scholarly journals Ubiquitination of G3BP1 mediates stress granule disassembly in a context-specific manner

Science ◽  
2021 ◽  
Vol 372 (6549) ◽  
pp. eabf6548
Author(s):  
Youngdae Gwon ◽  
Brian A. Maxwell ◽  
Regina-Maria Kolaitis ◽  
Peipei Zhang ◽  
Hong Joo Kim ◽  
...  
Keyword(s):  
Specific Interaction ◽  
Interaction Network ◽  
Stress Granules ◽  
Stress Granule ◽  
Eukaryotic Cells ◽  
Central Protein ◽  
Specific Manner ◽  
Cultured Human Cells ◽  
Context Specific ◽  
Lateral Sclerosis

Stress granules are dynamic, reversible condensates composed of RNA and protein that assemble in eukaryotic cells in response to a variety of stressors and are normally disassembled after stress is removed. The composition and assembly of stress granules is well understood, but little is known about the mechanisms that govern disassembly. Impaired disassembly has been implicated in some diseases including amyotrophic lateral sclerosis, frontotemporal dementia, and multisystem proteinopathy. Using cultured human cells, we found that stress granule disassembly was context-dependent: Specifically in the setting of heat shock, disassembly required ubiquitination of G3BP1, the central protein within the stress granule RNA-protein network. We found that ubiquitinated G3BP1 interacted with the endoplasmic reticulum–associated protein FAF2, which engaged the ubiquitin-dependent segregase p97/VCP (valosin-containing protein). Thus, targeting of G3BP1 weakened the stress granule–specific interaction network, resulting in granule disassembly.

scholarly journals Ubiquitination of G3BP1 mediates stress granule disassembly in a stress-specific manner

2021 ◽  
Author(s):  
Youngdae Gwon ◽  
Brian A. Maxwell ◽  
Regina-Maria. Kolaitis ◽  
Peipei Zhang ◽  
Hong Joo Kim ◽  
...  
Keyword(s):  
Phase Separation ◽  
Heat Shock ◽  
Percolation Threshold ◽  
Specific Interaction ◽  
Interaction Network ◽  
Stress Granules ◽  
Stress Granule ◽  
Induced Stress ◽  
Central Protein ◽  
Specific Manner

AbstractStress granules are dynamic, reversible condensates composed of RNA and protein that assemble in response to a variety of stressors and are normally disassembled after stress is removed. Whereas the composition of stress granules and the mechanisms underlying their assembly have been extensively studied, far less is known about the mechanisms that govern disassembly. Impaired disassembly has been implicated in some diseases. Here we report that stress granule disassembly is context-dependent and, in the setting of heat shock, requires ubiquitination of G3BP1, the central protein within the stress granule RNA-protein network. Ubiquitinated G3BP1 interacts with the ER-resident protein FAF2, which engages the ubiquitin-dependent segregase p97/VCP. Targeting G3BP1 enables the stress granule-specific interaction network to fall below the percolation threshold for phase separation, which causes disassembly.One Sentence SummaryUbiquitination of G3BP1 mediates FAF2- and p97/VCP-dependent disassembly of heat-induced stress granules

scholarly journals Small molecules for modulating protein driven liquid-liquid phase separation in treating neurodegenerative disease

2019 ◽  
Author(s):  
Richard J. Wheeler ◽  
Hyun O. Lee ◽  
Ina Poser ◽  
Arun Pal ◽  
Thom Doeleman ◽  
...  
Keyword(s):  
Phase Separation ◽  
Neurodegenerative Disease ◽  
Stress Granules ◽  
Life Time ◽  
Stress Granule ◽  
Phase Behaviour ◽  
Granule Proteins ◽  
Lateral Sclerosis ◽  
Liquid Liquid Phase Separation

AbstractAmyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with few avenues for treatment. Many proteins implicated in ALS associate with stress granules, which are examples of liquid-like compartments formed by phase separation. Aberrant phase transition of stress granules has been implicated in disease, suggesting that modulation of phase transitions could be a possible therapeutic route. Here, we combine cell-based and protein-based screens to show that lipoamide, and its related compound lipoic acid, reduce the propensity of stress granule proteins to aggregate in vitro. More significantly, they also prevented aggregation of proteins over the life time of Caenorhabditis elegans. Observations that they prevent dieback of ALS patient-derived (FUS mutant) motor neuron axons in culture and recover motor defects in Drosophila melanogaster expressing FUS mutants suggest plausibility as effective therapeutics. Our results suggest that altering phase behaviour of stress granule proteins in the cytoplasm could be a novel route to treat ALS.

scholarly journals The UBAP2L ortholog PQN-59 contributes to stress granule assembly and development in C. elegans

2021 ◽  
Author(s):  
Simona Abbatemarco ◽  
Alexandra Bondaz ◽  
Françoise Schwager ◽  
Jing Wang ◽  
Christopher M Hammell ◽  
...  
Keyword(s):  
Stress Granules ◽  
Stress Granule ◽  
Eukaryotic Cells ◽  
Stress Exposure ◽  
Exact Role ◽  
Granule Formation ◽  
Protective Function ◽  
C Elegans ◽  
Ribonucleoprotein Complexes ◽  
Higher Sensitivity

When exposed to stressful conditions, eukaryotic cells respond by inducing the formation of cytoplasmic ribonucleoprotein complexes called stress granules. Stress granules are thought to have a protective function but their exact role is still unclear. Here we use C. elegans to study two proteins that have been shown to be important for stress granule assembly in human cells: PQN-59, the ortholog of human UBAP2L, and GTBP-1, the ortholog of the human G3BP1 and G3BP2 proteins. Both proteins fall into stress granules in the embryo and in the germline when C. elegans is exposed to stressful conditions. None of the two proteins is essential for the assembly of stress induced granules, but the granules formed in absence of PQN-59 or GTBP-1 are less numerous and dissolve faster than the ones formed in control embryos. Despite these differences, pqn-59 or gtbp-1 mutant embryos do not show a higher sensitivity to stress than control embryos. pqn-59 mutants display reduced progeny and a high percentage of embryonic lethality, phenotypes that are not dependent on stress exposure and that are not shared with gtbp-1 mutants. Our data indicate that both GTBP-1 and PQN-59 contribute to stress granule formation but that PQN-59 is, in addition, required for C. elegans development.

scholarly journals From random to predictive: a context-specific interaction framework improves selection of drug protein-protein interactions for unknown drug pathways

2020 ◽  
Author(s):  
Jennifer Wilson ◽  
Alessio Gravina ◽  
Kevin Grimes
Keyword(s):  
Decision Making ◽  
Protein Interactions ◽  
False Positive ◽  
Specific Interaction ◽  
Interaction Network ◽  
Protein Protein Interactions ◽  
Data Set ◽  
Network Methods ◽  
Context Specific ◽  
Selection Of

With high drug attrition, interaction network methods are increasingly attractive as quick and inexpensive methods for prediction of drug safety and efficacy effects when a drug pathway is unknown. However, these methods suffer from high false positive rates for selecting drug phenotypic effects, their performance is often no better than random (AUROC ~0.5), and this limits the use of network methods in regulatory and industrial decision making. In contrast to many network engineering approaches that apply mathematical thresholds to discover phenotype associations, we hypothesized that interaction networks associated with true positive drug phenotypes are context specific. We tested this hypothesis on 16 designated medical event (DMEs) phenotypes which are a subset of adverse events that are of upmost concern to FDA review using a novel data set extracted from drug labels. We demonstrated that context-specific interactions (CSIs) distinguished true from false positive DMEs with an 50% improvement over non-context-specific approaches (AUROC 0.77 compared to 0.51). By reducing false positives, CSI analysis has the potential to advance network techniques to influence decision making in regulatory and industry settings.

scholarly journals Stress granules regulate stress-induced paraspeckle assembly

2019 ◽  
Vol 218 (12) ◽  
pp. 4127-4140 ◽  
Author(s):  
Haiyan An ◽  
Jing Tong Tan ◽  
Tatyana A. Shelkovnikova
Keyword(s):  
Stress Granules ◽  
Inhibitory Effect ◽  
Eukaryotic Cells ◽  
Negative Regulators ◽  
Multiple Protein ◽  
Different Types ◽  
Positive Regulators ◽  
Protein Components ◽  
Rnp Granules ◽  
Lateral Sclerosis

Eukaryotic cells contain a variety of RNA-protein macrocomplexes termed RNP granules. Different types of granules share multiple protein components; however, the crosstalk between spatially separated granules remains unaddressed. Paraspeckles and stress granules (SGs) are prototypical RNP granules localized exclusively in the nucleus and cytoplasm, respectively. Both granules are implicated in human diseases, such as amyotrophic lateral sclerosis. We characterized the composition of affinity-purified paraspeckle-like structures and found a significant overlap between the proteomes of paraspeckles and SGs. We further show that paraspeckle hyperassembly is typical for cells subjected to SG-inducing stresses. Using chemical and genetic disruption of SGs, we demonstrate that formation of microscopically visible SGs is required to trigger and maintain stress-induced paraspeckle assembly. Mechanistically, SGs may sequester negative regulators of paraspeckle formation, such as UBAP2L, alleviating their inhibitory effect on paraspeckles. Our study reveals a novel function for SGs as positive regulators of nuclear RNP granule assembly and suggests a role for disturbed SG-paraspeckle crosstalk in human disease.

scholarly journals Molecularly distinct cores coexist inside stress granules

2019 ◽  
Author(s):  
Luca Cirillo ◽  
Adeline Cieren ◽  
Monica Gotta
Keyword(s):  
Reverse Genetics ◽  
Core Protein ◽  
Super Resolution ◽  
Stress Granules ◽  
Stress Granule ◽  
Eukaryotic Cells ◽  
Stress Exposure ◽  
The Core ◽  
Stable Core ◽  
Liquid Liquid Phase Separation

SummaryStress granules are membraneless organelles that form in eukaryotic cells after stress exposure. Stress granules are constituted by a stable core and a dynamic shell that establishes a liquid-liquid phase separation with the surrounding cytosol. The structure and assembly of stress granules and how different components contribute to their formation are not fully understood. Here, using super resolution and expansion microscopy, we find that the stress granule component UBAP2L and the core protein G3BP1 occupy different domains inside stress granules. Since UBAP2L displays typical properties of a core protein, our results indicate that different cores coexist inside the same granule. Consistent with a role as a core protein, UBAP2L is required for stress granule assembly in several stress conditions and reverse genetics show that it acts upstream of G3BP1. We propose a model in which UBAP2L is an essential stress granule nucleator that facilitates G3BP1 core formation and stress granule assembly and growth.

scholarly journals PQN-59 and GTBP-1 contribute to stress granule formation but are not essential for their assembly in C. elegans embryos

2021 ◽  
Author(s):  
Simona Abbatemarco ◽  
Alexandra Bondaz ◽  
Francoise Schwager ◽  
Jing Wang ◽  
Christopher M. Hammell ◽  
...  
Keyword(s):  
Stress Granules ◽  
Human Cells ◽  
Embryonic Lethality ◽  
Stress Granule ◽  
Eukaryotic Cells ◽  
Stress Exposure ◽  
Granule Formation ◽  
C Elegans ◽  
Ribonucleoprotein Complexes ◽  
Higher Sensitivity

When exposed to stressful conditions, eukaryotic cells respond by inducing the formation of cytoplasmic ribonucleoprotein complexes called stress granules. Here we use C. elegans to study two proteins that are important for stress granule assembly in human cells: PQN-59, the human UBAP2L ortholog, and GTBP-1, the human G3BP1/2 ortholog. Both proteins assemble into stress granules in the embryo and in the germline when C. elegans is exposed to stressful conditions. None of the two proteins is essential for the assembly of stress-induced granules, as shown by the single and combined depletions by RNAi, and neither pqn-59 nor gtbp-1 mutant embryos show higher sensitivity to stress than control embryos. We find that pqn-59 mutants display reduced progeny and a high percentage of embryonic lethality, phenotypes that are not dependent on stress exposure and that are not shared with gtbp-1 mutants. Our data indicate that, in contrast to human cells, PQN-59 and GTBP-1 are not required for stress granule formation but that PQN-59 is important for C. elegans development.

scholarly journals Transcriptome-Wide Comparison of Stress Granules and P-Bodies Reveals that Translation Plays a Major Role in RNA Partitioning

2019 ◽  
Vol 39 (24) ◽  
Author(s):  
Tyler Matheny ◽  
Bhalchandra S. Rao ◽  
Roy Parker
Keyword(s):  
Stress Granules ◽  
Stress Granule ◽  
Dominant Factor ◽  
Differential Centrifugation ◽  
P Bodies ◽  
Translation Repression ◽  
First Approximation ◽  
Rnp Granules ◽  
Interpretation Of Results

ABSTRACT The eukaryotic cytosol contains multiple RNP granules, including P-bodies and stress granules. Three different methods have been used to describe the transcriptome of stress granules or P-bodies, but how these methods compare and how RNA partitioning occurs between P-bodies and stress granules have not been addressed. Here, we compare the analysis of the stress granule transcriptome based on differential centrifugation with and without subsequent stress granule immunopurification. We find that while differential centrifugation alone gives a first approximation of the stress granule transcriptome, this methodology contains nonspecific transcripts that play a confounding role in the interpretation of results. We also immunopurify and compare the RNAs in stress granules and P-bodies under arsenite stress and compare those results to those for the P-body transcriptome described under nonstress conditions. We find that the P-body transcriptome is dominated by poorly translated mRNAs under nonstress conditions, but during arsenite stress, when translation is globally repressed, the P-body transcriptome is very similar to the stress granule transcriptome. This suggests that translation is a dominant factor in targeting mRNAs into both P-bodies and stress granules, and during stress, when most mRNAs are untranslated, the composition of P-bodies reflects this broader translation repression.

scholarly journals Puumala and Andes Orthohantaviruses Cause Transient Protein Kinase R-Dependent Formation of Stress Granules

2019 ◽  
Vol 94 (3) ◽  
Author(s):  
Wanda Christ ◽  
Janne Tynell ◽  
Jonas Klingström
Keyword(s):  
Protein Kinase ◽  
Host Cell ◽  
Stress Responses ◽  
Stress Granules ◽  
Cell Stress ◽  
Stress Granule ◽  
Hantavirus Infection ◽  
Stress Signaling ◽  
Protein Kinase R ◽  
Granule Formation

ABSTRACT Virus infection frequently triggers host cell stress signaling resulting in translational arrest; as a consequence, many viruses employ means to modulate the host stress response. Hantaviruses are negative-sense, single-stranded RNA viruses known to inhibit host innate immune responses and apoptosis, but their impact on host cell stress signaling remains largely unknown. In this study, we investigated activation of host cell stress responses during hantavirus infection. We show that hantavirus infection causes transient formation of stress granules (SGs) but does so in only a limited proportion of infected cells. Our data indicate some cell type-specific and hantavirus species-specific variability in SG prevalence and show SG formation to be dependent on the activation of protein kinase R (PKR). Hantavirus infection inhibited PKR-dependent SG formation, which could account for the transient nature and low prevalence of SG formation observed during hantavirus infection. In addition, we report only limited colocalization of hantaviral proteins or RNA with SGs and show evidence indicating hantavirus-mediated inhibition of PKR-like endoplasmic reticulum (ER) kinase (PERK). IMPORTANCE Our work presents the first report on stress granule formation during hantavirus infection. We show that hantavirus infection actively inhibits stress granule formation, thereby escaping the detrimental effects on global translation imposed by host stress signaling. Our results highlight a previously uncharacterized aspect of hantavirus-host interactions with possible implications for how hantaviruses are able to cause persistent infection in natural hosts and for pathogenesis.

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