DeBerardinis R J, Goodier J L, Ostertag E M, Kazazian H H
Department of Genetics, University of Pennsylvania, Philadelphia 19104, USA.
Nat Genet. 1998 Nov;20(3):288-90. doi: 10.1038/3104.
Retrotransposition affects genome structure by increasing repetition and producing insertional mutations. Dispersion of the retrotransposon L1 throughout mammalian genomes suggests that L1 activity might be an important evolutionary force. Here we report that L1 retrotransposition contributes to rapid genome evolution in the mouse, because a number of L1 sequences from the T(F) subfamily are retrotransposition competent. We show that the T(F) subfamily is large, young and expanding, containing approximately 4,800 full-length members in strain 129. Eleven randomly isolated, full-length T(F) elements averaged 99.8% sequence identity to each other, and seven of these retrotransposed in cultured cells. Thus, we estimate that the mouse genome contains approximately 3,000 active T(F) elements, 75 times the estimated number of active human L1s. Moreover, as T(F) elements are polymorphic among closely related mice, they have retrotransposed recently, implying rapid amplification of the subfamily to yield genomes with different patterns of interspersed repetition. Our data show that mice and humans differ considerably in the number of active L1s, and probably differ in the contribution of retrotransposition to ongoing sequence evolution.
逆转座通过增加重复序列和产生插入突变来影响基因组结构。逆转座子L1在整个哺乳动物基因组中的分散表明L1活性可能是一种重要的进化力量。在此我们报告，L1逆转座有助于小鼠基因组的快速进化，因为来自T(F)亚家族的许多L1序列具有逆转座能力。我们表明，T(F)亚家族庞大、年轻且在不断扩展，在129品系中包含约4800个全长成员。随机分离的11个全长T(F)元件彼此之间的平均序列同一性为99.8%，其中7个在培养细胞中发生了逆转座。因此，我们估计小鼠基因组包含约3000个活跃的T(F)元件，是估计的活跃人类L1数量的75倍。此外，由于T(F)元件在亲缘关系密切的小鼠中具有多态性，它们最近发生了逆转座，这意味着该亚家族快速扩增，从而产生具有不同散在重复模式的基因组。我们的数据表明，小鼠和人类在活跃L1的数量上有很大差异，并且逆转座对正在进行的序列进化的贡献可能也不同。
