The cochaperone shutdown defines a group of biogenesis factors essential for all piRNA populations in Drosophila.
In animal gonads, PIWI proteins and their bound 23-30 nt piRNAs guard genome integrity by the sequence specific silencing of transposons. Two branches of piRNA biogenesis, namely primary processing and ping-pong amplification, have been proposed. Despite an overall conceptual understanding of piRNA biogenesis, identity and/or function of the involved players are largely unknown. Here, we demonstrate an essential role for the female sterility gene shutdown in piRNA biology. Shutdown, an evolutionarily conserved cochaperone collaborates with Hsp90 during piRNA biogenesis, potentially at the loading step of RNAs into PIWI proteins. We demonstrate that Shutdown is essential for both primary and secondary piRNA populations in Drosophila. An extension of our study to previously described piRNA pathway members revealed three distinct groups of biogenesis factors. Together with data on how PIWI proteins are wired into primary and secondary processing, we propose a unified model for piRNA biogenesis.
Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohrgasse 3, 1030 Vienna, Austria.
Daniel
D
Olivieri
Kirsten-André
KA
Senti
Sailakshmi
S
Subramanian
Ravi
R
Sachidanandam
Julius
J
Brennecke
D000818:Animals; D060565:Argonaute Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D004251:DNA Transposable Elements; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism
D060565:Argonaute Proteins; D004251:DNA Transposable Elements; D029721:Drosophila Proteins; D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; D034741:RNA, Small Interfering