Elucidation of piRNA biogenesis in silkworm germ line BmN4 cells

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K06948
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Molecular biology
• Research Institution: The University of Tokyo
• Principal Investigator: Nishida Kazumichi 東京大学, 大学院理学系研究科(理学部), 特任助教 (10598436)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: piRNA / PIWIタンパク質 / Papi / Zucchini / ミトコンドリア / 生殖細胞

Outline of Final Research Achievements

piRNAs bind PIWI proteins to control transposons to maintain germline genome integrity. piRNA intermediates are bound with PIWI anchored onto mitochondrial PAPI. However, whether Zucchini (Zuc) endonuclease, which play pivotal roles in Drosophila piRNA biogenesis, are required for this remains elusive.
We show that loss of Zuc in Bombyx aberrantly accumulated piRNA intermediates within the PAPI complex. PAPI exerted its RNA-binding activity only when being bound with PIWI and phosphorylated, suggesting a hierarchical process of the complex assembly. Both 5′ and 3′ ends of piRNA intermediates showed the hallmark of PIWI-Slicer. The 5′ end of Bombyx piRNA is formed by PIWI-Slicer, while the 3′ end is formed by Zuc endonuclease. The Bombyx piRNA biogenesis is simpler than that of Drosophila, because Bombyx has no phased piRNAs.

Free Research Field

RNA生物学