Naas T P, DeBerardinis R J, Moran J V, Ostertag E M, Kingsmore S F, Seldin M F, Hayashizaki Y, Martin S L, Kazazian H H
Department of Genetics, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA.
EMBO J. 1998 Jan 15;17(2):590-7. doi: 10.1093/emboj/17.2.590.
Retrotransposition of LINEs and other retroelements increases repetition in mammalian genomes and can cause deleterious mutations. Recent insertions of two full-length L1s, L1spa and L1Orl, caused the disease phenotypes of the spastic and Orleans reeler mice respectively. Here we show that these two recently retrotransposed L1s are nearly identical in sequence, have two open reading frames and belong to a novel subfamily related to the ancient F subfamily. We have named this new subfamily TF (for transposable) and show that many full-length members of this family are present in the mouse genome. The TF 5' untranslated region has promoter activity, and TF-type RNA is abundant in cytoplasmic ribonucleoprotein particles, which are likely intermediates in retrotransposition. Both L1spa and L1Orl have reverse transcriptase activity in a yeast-based assay and retrotranspose at high frequency in cultured cells. Together, our data indicate that the TF subfamily of L1s contains a major class of mobile elements that is expanding in the mouse genome.
长散在核元件（LINEs）和其他反转录元件的反转录转座增加了哺乳动物基因组中的重复序列，并可能导致有害突变。最近插入的两个全长L1元件，即L1spa和L1Orl，分别导致了痉挛性小鼠和奥尔良reeler小鼠的疾病表型。在此，我们表明这两个最近反转录转座的L1元件在序列上几乎相同，具有两个开放阅读框，并且属于一个与古老的F亚家族相关的新亚家族。我们将这个新亚家族命名为TF（可转座的），并表明该家族的许多全长成员存在于小鼠基因组中。TF 5'非翻译区具有启动子活性，并且TF型RNA在细胞质核糖核蛋白颗粒中丰富，这些颗粒可能是反转录转座的中间体。在基于酵母的检测中，L1spa和L1Orl都具有逆转录酶活性，并且在培养细胞中高频反转录转座。总之，我们的数据表明L1的TF亚家族包含一类在小鼠基因组中正在扩展的主要移动元件。
