Hamster PIWI proteins bind to piRNAs with stage-specific size variations during oocyte maturation

Kyoko Ishino, Hidetoshi Hasuwa, Jun Yoshimura, Yuka W. Iwasaki, Hidenori Nishihara, Naomi M. Seki, Takamasa Hirano, Marie Tsuchiya, Hinako Ishizaki, Harumi Masuda, Tae Kuramoto, Kuniaki Saito, Yasubumi Sakakibara, Atsushi Toyoda, Takehiko Itoh, Mikiko C. Siomi, Shinichi Morishita, Haruhiko Siomi

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


In animal gonads, transposable elements are actively repressed to preserve genome integrity through the PIWI-interacting RNA (piRNA) pathway. In mice, piRNAs are abundantly expressed in male germ cells, and form effector complexes with three distinct PIWIs. The depletion of individual Piwi genes causes male-specific sterility with no discernible phenotype in female mice. Unlike mice, most other mammals have four PIWI genes, some of which are expressed in the ovary. Here, purification of PIWI complexes from oocytes of the golden hamster revealed that the size of the PIWIL1-associated piRNAs changed during oocyte maturation. In contrast, PIWIL3, an ovary-specific PIWI in most mammals, associates with short piRNAs only in metaphase II oocytes, which coincides with intense phosphorylation of the protein. An improved high-quality genome assembly and annotation revealed that PIWIL1- and PIWIL3-associated piRNAs appear to share the 5′-ends of common piRNA precursors and are mostly derived from unannotated sequences with a diminished contribution from TE-derived sequences, most of which correspond to endogenous retroviruses. Our findings show the complex and dynamic nature of biogenesis of piRNAs in hamster oocytes, and together with the new genome sequence generated, serve as the foundation for developing useful models to study the piRNA pathway in mammalian oocytes.

Original languageEnglish
Pages (from-to)2700-2720
Number of pages21
JournalNucleic acids research
Issue number5
Publication statusPublished - 2021 Mar 18

ASJC Scopus subject areas

  • Genetics


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