strategy, DNA sequence information was obtained corresponding to the site of early radiation-induced apoptotic DNA fragmentation within the human lymphoblastoid cell line TK6. Data were obtained from 88 distinct clones comprising approximately 65 kbp of sequenced material. Analysis of all cloned material showed that sequences in the 10 bp immediately adjacent to the cleavage sites were enriched in short oligoT tracts. The proportion of repetitive DNA within the entire cloned material was found to be within the normal range. However the distribution of Alu and LINE repetitive DNA were biased to positions at or adjacent to the apoptotic cleavage site. In particular, a non-random distribution of five cleavage sites was found clustered within the second ORF of the LINE L1 that partially overlapped with two binding sites for the nuclear matrix-associated protein SATB1. Three other clones, containing alpha satellite elements, were also linked to a DNA matrix binding function. These data indicate that the site of chromatin loop formation at the nuclear matrix may be a specific target for early DNA fragmentation events during apoptosis.
采用定向克隆策略，获得了与人类淋巴母细胞系TK6中早期辐射诱导的凋亡性DNA片段化位点相对应的DNA序列信息。数据来自88个不同的克隆，包含约65kbp的测序材料。对所有克隆材料的分析表明，紧邻切割位点的10bp序列中富含短oligoT序列。发现整个克隆材料中重复DNA的比例在正常范围内。然而，Alu和LINE重复DNA的分布偏向于凋亡切割位点或其附近的位置。特别是，发现五个切割位点呈非随机分布，聚集在LINE L1的第二个开放阅读框内，该开放阅读框与核基质相关蛋白SATB1的两个结合位点部分重叠。另外三个含有α卫星元件的克隆也与DNA基质结合功能相关。这些数据表明，核基质处染色质环形成的位点可能是凋亡过程中早期DNA片段化事件的特定靶点。
