LINE1 retrotransposons are mobile DNA elements that copy and paste themselves into new sites in the genome. To ensure their evolutionary success, heritable new LINE-1 insertions accumulate in cells that can transmit genetic information to the next generation (i.e., germ cells and embryonic stem cells). It is our hypothesis that LINE1 retrotransposons, insertional mutagens that affect expression of genes, may be causal agents of early miscarriage in humans. The cell has evolved various defenses restricting retrotransposition-caused mutation, but these are occasionally relaxed in certain somatic cell types, including those of the early embryo. We predict that reduced suppression of L1s in germ cells or early-stage embryos may lead to excessive genome mutation by retrotransposon insertion, or to the induction of an inflammatory response or apoptosis due to increased expression of L1-derived nucleic acids and proteins, and so disrupt gene function important for embryogenesis. If correct, a novel threat to normal human development is revealed, and reverse transcriptase therapy could be one future strategy for controlling this cause of embryonic damage in patients with recurrent miscarriages.

中文翻译：

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潜在的妊娠流失新机制：考虑LINE-1逆转座子在早期自然流产中的作用。

LINE1逆转座子是可移动的DNA元件，可将自身复制并粘贴到基因组的新位点中。为了确保其进化成功，可遗传的新LINE-1插入物积聚在可以将遗传信息传递给下一代的细胞（即生殖细胞和胚胎干细胞）中。我们的假设是，LINE1逆转座子是影响基因表达的插入诱变剂，可能是人类早期流产的病因。该细胞已进化出多种防御机制，可限制逆转录转座引起的突变，但在某些体细胞类型（包括早期胚胎的那些）中有时会放松。我们预测，生殖细胞或早期胚胎中L1的抑制作用降低可能会导致反转录转座子插入导致基因组突变过多，或由于L1衍生的核酸和蛋白质表达增加而引起的炎症反应或凋亡，因此破坏了对胚胎发生重要的基因功能。如果正确，则揭示出对人类正常发育的新威胁，逆转录酶疗法可能是控制复发性流产患者这种胚胎损伤原因的一种未来策略。