Project description:Ribonucleoprotein (RNP) granules are non-membrane bound organelles thought to assemble by protein-protein interactions of RNA-binding proteins. We present evidence that a wide variety of RNAs self-assemble in vitro into either liquid-liquid phase separations or more stable assembles, referred to as RNA tangles. Self-assembly in vitro is affected by RNA length, ionic conditions, and sequence. Remarkably, self-assembly of yeast RNA in vitro under physiological salt mimics the composition of mRNAs within yeast stress granules. This suggests that the biophysical principles that drive RNA self-assembly in vitro contribute to determining the stress granule transcriptome. Consistent with RNA self-assembly contributing to RNP granule formation, an excess of purified RNA injected into C. elegans syncytium coalesces into droplet-like assemblies. We suggest that diverse RNA-RNA interactions in trans contribute to RNP granule formation and may explain the prevalence of large RNA-protein assemblies in eukaryotic cells.
2017-05-23 | GSE99170 | GEO
Project description:Metagenomic analysis of ionic liquid exposure
Project description:Non-membrane bound organelles such as nucleoli, processing bodies, cajal bodies, and germ granules form via spontaneous self-assembly of specific proteins and RNAs. How these biomolecular condensates form and interact are poorly understood. Here we identify two proteins (ZNFX-1 and WAGO-4) that localize to C. elegans germ granules (P granules) in early germline blastomeres. Later in germline development, ZNFX-1/WAGO-4 separate from P granules to define an independent liquid-like condensate that we term the Z granule. In adult germ cells, Z granules assemble into ordered tri-droplet assemblages with P granules and Mutator foci that we term the PZM granule. Finally, we show that one biological function of ZNFX-1 and WAGO-4 is to interact with RNAs in the C. elegans germline to promote transgenerational epigenetic inheritance (TEI). We speculate that the temporal and spatial ordering of liquid droplet organelles may help cells organize and coordinate the complex RNA processing pathways underlying gene regulatory systems, such as RNA-directed TEI.
2018-03-21 | GSE112109 | GEO
Project description:Microbial community in aerobic granules
Project description:Abstract : "A hallmark of the cellular response to environmental stress is the formation of stress granules. Stress granules are RNA-protein assemblies that provide an adaptive response to stress; however, the basis for their formation and how they contribute to the stress response remains incompletely understood. Here we show that the mRNA modification N6-methyladenosine (m6A) is a mark that targets mRNAs to stress granules. We find that m6A mRNAs are highly enriched in stress granules, and this is mediated by m6A-induced liquid-liquid phase separation of the YTHDF family of m6A-binding proteins. These proteins bind poly-methylated m6A mRNAs, causing them to form liquid droplets that partition into stress granules. Moreover, disrupting either m6A or YTHDF proteins prevents stress granule formation." The goal of this experiment is to understand how recruitment of m6A mRNA to stress granules influences the translational response to heat shock. Result: we found that m6A-containing mRNA are preferentially repressed during stress, and that m6A is required for translational recovery after heat shock