Formation and Maturation of Phase Separated Liquid Droplets by RNA Binding Proteins

By Yuan Lin, David S. W. Protter, M. Rosen, R. Parker. Molecules and Cells, 2015

1,435 citations recorded by the source corpus.

Eukaryotic cells possess numerous dynamic membrane-less organelles, RNP granules, enriched in RNA and RNA binding proteins containing disordered regions. We demonstrate that the disordered regions of key RNP granule components, and the full-length granule protein hnRNPA1, can phase separate in vitro, producing dynamic liquid droplets. Phase separation is promoted by low salt concentrations or RNA. Over time, the droplets mature to more stable states, as assessed by slowed fluorescence recovery after photobleaching and resistance to salt. Maturation often coincides with formation of fibrous structures. Different disordered domains can co-assemble into phase-separated droplets. These biophysical properties demonstrate a plausible mechanism by which interactions between disordered regions, coupled with RNA binding, could contribute to RNP granule assembly in vivo through promoting phase separation. Progression from dynamic liquids to stable fibers may be regulated to produce cellular structures with diverse physiochemical properties and functions. Misregulation could contribute to diseases involving aberrant RNA granules.

Subfields: Aerospace Engineering, Biochemistry, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/dd4e2fac1772522dc250d5c5bfa7100955b0e00e

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Citations in the corpus

A molecular grammar governing the driving forces for phase separation of prion-like RNA binding proteins (2018, positive): “Aberrant phase transitions of many FUS family proteins have been associated with the onset of age-related neurodegenerative diseases (Lin et al., 2015; Molliex et al., 2015; Patel et al., 2015).”
Sequence determinants of protein phase behavior from a coarse-grained model (2017, positive): “First, 18 the formation and dissolution processes can be tuned by the cellular environment such 19 as changes in temperature, pH and salt concentration [25], by post-translational 20 modification such as phosphorylation [19,26], and by mixing with other biomolecules 21 such as proteins [27], RNA [28”
Tau protein liquid–liquid phase separation can initiate tau aggregation (2018, positive): “Next, we tested whether tau LLPS could occur at physiologically relevant tau concentrations, intracellular molecular crowding ( (cid:1) 50 – 400 mg/ml macromolecular density; Fulton, 1982), and electrolyte concentrations ( (cid:1) 100 – 200 mM; Lodish et al , 2000) conditions.”
Liquid phase condensation in cell physiology and disease (2017, background): “prion-like domains, often undergo a liquid-to-solid transition to form fibrous structures (14, 15, 69).”
Sequence Determinants of Intracellular Phase Separation by Complex Coacervation of a Disordered Protein (2016, background): “At high concentrations, many proteins containing low-complexity IDRs form amyloid-like filaments consisting of repeated cross-beta strand elements (Han et al., 2012; Kato et al., 2012; Lin et al., 2015; Molliex et al., 2015).”
Distinct stages in stress granule assembly and disassembly (2016, methodology): “…of in vitro liquid droplets by IDRs have been observed to mature into a second, less dynamic phase comprised in part of stable amyloid-like assemblies (Han et al., 2012; Kato et al., 2012; Kwon et al., 2013; Lin et al., 2015; Molliex et al., 2015; Murakami et al., 2015; Patel et al., 2015).”
Phase separation in biology; functional organization of a higher order (2016, background): “proteins, along with the RRM domains [44, 45, 53], contribute to phase separation.”
Coexisting liquid phases underlie nucleolar sub-compartments (2016, positive): “These data are consistent with the hypothesis that disordered regions can facilitate the transition from liquid-like to solid-like structures (Weber and Brangwynne, 2012), which is supported by recent studies on a variety of RNA binding proteins (Zhang et al., 2015; Patel et al., 2015; Lin et al., 2”
Principles and Properties of Stress granules (2016, background): “Third, since IDRs can often form amyloid-like fibers in vitro, including both hetero- and homotypic interactions, perhaps IDRs function to stabilize granules by the formation of cross-strand beta zippers [45,46,39,50].”
Protein Phase Separation: A New Phase in Cell Biology (2018, background): “(FUS) can also make liquid droplets [10, 14, 16, 47-49].”
RNA controls PolyQ protein phase transitions (2015, result): “These observations are consistent with very recent studies on the ALS-proteins FUS and hnRNPA1, as well as other RNP body proteins, which exist in a liquid-like state that evolves with time into more solid-like and fibrous states (Patel et al., 2015; Lin et al., 2015; Molliex et al., 2015).”