Biology subjects

Wang, R.

Publications and source records attributed to Wang, R..

At least 217 records · Page 12Linked to original sources

bioRxiv2024

Parvalbumin interneuron ErbB4 controls ongoing network oscillations and olfactory behaviors in mice

Parvalbumin (PV)-positive interneurons modulate the processing of odour information. However, little is known about how PV interneurons dynamically remodel neural circuit responses in the olfactory bulb (OB) and their physiological significance. This study showed that a reinforced odour-discrimination task upregulated ErbB4 kinase activity in the mouse OB. ErbB4 knockout in the OB impaired the dishabituation of odour responses and discrimination of complex odours, whereas odour memory or adaptation was not altered in mice. ErbB4-positive neurones were localised throughout the OB, whereas ErbB4 was largely expressed in PV-positive interneurons within the internal and external plexiform layers. Similarly, ErbB4 ablation in PV interneurons disrupted olfactory discrimination and dishabituation in mice. ErbB4 knockout in PV interneurons disrupted the odour-evoked responses of mitral/tufted cells and increased the power of the ongoing local field potential in awake mice. We also observed a decrease in the frequency of miniature inhibitory postsynaptic currents and deficits in stimulus-evoked recurrent and lateral inhibition of mitral cells following PV-ErbB4 loss, suggesting a broad impairment in inhibitory microcircuits. These findings demonstrate that PV-ErbB4 signalling regulates inhibitory microcircuit activity, ongoing oscillations, and OB output, which underlie normal olfactory behaviour.

neuroscience↗

bioRxiv2024

A Ketogenic Diet Sensitizes Pancreatic Cancer to Inhibition of Glutamine Metabolism

Pancreatic cancer is the third leading cause of cancer death in the United States, and while conventional chemotherapy remains the standard treatment, responses are poor. Safe and alternative therapeutic strategies are urgently needed1. A ketogenic diet has been shown to have anti-tumor effects across diverse cancer types but will unlikely have a significant effect alone. However, the diet shifts metabolism in tumors to create new vulnerabilities that can be targeted (1). Modulators of glutamine metabolism have shown promise in pre-clinical models but have failed to have a marked impact against cancer in the clinic. We show that a ketogenic diet increases TCA and glutamine-associated metabolites in murine pancreatic cancer models and under metabolic conditions that simulate a ketogenic diet in vitro. The metabolic shift leads to increased reliance on glutamine-mediated anaplerosis to compensate for low glucose abundance associated with a ketogenic diet. As a result, glutamine metabolism inhibitors, such as DON and CB839 in combination with a ketogenic diet had robust anti-cancer effects. These findings provide rationale to study the use of a ketogenic diet with glutamine targeted therapies in a clinical context. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=186 SRC="FIGDIR/small/604377v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1ebeefforg.highwire.dtl.DTLVardef@97e2ceorg.highwire.dtl.DTLVardef@1ab45c3org.highwire.dtl.DTLVardef@1713540_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical Abstract Description: Mechanistic rationale for combining a ketogenic diet and glutamine metabolism inhibitors. The combination of low glucose from a ketogenic diet and pharmacologic glutamine inhibition impairs nutrient input to mitochondria, reducing cancer growth.

cancer biology↗

bioRxiv2024

SMYD5 is a ribosomal methyltransferase that catalyzes RPL40 lysine methylation to enhance translation output and promote hepatocellular carcinoma

While lysine methylation is well-known for regulating gene expression transcriptionally, its implications in translation have been largely uncharted. Trimethylation at lysine 22 (K22me3) on RPL40, a core ribosomal protein located in the GTPase activation center (GAC), was first reported 27 years ago. Yet, its methyltransferase and role in translation remain unexplored. Here, we report that SMYD5 has robust in vitro activity toward RPL40 K22 and primarily catalyzes RPL40 K22me3 in cells. The loss of SMYD5 and RPL40 K22me3 leads to reduced translation output and disturbed elongation as evidenced by increased ribosome collisions. SMYD5 and RPL40 K22me3 are upregulated in hepatocellular carcinoma (HCC) and negatively correlated with patient prognosis. Depleting SMYD5 renders HCC cells hypersensitivity to mTOR inhibition in both 2D and 3D cultures. Additionally, the loss of SMYD5 markedly inhibits HCC development and growth in both genetically engineered mouse (GEM) and patient-derived xenograft (PDX) models, with the inhibitory effect in the PDX model further enhanced by concurrent mTOR suppression. Our findings reveal a novel role of the SMYD5 and RPL40 K22me3 axis in translation elongation and highlight the therapeutic potential of targeting SMYD5 in HCC, particularly with concurrent mTOR inhibition. This work also broadens the understanding of lysine methylation, extending its significance from transcriptional regulation to translational control.

cancer biology↗

bioRxiv2024

Trait anxiety impairs reciprocity behavior: A multi-modal and computational modeling study

Anxiety significantly impacts reciprocal behavior, crucial for positive social interactions. The neurocomputational mechanisms of anxietys effects on the core (individual propensity) and peripheral (decision context) factors shaping reciprocity remain unclear. Here, we investigated reciprocity in individuals with low and high trait anxiety using a binary trust game with gain/loss framing, combining computational modeling, eye-tracking, and event-related potentials (ERPs). Our computational model, validated by eye-tracking data, identified four psychological components driving reciprocal behavior: reward, guilt aversion, superiority aversion, and superiority attraction. Regarding the core of reciprocity, trait anxiety diminished both overall reciprocity and specific psychological components like guilt aversion and superiority attraction, irrespective of context. The reduction in guilt aversion was supported by ERP findings showing decreased P2 (selective attention) and increased LPP (emotion regulation) amplitudes in anxious individuals. Regarding the periphery of reciprocity, trait anxiety altered the contextual perception of both superiority aversion and reward. Further, trait anxiety reversed the perception of superiority aversion from gain to loss contexts, a pattern that was linked to the N2 amplitudes (cognitive control). Our findings revealed distinct effects of trait anxiety on core and peripheral factors in reciprocity, offering potential targets for interventions aimed at improving reciprocity in individuals with anxiety disorders.

neuroscience↗

bioRxiv2024

Constructing Ensemble Gene Functional Networks Capturing Tissue/condition-specific Co-expression from Unlabled Transcriptomic Data with TEA-GCN

Gene co-expression networks (GCNs) can reveal useful gene co-functional and co-regulatory relationships. However, current GCN construction methodologies are sensitive to batch effects and sample composition, limiting their performance in generating GCNs from public RNA-seq samples abundant for many species. Here, we detail the development of TEA-GCN (Two-Tier Ensemble Aggregation-GCN), a GCN construction method that leverages unsupervised transcriptomic dataset partitioning and multi-metric co-expression scoring to derive ensemble gene co-expression. Benchmarking over 450,000 public RNA-seq samples across 12 species, TEA-GCN outperforms the state-of-the-art in predicting gene functions and inferring gene regulatory networks. Through the use of natural language processing, we also show that the biologically-relevant dataset partitions with high co-expression can identify tissue-/condition-specific co-expression in TEA-GCN, providing an unprecedented level of explainability. Furthermore, we show that TEA-GCNs exhibit enhanced conservation across species, making them suitable for multi-species comparative studies. TEA-GCN is available at https://github.com/pengkenlim/TEA-GCN.

systems biology↗

bioRxiv2024

DREAMER: Exploring Common Mechanisms of Adverse Drug Reactions and Disease Phenotypes through Network-Based Analysis

Adverse drug reactions (ADRs) are a major concern in clinical healthcare, significantly affecting patient safety and drug development. The need for a deeper understanding of ADR mechanisms is crucial for improving drug safety profiles in drug design and drug repurposing. This study introduces DREAMER (Drug adverse REAction Mechanism ExplaineR), a novel network-based method for exploring the mechanisms underlying adverse drug reactions and disease phenotypes at a molecular level by leveraging a comprehensive knowledge graph obtained from various datasets. By considering drugs and diseases that cause similar phenotypes, and investigating their commonalities regarding their impact on specific modules of the protein-protein interaction network, DREAMER can robustly identify protein sets associated with the biological mechanisms underlying ADRs and unravel the causal relationships that contribute to the observed clinical outcomes. Applying DREAMER to 649 ADRs, we identified proteins associated with the mechanism of action for 67 ADRs across multiple organ systems, e.g., ventricular arrhythmia, metabolic acidosis, and interstitial pneumonitis. In particular, DREAMER highlights the importance of GABAergic signaling and proteins of the coagulation pathways for personality disorders and intracranial hemorrhage, respectively. We further demonstrate the application of DREAMER in drug repurposing and propose sotalol (targeting KCNH2), ranolazine (targeting SCN5A, currently under clinical trial), and diltiazem (indicated drug targeting CACNA1C and SCN3A) as candidate drugs to be repurposed for cardiac arrest. In summary, DREAMER effectively detects molecular mechanisms underlying phenotypes emphasizing the importance of network-based analyses with integrative data for enhancing drug safety and accelerating the discovery of novel therapeutic strategies.

systems biology↗

bioRxiv2024

Molecular basis of FIGNL1 in dissociating RAD51 from DNA and chromatin

Maintaining genome integrity is an essential and challenging process. RAD51 recombinase, the central player of several crucial processes in repairing and protecting genome integrity, forms filaments on DNA. RAD51 filaments are tightly regulated. One of these regulators is FIGNL1, that prevents persistent RAD51 foci post-damage and genotoxic chromatin association in cells. The cryogenic electron microscopy structure of FIGNL1 in complex with RAD51 reveals that the FIGNL1 forms a non-planar hexamer and RAD51 N-terminus is enclosed in the FIGNL1 hexamer pore. Mutations in pore loop or catalytic residues of FIGNL1 render it defective in filament disassembly and are lethal in mouse embryonic stem cells. Our study reveals a unique mechanism for removing RAD51 from DNA and provides the molecular basis for FIGNL1 in maintaining genome stability.

biochemistry↗

bioRxiv2024

Dynamics and Regulatory Roles of RNA m6A Methylation in Unbalanced Genomes

N6-methyladenosine (m6A) in eukaryotic RNA is an epigenetic modification that is critical for RNA metabolism, gene expression regulation, and the development of organisms. Aberrant expression of m6A components appears in a variety of human diseases. RNA m6A modification in Drosophila has proven to be involved in sex determination regulated by Sxl and may affect X chromosome expression through the MSL complex. The dosage-related effects under the condition of genomic imbalance (i.e., aneuploidy) are related to various epigenetic regulatory mechanisms. Here, we investigated the roles of RNA m6A modification in unbalanced genomes using aneuploid Drosophila. The results showed that the expression of m6A components changed significantly under genomic imbalance, and affected the abundance and genome-wide distribution of m6A, which may be related to the developmental abnormalities of aneuploids. The relationships between methylation status and classical dosage effect, dosage compensation, and inverse dosage effect were also studied. In addition, we demonstrated that RNA m6A methylation may affect dosage-dependent gene regulation through dosage-sensitive modifiers, alternative splicing, the MSL complex, and other processes. More interestingly, there seems to be a closely relationship between MSL complex and RNA m6A modification. It is found that ectopically overexpressed MSL complex, especially the levels of H4K16Ac through MOF could influence the expression levels of m6A modification and genomic imbalance may be involved in this interaction. We found that m6A could affect the levels of H4K16Ac through MOF, a component of the MSL complex, and that genomic imbalance may be involved in this interaction. Altogether, our work reveals the dynamic and regulatory role of RNA m6A modification in unbalanced genomes, and may shed new light on the mechanisms of aneuploidy-related developmental abnormalities and diseases.

genomics↗

bioRxiv2024

Activity-dependent synthesis of Emerin gates neuronal plasticity by regulating proteostasis

Neurons dynamically regulate their proteome in response to sensory input, a key process underlying experience-dependent plasticity. We characterized the visual experience-dependent nascent proteome within a brief, defined time window after stimulation using an optimized metabolic labeling approach. Visual experience induced cell type-specific and age-dependent alterations in the nascent proteome, including proteostasis-related processes. We identified Emerin as the top activity-induced candidate plasticity protein and demonstrated that its rapid activity-induced synthesis is transcription-independent. In contrast to its nuclear localization and function in myocytes, activity-induced neuronal Emerin is abundant in the endoplasmic reticulum and broadly inhibits protein synthesis, including translation regulators and synaptic proteins. Downregulating Emerin shifted the dendritic spine population from predominantly mushroom morphology to filopodia and decreased network connectivity. In mice, decreased Emerin reduced visual response magnitude and impaired visual information processing. Our findings support an experience-dependent feed-forward role for Emerin in temporally gating neuronal plasticity by negatively regulating translation.

neuroscience↗

bioRxiv2024

Transcriptional pathobiology and multi-omics predictors for Parkinson's disease

Early diagnosis and biomarker discovery to bolster the therapeutic pipeline for Parkinsons disease (PD) are urgently needed. In this study, we leverage the large-scale whole-blood total RNA-seq dataset from the Accelerating Medicine Partnership in Parkinsons Disease (AMP PD) program to identify PD-associated RNAs, including both known genes and novel circular RNAs (circRNA) and enhancer RNAs (eRNAs). There were 1,111 significant marker RNAs, including 491 genes, 599 eRNAs, and 21 circRNAs, that were first discovered in the PPMI cohort (FDR < 0.05) and confirmed in the PDBP/BioFIND cohorts (nominal p < 0.05). Functional enrichment analysis showed that the PD-associated genes are involved in neutrophil activation and degranulation, as well as the TNF-alpha signaling pathway. We further compare the PD-associated genes in blood with those in post-mortem brain dopamine neurons in our BRAINcode cohort. 44 genes show significant changes with the same direction in both PD brain neurons and PD blood, including neuroinflammation-associated genes IKBIP, CXCR2, and NFKBIB. Finally, we built a novel multi-omics machine learning model to predict PD diagnosis with high performance (AUC = 0.89), which was superior to previous studies and might aid the decision-making for PD diagnosis in clinical practice. In summary, this study delineates a wide spectrum of the known and novel RNAs linked to PD and are detectable in circulating blood cells in a harmonized, large-scale dataset. It provides a generally useful computational framework for further biomarker development and early disease prediction. Significance statementEarly and accurate diagnosis of Parkinsons disease (PD) is urgently needed. However, biomarkers for early detection of PD are still lacking. Also, the limit of sample size remains one of the main pitfalls of current PD biomarker studies. We employed an analysis of large-scale whole-blood RNA-seq data. By identifying 1,111 significant marker RNAs, we establish a robust foundation for early PD detection, which implicated in neutrophil activation, degranulation, and TNF-alpha signaling, offer unprecedented insights into PD pathogenesis. Our multi-omics machine learning model, boasting an AUC of 0.89, outperforms previous studies, promising a transformative tool for precise PD diagnosis in clinical settings. This study marks a pivotal step toward enhanced biomarker development and early disease prediction.

neuroscience↗

bioRxiv2024

Immunological correlates of protection mediated by a whole organism Cryptococcus neoformans vaccine deficient in chitosan

The global burden of infections due to the pathogenic fungus Cryptococcus is substantial in persons with low CD4+ T cell counts. Previously, we deleted three chitin deacetylase genes from C. neoformans to create a chitosan-deficient, avirulent strain, designated cda1{Delta}2{Delta}3{Delta} which, when used as a vaccine, protected mice from challenge with virulent C. neoformans strain KN99. Here, we explored the immunological basis for protection. Vaccine-mediated protection was maintained in mice lacking B cells or CD8+ T cells. In contrast, protection was lost in mice lacking /{beta} T cells or CD4+ T cells. Moreover, CD4+ T cells from vaccinated mice conferred protection upon adoptive transfer to naive mice. Importantly, while monoclonal antibody-mediated depletion of CD4+ T cells just prior to vaccination resulted in complete loss of protection, significant protection was retained in mice depleted of CD4+ T cells after vaccination, but prior to challenge. Vaccine-mediated protection was lost in mice genetically deficient in IFN{gamma}, TNF, or IL-23p19. A robust influx of leukocytes and IFN{gamma}- and TNF-expressing CD4+ T cells was seen in the lungs of vaccinated and challenged mice. Finally, a higher level of IFN{gamma} production by lung cells stimulated ex vivo correlated with lower fungal burden in the lungs. Thus, while B cells and CD8+ T cells are dispensable, IFN{gamma} and CD4+ T cells have overlapping roles in generating protective immunity prior to cda1{Delta}2{Delta}3{Delta} vaccination. However, once vaccinated, protection becomes less dependent on CD4+ T cells, suggesting a strategy for vaccinating HIV+ persons prior to loss of CD4+ T cells. ImportanceThe fungus Cryptococcus neoformans is responsible for >100,000 deaths annually, mostly in persons with impaired CD4+ T cell function such as AIDS. There are no approved human vaccines. We previously created a genetically engineered avirulent strain of C. neoformans, designated cda1{Delta}2{Delta}3{Delta}. When used as a vaccine, cda1{Delta}2{Delta}3{Delta} protects mice against a subsequent challenge with a virulent C. neoformans strain. Here, we defined components of the immune system responsible for vaccine-mediated protection. We found that while B cells and CD8+ T cells were dispensible, protection was lost in mice genetically deficient in CD4+ T cells, and the cytokines IFN{gamma}, TNF, or IL-23. A robust influx of cytokine-producing CD4+ T cells was seen in the lungs of vaccinated mice following infection. Importantly, protection was retained in mice depleted of CD4+ T cells following vaccination, suggesting a strategy to protect persons who are at risk for future CD4+ T cell dysfunction.

immunology↗

bioRxiv2024

CLCC1 Governs Bilayer Equilibration at the Endoplasmic Reticulum to Maintain Cellular and Systemic Lipid Homeostasis

The intricate orchestration of lipid production, storage, and mobilization is vital for cellular and systemic homeostasis1,2. Dysfunctional plasma lipid control represents the major risk factor for cardio-metabolic diseases, the leading cause of human mortality3,4. Within the cellular landscape, the endoplasmic reticulum (ER) is the central hub of lipid synthesis and secretion, particularly in metabolically active hepatocytes in the liver or enterocytes in the gut5,6. Initially assembled in the ER lumen, lipid-ferrying lipoproteins necessitate the cross-membrane transfer of both neutral and phospho-lipids onto the lumenal apolipoprotein B (APOB), in a poorly-defined process7-10. Here we show that trans-bilayer equilibration of phospholipids, regulated by the ER protein CLCC1, determines lipid partition across the ER membrane and consequently systemic lipid homeostasis. CLCC1 partners with the phospholipid scramblase TMEM41B11,12 to recognize imbalanced bilayers and promote lipid scrambling, thereby licensing lipoprotein biogenesis and the subsequent bulk lipid transport. Strikingly, loss of CLCC1 or TMEM41B leads to the emergence of giant lumenal lipid droplets enclosed by extensively imbalanced ER bilayers, and consequently drastically accelerated pathogenesis of metabolic-dysfunction-associated liver steatohepatitis (MASH). The above results establish phospholipid scrambling at the ER as the lynchpin to maintain a dynamic equilibrium. Considering the requirement of trans-bilayer phospholipid equilibration in numerous biological processes, ranging from catabolic autophagy to viral infection13-16, our study may enable further elucidation of a previously under-appreciated homeostatic control mechanism intrinsic to the ER function in lipid biogenesis and distribution.

cell biology↗

bioRxiv2024

An Infusible Extracellular Matrix Biomaterial Improves Survival in a Model of Severe Systemic Inflammation

Excess systemic inflammation can often be lethal in septic and trauma patients due to onset of multiple organ dysfunction syndrome (MODS). As of right now, there are no effective immunomodulatory therapeutics that can promote survival within this patient population. Pro-regenerative extracellular matrix (ECM) biomaterials have shown success for treatment of local inflammation but have not been fully explored for treating systemic inflammation. Here, we demonstrate efficacy of an intravenously delivered infusible ECM (iECM) material, which promotes increased survival in a murine model of MODS by decreasing systemic mediators of inflammation. Lung and kidney failure are associated with higher mortality in MODS compared to other organ failures, and we demonstrate that iECM localizes primarily to kidney and lung tissues during systemic inflammation induced by endotoxin. iECM successfully lowered vascular permeability within lung tissue and lowered levels of inflammatory cytokine signaling such as IL-6, verified via ELISA and gene expression analyses. We also demonstrated that immune cell infiltration into lung tissue was modulated with iECM treatment, with an increase in neutrophil retention in the lung and decreases in pro-inflammatory macrophage presence. In summation, iECM improves survival from severe systemic inflammation by decreasing the local and systemic inflammatory signaling pathways that contribute to MODS. These results provide a strong rationale for translational studies of iECM treatment in systemic inflammatory syndromes, including sepsis and trauma.

bioengineering↗

bioRxiv2024

Piximi - An Images to Discovery web tool for bioimages and beyond

Deep learning has greatly accelerated research in biological image analysis yet it often requires programming skills and specialized tool installation. Here we present Piximi, a modern, no-programming image analysis tool leveraging deep learning. Implemented as a web application at Piximi.app, Piximi requires no installation and can be accessed by any modern web browser. Its client-only architecture preserves the security of researcher data by running all computation locally. Piximi offers four core modules: a deep learning classifier, an image annotator, measurement modules, and pre-trained deep learning segmentation modules. Piximi is interoperable with existing tools and workflows by supporting import and export of common data and model formats. The intuitive researcher interface and easy access to Piximi allows biological researchers to obtain insights into images within just a few minutes. Piximi aims to bring deep learning-powered image analysis to a broader community by eliminating barriers to entry.

cell biology↗

bioRxiv2024

Amygdala engages non-emotional multi-item working memory maintenance through amygdala-hippocampus interaction

Retaining information in working memory (WM) is an active process that requires neural activity within and between regions. The human amygdala (AMY) and hippocampus (HPC) are known to play crucial roles in WM processing. Although electrophysiological studies have revealed that the HPC supports multi-item maintenance in a load-dependent manner, the characteristics of the AMY and the circuit-level mechanisms underlying AMY-HPC interactions remain largely unexplored. To address this knowledge gap, intracranial EEG recordings from the AMY and HPC in nine epileptic patients were employed to evaluate intraregional neural representations and interregional communications during maintenance under different non-emotional WM loads. High load enhanced low-frequency power and intraregional theta-gamma phase-amplitude coupling (PAC) in the AMY and HPC. At the network level, a high load elicited an increase in the strength of the HPC theta phase modulation, which entrains the AMY gamma amplitude. Furthermore, a high load increased AMY-anterior HPC (aHPC) theta phase synchrony and directional connectivity strength from the aHPC to the AMY. Conversely, posterior HPC (pHPC)-AMY synchrony was not affected by load variations. Overall, these findings highlight the importance of the AMY in non-emotional WM tasks and provide new insights into the neurophysiological basis of AMY-HPC interactions during WM maintenance.

neuroscience↗

bioRxiv2024

Triptolide sensitizes cancer cells to nucleoside DNA methyltransferase inhibitors through inhibition of DCTPP1-mediated cell-intrinsic resistance

While nucleoside DNA methyltransferase inhibitors (DNMTi) such as decitabine and azacitidine are effective in treating myelodysplatic syndrome (MDS)/leukemia, they have had limited utility for the majority of other cancers. Through a chemical library screen, we identified that triptolide, a diterpenoid epoxide from Tripterygium wilfordii, or analogs significantly augmented the epigenetic and anti-cancer effects of decitabine in vitro and in vivo. These effects were attributable to inhibition of DCTPP1-mediated cleavage of 5-aza-deoxycytidine triphosphate, the convergent activated metabolite of nucleoside DNMTi, leading to enhanced drug incorporation into genomic DNA, increased DNMT degradation, enhanced global DNA demethylation and associated transcriptional reprogramming. We show that high DCTPP1 expression was associated with cell-intrinsic resistance to nucleoside DNMTi, and that triptolide and its analogs could overcome this resistance. SIGNIFICANCEWe screened a library of existing drugs to identify those capable of enhancing the anti-cancer effects of the nucleoside DNMTi decitabine. The combination of triptolide and decitabine synergistically inhibited cancer cell growth and survival in vitro, and was highly effective in inhibiting xenograft growth in vivo. Biochemical, genetic and structural biology studies with triptolide and its analogs revealed that this synergy was due to their inhibition of DCTPP1-mediated pyrophosphate cleavage from 5-aza-deoxycytidine triphosphate, the active metabolite of DNMTi. The genomic incorporation and efficacy of decitabine in cancer cell lines were significantly correlated with DCTPP1 expression more so than those of other nucleoside metabolizing genes. Triptolide and its analogs comprise rational adjuncts to nucleoside DNMTi ripe for further pre-clinical/clinical translation. HIGHLIGHTSO_LITriptolide synergistically sensitizes cancer cells to DNMTi in vitro. C_LIO_LITriptolide and decitabine combination shows favorable efficacy and safety in vivo. C_LIO_LISynergy of triptolide and decitabine is mediated through inhibition of DCTPP1. C_LIO_LIHigh DCTPP1 expression confers cell intrinsic resistance to DNMTi. C_LI

cancer biology↗

bioRxiv2024

Improving Cell-type-specific 3D Genome Architectures Prediction Leveraging Graph Neural Networks

The mammalian genome organizes into complex three-dimensional structures, where interactions among chromatin regulatory elements play a pivotal role in mediating biological functions, highlighting the significance of genomic region interactions in biological research. Traditional biological sequencing techniques like HiC and MicroC, commonly employed to estimate these interactions, are resource-intensive and time-consuming, especially given the vast array of cell lines and tissues involved. With the advent of advanced machine learning (ML) methodologies, there has been a push towards developing ML models to predict genomic interactions. However, while these models excel in predicting interactions for cell lines similar to their training data, they often fail to generalize across distantly related cell lines or accurately predict interactions specific to certain cell lines. Identifying the potential oversight of excluding example genomic region interaction information from model inputs as a fundamental limitation, this paper introduces GRACHIP, a model rooted in graph neural network technology aiming to address this issue by incorporating detailed interaction information as a hint. Through extensive testing across various cell lines, GRACHIP not only demonstrates exceptional accuracy in predicting chromatin interaction intensity but showcases remarkable generalizability to cell lines not encountered during training. Consequently, GRACHIP emerges as a potent research tool, offering a viable alternative to conventional sequencing methods for analyzing the interactions and three-dimensional organization of mammalian genomes, thus alleviating the dependency on expensive and time-consuming biological sequencing techniques. It also offers an alternative way for researchers to investigate 3D chromatin interactions and simulate their changes in model systems to test their hypotheses.

genomics↗

bioRxiv2024

Dissecting neurofilament tail sequence-phosphorylation-structure relationships with multicomponent reconstituted protein brushes

Neurofilaments (NFs) are multi-subunit, bottlebrush-shaped intermediate filaments abundant in the axonal cytoskeleton, with "bristles" composed of the subunits disordered tail domains. Precisely how the tails variable charge patterns and repetitive phosphorylation sites mediate their conformation within the brush remains an open question in axonal biology. We address this problem by grafting recombinant NF tail protein constructs (NFL, NFM, and NFH) to functionalized substrates, forming phosphorylatable brushes of defined stoichiometry. Atomic force microscopy reveals that NFM-based brushes are highly extended, while brushes incorporating the much larger NFH are surprisingly compact even after multisite phosphorylation. A self-consistent field theory predicts multilayered brush morphologies for NFM and phosphorylated NFH brushes. Further experiments with designed mutants reveal that N-terminal negative charges in NFH repel phosphorylated residues to generate the multilayer morphology and that charge segregation in NFM promotes collapsed conformations, lending new insight into how NF tail sequence features determine protein brush conformation.

biophysics↗