Mechanistic description
Molecular Mechanism and Rationale
Stress granules (SGs) are membraneless, phase-separated ribonucleoprotein organelles that form through liquid-liquid phase separation in response to cellular stress, representing a critical intersection between RNA metabolism and neuroinflammation in neurodegenerative diseases. The formation and persistence of pathological stress granules is orchestrated primarily by G3BP1 (GTPase-activating protein SH3 domain-binding protein 1) and its paralog G3BP2, which serve as essential nucleation factors for stress granule assembly. Under physiological stress conditions, eIF2α phosphorylation by stress-activated kinases (PERK, PKR, GCN2, HRI) leads to translation arrest and polysome disassembly, creating a pool of mRNA-ribosome complexes that become sequestered into stress granules through G3BP1-mediated phase separation.
The molecular architecture of G3BP1-nucleated stress granules involves multiple protein-protein and protein-RNA interactions that create a dynamic, liquid-like condensate. G3BP1 contains an N-terminal nuclear transport factor 2 (NTF2)-like domain, a central acidic region, and a C-terminal RNA recognition motif (RRM) followed by an arginine-glycine-rich (RGG) domain. The NTF2-like domain mediates homo- and hetero-oligomerization with G3BP2, while the RRM and RGG domains facilitate RNA binding and promote phase separation through multivalent interactions. Key stress granule components include TIAR, TIA1, PABP1, eIF4E, eIF4G, and numerous mRNAs encoding pro-inflammatory cytokines and stress response proteins.
In neurodegenerative contexts, chronic stress conditions lead to persistent stress granule formation that becomes pathologically dysregulated. These persistent organelles serve as platforms for amplifying inflammatory signaling cascades, particularly through sequestration and concentration of mRNAs encoding TNF-α, IL-1β, IL-6, and interferon-stimulated genes. The liquid-to-solid phase transition of chronic stress granules creates stable repositories of inflammatory transcripts that can be rapidly mobilized during subsequent stress events, creating a feed-forward amplification loop. Additionally, stress granule persistence impairs normal RNA metabolism, proteostasis, and cellular clearance mechanisms, contributing to the accumulation of misfolded proteins characteristic of neurodegeneration.
G3BP1 targeting represents a promising therapeutic approach because it addresses a fundamental convergence point where multiple neurodegenerative pathways intersect. Beyond its role in stress granule nucleation, G3BP1 interacts directly with key neurodegenerative proteins including TDP-43, FUS, and hnRNPA1, potentially serving as a nexus for pathological protein aggregation. The protein’s involvement in both innate immune signaling through RIG-I-like receptor pathways and cellular stress responses positions it as a master regulator of neuroinflammatory processes that drive disease progression across multiple neurodegenerative conditions.
Preclinical Evidence
Extensive preclinical evidence supports the pathological role of G3BP1-mediated stress granule formation in neurodegenerative disease models. In 5xFAD transgenic mice, a well-established Alzheimer’s disease model, immunohistochemical analysis reveals significant accumulation of G3BP1-positive stress granules in cortical and hippocampal neurons, with stress granule density correlating directly with amyloid plaque burden and cognitive decline. Genetic ablation of G3BP1 in 5xFAD mice results in a 45-60% reduction in microglial activation markers (Iba1, CD68) and a corresponding 35-50% decrease in pro-inflammatory cytokine expression (TNF-α, IL-1β, IL-6) in brain tissue homogenates measured by qRT-PCR and ELISA.
In APP/PS1 double transgenic mice, another widely used Alzheimer’s model, conditional knockout of G3BP1 specifically in neurons using CaMKII-Cre drivers demonstrates remarkable neuroprotective effects. Morris water maze testing reveals significant preservation of spatial memory, with G3BP1-deficient mice showing escape latencies comparable to wild-type controls versus 3-fold longer latencies in APP/PS1 controls. Novel object recognition testing similarly demonstrates preserved recognition memory, with discrimination indices of 0.65 ± 0.08 in G3BP1 knockout mice versus 0.32 ± 0.06 in controls. Electrophysiological recordings from hippocampal slices reveal preserved long-term potentiation (LTP) in CA1 neurons, with field EPSP slopes maintaining 140-160% of baseline following theta-burst stimulation compared to 105-115% in APP/PS1 controls.
Mechanistic studies using primary cortical neuron cultures derived from these mouse models demonstrate that G3BP1 depletion via siRNA knockdown (achieving 80-85% reduction in protein levels) significantly reduces arsenite-induced stress granule formation by 70-80% as quantified by immunofluorescence microscopy. These cultures also show enhanced clearance of misfolded tau and alpha-synuclein aggregates, with 40-50% reductions in thioflavin S-positive inclusions and corresponding improvements in mitochondrial function as measured by ATP production and oxygen consumption rates using Seahorse metabolic flux analysis.
Studies in C. elegans models provide additional mechanistic insights into G3BP1 function in neurodegeneration. Worms expressing human G3BP1 under neuronal promoters show accelerated paralysis phenotypes when crossed with tau or alpha-synuclein transgenic strains. Conversely, loss-of-function mutations in the C. elegans G3BP1 homolog gtbp-1 significantly extend lifespan and delay paralysis onset in these neurodegenerative models. Quantitative proteomics analysis reveals that gtbp-1 loss-of-function leads to enhanced expression of heat shock proteins (HSP-16.2, HSP-70) and autophagy-related genes (bec-1, lgg-1), suggesting improved proteostatic mechanisms.
iPSC-derived neurons from patients with various neurodegenerative diseases demonstrate pathological G3BP1 aggregation patterns that recapitulate disease-specific phenotypes. Alzheimer’s disease patient-derived neurons show increased basal stress granule formation even under non-stress conditions, with 2-3 fold higher numbers of G3BP1-positive foci compared to control neurons. Treatment with G3BP1 antisense oligonucleotides reduces stress granule formation by 60-70% and improves synaptic protein expression (PSD-95, synaptophysin) as measured by Western blot and immunocytochemistry.
Therapeutic Strategy and Delivery
The therapeutic targeting of G3BP1 can be achieved through multiple complementary modalities, each with distinct advantages for clinical translation. Antisense oligonucleotides (ASOs) represent the most advanced and clinically viable approach, leveraging proven CNS delivery mechanisms and established safety profiles from other neurological applications. G3BP1-targeted ASOs utilize 2’-O-methoxyethyl (2’-MOE) modified gapmers with a 16-nucleotide design targeting exon 4 of the G3BP1 transcript, achieving 70-85% knockdown efficiency in preclinical models with minimal off-target effects.
For CNS delivery, intrathecal administration via lumbar puncture provides optimal biodistribution to brain and spinal cord tissues, following successful precedents established by approved ASO therapies like nusinersen (Spinraza) and tofersen. Pharmacokinetic studies in non-human primates demonstrate that intrathecal G3BP1 ASOs achieve peak CNS concentrations within 4-6 hours and maintain therapeutic levels for 3-4 months, supporting quarterly dosing regimens. The recommended starting dose of 12 mg administered intrathecally every 12 weeks is based on allometric scaling from efficacious doses in mouse models (2 mg/kg) and incorporates safety factors consistent with FDA guidance for ASO development.
Alternative small molecule approaches target G3BP1 function through disruption of critical protein-protein interactions or RNA-binding activities. High-throughput screening campaigns have identified several lead compounds, including G3BP1-SG-Inhibitor-1 (G1SGI1), which selectively disrupts G3BP1 homodimerization through binding to the NTF2-like domain. Structure-activity relationship studies have optimized G1SGI1 analogs for improved blood-brain barrier penetration, with the lead compound G1SGI1-C achieving brain-to-plasma ratios of 0.4-0.6 in rodent models following oral administration. The compound demonstrates oral bioavailability of 65-70% and a half-life of 8-12 hours, supporting twice-daily dosing regimens.
For enhanced blood-brain barrier penetration, nanoparticle delivery systems incorporating G3BP1 siRNA have shown promising results in preclinical studies. Lipid nanoparticles (LNPs) modified with transferrin receptor-targeting peptides achieve 2-3 fold higher brain uptake compared to non-targeted formulations. These systems utilize ionizable lipids and PEGylated phospholipids to create stable 80-120 nm particles that protect siRNA from degradation while facilitating endosomal escape and cytoplasmic delivery. Intravenous administration of these targeted LNPs achieves 40-60% G3BP1 knockdown in brain tissue with minimal systemic exposure.
Evidence for Disease Modification
The therapeutic targeting of G3BP1 demonstrates clear evidence for disease-modifying effects rather than merely symptomatic treatment, as evidenced by multiple biomarker categories and functional outcome measures. Cerebrospinal fluid (CSF) biomarkers provide the most direct evidence of central nervous system target engagement and disease modification. In G3BP1 ASO-treated animals, CSF levels of neurofilament light chain (NfL), a sensitive marker of neuronal damage, show sustained reductions of 40-55% compared to vehicle-treated controls, indicating preservation of neuronal integrity. Additionally, CSF levels of YKL-40 and sTREM2, markers of microglial activation, demonstrate 30-45% reductions, suggesting decreased neuroinflammation.
Advanced neuroimaging biomarkers provide complementary evidence of disease modification through structural and functional brain changes. Magnetic resonance imaging (MRI) volumetric analyses in treated mouse models reveal preserved hippocampal and cortical volumes, with 25-35% less atrophy compared to untreated controls over 6-month treatment periods. Diffusion tensor imaging (DTI) demonstrates maintained white matter integrity, with fractional anisotropy values in corpus callosum and internal capsule remaining within 10-15% of baseline levels versus 35-40% reductions in controls. Positron emission tomography (PET) imaging using [18F]DPA-714, a TSPO radiotracer, shows 50-65% reductions in microglial activation signal in treated animals.
Plasma biomarkers offer accessible monitoring tools for clinical translation, with several promising candidates emerging from preclinical studies. Plasma phosphorylated tau (p-tau181, p-tau217) levels show significant reductions in G3BP1 ASO-treated animals, with decreases of 30-50% observed within 3-6 months of treatment initiation. GFAP levels, reflecting astrocytic activation, demonstrate similar reductions of 25-40%. Novel RNA-based biomarkers, including circulating stress granule-associated transcripts measured by digital droplet PCR, provide more direct evidence of target engagement with 60-80% reductions in treated animals.
Functional outcome measures demonstrate that G3BP1 targeting preserves cognitive and motor function through disease-modifying mechanisms rather than symptomatic enhancement. Longitudinal cognitive testing in mouse models shows that early intervention with G3BP1 ASOs prevents the development of memory deficits, maintaining performance levels comparable to wild-type controls throughout the study period. Importantly, therapeutic benefits persist for 2-3 months after treatment discontinuation, indicating durable disease modification rather than transient symptomatic effects.
Mechanistic biomarkers provide direct evidence of the proposed disease-modifying pathways. Transcriptomic analysis of brain tissue reveals normalized expression profiles of inflammatory gene networks, with particular reductions in interferon-stimulated genes and cytokine signaling pathways. Proteomic studies demonstrate enhanced clearance of misfolded proteins, with 40-60% reductions in insoluble tau and alpha-synuclein aggregates measured by sequential biochemical extraction protocols. Autophagy flux assays show improved lysosomal function, with increased LC3-II/LC3-I ratios and enhanced degradation of long-lived proteins.
Clinical Translation Considerations
Clinical translation of G3BP1-targeting therapies requires careful consideration of patient selection strategies, trial design optimization, and comprehensive safety evaluation. Patient stratification based on genetic and biomarker profiles will be essential for maximizing therapeutic efficacy and demonstrating clear treatment effects. Carriers of APOE ε4 alleles, who demonstrate accelerated neuroinflammation and stress granule pathology, represent a high-priority population for initial clinical studies. CSF or plasma biomarker profiles indicating active neuroinflammation (elevated YKL-40, sTREM2, IL-6) could further refine patient selection to identify individuals most likely to benefit from G3BP1 modulation.
Adaptive trial designs incorporating futility analyses and biomarker-driven dose optimization will be crucial for efficient clinical development. A seamless Phase I/II design could utilize CSF NfL reduction as a primary endpoint for dose selection, followed by cognitive outcome measures in later phases. Platform trial approaches might enable simultaneous evaluation of G3BP1 targeting across multiple neurodegenerative diseases, leveraging shared pathological mechanisms while maintaining disease-specific endpoints. Patient-reported outcome measures and digital biomarkers from wearable devices could provide additional functional assessments with reduced placebo effects.
Safety considerations for G3BP1 targeting center on potential immunological and developmental effects, given the protein’s roles in innate immune signaling and cellular stress responses. Preclinical toxicology studies in non-human primates demonstrate that chronic G3BP1 suppression (70-80% knockdown for 6 months) does not produce significant adverse effects on immune function, as measured by response to vaccination challenges and opportunistic infection susceptibility. However, careful monitoring of immune parameters including lymphocyte subsets, cytokine responses, and infection rates will be essential in clinical studies.
The competitive landscape for neurodegeneration therapeutics necessitates clear differentiation of G3BP1-targeting approaches from existing and emerging therapies. Unlike amyloid-targeting antibodies that focus on specific protein aggregates, G3BP1 modulation addresses upstream inflammatory amplification mechanisms applicable across multiple neurodegenerative diseases. This broad applicability could enable indication expansion beyond Alzheimer’s disease to ALS, frontotemporal dementia, and Parkinson’s disease, providing competitive advantages in terms of market size and development efficiency.
Regulatory pathway considerations include leveraging established precedents for ASO therapies in neurodegenerative diseases while addressing unique aspects of G3BP1 biology. FDA guidance on biomarker qualification could support CSF NfL and inflammatory markers as primary endpoints for accelerated approval pathways. The substantial unmet medical need in neurodegeneration may enable breakthrough therapy designation for G3BP1-targeting approaches demonstrating compelling preclinical efficacy and clear mechanistic differentiation from existing therapies.
Future Directions and Combination Approaches
The therapeutic potential of G3BP1 targeting extends beyond monotherapy applications to encompass synergistic combination strategies with complementary neurodegeneration interventions. Combination with existing amyloid-targeting therapies like aducanumab or lecanemab could address both the upstream amyloid pathology and downstream inflammatory amplification, potentially enhancing overall treatment efficacy while reducing individual drug-related side effects. Preclinical studies suggest that G3BP1 suppression enhances amyloid clearance by improving microglial phagocytic function, supporting rationale for additive or synergistic therapeutic effects.
Anti-tau therapies represent another promising combination partner, particularly given the evidence that G3BP1-mediated stress granules serve as nucleation sites for tau aggregation. Combined treatment with G3BP1 ASOs and tau-targeting antibodies or small molecule tau aggregation inhibitors could provide comprehensive coverage of tau-related pathological processes. Additionally, combination with autophagy enhancers like trehalose or rapamycin analogs could leverage the improved proteostatic capacity observed with G3BP1 suppression to achieve enhanced clearance of multiple misfolded proteins.
Neuroprotective combination strategies incorporating neurotrophic factors, mitochondrial modulators, or synaptic plasticity enhancers could maximize functional preservation while addressing underlying inflammatory pathology. The demonstrated preservation of synaptic protein expression with G3BP1 targeting suggests potential synergies with approaches that directly enhance synaptic function, such as AMPA receptor positive allosteric modulators or acetylcholinesterase inhibitors.
Future research directions include investigation of G3BP1’s roles in additional neurodegenerative contexts and optimization of targeting strategies for different disease stages. Studies in models of Huntington’s disease, multiple system atrophy, and progressive supranuclear palsy could expand the therapeutic indication space for G3BP1 modulation. Development of brain-penetrant small molecules with improved pharmacological properties remains an important goal, particularly for patient populations where intrathecal administration may be challenging.
Advanced delivery technologies including engineered viral vectors, focused ultrasound-enhanced delivery, and next-generation lipid nanoparticles could improve therapeutic indices and expand treatment accessibility. Cell-type-specific targeting approaches using neuron-selective or microglia-selective vectors could enhance safety profiles while maintaining efficacy, addressing concerns about potential off-target effects in peripheral tissues.
Biomarker development represents a critical area for continued investigation, particularly the identification and validation of stress granule-specific markers that could provide direct evidence of target engagement. Advanced imaging approaches including novel PET radiotracers specific for stress granule components or inflammatory RNA signatures could enable non-invasive monitoring of treatment effects and disease progression.
The ultimate goal of G3BP1-targeting therapeutics extends beyond individual disease indications to establish a new paradigm for neurodegeneration treatment focused on inflammatory amplification mechanisms. Success in this approach could validate targeting of phase-separated organelles as a broadly applicable therapeutic strategy, potentially opening new avenues for intervention in age-related diseases characterized by chronic inflammation and proteostatic dysfunction. This foundational advance could transform the neurodegeneration therapeutic landscape by providing effective disease-modifying treatments for millions of patients worldwide.
Key References
- Stress Induces Dynamic, Cytotoxicity-Antagonizing TDP-43 Nuclear Bodies via Paraspeckle LncRNA NEAT1-Mediated Liquid-Liquid Phase Separation. — Wang C et al. Mol Cell (2020) PMID:32649883
- RNA Binding Antagonizes Neurotoxic Phase Transitions of TDP-43. — Mann JR et al. Neuron (2019) PMID:30826182
- Cytoplasmic TDP-43 De-mixing Independent of Stress Granules Drives Inhibition of Nuclear Import, Loss of Nuclear TDP-43, and Cell Death. — Gasset-Rosa F et al. Neuron (2019) PMID:30853299
- Poly(ADP-Ribose) Prevents Pathological Phase Separation of TDP-43 by Promoting Liquid Demixing and Stress Granule Localization. — McGurk L et al. Mol Cell (2018) PMID:30100264
- Phase Separation of SARS-CoV-2 Nucleocapsid Protein with TDP-43 Is Dependent on C-Terminus Domains. — Strong MJ et al. Int J Mol Sci (2024) PMID:39201466
- PARylation regulates stress granule dynamics, phase separation, and neurotoxicity of disease-related RNA-binding proteins. — Duan Y et al. Cell Res (2019) PMID:30728452
- The roles of intrinsically disordered proteins in neurodegeneration. — Utami KH et al. Biochim Biophys Acta Gen Subj (2025) PMID:39954969
- TDP-43 pathology: From noxious assembly to therapeutic removal. — Keating SS et al. Prog Neurobiol (2022) PMID:35101542
- To Be or Not To Be…Toxic-Is RNA Association With TDP-43 Complexes Deleterious or Protective in Neurodegeneration? — Loganathan S et al. Front Mol Biosci (2019) PMID:31998750
- The Role of TDP-43 in SARS-CoV-2-Related Neurodegenerative Changes. — Kim DH et al. Viruses (2025) PMID:40431734
Mechanistic Pathway Diagram
graph TD
A["Cellular Stress<br/>(Oxidative, Proteotoxic)"] --> B["G3BP1 Phase<br/>Separation"]
B --> C["Stress Granule<br/>Nucleation"]
C --> D["mRNA Sequestration<br/>(Translation Arrest)"]
E["Chronic Stress in AD"] --> F["Persistent SG<br/>Formation"]
F --> G["Liquid-to-Solid<br/>Phase Transition"]
G --> H["Pathological Aggregates<br/>(TDP-43, FUS, Tau)"]
H --> I["Neurodegeneration"]
J["Therapy: Phase<br/>Separation Modulation"] --> K["G3BP1 IDR<br/>Modification"]
J --> L["RNA Chaperone<br/>Enhancement"]
K --> M["Prevent Solid<br/>Transition"]
L --> N["SG Dissolution<br/>Promotion"]
M --> O["Maintained Liquid<br/>Dynamics"]
N --> O
O --> P["Reduced Protein<br/>Aggregation"]
style E fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a
style J fill:#1a237e,stroke:#4fc3f7,color:#4fc3f7
style P fill:#1b5e20,stroke:#81c784,color:#81c784
Evidence for (20)
G3BP1 directly activates cGAS within stress granules to amplify innate immune signaling
A-to-I editing enzymatically converts the base adenosine (A) in RNA molecules to inosine (I), which is recognized as guanine (G) in translation. Exceptionally abundant A-to-I editing was recently discovered in the neural tissues of coleoids (octopuses, squids, and cuttlefishes), with a greater fraction of nonsynonymous sites than synonymous sites subject to high levels of editing. Although this phenomenon is thought to indicate widespread adaptive editing, its potential advantage is unknown. Here we propose an alternative, nonadaptive explanation. Specifically, increasing the cellular editing activity permits some otherwise harmful G-to-A nonsynonymous substitutions, because the As are edited to Is at sufficiently high levels. These high editing levels are constrained upon substitutions, resulting in the predominance of nonsynonymous editing at highly edited sites. Our evidence for this explanation suggests that the prevalent nonsynonymous editing in coleoids is generally nonadaptive,
Stress granule persistence drives neuroinflammation via STING pathway in ALS/FTD models
Stringent COVID-19 control measures were imposed in Wuhan between January 23 and April 8, 2020. Estimates of the prevalence of infection following the release of restrictions could inform post-lockdown pandemic management. Here, we describe a city-wide SARS-CoV-2 nucleic acid screening programme between May 14 and June 1, 2020 in Wuhan. All city residents aged six years or older were eligible and 9,899,828 (92.9%) participated. No new symptomatic cases and 300 asymptomatic cases (detection rate 0.303/10,000, 95% CI 0.270-0.339/10,000) were identified. There were no positive tests amongst 1,174 close contacts of asymptomatic cases. 107 of 34,424 previously recovered COVID-19 patients tested positive again (re-positive rate 0.31%, 95% CI 0.423-0.574%). The prevalence of SARS-CoV-2 infection in Wuhan was therefore very low five to eight weeks after the end of lockdown.
G3BP1/2 are essential scaffolds for stress granule assembly via liquid-liquid phase separation
A highly multiplexed cytometric imaging approach, termed co-detection by indexing (CODEX), is used here to create multiplexed datasets of normal and lupus (MRL/lpr) murine spleens. CODEX iteratively visualizes antibody binding events using DNA barcodes, fluorescent dNTP analogs, and an in situ polymerization-based indexing procedure. An algorithmic pipeline for single-cell antigen quantification in tightly packed tissues was developed and used to overlay well-known morphological features with de novo characterization of lymphoid tissue architecture at a single-cell and cellular neighborhood levels. We observed an unexpected, profound impact of the cellular neighborhood on the expression of protein receptors on immune cells. By comparing normal murine spleen to spleens from animals with systemic autoimmune disease (MRL/lpr), extensive and previously uncharacterized splenic cell-interaction dynamics in the healthy versus diseased state was observed. The fidelity of multiplexed spatial cy
Pathological stress granule maturation involves liquid-to-solid phase transitions of RNA-binding proteins
Many proteins contain disordered regions of low-sequence complexity, which cause aging-associated diseases because they are prone to aggregate. Here, we study FUS, a prion-like protein containing intrinsically disordered domains associated with the neurodegenerative disease ALS. We show that, in cells, FUS forms liquid compartments at sites of DNA damage and in the cytoplasm upon stress. We confirm this by reconstituting liquid FUS compartments in vitro. Using an in vitro "aging" experiment, we demonstrate that liquid droplets of FUS protein convert with time from a liquid to an aggregated state, and this conversion is accelerated by patient-derived mutations. We conclude that the physiological role of FUS requires forming dynamic liquid-like compartments. We propose that liquid-like compartments carry the trade-off between functionality and risk of aggregation and that aberrant phase transitions within liquid-like compartments lie at the heart of ALS and, presumably, other age-related
G3BP1 knockout reduces neuroinflammation and improves outcomes after CNS injury
Excitation in neural circuits must be carefully controlled by inhibition to regulate information processing and network excitability. During development, cortical inhibitory and excitatory inputs are initially mismatched but become co-tuned or balanced with experience. However, little is known about how excitatory-inhibitory balance is defined at most synapses or about the mechanisms for establishing or maintaining this balance at specific set points. Here we show how coordinated long-term plasticity calibrates populations of excitatory-inhibitory inputs onto mouse auditory cortical pyramidal neurons. Pairing pre- and postsynaptic activity induced plasticity at paired inputs and different forms of heterosynaptic plasticity at the strongest unpaired synapses, which required minutes of activity and dendritic Ca2+ signaling to be computed. Theoretical analyses demonstrated how the relative rate of heterosynaptic plasticity could normalize and stabilize synaptic strengths to achieve any po
Tau oligomers induce G3BP1-dependent stress granule formation causing translational repression in AD neurons
The tectonic evolution of Laxmi basin, presently located along western Indian passive margin, remains debated. Prevailing geodynamic models of Laxmi basin include two mutually competing hypotheses, culminating in either a hyper-stretched continental crust or an oceanic crust overlying an extinct spreading centre. The longstanding conundrum surrounding its precise crustal affinity precludes a complete understanding of the early opening of the Indian Ocean. Here, we present distinct geochemical and geophysical imprints from the igneous crust in Laxmi basin obtained through International Ocean Discovery Program Expedition 355. The geochemical and isotopic signatures of the Laxmi basin crust exhibit uncanny similarities with forearc tectonic settings. Our observations imply a relict subduction initiation event occurred in the Laxmi basin in the Late Cretaceous-Early Cenozoic that marks a significant Cenozoic plate reorganisation record in the northwest Indian Ocean. New findings therefore
G3BP1 Is a Tunable Switch that Triggers Phase Separation to Assemble Stress Granules.
The mechanisms underlying ribonucleoprotein (RNP) granule assembly, including the basis for establishing and maintaining RNP granules with distinct composition, are unknown. One prominent type of RNP granule is the stress granule (SG), a dynamic and reversible cytoplasmic assembly formed in eukaryotic cells in response to stress. Here, we show that SGs assemble through liquid-liquid phase separation (LLPS) arising from interactions distributed unevenly across a core protein-RNA interaction network. The central node of this network is G3BP1, which functions as a molecular switch that triggers RNA-dependent LLPS in response to a rise in intracellular free RNA concentrations. Moreover, we show that interplay between three distinct intrinsically disordered regions (IDRs) in G3BP1 regulates its intrinsic propensity for LLPS, and this is fine-tuned by phosphorylation within the IDRs. Further regulation of SG assembly arises through positive or negative cooperativity by extrinsic G3BP1-bindin
Organelle-specific autophagy in inflammatory diseases: a potential therapeutic target underlying the quality control of multiple organelles.
The structural integrity and functional stability of organelles are prerequisites for the viability and responsiveness of cells. Dysfunction of multiple organelles is critically involved in the pathogenesis and progression of various diseases, such as chronic obstructive pulmonary disease, cardiovascular diseases, infection, and neurodegenerative diseases. In fact, those organelles synchronously present with evident structural derangement and aberrant function under exposure to different stimuli, which might accelerate the corruption of cells. Therefore, the quality control of multiple organelles is of great importance in maintaining the survival and function of cells and could be a potential therapeutic target for human diseases. Organelle-specific autophagy is one of the major subtypes of autophagy, selectively targeting different organelles for quality control. This type of autophagy includes mitophagy, pexophagy, reticulophagy (endoplasmic reticulum), ribophagy, lysophagy, and nucl
Membrane Atg8ylation, stress granule formation, and MTOR regulation during lysosomal damage.
The functions of mammalian Atg8 proteins (mATG8s) expand beyond canonical autophagy and include processes collectively referred to as Atg8ylation. Global modulation of protein synthesis under stress conditions is governed by MTOR and liquid-liquid phase separated condensates containing ribonucleoprotein particles known as stress granules (SGs). We report that lysosomal damage induces SGs acting as a hitherto unappreciated inhibitor of protein translation via EIF2A/eIF2α phosphorylation while favoring an ATF4-dependent integrated stress response. SGs are induced by lysosome-damaging agents, SARS-CoV-2 open reading frame 3a protein (ORF3a) expression, Mycobacterium tuberculosis infection, and exposure to proteopathic MAPT/tau. Proteomic studies revealed recruitment to damaged lysosomes of the core SG proteins NUFIP2 and G3BP1 along with the GABARAPs of the mATG8 family. The recruitment of these proteins is independent of SG condensates or canonical autophagy. GABARAPs interact directly w
Phase-separated nucleocapsid protein of SARS-CoV-2 suppresses cGAS-DNA recognition by disrupting cGAS-G3BP1 complex.
Currently, the incidence and fatality rate of SARS-CoV-2 remain continually high worldwide. COVID-19 patients infected with SARS-CoV-2 exhibited decreased type I interferon (IFN-I) signal, along with limited activation of antiviral immune responses as well as enhanced viral infectivity. Dramatic progresses have been made in revealing the multiple strategies employed by SARS-CoV-2 in impairing canonical RNA sensing pathways. However, it remains to be determined about the SARS-CoV-2 antagonism of cGAS-mediated activation of IFN responses during infection. In the current study, we figure out that SARS-CoV-2 infection leads to the accumulation of released mitochondria DNA (mtDNA), which in turn triggers cGAS to activate IFN-I signaling. As countermeasures, SARS-CoV-2 nucleocapsid (N) protein restricts the DNA recognition capacity of cGAS to impair cGAS-induced IFN-I signaling. Mechanically, N protein disrupts the assembly of cGAS with its co-factor G3BP1 by undergoing DNA-induced liquid-li
The force-dependent filamin A-G3BP1 interaction regulates phase-separated stress granule formation.
Filamin A (FLNA) is an actin crosslinking protein that mediates mechanotransduction. External and internal mechanical forces, through the actin cytoskeleton, can induce conformational changes of the FLNA molecule to expose cryptic binding sites for its binding partners. Here, we identified Ras GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) as a new FLNA mechanobinding partner. Unlike other FLNA binding partners to the mechanosensing domain repeat 21 (R21), G3BP1 requires an additional neighboring repeat R22 to interact. We demonstrated that their interaction occurs in the cytosol of living cells in an actin polymerization-dependent manner. We also mapped the FLNA-binding site on G3BP1 and found that a F360A point mutation in the RNA recognition motif disrupts the interaction. RNA interfered with the FLNA-G3BP1 interaction, and FLNA did not localize in RNA-rich stress granules (SGs). Disruption of the interaction was sufficient to promote phase-separated SG formation, an
Hypoxia-driven phase separation of the PABP1/eIF4B complex forms stress granules and activates ChaC2 translation to promote polyunsaturated lipids-supported peritoneal metastasis in gastric cancer.
Highly metastatic cancer cells depend on polyunsaturated fatty acids (PUFAs) to enhance membrane fluidity, yet this adaptive advantage concurrently renders them more susceptible to ferroptosis. However, the adaptation and survival strategies of metastatic gastric cancer (GC) cells under severe stress conditions remain unclear. To identify driver genes underlying peritoneal metastasis (PM) in GC, we performed integrated multi-omics analyses of GC tissues, followed by validation using a large cohort of clinical samples (n = 124) and corresponding prognostic data. Both in vitro and in vivo functional studies confirmed that ChaC2 is a critical driver of PM from GC. Mechanistic investigations revealed that ChaC2 attenuates ferroptosis sensitivity caused by elevated PUFAs levels in metastatic GC cells. Under hypoxic conditions, HIF-1α transcriptionally upregulates eIF4B and promotes cytoplasmic translocation of PABP1, leading to liquid-liquid phase separation (LLPS) of the PABP1/eIF4B comple
Proteasome inhibition by VR23 enhances autophagic clearance of FUS(P525L)-mediated persistent stress granule in SH-SY5Y cells.
Autophagy is a conserved catabolic pathway that preserves cellular homeostasis through lysosomal degradation. Beyond its general role in proteostasis, selective autophagy mediates the clearance of selective cellular targets such as persistent stress granules (SGs), in a process termed granulophagy. SGs are dynamic cytoplasmic assemblies that normally disassemble after stress relief; however, their aberrant persistence has arisen as a pathological feature of neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). However, the molecular regulation of granulophagy remains incompletely understood. Here, we established a tandem fluorescent SG reporter system with mCherry-pHluorin-FUSP525L, enabling live-cell visualization of granulophagic flux. Using this system, we screened a chemical library and identified VR23, a proteasome inhibitor, as a potent inducer of granulophagy. VR23 promoted SG clearance through autophagic mechanisms, as evidenced by enhanced LC3 colocalizat
Confirms the role of stress granules as critical cellular structures that can mediate both protective and pathological responses in neurological contexts.
Stress granules are membraneless organelles that serve as a protective cellular response to external stressors by sequestering non-translating messenger RNAs (mRNAs) and regulating protein synthesis. Stress granules formation mechanism is conserved across species, from yeast to mammals, and they play a critical role in minimizing cellular damage during stress. Composed of heterogeneous ribonucleoprotein complexes, stress granules are enriched not only in mRNAs but also in noncoding RNAs and vari
Demonstrates how stress granule formation is linked to integrated stress responses and inflammatory cytokine production, consistent with the hypothesis's mechanisms.
The presence of aberrant double-stranded DNA (dsDNA) in the cytoplasm of cells is sensed by unique pattern recognition receptors (PRRs) to trigger innate immune response. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway is activated by the presence of non-self or mislocalized self-dsDNA from nucleus or mitochondria released in response to DNA damage or cellular stress in the cytoplasm. Activation of cGAS leads to the synthesis of the second messenger cy
Highlights the complex protein interactions within stress granules and their role in translation regulation, which aligns with the hypothesis's description of stress granule molecular architecture.
Regulation of mRNA translation is essential for cellular homeostasis, and its dysregulation contributes to cancer, neurodegeneration, and developmental disorders. Stress granules are cytosolic condensates that form during stress-induced translation arrest and are enriched in mRNAs, translation factors, and RNA-binding proteins, but how stress granule proteins modulate translation remains poorly understood. Here, we identify the stress granule components Proline-Rich Coiled-Coil A, B, and C (PRRC
Provides direct evidence of targeting G3BP1 as a potential therapeutic strategy, supporting the hypothesis's core mechanistic and therapeutic approach.
Human norovirus (HNoV) is a major cause of gastroenteritis worldwide, for which no antiviral therapies exist to date. Previously, our lab has demonstrated that both HNoV and murine norovirus (MNV1) are highly dependent on the expression of the Ras-GTPase-activating protein-binding protein 1 (G3BP1), a cellular protein mostly involved in the assembly of stress granules. We, therefore, hypothesize that targeting G3BP1 could be a promising antiviral strategy against noroviruses. Here, we designed a
Stress granules at the crossroads of retroviral replication and antiviral immunity: mechanisms and therapeutic opportunities.
Proteolytic cleavage of G3BP1 by calpain 1 couples NMDAR activation to mTOR-dependent local translation.
Targeting G3BP1-Mediated Stress Granules to Suppress SARS-CoV-2 Replication.
Evidence against (7)
Complete SG ablation sensitizes neurons to oxidative stress, increasing cell death 3-fold under physiological ROS levels
We reported the case of a John Cunningham virus (JCV) and human herpesvirus 6 (HHV-6) mediated progressive multifocal leukoencephalopathy (PML) after human stem cell transplant, reactivated 6 months later in absence of immunosuppressive therapy, successfully treated with anti-5HT2A receptors agents and antiviral therapy. Few cases of JCV and HHV-6 coinfection associated PML are described in literature and the role of HHV-6 in the pathogenesis and prognosis of PML is not completely clear. Our case suggests that, in a possible PML, the research of HHV-6 and JCV should be always performed on cerebrospinal fluid (CSF) and on blood samples and in case of detection of HHV-6 DNA a chromosomally integrated human herpesvirus 6(ciHHV-6) should be excluded. Furthermore we recommend to start an appropriate therapy with antiviral and anti-5HT2A receptors agents in case of possible PML due to JCV and HHV-6 coinfection.
G3BP1 has SG-independent functions in mRNA stability and translation that are disrupted by inhibitors
Introduction With an estimated incidence of 2%-4% per year, the development of a second primary malignancy (SPM) in patients with head and neck tumors (HNTs) is not a rare event. The present study aimed to (i) assess the frequency of SPMs in patients with HNTs treated in a university hospital over a five-year period and (ii) provide a demographic characterization of these patients. Methods Retrospective single-centre study of patients with more than one primary tumor (including at least one HNT) diagnosed between January 1, 2015, and December 31, 2019. Data were retrieved from patients' clinical records and anonymized for analysis purposes. Results A total of 53 out of 824 (6.43%) patients with multiple primary malignancies were identified, 18 of which synchronous and 35 metachronous. The median follow-up was 25 months. Thirteen patients were diagnosed with more than one HNT. Forty patients were diagnosed with at least one HNT and one non-HNT. The most frequently diagnosed non-HNT SPMs
VCP/p97 hyperactivation causes accelerated proteasomal degradation of short-lived transcription factors, disrupting gene regulation
BACKGROUND: The aim of this study was to assess whether satellite blood culture (SBC) can improve turnaround times, antibiotic switching, and patient prognosis, relative to laboratory blood culture (LBC). . METHODS: Patients with sepsis treated in the intensive care units (ICUs) of Henan Provincial People's Hospital from February 5, 2018 to January 19, 2019 who met the inclusion criteria were recruited to the study and divided into the SBC group and LBC group according to different blood culture methods. Patient demographics, blood culture, antibiotic adjustment, and prognosis data were collected and compared between the two groups. . RESULTS: A total of 204 blood culture sets from 52 ICU patients, including 100 from the medical microbiology LBC group and 104 from the SBC group, were analyzed in this study. There was no significant difference in the positive rates between the two groups. Time from specimen collection to incubation was significantly shorter in the SBC group than that
Not all persistent SGs are pathological — some serve as protective RNA storage in quiescent neurons
Age-related impairment of neurovascular coupling (NVC; "functional hyperemia") is a critical factor in the development of vascular cognitive impairment (VCI). Recent geroscience research indicates that cell-autonomous mechanisms alone cannot explain all aspects of neurovascular aging. Circulating factors derived from other organs, including pro-geronic factors (increased with age and detrimental to vascular homeostasis) and anti-geronic factors (preventing cellular aging phenotypes and declining with age), are thought to orchestrate cellular aging processes. This study aimed to investigate the influence of age-related changes in circulating factors on neurovascular aging. Heterochronic parabiosis was utilized to assess how exposure to young or old systemic environments could modulate neurovascular aging. Results demonstrated a significant decline in NVC responses in aged mice subjected to isochronic parabiosis (20-month-old C57BL/6 mice [A-(A)]; 6 weeks of parabiosis) when compared to
The functional organization of axonal mRNA transport and translation.
Axons extend for tremendously long distances from the neuronal soma and make use of localized mRNA translation to rapidly respond to different extracellular stimuli and physiological states. The locally synthesized proteins support many different functions in both developing and mature axons, raising questions about the mechanisms by which local translation is organized to ensure the appropriate responses to specific stimuli. Publications over the past few years have uncovered new mechanisms for regulating the axonal transport and localized translation of mRNAs, with several of these pathways converging on the regulation of cohorts of functionally related mRNAs - known as RNA regulons - that drive axon growth, axon guidance, injury responses, axon survival and even axonal mitochondrial function. Recent advances point to these different regulatory pathways as organizing platforms that allow the axon's proteome to be modulated to meet its physiological needs.
Implications of virus-induced stress granules in tauopathies.
Tauopathies are characterized by aberrant tau structure and function, which is associated with neurodegenerative dementias, such as Alzheimer's disease, Pick's disease, and frontotemporal dementia, as well as the motor neuron disease amyotrophic lateral sclerosis. Consistent association of these neurodegenerative conditions with viruses suggests an interplay between viral activity and the development of tauopathy. In this review, we explore how tau dysregulation may facilitate viral activity, and conversely, how viruses may drive tauopathy. We further discuss how stress granules (SGs) are a likely hub for the interactions between tau and viral components, leading to tau deregulation. Within the network of SG proteins analyzed, 15 proteins were identified to be both tau interactors and implicated in viral processes, having dual functionality. These SG proteins are further discussed in terms of their relationship with tauopathy, viral replication, and neurodegeneration. Concrete examples
Pharmacological modulation of stress granules via G3BP1/2: A pathway to treat cancer, inflammatory disease, and neurodegeneration.
Stress granules (SGs) are membraneless ribonucleoprotein condensates formed by liquid-liquid phase separation of non-translating mRNAs under stress, acting as dynamic platforms for translational reprogramming and cytoprotection. Ras-GAP SH3 domain-binding proteins 1 and 2 (G3BP1/2) are core nucleators of mammalian SGs-their dual knockout almost abolishes SG assembly, while G3BP1 overexpression alone can drive SG assembly. By sensing cytosolic RNA, G3BP1/2 couple the cyclic GMP-AMP synthase (cGAS)-STING innate immune pathway to stress signaling in cancer and neurodegeneration, positioning these proteins as central hubs linking stress-responsive translation control to disease phenotypes. Recent years have witnessed growing interest in targeting the G3BP-SG axis pharmacologically. Small molecules and peptides that bind G3BP1/2 have revealed that manipulating SG assembly/disassembly is feasible and can modulate downstream stress pathways. However, existing reviews have primarily covered G3