Elucidation of molecular mechanisms of how piRNAs maintain the germline genome integrity from invasive mobile elements

2017 Fiscal Year Final Research Report

• Project/Area Number: 25221101
• Research Category: Grant-in-Aid for Scientific Research (S)
• Allocation Type: Single-year Grants
• Research Field: Molecular biology
• Research Institution: The University of Tokyo
• Principal Investigator: Siomi Mikiko 東京大学, 大学院理学系研究科(理学部), 教授 (20322745)
• Co-Investigator(Renkei-kenkyūsha): ISHIZU Hirotsugu 慶應義塾大学, 医学部, 助教 (40574588)
• Project Period (FY): 2013-05-31 – 2018-03-31
• Keywords: PIWI / piRNA / トランスポゾン / RNAサイレンシング / ショウジョウバエ

Outline of Final Research Achievements

piRNAs arm race with mobile transposons in the germline to maintain the genome integrity from injurious invasion of the transposable elements. However, the molecular mechanism underlying the piRNA pathway remains elusive. In this study supported by KIBAN-S, we focused on understanding [I] the mechanisms of piRNA biogenesis and [II] the mechanism of Piwi-piRISC-mediated transcriptional transposon silencing. Moreover, [III] we aimed to establish a gene silencing system based on artificial piRNAs ectopically expressed in ovarian somatic cells. We made a lot of progress in this study; for example, we found that Yb body formation occurs in a hierarchical manner and that Vasa is necessary for releasing RNAs from Siwi-piRISC upon cleavage. Knock out of l(3)mbt induced the ping-pong machinery that was otherwise undetected in OSCs. We also solved the crystal structure of Siwi-piRISC. Moreover, we identified the cis-element necessary for producing piRNAs and its partner trans-acting protein, Yb.

Free Research Field

分子生物学