Regulation of RNA granule dynamics by phosphorylation of serine-rich, intrinsically disordered proteins in C. elegans

• Published in: eLife 2014-12, Vol.3, p.e04591-e04591
• Main Authors: Wang, Jennifer T, Smith, Jarrett, Chen, Bi-Chang, Schmidt, Helen, Rasoloson, Dominique, Paix, Alexandre, Lambrus, Bramwell G, Calidas, Deepika, Betzig, Eric, Seydoux, Geraldine
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Caenorhabditis elegans - genetics; Caenorhabditis elegans - growth & development; Caenorhabditis elegans - metabolism; Caenorhabditis elegans Proteins - chemistry; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Cell Biology; Cytoplasm; Cytoplasmic Granules - chemistry; Cytoplasmic Granules - metabolism; Dephosphorylation; Developmental Biology and Stem Cells; Embryo, Nonmammalian; Embryos; Fertility; Gene Expression Regulation; Genes, Reporter; germ plasm; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; intrinsically disordered protein; Molecular Sequence Data; Phosphatase; Phosphorylation; Protein Conformation; Protein Folding; Protein Phosphatase 2 - genetics; Protein Phosphatase 2 - metabolism; Protein-Tyrosine Kinases - genetics; Protein-Tyrosine Kinases - metabolism; Proteins; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Ribonucleic acid; RNA; RNA granule; RNA, Helminth - chemistry; RNA, Helminth - genetics; RNA, Helminth - metabolism; Serine; Serine - metabolism
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.04591

RNA granules have been likened to liquid droplets whose dynamics depend on the controlled dissolution and condensation of internal components. The molecules and reactions that drive these dynamics in vivo are not well understood. In this study, we present evidence that a group of intrinsically disordered, serine-rich proteins regulate the dynamics of P granules in C. elegans embryos. The MEG (maternal-effect germline defective) proteins are germ plasm components that are required redundantly for fertility. We demonstrate that MEG-1 and MEG-3 are substrates of the kinase MBK-2/DYRK and the phosphatase PP2A(PPTR-½). Phosphorylation of the MEGs promotes granule disassembly and dephosphorylation promotes granule assembly. Using lattice light sheet microscopy on live embryos, we show that GFP-tagged MEG-3 localizes to a dynamic domain that surrounds and penetrates each granule. We conclude that, despite their liquid-like behavior, P granules are non-homogeneous structures whose assembly in embryos is regulated by phosphorylation.