Characterization of PIWI proteins and their associated-piRNAs in primates — University of Technology
  1. Schedule
  2. Posters
  3. Characterization of PIWI proteins and their associated-piRNAs in primates

Characterization of PIWI proteins and their associated-piRNAs in primates (14249)

Takamasa Hirano 1 , Naomi M Seki 1 2 , Yuka W Iwasaki 1 , Zachary Y-C Lin 3 , Masanori Imamura 3 4 , Shinsuke Shibata 3 , Erika Sasaki 5 , Kuniaki Saito 1 , Hideyuki Okano 3 , Mikiko C Siomi 2 , haruhiko Siomi 1
  1. Department of Molecular Biology, Keio University School of Medicine, Tokyo, Japan
  2. Department of Biological Sciences, The University of Tokyo Graduate School of Sciences, Tokyo, Japan
  3. Department of Physiology, Keio University School of Medicine, Tokyo, Japan
  4. Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan
  5. Central Institute for Experimental Animals, Kawasaki, Kanagawa, Japan

Background

PIWI proteins are predominantly present in the reproductive tissue, where they form RNA-induced silencing complexes (RISCs) with Piwi-interacting RNAs (piRNAs) to silence transposons. Mice express three PIWI proteins, MIWI (PIWIL1), MILI (PIWIL2) and MIWI2 (PIWIL4), which show different expression patterns spatiotemporally in spermatogenesis and associate with distinct piRNA populations, inferring their specific functions. Indeed, depletion of individual Piwi genes causes male-specific sterility due to developmental arrest of spermatogenesis. Unlike rodents, primates possess four PIWI genes (PIWIL1 - PIWIL4); thus, piRNA-mediated silencing may be distinct between the two species.

Aims

The purpose of this study is to explore the PIWI-piRNA system in primates. To elucidate PIWI-associated piRNAs in primates, we sequence small RNAs from germ line tissues and determine their responsible PIWI proteins.

Methods

To study primate PIWI proteins and their associated piRNAs, we use adult testes and ovaries of common marmoset (Callithrix jacchus), a model primate. And to gain insights into the expression and functions of PIWI proteins and their bound small RNAs, we generate monoclonal antibodies against PIWIL1 and PIWIL3.

Conclusion

Immunofluorescence analysis using anti-marmoset PIWIL1 (called as MARWI) antibody showed that MARWI is detected from spermatocytes to elongating spermatids in the marmoset testes. This result agrees with those from earlier studies of MIWI. However, deep sequencing analysis of MARWI-piRNAs revealed that they are derived from not only intergenic regions and transposons but also specific tRNA genes and pseudogenes. Immunofluorescence analysis using anti-PIWIL3 antibody showed that PIWIL3, the nonexistent PIWI protein in mice, is expressed in follicular oocytes in the human fetal and the common marmoset adult ovaries. These results suggest that primates have unique PIWI-piRNA pathways both in testes and ovaries.

#jajRNA14