Svoboda Petr, Stein Paula, Anger Martin, Bernstein Emily, Hannon Gregory J, Schultz Richard M
Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA.
Dev Biol. 2004 May 1;269(1):276-85. doi: 10.1016/j.ydbio.2004.01.028.
Both murine endogenous retrovirus-L (MuERV-L) and intracisternal A particle (IAP), two autonomous long terminal repeat (LTR) retrotransposons, are activated during genome activation in the preimplantation mouse embryo, and both sense and antisense transcripts are detected in 2-cell and 8-cell stage embryos. Because RNA interference (RNAi) functions in the preimplantation mouse embryo, we analyzed the relationship between RNAi and MuERV-L and IAP expression by inhibiting RNAi and measuring relative changes of the levels of these transcripts. We inhibited the initial step in the RNAi pathway by injecting 1-cell embryos with mDicer siRNA or long mDicer dsRNA and analyzed MuERV-L and IAP expression at the 8-cell stage. This approach resulted in the targeted destruction of mDicer mRNA, but not Hdac1 mRNA, inhibited the RNAi pathway, and resulted in a 50% increase in IAP and MuERV-L transcript abundance. These results suggest that RNAi constrains expression of repetitive parasitic sequences in preimplantation embryos, and thereby contributes to preserving genomic integrity at a stage of development when the organism consists of only a few cells.
小鼠内源性逆转录病毒-L（MuERV-L）和核内A颗粒（IAP）这两种自主长末端重复序列（LTR）逆转座子，在植入前小鼠胚胎的基因组激活过程中被激活，并且在2细胞和8细胞期胚胎中均可检测到正义和反义转录本。由于RNA干扰（RNAi）在植入前小鼠胚胎中发挥作用，我们通过抑制RNAi并测量这些转录本水平的相对变化，分析了RNAi与MuERV-L和IAP表达之间的关系。我们通过向1细胞胚胎注射mDicer siRNA或长链mDicer dsRNA来抑制RNAi途径的起始步骤，并在8细胞期分析MuERV-L和IAP的表达。这种方法导致mDicer mRNA被靶向破坏，但不影响Hdac1 mRNA，抑制了RNAi途径，并使IAP和MuERV-L转录本丰度增加了50%。这些结果表明，RNAi在植入前胚胎中限制了重复寄生序列的表达，从而在生物体仅由少数细胞组成的发育阶段有助于维持基因组完整性。
