Laboratory of Marine Protozoan Biodiversity & Evolution, Marine College, Shandong University, Weihai 264209, China.
Key Laboratory of Evolution & Marine Biodiversity (Ministry of Education), and Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China.
Nucleic Acids Res. 2024 Nov 27;52(21):13206-13223. doi: 10.1093/nar/gkae925.
The PIWI-interacting RNA (piRNA) pathway is crucial for transposon repression and the maintenance of genomic integrity. Gametocyte-specific factor 1 (GTSF1), a PIWI-associated protein indispensable for transposon repression, has been recently shown to potentiate the catalytic activity of PIWI in many metazoans. Whether the requirement of GTSF1 extends to PIWI proteins beyond metazoans is unknown. In this study, we identified a homolog of GTSF1 in the unicellular eukaryote Paramecium tetraurelia (PtGtsf1) and found that its role as a PIWI-cofactor is conserved. PtGtsf1 interacts with PIWI (Ptiwi09) and Polycomb Repressive Complex 2 and is essential for PIWI-dependent DNA elimination of transposons during sexual development. PtGtsf1 is crucial for the degradation of PIWI-bound small RNAs that recognize the organism's own genomic sequences. Without PtGtsf1, self-matching small RNAs are not degraded and results in an accumulation of H3K9me3 and H3K27me3, which may disturb transposon recognition. Our results demonstrate that the PIWI-GTSF1 interaction also exists in unicellular eukaryotes with a role in transposon silencing.
PIWI 相互作用 RNA（piRNA）途径对于转座子的抑制和基因组完整性的维持至关重要。配子细胞特异性因子 1（GTSF1）是一种与 PIWI 相关的蛋白，对于转座子的抑制是不可或缺的，最近已经在许多后生动物中被证明可以增强 PIWI 的催化活性。GTSF1 是否对后生动物以外的 PIWI 蛋白有需求尚不清楚。在本研究中，我们在单细胞真核生物 Paramecium tetraurelia 中鉴定到了 GTSF1 的同源物（PtGtsf1），并发现其作为 PIWI 共因子的作用是保守的。PtGtsf1 与 PIWI（Ptiwi09）和多梳抑制复合物 2 相互作用，对于有性发育过程中 PIWI 依赖性转座子 DNA 消除是必需的。PtGtsf1 对于 PIWI 结合的小 RNA 的降解至关重要，这些小 RNA 可以识别生物体自身的基因组序列。没有 PtGtsf1，自我匹配的小 RNA 就不会被降解，从而导致 H3K9me3 和 H3K27me3 的积累，这可能会干扰转座子的识别。我们的结果表明，PIWI-GTSF1 相互作用也存在于具有转座子沉默作用的单细胞真核生物中。
