Phase transitioned nuclear Oskar promotes cell division of Drosophila primordial germ cells
Kathryn E Kistler,
Tatjana Trcek,
Thomas R Hurd,
Ruoyu Chen,
Feng-Xia Liang,
Joseph Sall,
Masato Kato,
Ruth Lehmann
Affiliations
Kathryn E Kistler
Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States; Department of Molecular and Cellular Biology, University of Washington, Washington, United States
Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States
Thomas R Hurd
Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States; Department of Molecular Genetics, University of Toronto, Toronto, Canada
Ruoyu Chen
Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States
Feng-Xia Liang
Department of Cell Biology, NYU School of Medicine, New York, United States; DART Microscopy Laboratory, NYU Langone Health, New York, United States
Joseph Sall
DART Microscopy Laboratory, NYU Langone Health, New York, United States
Masato Kato
Department of Biochemistry, University of Texas Southwestern Medical Center, Texas, United States
Skirball Institute of Biomolecular Medicine, Howard Hughes Medical Institute, NYU School of Medicine, New York, United States; Department of Cell Biology, NYU School of Medicine, New York, United States
Germ granules are non-membranous ribonucleoprotein granules deemed the hubs for post-transcriptional gene regulation and functionally linked to germ cell fate across species. Little is known about the physical properties of germ granules and how these relate to germ cell function. Here we study two types of germ granules in the Drosophila embryo: cytoplasmic germ granules that instruct primordial germ cells (PGCs) formation and nuclear germ granules within early PGCs with unknown function. We show that cytoplasmic and nuclear germ granules are phase transitioned condensates nucleated by Oskar protein that display liquid as well as hydrogel-like properties. Focusing on nuclear granules, we find that Oskar drives their formation in heterologous cell systems. Multiple, independent Oskar protein domains synergize to promote granule phase separation. Deletion of Oskar’s nuclear localization sequence specifically ablates nuclear granules in cell systems. In the embryo, nuclear germ granules promote germ cell divisions thereby increasing PGC number for the next generation.