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Xu, W.

Publications and source records attributed to Xu, W..

At least 73 records · Page 4Linked to original sources

Structural and biochemical studies of human PP2A(B55) holoenzyme and ENSA protein complex

The serine/threonine protein phosphatase 2A (B55) holoenzyme (PP2A(B55)), a key cell cycle regulator, is tightly regulated by ENSA, whose phosphorylation at Ser67 inhibits PP2A(B55). The structural basis for how pENSA orchestrates this inhibition to govern mitotic progression remains unclear. In this study, we disapproved the previous hypothesis of direct ENSA-PP2A A subunit interaction, and showed that the ENSA-PP2A(B55) interaction requires the PP2A holoenzyme. We then determined cryo-EM structure of the PP2A(B55)-ENSAS67D complex at 3.03 [A] resolution, which reveals four distinct regions of ENSA, each engaging specific sites on the B55 or C subunits. The structure reveals an extended, inhibited conformation of the PP2A(B55) holoenzyme, which contrasts sharply with the contracted, active state of apo PP2A(B55). pENSA binding induces the C subunit to shift away from the B55 subunit, with the pS67-containing motif inserting into the catalytic site of C subunit and locking the PP2A(B55) holoenzyme in an inactive state. Our work also revealed novel ligand-binding surfaces on B55, and expanded definition of the short linear motif (SliM). Overall, our work provided novel insights into PP2A regulation during cell cycle, and offers new avenues for the discovery of specific PP2A(B55) inhibitors and modulators.

biophysics↗

Panax notoginseng saponins protect the blood brain barrier against oxidative stress by activating the Akap12/PI3K/AKT/AQP1 signaling axis

Oxidative stress is a key pathological factor that contributes to blood-brain barrier (BBB) disruption during ischemic injury. Panax notoginseng saponins (PNS), the primary bioactive components of Panax notoginseng, possess potent antioxidative and vasoprotective activities. This study aimed to elucidate the molecular mechanisms by which PNS regulate endothelial integrity and BBB permeability under oxidative stress conditions. Mouse brain microvascular endothelial cells (bEnd.3) were treated with hydrogen peroxide to induce oxidative damage, followed by intervention with PNS. Transcriptomic and proteomic analyses revealed that Akap12 (A-kinase anchoring protein 12) and Aquaporin 1 (AQP1) were key molecules involved in PNS-mediated endothelial protection. H2O2 exposure markedly suppressed Akap12 expression and inhibited the PI3K/AKT signaling pathway, leading to elevated AQP1 expression and increased BBB permeability. PNS treatment reversed these effects by restoring Akap12 expression, reactivating PI3K/AKT signaling, and reducing AQP1 levels. Functional validation further showed that AQP1 dysregulation altered the expression balance of tight junction proteins, including Claudin-5 and ZO-1, thereby impairing barrier function. Collectively, these findings demonstrate that PNS protect endothelial cells from oxidative injury by activating Akap12-dependent PI3K/AKT signaling and modulating AQP1-associated tight junction remodeling. This study provides new mechanistic insights into the molecular basis of PNS-mediated BBB protection and suggests potential therapeutic targets for oxidative or ischemic cerebrovascular diseases.

pharmacology and toxicology↗

Cross-Species Insights from ART-D to Uncover Evolutionarily Conserved Oncogenic Mechanisms

Cancer arises from oncogenic clones, yet the dynamic mechanisms governing their stepwise evolution toward malignancy remain incompletely understood. Here, we establish the Atlas of Ras-driven Tumors in Drosophila (ART-D), a systematic, cross-species platform that dissects the molecular and phenotypic trajectories of tumorigenesis through ten genetically defined RasV12-driven models. By integrating longitudinal phenotypic profiling, we define three conserved stages of tumor development--initiation, promotion, and progression--distinguished by dynamic changes in tumor burden and tumor-induced cachexia. Transcriptomic dynamics reveal stage-specific signaling rewiring: early tumorigenesis is marked by co-activation of JAK/STAT, NF-{kappa}B/Toll, and MAPK pathways, whereas malignant progression is driven by Notch hyperactivation and Hippo pathway inactivation. Through integrative multi-omics and machine learning, we uncover an evolutionarily conserved pathogenic network involving coordinated JNK, NF-{kappa}B/Toll, Notch, and Hippo signaling that is functionally validated across species. ART-D provides a transformative resource that bridges Drosophila genetics and human cancer biology, offering a framework for decoding conserved oncogenic principles and enabling precision targeting of stage-specific vulnerabilities in RAS-driven cancers.

genetics↗

Parallel circadian-like oscillations in LTP and excitation inhibition balance in mouse CA1 reverse direction after puberty

Long-term potentiation (LTP), the best-characterized form of Hebbian synaptic plasticity, is well known to be under strong circadian regulation. In mice and rats, both nocturnal species, most studies indicate that LTP in the hippocampal CA1 region is more robust when induced during the dark phase. Our examination of the underlying mechanisms at the CA3 to CA1 synapse provides evidence that the capacity to express LTP does not differ between the light and dark cycles of the 24-hour day. Instead, the magnitude of theta-burst stimulation-induced LTP (TBS-LTP) correlates with daily fluctuations in the ratio of synaptic excitation to inhibition (E/I ratio): both the E/I ratio and TBS-LTP are higher during the dark phase. Consistent with a causal relationship, blockade of inhibition abolishes the light-dark difference in TBS-LTP induction, likewise, pairing-induced LTP, which is less constrained by inhibitory recruitment, does not differ between cycles. Supporting this model, using the APP/PS1 model of AD we observed that neither the E/I ratio nor TBS-LTP change during the light cycle. Finally, we made the intriguing observation that these daily oscillations reverse direction after puberty in WT mice, shifting from being larger in the dark cycle of 2-month-old mice to being larger in the light cycle in 8-month-old mice. This developmental switch may reflect an age-dependent reorganization of circadian control over hippocampal plasticity.

neuroscience↗

Beyond Pollination: Computer Vision Reveals how Flower Visitors, Climate and Agroforestry Management Drive Cocoa Yields in China and Brazil

Cocoa (Theobroma cacao L.) is a multi-billion-dollar crop that is strongly affected by climate change. As a pollination-limited crop, improving little-understood pollination services in agroforestry systems may offer a scalable solution to increase yield sustainably in a changing climate. Here, we use embedded computer vision devices and structural equation models to quantify the interactions of flower visitors and temperature across shade tree-diversity and canopy cover gradients in cocoa systems on fruit set, as a yield precursor. In China and Brazil we show that flower visits are done by nectar and pollen foragers (23.1%), herbivores (6.1%), predators (2.3%), and visitors combining the three functions (63%). Forager visits were driven by increased shade-tree diversity and canopy cover management, with stronger effects in China than in Brazil. Foraging midges in China and multifunctional ants in Brazil enhanced fruit set, showing that diverse pollinators across continents affect cocoa yields. In China, higher canopy cover reduced aphids foraging and feeding on flower tissue, while in Brazil temperature increase reduced flowering. Overall, new technologies can guide implementation of agroforestry management strategies to enhance pollination while reducing pest pressures to ensure sustainable cocoa production under climate change.

ecology↗

De Novo Design of Anti-Aging Peptides

Aging, a universal biological process in complex organisms, is increasingly recognized to be driven by progressive loss of epigenetic information, as proposed in the Information Theory of Aging (ITOA). However, research on anti-aging peptides remains scarce, with most existing efforts confined to derivatives of natural proteins, while systematic design attempts are virtually absent. This limitation not only restricts discovery within the evolutionary sequence space but also hampers the identification of candidates with novel mechanisms and improved efficacy. Here, we present ElixirSeeker2, the first computational framework for de novo design of anti-aging peptides. By integrating modeling of known anti-aging peptides, activity scoring from the IC50 database, and penalty constraints from toxic peptides, ElixirSeeker2 enables large-scale virtual screening and identification of novel peptide candidates. Several lead peptides demonstrated significant effects in delaying cellular senescence, restoring cellular functions in vitro and in enhancing locomotor activity of aged Caenorhabditis elegans. This study not only validates the feasibility of de novo design in anti-aging interventions but also establishes a strategy for the development of next-generation biologics.

bioinformatics↗

Development of a High-Throughput Screening Method for Anti-NNV Drugs

Nervous necrosis virus (NNV) is an infectious pathogen, characterized by rapid infection and high mortality, commonly encountered in the aquaculture industry. Therefore, there is an urgent need to develop effective antiviral drugs against NNV, which is crucial for targeted treatment strategies, pathogen control, and loss reduction. Screening of effective antiviral active compounds, namely drug precursors, is key to developing highly efficient drugs against NNV. Reverse transcription-quantitative real-time PCR (RT-qPCR) is widely applied to screen and evaluate various substances to prevent and control virus infection. However, RT-qPCR is a cumbersome procedure and not suitable for high-throughput rapid screening. The aptamer TNA1c, which specifically binds to NNV-infected cells, was used to construct a target-driven activatable aptamer probe (TAA). Then, the TAA probe was applied to establish a high-throughput screening (TAA-HTS) method for efficient evaluation of substances against NNV infection. TAA-HTS technology achieved rapid, sensitive, and specific screening of bioactive substances with significant anti-NNV effects. As compared to commonly used analytical methods, such as RT-qPCR, TAA-HTS has the advantages of easy operation and high sensitivity and specificity. The findings of this study provide data support and a theoretical basis for the development of effective antivirus preparations. IMPORTANCEIn this study, a target-driven activatable aptamer probe was employed to establish a high-throughput screening method for anti-NNV drugs. This method enables rapid, sensitive, and specific screening of anti-NNV compounds while reducing background interference. Although RT-qPCR is currently the most widely used technique for antiviral drug screening and validation, the screening approach developed in this study significantly shortens screening time while achieving results consistent with those of RT-qPCR. This demonstrates that the screening method presented here has the potential to become a universal strategy for future drug screening against viral diseases. Moreover, this study not only provides a novel technical solution for NNV control but also demonstrates the potential of aptamer-based probes in high-throughput antiviral screening, serving as a model for combating viral pathogens in aquaculture and other fields.

pathology↗

Evolutionary patterns and repeated adaptive strategies of deep-sea anemones

Sea anemones occupy the full depth of the oceans, yet their evolutionary patterns and adaptive strategies to the enigmatic deep sea have remained contentious and poorly resolved. Here, we assemble genomes (n = 13) and transcriptomes for 15 species collected between 432 and 6,000 m and integrate them with all publicly available actiniarian data. Phylogenomic analyses reveal a mosaic topology among deep-sea and shallow-water clades. Using a novel framework that contrasts convergent gene-loss patterns, we show that a large number of light-associated gene families-- including the complete circadian toolkit--were independently deleted after lineages entered the aphotic realm, whereas comparable loss in shallow taxa is negligible, providing decisive support for a shallow-water origin followed by multiple descents. Intriguingly, some deep-sea lineages further streamline energy budgets by recurrent loss or pseudogenisation of key meiotic genes (e.g., Meiosin, Ythdc2, Spo11, Rad21, Mlh3), indicating a shift towards asexual reproduction. Despite this extensive genomic erosion, deep-sea anemones exhibit sophisticated molecular tuning: specific amino-acid substitutions enhance protein stability and activity under deep-sea conditions, while selective expansions of gene families related to neural excitability, membrane systems, etc., likely mitigate the suppressive environmental effects on vital physiological processes. Enzyme activity assays in the yeast system confirm that the deep-sea variants exhibit superior activity and enhanced growth at 4{degrees}C. These results define a "loss-optimization-innovation" triad that underlies bathymetric adaptations and may apply to other deep-sea fauna worldwide.

evolutionary biology↗

Resolving the estrogen paradox in hereditary retinal degeneration: Esr1 activation suppresses Tnf-α signaling as a photoreceptor self-protection mechanism

Retinitis pigmentosa (RP) is an inherited retinal degenerative disorder characterized by progressive photoreceptor loss and irreversible blindness. Increasing evidence implicates neuroinflammation as a contributor to photoreceptor degeneration extending beyond the initial genetic insult. Although estrogen has been reported to exert anti-inflammatory effects in the central nervous system, its role in RP remains controversial, with some studies suggesting a paradoxical exacerbation of retinal pathology. To address this discrepancy, we identify estrogen receptor alpha (Esr1) as a central immunoregulatory hub in RP. Transcriptomic analyses of rd1 and rd10 revealed upregulation of estrogen-responsive and inflammatory pathways, with Esr1 expression markedly elevated during degeneration. TUNEL assays demonstrated that systemic estradiol (E2) exerted divergent effects, protective in rd1 yet deleterious in rd10, whereas selective pharmacological activation of Esr1 with propyl pyrazole triol (PPT) consistently reduced photoreceptor death, preserved dark-adapted ERG responses, and downregulated inflammatory mediators including Tnf-, Cx3cl1/Cx3cr1, Cd68, and Iba1. Mechanistically, Esr1 activation repressed microglial Tnf transcription and disrupted a self-sustaining Cx3cl1/Cx3cr1-Tnf- signaling loop driving microglial recruitment, activation and neurotoxicity in the outer nuclear layer (ONL). Targeted interventions confirmed tumor necrosis factor receptor 1 (Tnfr1) as the principal mediator of Tnf-induced photoreceptor death: selective inhibition with R7050 conferred superior protection compared with broad-spectrum Tnf- inhibitors (etanercept, infliximab). Cx3cr1 blockade likewise suppressed microglial activation and improved visual outcomes. Collectively, our findings establish Esr1 activation as not merely an external intervention but the amplification of an intrinsic self-protective program, positioning Esr1, Tnfr1, and Cx3cr1 as actionable therapeutic targets to suppress neuroinflammation and preserve vision in RP and related retinal disorders.

neuroscience↗

Land use influences on freshwater biodiversity

Land-use change is a major driver of biodiversity loss, but most generalizations about its effects come from terrestrial ecosystems. In freshwater systems, impacts are often indirect, driven by changes in the surrounding landscape that alter flow, chemistry, and connectivity. Using species-level abundance data from 163 studies across 6 biological groups, we examined how urban, agricultural, and forestry land uses affect freshwater biodiversity at local and regional scales. All three land-use types reduced species richness and altered relative abundance structure compared to natural vegetation, with urban systems showing the strongest and most consistent declines. Only urbanization was associated with biotic homogenization, particularly among abundant species. Biodiversity responses to land-use change also varied with latitude and taxonomic group: tropical assemblages tended to differentiate across sites, while homogenization was more common at higher latitudes. Macroinvertebrates and fish showed the strongest overall declines. These findings challenge assumptions of generality across ecosystems and highlight the need to explicitly incorporate freshwater biodiversity into global change research and policy.

ecology↗

The MEK inhibitor trametinib incurs mitochondrial injury and induces innate immune responses in the mouse heart

Trametinib (Trm) is a highly selective MEK inhibitor that potently and persistently abrogates ERK1/2 activation. Trm initially was used to treat BRAF V600E-mutated melanoma but its FDA-approved indications are expanding rapidly. Trm generally is well tolerated but it can cause dose-limiting cardiomyopathy and heart failure. Here we characterize a mouse model of Trm cardiotoxicity using complementary in vitro approaches to show that Trm induces mitochondrial dysfunction in cardiomyocytes and some cancer cell types. In vivo, Trm caused contractile dysfunction within 3 days and heart failure within 2 weeks. High resolution respirometry using isolated cardiac mitochondria revealed that Trm compromises oxidative metabolism, in part through blunted activity of Electron Transport System Complexes. Trm-mediated mitochondrial injury led to the release of mitochondrial Damage-Associated Molecular Patterns including mitochondrial DNA in both mice and humans, triggering activation of canonical innate immune pathways including cGAS-STING. In multiple rodent and human cardiomyocyte platforms, Trm diminished mitochondrial respiratory capacity at nanomolar concentrations but this lesion was reversed by expression of a phosphomimetic STAT3-S727 construct. We also found that Trm induced mitochondrial dysfunction in some but not all cancer cell lines, identifying a previously unrecognized effect that could contribute to Trms anti-cancer efficacy.

physiology↗

Arabidopsis Group I Pumilio RNA-binding factors are vital for embryo development and balancing between growth and stress resistance

Pumilio (PUM) RNA binding proteins are crucial for regulating gene expression by binding to a conserved motif in the 3'-untranslated region (3'-UTR). Despite their importance, the role of PUM in plants is largely unexplored. Here, we investigated the functions of Arabidopsis group I PUMs (APUM1-APUM6), which are ubiquitously expressed and localized in the cytosol. While single apum mutants exhibit no visible phenotypes, CRISPR/Cas9-generated apum1 apum2 apum3 triple mutants (apum1/2/3) display reduced growth in both vegetative and reproductive organs, alongside hypersensitivity to various stresses. Remarkably, apum1/2/3/4 quadruple mutants are embryonically lethal, highlighting their essential role in embryo development. Transcriptomic profiling revealed that differentially expressed genes (DEGs) upregulated in apum1/2/3 are enriched in pathways related to photosynthesis, stress responses and anthocyanin biosynthesis, while downregulated DEGs are associated with biotic stress defense and hydrogen peroxide metabolism. This suggests that APUM1/2/3 act as molecular hubs balancing plant growth and stress adaptation. Biochemical assays showed that recombinant APUM homologous domains bind to the 5-UGUGUAUA-3 core motif in the 3-UTR of the transcription factor Production of Anthocyanin Pigment1 (PAP1), crucial for anthocyanin biosynthesis. Notably, single nucleotide substitutions, except for the third U, do not affect binding, while multiple mutations disrupt interaction. Consistently, apum1/2/3 mutants accumulate significantly more anthocyanin than wild-type plants. Furthermore, we predicted 7053 potential target genes for APUM1/2/3, with 1609 present among the upregulated DEGs in apum1/2/3. Taken together, our findings demonstrate that group I APUMs are vital posttranscriptional regulators, providing a new perspective on the trade-offs between growth and stress resilience in plants.

plant biology↗

Finding ancestry-specific chromatin architecture in Alzheimer's disease

Genetic risk for Alzheimers Disease (AD) varies across populations. We hypothesized that three-dimensional (3D) genome architecture variations could offer novel epigenetic understanding of ancestry-specific genetic risk. Herein, we performed Hi-C analyses of frontal cortex from APOE {varepsilon}4/{varepsilon}4 individuals with African (AF) or European (EU) ancestry who also had single nuclei ATAC-seq and RNA-seq data available. Ancestry-specific 3D genome architecture was found at both compartment and chromatin loop levels. EU genomes have more active compartments than AF genomes, consistent with our previous report of higher chromatin accessibility in EU than AF genome. Of the over one million chromatin loops identified by the DeepLoop pipeline, we called 12,082 putative EU-specific and 2885 putative AF- specific loops. The AF-specific loops are smaller (median size =158 kb) and likely represent promoter-enhancer interactions, while EU-specific loops are larger (median size = 496 kb) and enriched for CTCF loops. We found that differently expressed genes between AF and EU ancestries were significantly enriched at the putative ancestry-specific loop loci (Fisher-test; p<2.2x10-16; OR=5.13). High confidence HiC-QTLs (N=38) were identified after filtering with CTCF consensus sequence and chromatin accessibility-QTLs. Our study demonstrates variations in 3D genome structure between ancestries, which may contribute to the ancestry-specific genetic risk.

genetics↗

MORC2 Mediates Transcriptional Regulation Through Liquid-Liquid Phase Separation and DNA Binding

MORC2 is a chromatin-associated ATPase essential for transcriptional silencing and genome stability, yet the biophysical principles governing its regulatory activity remain elusive. Here, we demonstrate that full-length MORC2 undergoes biomolecular condensation to form dynamic nuclear assemblies, a process fundamentally required for its repressor function. Endogenous MORC2 forms discrete, dynamic condensates in neurons from EGFP-MORC2 knock-in mice, supporting the physiological relevance of these assemblies in vivo. Mechanistically, a 3.1 [A] crystal structure of coiled-coil 3 (CC3) identifies a dimeric scaffold that serves as a structural hub, while multivalent sticker interactions between an intrinsically disordered region (IDR) and a newly defined IDR-binding domain (IBD) drive condensation. We show that DNA acts as a molecular scaffold that triggers MORC2 condensation, which in turn allosterically stimulates its ATPase activity. Critically, by employing a "killswitch" strategy to decouple assembly from internal fluidity, we reveal that only dynamic MORC2 condensates--not static aggregates or condensation-deficient mutants--can restore transcriptional repression in MORC2-knockout cells. Furthermore, pathogenic variants linked to CMT2Z and SMA differentially perturb these material properties and enzymatic turnover, providing a mechanistic link between condensate dysregulation and human neuropathies. Together, our findings establish a DNA-templated condensation mechanism for MORC2 and provide a molecular framework for understanding how the material state of chromatin-associated machinery dictates gene regulation and disease pathogenesis

cell biology↗

HerbComb: an integrated database for the discovery of novel combinational therapies from herbal medicines

Drug combinations have gained increasing interest due to their potential for optimal efficacy and the ability to overcome drug resistance. Herbal medicine is a complex system with multiple ingredients and has illustrated apparent therapeutic effects through thousands of years of clinical experience, offering a rich resource for combinational therapies. However, the underlying mechanism of their synergistic therapeutic effects for disease treatment remains obscure for most herbal medicines. To fill this gap, we developed an integrated database named HerbComb (https://herbcomb.com/) to discover combinatorial therapies in herbal medicine, featuring three unique functions: drug prepositioning, customized combinatorial analysis, and biological and pharmacological features. Additionally, transcriptional gene signatures and ADMET properties were also interrogated as interactive functionalities to facilitate combinational analysis. Using Tongxinluo for Stroke as a case study, we identified and validated Oleanolic acid and Ferulic acid as synergistic ingredients. In summary, HerbComb is a versatile data exploration platform designed to characterize synergistic interactions among herbal medicines, enhancing the understanding of synergistic mechanisms and facilitating the discovery of effective drug combinations.

pharmacology and toxicology↗

Dual Inhibition of CDK4/6 and mTORC1 Establishes a Preclinical Strategy for Translocation Renal Cell Carcinoma

PurposeTranslocation renal cell carcinoma (tRCC) is a rare and aggressive subtype of kidney cancer driven by an oncogenic fusion involving a transcription factor in the MiT/TFE gene family, most commonly TFE3. Treatment of tRCC currently lacks a clear standard of care, underscoring the pressing need to nominate new therapeutic targets with mechanistic rationale in this cancer. Experimental DesignIn this study, we applied integrative genomic approaches to identify activation of the cyclin-dependent kinase 4/6 (CDK4/6) and mammalian target of rapamycin complex 1 (mTORC1) pathways in tRCC. We tested the activity of CDK4/6 inhibitors (CDK4/6i), alone or in combination with mTORC1-selective inhibition, using in vitro and in vivo models of tRCC. ResultstRCC tumors displayed multiple genomic and transcriptional features associated with activation of the CDK4/6 and mTORC1 signaling pathways. Genetic or pharmacologic inhibition of CDK4/6 suppressed tRCC cell growth and induced cell cycle arrest in vitro but was not cytotoxic, with rapid cell regrowth observed after drug withdrawal. The mTORC1-selective inhibitor, RMC-5552, potently reduced translation of Cyclin D1, which complexes with CDK4/6 proteins to regulate G1-S cell cycle progression. Combined treatment with the CDK4/6 inhibitor, palbociclib, and RMC-5552 resulted in synergistic suppression of tRCC cell viability and increased markers of apoptosis in vitro. The combination of palbociclib and RMC-5552 in a tRCC xenograft model showed greater eOicacy than either single agent while also being well-tolerated. ConclusionsOur study indicates the therapeutic potential of combined CDK4/6 and mTORC1 inhibition in tRCC, providing the rationale for further clinical evaluation of this strategy. Translational RelevanceTranslocation renal cell carcinoma (tRCC) is a rare and aggressive form of kidney cancer that accounts for 2-5% of all RCCs in adults and around 50% of RCCs in children. tRCC lacks effective therapies and represents a significant unmet clinical need. Therapies approved for clear cell RCC (ccRCC), including VEGF/multikinase inhibitors and immune checkpoint blockade, typically show decreased efficacy in tRCC. Via an integrative genomic analysis, we nominate combined inhibition of the cyclin-dependent kinase 4/6 (CDK4/6) and mammalian target of rapamycin complex 1 (mTORC1) pathways in tRCC. We demonstrate that combining the CDK4/6 inhibitor palbociclib with the mTORC1-selective inhibitor RMC-5552 synergistically inhibits the growth of tRCC cells in vitro and of tRCC xenografts in vivo, where the combination is well-tolerated. This proof-of-concept study provides preclinical evidence supporting CDK4/6 inhibitor-based combination regimens tailored to tRCC biology, offering a foundation for future clinical studies in tRCC, which currently has no clear standard of care.

cancer biology↗

Multiplicative couplings facilitate rapid learning and information gating in recurrent neural networks

The mammalian forebrain is the seat of higher cognition with architectural parallels to modern machine learning systems. Specifically, the cortex resembles recurrent neural networks (RNNs) while the thalamus resembles feedforward neural networks (FNNs). How such architectural features endow the forebrain with its learning capacity, is unknown. Here we take inspiration from empirical thalamocortical discovery and develop a multiplicative coupling mechanism between RNN-FNN architectures that collectively enhance their computational strengths and learning. The multiplicative interaction imposes a Hebbian-weight amplification onto synaptic-neuronal coupling, enabling context-dependent gating and rapid switching. We demonstrate that multiplicative feedback-driven synaptic plasticity achieves 2-100 folds of speed improvement in supervised, reinforcement and unsupervised learning settings, boosting memory capacity, model robustness and generalization of RNNs. We further demonstrate the efficacy and biological plausibility of multiplicative gating in modeling multiregional circuits, including a prefrontal cortex-mediodorsal thalamus network for context-dependent decision making, a cortico-thalamic-cortical network for working memory and attention, and an entorhinal cortex-hippocampus network for visuospatial navigation and sequence replay. Taken together, our results demonstrate the profound insights into neuroscience-inspired computation that enable multi-plastic attractor dynamics and computation in recurrent neural circuits.

neuroscience↗

Antimicrobial Loaded Graft-Copolymer Nanoparticles for Treatment of Pseudomonas aeruginosa Infections

Nearly 80% of cystic fibrosis patients are affected by persistent lung infections, with Pseudomonas aeruginosa being one of the major culprits. Treatment of P. aeruginosa is further complicated by its ability to form biofilms. Anionic compounds within the biofilm and thick cystic fibrosis mucus interact with cationic antimicrobials, hindering treatment efficacy. In this study, we investigated the treatment of lung infections by delivering antimicrobials via polyelectrolyte surfactants that are composed of an anionic poly(alkylacrylic acid) backbone with grafted polyetheramine pendent chains. When combined with cationic antimicrobials, they self-assemble into nanoparticles via electrostatic interactions. We assessed the role of backbone chemistry and graft density on nanoparticle physical properties and evaluated the antimicrobial activity of these formulations against planktonic and biofilm cultures of P. aeruginosa strains derived from clinical isolates. All synthesized polyelectrolyte surfactants demonstrated high levels of antimicrobial encapsulation, with the extent of drug bound corresponding to the calculated hydrophilic-lipophilic balance values. We observed significantly increased antimicrobial activity against planktonic cultures using nanoformulations containing one of the polyelectrolyte surfactants, PMAA-g-10%J. In contrast, all tested nanoformulations retained, but did not increase, activity against biofilms. By monitoring membrane potentials and nanoparticle uptake, it was found that the nanoparticles directly associate with the bacterial cell membranes, which may enhance drug delivery and underlie the improved activity against the planktonic bacteria. In conclusion, we provide a proof of concept for the design of polyelectrolyte surfactants for the nanoencapsulation and delivery of cationic drug cargoes against P. aeruginosa infections.

bioengineering↗