TY - JOUR
T1 - Maelstrom functions in the production of Siwi-piRISC capable of regulating transposons in Bombyx germ cells
AU - Namba, Yurika
AU - Iwasaki, Yuka W.
AU - Nishida, Kazumichi M.
AU - Nishihara, Hidenori
AU - Sumiyoshi, Tetsutaro
AU - Siomi, Mikiko C.
N1 - Funding Information:
We are grateful to I. Sagawa for mass spectrometry, Y. Okada for confocal microscopy, A. Nakamura for the anti-Me31B antibody, and Y. Miyata and A. Kajiya for technical assistance. We also thank H. Siomi, K. Sato, S. Hirakata, R. Onishi, H. Ishizu, H. Yamazaki, and K. Sakakibara for the discussion. This study was supported by research grants from MEXT to M.C.S. ( 19H05466 ), K.M.N. ( 20K06483 ), and Y.W.I. ( 21H00259 ). Y.N. ( 16J02082 ) and T.S. ( 18J11121 ) were supported by JSPS , and Y.W.I. was supported by JST PRESTO ( JPMJPR20E2 ).
Publisher Copyright:
© 2022 The Author(s)
PY - 2022/3/18
Y1 - 2022/3/18
N2 - PIWI-interacting RNAs (piRNAs) bind to PIWI proteins to assemble the piRISC, which represses germline transposons. Maelstrom (Mael) is necessary for piRISC biogenesis in germ cells, but its function remains unclear. Here, we show that Mael interconnects Spindle-E (Spn-E), a key piRISC biogenesis factor, with unloaded Siwi, one of two silkworm PIWI members. Mael also assembles a subset of nuage, a non-membranous organelle involved in piRISC biogenesis. Loss of Mael abrogated the Spn-E–Siwi interaction and Ago3-piRISC biogenesis, but Siwi-piRISC was produced. Bioinformatic analysis showed that Siwi-bound piRNAs in Mael-lacking cells were rich in transposon-targeting piRNAs as in normal cells but were biased toward transposons that are marginally controlled by Siwi-piRISC. This explains the impairment in Ago3-piRISC production because transposon mRNAs cleaved by Siwi are the origin of Ago3-loaded piRNAs. We argue that Mael plays a role in the production of primary Siwi-piRISC capable of regulating transposon expression in germ cells.
AB - PIWI-interacting RNAs (piRNAs) bind to PIWI proteins to assemble the piRISC, which represses germline transposons. Maelstrom (Mael) is necessary for piRISC biogenesis in germ cells, but its function remains unclear. Here, we show that Mael interconnects Spindle-E (Spn-E), a key piRISC biogenesis factor, with unloaded Siwi, one of two silkworm PIWI members. Mael also assembles a subset of nuage, a non-membranous organelle involved in piRISC biogenesis. Loss of Mael abrogated the Spn-E–Siwi interaction and Ago3-piRISC biogenesis, but Siwi-piRISC was produced. Bioinformatic analysis showed that Siwi-bound piRNAs in Mael-lacking cells were rich in transposon-targeting piRNAs as in normal cells but were biased toward transposons that are marginally controlled by Siwi-piRISC. This explains the impairment in Ago3-piRISC production because transposon mRNAs cleaved by Siwi are the origin of Ago3-loaded piRNAs. We argue that Mael plays a role in the production of primary Siwi-piRISC capable of regulating transposon expression in germ cells.
KW - Molecular biology
UR - http://www.scopus.com/inward/record.url?scp=85125204832&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85125204832&partnerID=8YFLogxK
U2 - 10.1016/j.isci.2022.103914
DO - 10.1016/j.isci.2022.103914
M3 - Article
AN - SCOPUS:85125204832
SN - 2589-0042
VL - 25
JO - iScience
JF - iScience
IS - 3
M1 - 103914
ER -