Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan.
Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan.
Sci Rep. 2018 Apr 12;8(1):5869. doi: 10.1038/s41598-018-24319-w.
The mRNAs stored in eggs are crucial for embryogenesis. To address functions of maternal mRNAs, we recently reported the novel method MASK (maternal mRNA-specific knockdown), which we used to specifically knockdown maternal transcripts in the ascidian Ciona intestinalis Type A. In MASK, the cis element of a maternal gene is fused with eGFP or Kaede reporter gene, and the cassette is introduced into Ciona genome by transposon-mediated transgenesis. In eggs of the transgenic lines, the maternal expression of the gene whose cis element is used for driving the reporter gene is suppressed. The zygotic expression of the gene is not suppressed, suggesting that the MASK method can distinguish between maternal and zygotic functions of a gene. Here we investigated the cis and trans factors responsible for MASK results. In the ovaries in which knockdown of a maternal gene occurs, a number of antisense small RNAs are expressed that are complementary to the sequence of the knocked-down genes. We suspect that these antisense small RNAs are the factor responsible for MASK results. The antisense small RNAs have several features that are seen in PIWI-interacting RNAs (piRNAs), suggesting that MASK is likely to use a piRNA-mediated mechanism to knock down maternal mRNAs.
储存在卵子中的 mRNA 对于胚胎发生至关重要。为了研究母体 mRNA 的功能，我们最近报道了一种新的方法 MASK（母体 mRNA 特异性敲低），我们用它来特异性敲低海鞘 Ciona intestinalis Type A 中的母体转录本。在 MASK 中，母体基因的顺式元件与 eGFP 或 Kaede 报告基因融合，然后通过转座子介导的转基因将盒式元件导入海鞘基因组。在转基因系的卵子中，其顺式元件用于驱动报告基因表达的基因的母体表达受到抑制。该基因的合子表达不受抑制，这表明 MASK 方法可以区分基因的母体和合子功能。在这里，我们研究了负责 MASK 结果的顺式和反式因素。在发生母体基因敲低的卵巢中，表达了许多与敲低基因互补的反义小 RNA。我们怀疑这些反义小 RNA 是 MASK 结果的原因。反义小 RNA 具有几种在 PIWI 相互作用 RNA (piRNA) 中看到的特征，这表明 MASK 可能利用 piRNA 介导的机制来敲低母体 mRNA。
