Kato Takema, Inagaki Hidehito, Tong Maoqing, Kogo Hiroshi, Ohye Tamae, Yamada Kouji, Tsutsumi Makiko, Emanuel Beverly S, Kurahashi Hiroki
Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.
Mol Cytogenet. 2011 Sep 8;4:18. doi: 10.1186/1755-8166-4-18.
Cumulative evidence suggests that DNA secondary structures impact DNA replication, transcription and genomic rearrangements. One of the best studied examples is the recurrent constitutional t(11;22) in humans that is mediated by potentially cruciform-forming sequences at the breakpoints, palindromic AT-rich repeats (PATRRs). We previously demonstrated that polymorphisms of PATRR sequences affect the frequency of de novo t(11;22)s in sperm samples from normal healthy males. These studies were designed to determine whether PATRR polymorphisms affect DNA secondary structure, thus leading to variation in translocation frequency.
We studied the potential for DNA cruciform formation for several PATRR11 polymorphic alleles using mobility shift analysis in gel electrophoresis as well as by direct visualization of the DNA by atomic force microscopy. The structural data for various alleles were compared with the frequency of de novo t(11;22)s the allele produced.
The data indicate that the propensity for DNA cruciform structure of each polymorphic allele correlates with the frequency of de novo t(11;22)s produced (r = 0.77, P = 0.01).
Although indirect, our results strongly suggest that the PATRR adopts unstable cruciform structures during spermatogenesis that act as translocation hotspots in humans.
越来越多的证据表明，DNA二级结构会影响DNA复制、转录和基因组重排。其中一个研究得最为深入的例子是人类中常见的染色体结构变异t(11;22)，它由断点处潜在的十字形形成序列——富含AT的回文重复序列（PATRRs）介导。我们之前证明，PATRR序列的多态性会影响正常健康男性精子样本中新生t(11;22)的频率。这些研究旨在确定PATRR多态性是否会影响DNA二级结构，从而导致易位频率的变化。
我们使用凝胶电泳中的迁移率变动分析以及通过原子力显微镜直接观察DNA，研究了几种PATRR11多态性等位基因形成DNA十字形的可能性。将各种等位基因的结构数据与该等位基因产生的新生t(11;22)频率进行比较。
数据表明，每个多态性等位基因的DNA十字形结构倾向与产生的新生t(11;22)频率相关（r = 0.77，P = 0.01）。
虽然是间接证据，但我们的结果强烈表明，PATRR在精子发生过程中会形成不稳定的十字形结构，这些结构在人类中充当易位热点。
