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Author Spotlight: Advancing Gene Silencing Research in Silkworms with dsRNA Delivery Through Feeding Chitosan Nanoparticles
Published on: October 4, 2024
Identification and Functional Analysis of the Pre-piRNA 3' Trimmer in Silkworms
Natsuko Izumi1, Keisuke Shoji2, Yuriko Sakaguchi3
1Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan.
Abstract:
PIWI-interacting RNAs (piRNAs) play a crucial role in transposon silencing in animal germ cells. In piRNA biogenesis, single-stranded piRNA intermediates are loaded into PIWI-clade proteins and cleaved by Zucchini/MitoPLD, yielding precursor piRNAs (pre-piRNAs). Pre-piRNAs that are longer than the mature piRNA length are then trimmed at their 3' ends. Although recent studies implicated the Tudor domain protein Papi/Tdrkh in pre-piRNA trimming, the identity of Trimmer and its relationship with Papi/Tdrkh remain unknown. Here, we identified PNLDC1, an uncharacterized 3'-5' exonuclease, as Trimmer in silkworms. Trimmer is enriched in the mitochondrial fraction and binds to Papi/Tdrkh. Depletion of Trimmer and Papi/Tdrkh additively inhibits trimming, causing accumulation of ∼35-40-nt pre-piRNAs that are impaired for target cleavage and prone to degradation. Our results highlight the cooperative action of Trimmer and Papi/Tdrkh in piRNA maturation.
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