Phase transitioned nuclear Oskar promotes cell division of Drosophila primordial germ cells

Kistler, Kathryn E.; Trcek, Tatjana; Hurd, Thomas R.; Chen, Ruoyu; Liang, Feng; Sall, Joseph; Kato, Masato; Lehmann, Ruth

doi:10.7554/elife.37949

Cited by 96 publications

(118 citation statements)

References 101 publications

(262 reference statements)

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“…Annuli similar to those formed by acetylated TDP-43 have been reported in Drosophila germ granules, first reported as intranuclear spherical annuli (52) and later shown to be gel-like (53).…”

Section: Discussionmentioning

confidence: 55%

TDP-43 and HSP70 phase separate into anisotropic, intranuclear liquid spherical annuli

Gasior

et al. 2020

Preprint

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One Sentence Summary:Acetylation of TDP-43 drives its phase separation into spherical annuli that form a liquid-insidea-liquid-inside-a-liquid. AbstractThe RNA binding protein TDP-43 naturally phase separates within cell nuclei and forms cytoplasmic aggregates in age-related neurodegenerative diseases. Here we show that acetylation-mediated inhibition of TDP-43 binding to RNA produces co-de-mixing of acetylated and unmodified TDP-43 into symmetrical, intranuclear spherical annuli whose shells and cores have liquid properties. Shells are anisotropic, like liquid crystals. Consistent with our modelling predictions that annulus formation is driven by components with strong self-interactions but weak interaction with TDP-43, the major components of annuli cores are identified to be HSP70 family proteins, whose chaperone activity is required to maintain liquidity of the core. Proteasome inhibition, mimicking reduction in proteasome activity during aging, induces TDP-43-containing annuli in neurons in rodents. Thus, we identify that TDP-43 phase separation is regulated by acetylation, proteolysis, and ATPase-dependent chaperone activity of HSP70.A seminal discovery in the last decade has been recognition that large biological molecules, especially RNA binding proteins, can undergo liquid-liquid phase separation (LLPS), resembling oil droplets in vinegar. Under certain physical conditions, proteins, nucleic acids, or a mixture of both in a complex solution can form two phases, a condensed de-mixed phase and more dilute aqueous phase (1). Inside the cell, proteins and/or nucleic acids de-mix into a condensed phase to form membraneless organelles which have been proposed to promote biological functions (2).One membraneless organelle is the nucleolus, first described in the early 1800's and now recognized to be composed of proteins that undergo LLPS (3-5). Discovery that P-granules are de-mixed compartments with liquid behaviour brought widespread recognition to LLPS and its ability to mediate subcellular compartmentalization in a biological context (6). Phase separation has been also proposed for heterochromatin and RNA bodies (1, 6, 7). LLPS potentially underlies the operational principle governing formation of important organelles and structures, such as centrosomes, nuclear pore complexes, and super enhancers (8-10).Few mechanisms to modulate intracellular LLPS have been identified. Disease-causing mutations of proteins such as FUS (11) and HNRNPA2B1 (12) alter their LLPS behaviors in vitro, but the physiological or pathological relevance of their intracellular LLPS has not been fully elucidated. Random, multivalent interactions among intrinsically disordered, low complexity domains (LCDs) of proteins are a major driving force for LLPS in vitro. Oligomerization of other domains is thought to be required for LLPS in vivo (13). The inherent randomness of multivalent interactions (14) favors a model of disordered alignment -a conventional liquid phase in which molecules randomly move. The evidence is compelling that multi...

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Section: Discussionmentioning

confidence: 55%

TDP-43 and HSP70 phase separate into anisotropic, intranuclear liquid spherical annuli

Gasior

et al. 2020

Preprint

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“…Germ plasm is a specialized cytoplasm that forms at the embryo's posterior pole and is populated by core granule proteins Oskar, Vasa, Tud and Aub, a variety of RNA‐binding proteins involved in various aspects of RNA biology, maternally deposited mRNAs, piRNAs and mitochondria (Figure A‐D) (reviewed in Reference ). While most of the RNA‐binding proteins enriched in germ plasm are also found elsewhere in the embryo, the core granule proteins are almost exclusively found only at the posterior pole . The exact composition of germ plasm is not known, however, recent quantitative imaging data demonstrated that the vast majority of core germ plasm proteins (>94%) are condensed into granules, with very little of these proteins diffusing in the intergranular germ plasm space .…”

Section: Ontogeny and Organization Of Germplasmmentioning

confidence: 99%

“…While most of the RNA‐binding proteins enriched in germ plasm are also found elsewhere in the embryo, the core granule proteins are almost exclusively found only at the posterior pole . The exact composition of germ plasm is not known, however, recent quantitative imaging data demonstrated that the vast majority of core germ plasm proteins (>94%) are condensed into granules, with very little of these proteins diffusing in the intergranular germ plasm space . Indeed, their concentration in the intergranular space is similar to their concentration in somatic regions .…”

Section: Ontogeny and Organization Of Germplasmmentioning

confidence: 99%

Germ granules in Drosophila

Trcek

Lehmann

2019

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Germ granules are hallmarks of all germ cells. Early ultrastructural studies in Drosophila first described these membraneless granules in the oocyte and early embryo as filled with amorphous to fibrillar material mixed with RNA. Genetic studies identified key protein components and specific mRNAs that regulate germ cell‐specific functions. More recently these ultrastructural studies have been complemented by biophysical analysis describing germ granules as phase‐transitioned condensates. In this review, we provide an overview that connects the composition of germ granules with their function in controlling germ cell specification, formation and migration, and illuminate these mysterious condensates as the gatekeepers of the next generation.

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“…However, a different class of multilayered MLOs has also been reported, where the layered topology is manifested due to the presence of a hollow internal space. For example, in vivo experiments have demonstrated that both nuclear and cytoplasmic germ granules of Drosophilla can exhibit hollow morphologies (14)(15)(16). In another system, it was observed that simple overexpression of TDP-43, a stress granule protein, can give rise to multilayered compartments with vacuolated nucleoplasm-filled internal space (17).…”

Section: Introductionmentioning

confidence: 99%

Phase Transition of RNA-protein Complexes into Ordered Hollow Condensates

Alshareedah¹,

Moosa²,

Raju

et al. 2020

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Charge driven condensation of intrinsically disordered protein-RNA complexes is ubiquitous in both natural and biomimetic systems. So far, isotropic liquid droplets are the most commonly observed topology of RNA-protein condensates in experiments and simulations. Here, by systematically studying the phase behavior of RNA-protein complexes across varied mixture compositions, we report a hollow vesicle-like condensate phase of nucleoprotein assemblies that is distinct from RNA-protein droplets. We show that these vesicular condensates are stable at specific charge disproportionate regimes within the phase diagram and are formed through the self-assembly of highly charged anisotropic protein-RNA complexes. Similar to membranes composed of amphiphilic lipids, these nucleoprotein-RNA vesicular membranes exhibit local ordering, size-dependent permeability, and selective encapsulation capacity without sacrificing their dynamic formation and dissolution in response to physicochemical stimuli. Our findings suggest that protein-RNA complexes can robustly create lipid-free vesicle-like enclosures by phase separation. Significance statementVesicular assemblies play crucial roles in subcellular organization as well as in biotechnological applications. Classically, the ability to form such assemblies were primarily assigned to lipids and lipid-like amphiphilic molecules. Here, we show that complexes of negatively charged RNAs and positively charged disordered polypeptides can form vesicle-like ordered assemblies at charge disproportionate mixture compositions. We also show that the ability to form vesicular assemblies is not specific to RNA-protein complexes, rather is generic to complexes of oppositely charged polyionic chains. We speculate that such vesicular assemblies play crucial roles in the formation of dynamic multi-layered subcellular membrane-less organelles and can be utilized to fabricate novel stimuli-responsive microscale systems.

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Phase transitioned nuclear Oskar promotes cell division of Drosophila primordial germ cells

Cited by 96 publications

References 101 publications

TDP-43 and HSP70 phase separate into anisotropic, intranuclear liquid spherical annuli

TDP-43 and HSP70 phase separate into anisotropic, intranuclear liquid spherical annuli

Germ granules in Drosophila

Phase Transition of RNA-protein Complexes into Ordered Hollow Condensates

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