1: Krimper Enforces an Antisense Bias on piRNA Pools by Binding AGO3 in the Drosophila Germline.

MOLECULAR CELL

59 (4):553-563; 10.1016/j.molcel.2015.06.024 AUG 20 2015

Kaoru Sato, Yuka W. Iwasaki, Aoi Shibuya, Piero Carninci, Yuuta Tsuchizawa, Hirotsugu Ishizu, Mikiko C. Siomi, Haruhiko Siomi

Transposons (transposable elements) are often found to be inserted into new locations in the genome in various diseases, including cancer. When a transposon is inserted into a gene region, it can lead to the inhibition or alteration of that gene's function. The function of PIWI proteins and small RNAs called PIWI-interacting RNAs (piRNAs) has garnered attention as a mechanism to prevent this. The key to suppressing transposons is the efficient production of antisense piRNAs that target their mRNA. In this study, we revealed that a protein called Krimper plays a crucial role in the production of these antisense piRNAs. Specifically, Krimper interacts with a specific PIWI protein, contributing to the creation of a strand bias (piRNAs derived from one of the two strands) within the piRNA population that binds to that PIWI protein. Based on this, we have proposed a new model in which this enables the efficient production of antisense piRNAs.

(Haruhiko Shiomi, Professor, Department of Molecular Biology, equivalent to the 61st graduating class)

Sense piRNAs bind to AGO3 (a PIWI protein) and cleave piRNA precursors to produce antisense piRNAs. Furthermore, antisense piRNAs bind to Aub (a PIWI protein) and cleave transposons, thereby suppressing their expression and simultaneously producing sense piRNAs. Krimper contributes to the proper sorting of these two by promoting the binding of sense piRNAs to AGO3 while inhibiting the binding of antisense piRNAs.

CELL STEM CELL

17 (1):23-34; 10.1016/j.stem.2015.05.013 JUL 2 2015

Masayuki Yamashita, Eriko Nitta, Toshio Suda