Reprogramming somatic cells into iPS cells activates LINE-1 retroelement mobility.
Reprogramming somatic cells into iPS cells activates LINE-1 retroelement mobility.
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DOI：
10.1093/hmg/ddr455
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发表时间：
2012
影响因子：
3.5
通讯作者：
S. Wissing;M. Muñoz-Lopez;Angela Macia;Zhiyuan Yang;M. Montaño;William O. Collins;J. García-Pérez;J. V. Moran;W. Greene
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文献类型：
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作者：
S. Wissing;M. Muñoz-Lopez;Angela Macia;Zhiyuan Yang;M. Montaño;William O. Collins;J. García-Pérez;J. V. Moran;W. Greene
长散布元件-1 （LINE-1或L1）逆转录转座子占人类基因组DNA的近17%，是重塑人类基因组结构和功能的主要进化力量。然而，关于体内L1逆转录转位的频率和发育时间，以及这些逆转录元件的移动性是否通常导致基因组损伤的插入和插入后机制，问题仍然存在。表现出高L1逆转录率的细胞可能特别有这种损伤的风险。我们评估了L1 mRNA在两种生物学相关的细胞类型——人胚胎干细胞（hESCs）和诱导多能干细胞（iPSCs）以及对照亲本人真皮成纤维细胞（HDFs）中的表达和L1逆转录。全长L1 mRNA和L1开放阅读框1编码蛋白（ORF1p）在hESCs和iPSCs中很容易检测到，但在HDFs中没有。测序分析证实了人类特异性L1元件mrna在iPSCs中的表达。亚硫酸氢盐测序显示，在iPSCs中观察到的L1表达增加与L1启动子区域CpG甲基化的总体降低相关。最后，在iPSCs中逆转录人L1元件的效率是在亲本HDFs中的10倍。这些研究结果表明，体细胞重编程与L1表达的显著增加以及内源性L1反转录转位的增加有关，这可能会潜在地影响所产生的iPSCs的基因组完整性。
Long interspersed element-1 (LINE-1 or L1) retrotransposons account for nearly 17% of human genomic DNA and represent a major evolutionary force that has reshaped the structure and function of the human genome. However, questions remain concerning both the frequency and the developmental timing of L1 retrotransposition in vivo and whether the mobility of these retroelements commonly results in insertional and post-insertional mechanisms of genomic injury. Cells exhibiting high rates of L1 retrotransposition might be especially at risk for such injury. We assessed L1 mRNA expression and L1 retrotransposition in two biologically relevant cell types, human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), as well as in control parental human dermal fibroblasts (HDFs). Full-length L1 mRNA and the L1 open reading frame 1-encoded protein (ORF1p) were readily detected in hESCs and iPSCs, but not in HDFs. Sequencing analysis proved the expression of human-specific L1 element mRNAs in iPSCs. Bisulfite sequencing revealed that the increased L1 expression observed in iPSCs correlates with an overall decrease in CpG methylation in the L1 promoter region. Finally, retrotransposition of an engineered human L1 element was ~10-fold more efficient in iPSCs than in parental HDFs. These findings indicate that somatic cell reprogramming is associated with marked increases in L1 expression and perhaps increases in endogenous L1 retrotransposition, which could potentially impact the genomic integrity of the resultant iPSCs.