Rapid, stabilizing palindrome rearrangements in somatic cells by the center-break mechanism
Rapid, stabilizing palindrome rearrangements in somatic cells by the center-break mechanism
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DOI：
10.1128/mcb.23.23.8740-8750.2003
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发表时间：
2003-12-01
影响因子：
5.3
通讯作者：
Lewis, SM
中科院分区：
文献类型：
--
作者：
Cunningham, LA;Coté, AG;Lewis, SM
DNA回文与多种生物体的重排有关。第78行小鼠品系为研究长回文对哺乳动物的影响提供了一个独特的机会。先前已经发现，第78行中的转基因很可能是回文的，而转基因的对称性是造成种系高度不稳定的原因。在这里，我们证明了第78行小鼠拥有一个真正的15.4 kb的回文，并且通过从第78行小鼠中建立细胞系，我们已经证明了回文以令人印象深刻的速度重排，每增加一倍大约0.5%。观察到的由快速回文修改引起的重排与中心断裂机制一致，其中双链断裂是通过挤压十字形的发夹切口产生的，不精确地重新连接，从而在回文中心引入缺失。值得注意的是，体细胞组织培养细胞中的回文重排几乎完全反映了小鼠生殖系体内产生的结构。生殖系和体细胞事件之间的密切对应表明，回文的中心断裂修饰可能是在这两种情况下防止突变的重要机制。携带验证回文的永久细胞系为将来对哺乳动物基因组中回文结果的机制分析提供了重要的工具。
DNA palindromes are associated with rearrangement in a variety of organisms. A unique opportunity to examine the impact of a long palindrome in mammals is afforded by the Line 78 strain of mice. Previously it was found that the transgene in Line 78 is likely to be palindromic and that the symmetry of the transgene was responsible for a high level of germ line instability. Here we prove that Line 78 mice harbor a true 15.4-kb palindrome, and through the establishment of cell lines from Line 78 mice we have shown that the palindrome rearranges at the impressive rate of about 0.5% per population doubling. The rearrangements observed to arise from rapid palindrome modification are consistent with a center-break mechanism where double-strand breaks, created through hairpin nicking of an extruded cruciform, are imprecisely rejoined, thus introducing deletions at the palindrome center. Significantly, palindrome rearrangements in somatic tissue culture cells almost completely mirrored the structures generated in vivo in the mouse germ line. The close correspondence between germ line and somatic events indicates the possibility that center-break modification of palindromes is an important mechanism for preventing mutation in both contexts. Permanent cell lines carrying a verified palindrome provide an essential tool for future mechanistic analyses into the consequences of palindromy in the mammalian genome.