Center for RNA Medicine, the Fourth Affiliated Hospital of School of Medicine, and International School of Medicine, International Institutes of Medicine, Zhejiang University, Yiwu, China, 322000.
Genome Biol Evol. 2024 Oct 9;16(10). doi: 10.1093/gbe/evae162.
PIWI-interacting RNAs (piRNAs), a class of small RNAs, are renowned for their roles in sequencing-dependent targeting and suppressing transposable elements (TEs). Nevertheless, a majority of mammalian piRNAs, expressing at pachytene stage of meiosis, known as pachytene piRNAs, are devoid of discernible targets, casting a veil of enigma over their functional significance. Overturning the notion that this unusual class of piRNAs functions beyond TE silencing, we recently demonstrated that pachytene piRNAs play an essential and conserved role in silencing young and actively transposing TEs across amniotes. However, only 1% of pachytene piRNAs target active TEs. The biological significance of the abundant non-TE piRNAs, coproduced from the same precursors as TE piRNAs, remains unclear. Here, we provide a comprehensive summary of the potential roles of non-TE piRNAs, and thus propose that these non-TE piRNAs either bolster the action of TE piRNAs or provide the host genome a preexisting mechanism to suppress the potential invasion of novel TEs in the future.
PIWI 相互作用 RNA（piRNAs）是一类小 RNA，以其在序列依赖性靶向和抑制转座元件（TE）中的作用而闻名。然而，大多数在减数分裂的粗线期表达的哺乳动物 piRNAs，即粗线期 piRNAs，缺乏可识别的靶标，这使得它们的功能意义蒙上了一层神秘的面纱。我们最近推翻了这种不寻常的 piRNA 类除了沉默 TE 之外没有其他功能的观点，证明了粗线期 piRNAs 在沉默脊椎动物中的年轻和活跃转座 TE 方面发挥着重要且保守的作用。然而，只有 1%的粗线期 piRNAs 靶向活跃的 TE。与 TE piRNAs 由相同前体产生的大量非 TE piRNAs 的生物学意义尚不清楚。在这里，我们全面总结了非 TE piRNAs 的潜在作用，并因此提出这些非 TE piRNAs 要么增强 TE piRNAs 的作用，要么为宿主基因组提供一种预先存在的机制，以抑制未来新 TE 的潜在入侵。
