Spindle-E cycling between nuage and cytoplasm is controlled by Qin and PIWI proteins.
Transposable elements (TEs) are silenced in germ cells by a mechanism in which PIWI proteins generate and use PIWI-interacting ribonucleic acid (piRNA) to repress expression of TE genes. piRNA biogenesis occurs by an amplification cycle in microscopic organelles called nuage granules, which are localized to the outer face of the nuclear envelope. One cofactor required for amplification is the helicase Spindle-E (Spn-E). We found that the Spn-E protein physically associates with the Tudor domain protein Qin and the PIWI proteins Aubergine (Aub) and Argonaute3 (Ago3). Spn-E and Qin proteins are mutually dependent for their exit from nuage granules, whereas Spn-E and both Aub and Ago3 are mutually dependent for their entry or retention in nuage. The result is a dynamic cycling of Spn-E and its associated factors in and out of nuage granules. This implies that nuage granules can be considered to be hubs for active, mobile, and transient complexes. We suggest that this is in some way coupled with the execution of the piRNA amplification cycle.
Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208.
Arlise
A
Andress
Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208.
Yanxia
Y
Bei
Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037.
Bryan R
BR
Fonslow
Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208.
Ritika
R
Giri
Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208.
Yilong
Y
Wu
Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037.
John R
JR
Yates
Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208 r-carthew@northwestern.edu.
Richard W
RW
Carthew
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D060565:Argonaute Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001692:Biological Transport; D004251:DNA Transposable Elements / Q000502:physiology; D004330:Drosophila / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008954:Models, Biological; D017711:Nonlinear Dynamics; D010448:Peptide Initiation Factors / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D012044:Regression Analysis; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
C518392:AGO3 protein, Drosophila; D060565:Argonaute Proteins; D004251:DNA Transposable Elements; D029721:Drosophila Proteins; D010448:Peptide Initiation Factors; D034741:RNA, Small Interfering; C436124:aub protein, Drosophila; C569287:Qin protein, Drosophila; D044767:Ubiquitin-Protein Ligases; D000251:Adenosine Triphosphatases; C096355:spn-E protein, Drosophila