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Biology subjects

Chen, B.

Publications and source records attributed to Chen, B..

At least 199 records · Page 11Linked to original sources

Hepatic IRE1 Protects Against Septic Cardiac Failure

SUMMARYMetabolic reprogramming in response to infection plays a critical role for septic survival. During a septic episode, the heart heavily relies on hepatic lipid particles to prevent heart damage and failure. Inositol- Requiring Enzyme 1 (IRE1) is the most conserved unfolded protein response (UPR) regulator that governs homeostasis of the endoplasmic reticulum (ER), the major site for lipid synthesis and processing. Here we show that hepatocyte IRE1 is indispensable for protecting against septic mortality in two different rodent models of experimental sepsis. The protective effect of hepatic IRE1 was not attributed to the inflammatory response since hepatic IRE1 deletion did not alter hepatic or systemic cytokine response. However, loss of IRE1 in the liver significantly augmented septic cardiac dysfunction in part due to a skewed immune-metabolic balance. Lipidomic and metabolomic analyses further revealed that loss of IRE1 in the liver compromised adaptive intrahepatic and circulating lipid reprogramming, including VLDL, in response to septic challenge. Furthermore, we identified that the protective effects against septic mortality are mediated by a non-canonical IRE1-dependent mechanism. Together, our study provides the first insight into how a disruption of hepatic ER-mediated lipid metabolic regulation promotes sepsis-associated cardiac immuno-metabolic imbalance.

pathology↗

Molecular cartography uncovers evolutionary and microenvironmental dynamics in sporadic colorectal tumors

Colorectal cancer exhibits dynamic cellular and genetic heterogeneity during progression from precursor lesions toward malignancy. Leveraging spatial molecular information to construct a phylogeographic map of tumor evolution can reveal individualized growth trajectories with diagnostic and therapeutic potential. Integrative analysis of spatial multi-omic data from 31 colorectal specimens revealed simultaneous microenvironmental and clonal alterations as a function of progression. Copy number variation served to re-stratify microsatellite stable and unstable tumors into chromosomally unstable (CIN+) and hypermutated (HM) classes. Phylogeographical maps classified tumors by their evolutionary dynamics, and clonal regions were placed along a global pseudotemporal progression trajectory. Cell-state discovery from a single-cell cohort revealed recurring epithelial gene signatures and infiltrating immune states in spatial transcriptomics. Charting these states along progression pseudotime, we observed a transition to immune exclusion in CIN+ tumors as characterized by a novel gene expression signature comprised of DDR1, TGFBI, PAK4, and DPEP1. We demonstrated how these genes and their protein products are key regulators of extracellular matrix components, are associated with lower cytotoxic immune infiltration, and show prognostic value in external cohorts. Through high-dimensional data integration, this atlas provides insights into co-evolution of tumors and their microenvironments, serving as a resource for stratification and targeted treatment of CRC.

systems biology↗

Bulk RNA-Sequencing of small airway cell cultures from IPF and post-COVID lung fibrosis patients illustrates disease signatures and differential responses to TGF-β1 treatment

IPF is a condition in which an injury to the lung leads to the accumulation of scar tissue. This fibrotic tissue reduces lung compliance and impairs gas exchange. Studies have shown that infection with COVID-19 significantly worsens the clinical outcomes of IPF patients. The exact etiology of IPF is unknown, but recent evidence suggests that the distal small airways, (those having a diameter less than 2 mm in adults), play a role in the early pathogenesis of IPF. TGF-{beta}1 is a main driver of fibrosis in a variety of tissues; the binding of TGF-{beta}1 to its receptor triggers a signaling cascade that results in inflammatory signaling, accumulation of collagen and other components of the extracellular matrix, and immune system activation. This study aimed to investigate possible mechanisms that contribute to worsening lung fibrosis in IPF patients after being diagnosed with COVID-19, with a particular focus on the role of TGF-{beta}1. Small airway cell cultures derived from IPF and post-COVID-19 IPF patient transplant tissues were submitted for RNA-sequencing and differential gene expression analysis. The genetic signatures for each disease state were determined by comparing the differentially expressed genes present in the cells cultured under control conditions to cells cultured with TGF-{beta}1. The genes shared between the culture conditions laid the framework for determining the genetic signatures of each disease. Our data found that genes associated with pulmonary fibrosis appeared to be more highly expressed in the post-COVID fibrosis samples, under both control and TGF-{beta}1-treated conditions. A similar trend was noted for genes involved in the TGF-{beta}1 signaling pathway; the post-COVID fibrosis cell cultures seemed to be more responsive to treatment with TGF-{beta}1. Gene expression analysis, RT-PCR, and immunohistochemistry confirmed increased levels of BMP signaling in the IPF small airway cell cultures. These findings suggest that TGF-{beta}1 signaling in IPF small airway cells could be inhibited by BMP signaling, leading to the differences in genetic signatures between IPF and post-COVID fibrosis.

cell biology↗

Positive coping supports children's emotional wellness: Behavioral evidence and neuroendocrine mechanisms

A positive coping style is recognized as a stable disposition to foster emotional wellness and resilience, enabling an adaptive process of assessing and dealing with environmental challenges. Such an adaptive process is believed to rely on a nuanced interplay of the hippocampal system and the primary stress hormone cortisol activity. As a hallmark of diurnal cortisol rhythm, cortisol awakening response (CAR) is sensitive to upcoming stress and subserves the preparation of the hippocampal system for rapid behavioral adaption. Yet, little is known about how the hippocampal system and CAR contribute to the merit of positive coping on emotional wellness. By two studies, we investigate the effects of positive coping on childrens emotional wellness and CAR, as well as longitudinal changes in hippocampal-neocortical functional systems involved in emotional processing. Behaviorally, positive coping predicted better emotional regulation ability, but lower anxiety and lower response caution in emotional decision-making. At the endocrine and neurocognitive level, positive coping was associated with greater CAR, which further predicted higher connectivity of the hippocampus with ventrolateral prefrontal cortex (vlPFC) and stimulus-sensitive neocortex one year later. Furthermore, CAR mediated an indirect association between positive coping and longitudinal increases in hippocampal-neocortical connectivity. Positive coping and CAR together could account for the maturity of vlPFC through longitudinal changes in hippocampal-neocortical connectivity. Overall, our findings suggest a cognitive-neuroendocrinal framework in which positive coping shapes hippocampal-neocortical maturation via stress hormone response to support emotional wellness. SignificanceThe role of the hippocampal system in regulating stress response is well recognized, but its contribution to emotional well-being is not yet understood. Here we show that the protective effects of positive coping on emotional well-being are contingent on two factors: the cortisol awakening response (CAR), which is sensitive to upcoming stress, and hippocampal development. We found that positive coping practices promoted emotional wellness, enhanced emotional decision-making and increased CAR in young children. Longitudinal neuroimaging analysis revealed that positive coping-related CAR predicted greater hippocampal connectivity with stimulus-sensitive neocortex one year later. Importantly, CAR acted as a mediator of the promotive influence of positive coping on the longitudinal development of hippocampal-neocortical connectivity, which contributed to the maturity of prefrontal control systems. Our findings emphasize the importance of hippocampal-neocortical development in resilient coping and emotional wellness.

neuroscience↗

Antibody-mediated cell entry of SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters host cells by first engaging its cellular receptor angiotensin converting enzyme 2 (ACE2) to induce conformational changes in the virus-encoded spike protein and fusion between the viral and target cell membranes. We report here that certain monoclonal neutralizing antibodies against distinct epitopic regions of the receptor-binding domain of the spike can replace ACE2 to serve as a receptor and efficiently support membrane fusion and viral infectivity. These receptor-like antibodies can function in the form of a complex of their soluble immunoglobulin G with Fc-gamma receptor I, a chimera of their antigen-binding fragment with the transmembrane domain of ACE2 or a membrane-bound B cell receptor, indicating that ACE2 and its specific interactions with the spike protein are dispensable for SARS-CoV-2 entry. These results suggest that antibody responses against SARS-CoV-2 may expand the viral tropism to otherwise nonpermissive cell types; they have important implications for viral transmission and pathogenesis.

microbiology↗

Dihydroxy-Metabolites of Dihomo-gamma-linolenic Acid Drive Ferroptosis- Mediated Neurodegeneration

Even after decades of research, the mechanism of neurodegeneration remains understudied, hindering the discovery of effective treatments for neurodegenerative diseases. Recent reports suggest that ferroptosis could be a novel therapeutic target for neurodegenerative diseases. While polyunsaturated fatty acid (PUFA) plays an important role in neurodegeneration and ferroptosis, how PUFAs may trigger these processes remains largely unknown. PUFA metabolites from cytochrome P450 and epoxide hydrolase metabolic pathways may modulate neurodegeneration. Here, we test the hypothesis that specific PUFAs regulate neurodegeneration through the action of their downstream metabolites by affecting ferroptosis. We find that the PUFA, dihomo gamma linolenic acid (DGLA), specifically induces ferroptosis-mediated neurodegeneration in dopaminergic neurons. Using synthetic chemical probes, targeted metabolomics, and genetic mutants, we show that DGLA triggers neurodegeneration upon conversion to dihydroxyeicosadienoic acid through the action of CYP-EH, representing a new class of lipid metabolite that induces neurodegeneration via ferroptosis.

neuroscience↗

Investigation of a mathematical model describing global cancer growth and treatment: An inhomogeneous model based on the generalized logistic equation

Tumor growth is manifestation of the evolution of a complex system. Researchers have limited scope of modelling studies on specific aspects or stages of the process. It has led to unsatisfactory explanation of clinical observations. We hereby demonstrated that an inhomogeneous model built on the generalized logistic equation could serve better. It was developed to describe the whole process of tumor progression, clinically observed independence of index tumor growth from spread of the disease and growth deceleration during early stage of solid tumors. It was validated by simulating the coexistence of exponential and sigmoidal growth in chronic lymphocytic leukaemia, theories of tumor heterogeneity, as well as by accommodating notions pertaining to tumor treatment and prognosis. We thought therefore it was an interesting and not unjustifiable description of actual tumor growth in human body and hoped it might encourage more researchers to look at tumor modelling from a clinical perspective.

cancer biology↗

Cryo-EM structure of SARS-CoV-2 postfusion spike in membrane

Entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into host cells depends on refolding of the virus-encoded spike protein from a prefusion conformation, metastable after cleavage, to a lower energy, stable postfusion conformation. This transition overcomes kinetic barriers for fusion of viral and target cell membranes. We report here a cryo-EM structure of the intact postfusion spike in a lipid bilayer that represents single-membrane product of the fusion reaction. The structure provides structural definition of the functionally critical membraneinteracting segments, including the fusion peptide and transmembrane anchor. The internal fusion peptide forms a hairpin-like wedge that spans almost the entire lipid bilayer and the transmembrane segment wraps around the fusion peptide at the last stage of membrane fusion. These results advance our understanding of the spike protein in a membrane environment and may guide development of intervention strategies.

biochemistry↗

Quantification of adulterated fox-derived components in meat Products by Drop Digital Polymerase Chain Reaction

There are still large research gaps in the testing standards for non-edible meat-derived components at present. Here we report a novel approach to quantification of adulterated fox-derived components in meat products by drop digital polymerase chain reaction(ddPCR). It was better to identify the adulteration that has been added either inadvertently or deliberately during the process by designing single primers on housekeeping genes. In this paper, the fox meat was used as the experimental materials and the relationship between sample quality and copy number was established by extracting DNA and using DNA concentration as an intermediary. The results of ddPCR showed that both the relationships between meat weight and DNA concentration and between DNA concentration and DNA copy number (C) were nearly linear within the dynamic range. The DNA concentration was utilized as an intermediate value to establish the formulae about the relationship between the original meat weight and DNA copy number: Mfox=0.05C+2.7. The methods feasibility was validated using artificial adulteration of different proportions The establishment of this method provides technical support for relevant regulatory authorities to monitor the adulteration of fox meat.

molecular biology↗

Evaluation of antibody kinetics and durability in health subjects vaccinated with inactivated COVID-19 vaccine (CoronaVac): A cross-sectional and cohort study in Zhejiang, China

BackgroundAlthough inactivated COVID-19 vaccines are proven to be safe and effective in the general population, the dynamic response and duration of antibodies after vaccination in the real world should be further assessed. MethodsWe enrolled 1067 volunteers who had been vaccinated with one or two doses of CoronaVac in Zhejiang Province, China. Another 90 healthy adults without previous vaccinations were recruited and vaccinated with three doses of CoronaVac, 28 days and 6 months apart. Serum samples were collected from multiple timepoints and analyzed for specific IgM/IgG and neutralizing antibodies (NAbs) for immunogenicity evaluation. Antibody responses to the Delta and Omicron variants were measured by pseudovirus-based neutralization tests. ResultsOur results revealed that binding antibody IgM peaked 14-28 days after one dose of CoronaVac, while IgG and NAbs peaked approximately 1 month after the second dose then declined slightly over time. Antibody responses had waned by month 6 after vaccination and became undetectable in the majority of individuals at 12 months. Levels of NAbs to live SARS-CoV-2 were correlated with anti-SARS-CoV-2 IgG and NAbs to pseudovirus, but not IgM. Homologous booster around 6 months after primary vaccination activated anamnestic immunity and raised NAbs 25.5-fold. The NAb inhibition rate subsequently rose to 36.0% for Delta (p=0.03) and 4.3% for Omicron (p=0.004), and the response rate for Omicron rose from 7.9% (7/89) to 17.8% (16/90). ConclusionsTwo doses of CoronaVac vaccine resulted in limited protection over a short duration. The homologous booster slightly increased antibody responses to the Delta and Omicron variants; therefore, the optimization of booster procedures is vital. FundingKey Research and Development Program of Zhejiang Province; Key Program of Health Commission of Zhejiang Province/ Science Foundation of National Health Commission; Major Program of Zhejiang Municipal Natural Science Foundation.

immunology↗

Discovery of aphid-transmitted Rice tiller inhibition virus from native plants through metagenomic sequencing

A major threat to rice production is the disease epidemics caused by insect-borne viruses that emerge and re-emerge with undefined origins. It is well known that some human viruses have zoonotic origins from wild animals. However, it remains unknown whether native plants host new endemic viruses with spillover potential to rice (Oryza sativa) as emerging pathogens. Here, we discovered rice tiller inhibition virus (RTIV), a novel RNA virus species, from colonies of Asian wild rice (O. rufipogon) in a genetic reserve by metagenomic sequencing. We identified the specific aphid vector to transmit RTIV and found RTIV would cause low-tillering disease in rice cultivar after transmission. We further demonstrated that an infectious molecular clone of RTIV initiated systemic infection and causes low-tillering disease in an elite rice variety after Agrobacterium-mediated inoculation or stable plant transformation, and RTIV can also be transmitted from transgenic rice plant through its aphid vector to cause disease. Finally, global transcriptome analysis indicated that RTIV may disturb defense and tillering pathway to cause low tillering disease in rice cultivar. Thus, our results show that new rice viral pathogens can emerge from native habitats, and RTIV, a rare aphid-transmitted rice viral pathogen from native wild rice, can threaten the production of rice cultivar after spillover.

pathology↗

A contamination focused approach for optimizing thesingle-cell RNA-seq experiment

Achieving high data quality in single-cell RNA-seq (scRNA-seq) experiments has always been a significant challenge stemming from minute signal that can be detected in individual cells. Droplet-based scRNA-seq additionally suffers from ambient contamination, comprising nucleic acid materials released by dead cells into the loading buffer and co-encapsulated with real cells, which further washes out real biological signals. Here, we developed quantitative, ambient contamination-based metrics and an associated software package that can both evaluate current datasets and guide new experimental optimizations. We performed a series of experimental optimizations using the inDrops platform to address the mechanical and microfluidic cell encapsulation aspect of an scRNA-seq experiment, with a focus on minimizing ambient contamination. We report improvements that can be achieved via cell fixation, microfluidic loading, microfluidic dilution, and nuclei versus cell preparation; many of these parameters are inaccessible on commercial platforms. We provide insights into previously obscured factors that can affect scRNA-seq data quality and suggest mitigation strategies that can guide future experiments.

genomics↗

HSPB1 facilitates chemoresistance through inhibiting ferroptotic cancer cell death and regulating NF-κB signaling pathway in breast cancer

Chemoresistance is one of the major causes of therapeutic failure and poor prognosis for breast cancer patients, especially for triple-negative breast cancer patients. However, the underlying mechanism remains elusive. Here, we identified novel functional roles of heat shock protein beta-1 (HSPB1), regulating the chemoresistance and ferroptotic cell death in breast cancer. Based on TCGA and GEO databases, HSPB1 expression was upregulated in breast cancer tissues and associated with poor prognosis of breast cancer patients, which was considered as an independent prognostic factor for breast cancer. Functional assays revealed that HSPB1 could promote cancer growth and metastasis in vitro and in vivo. Furthermore, HSPB1 facilitated doxorubicin resistance through protecting breast cancer cells from drug-induced ferroptosis. Mechanistically, HSPB1 could bind with Ik{beta}- and promote its ubiquitination-mediated degradation, leading to increased nuclear translocation and activation of NF-{kappa}B signaling. In addition, HSPB1 overexpression led to enhanced secretion of IL6, which further facilitated breast cancer progression. These findings revealed that HSPB1 upregulation might be a key driver to progression and chemoresistance through regulating ferroptosis in breast cancer, while targeting HSPB1 could be an effective strategy against breast cancer.

cancer biology↗

R-loop editing by DNA cytosine deaminase APOBEC3B determines the activity of estrogen receptor enhancers

Estrogen receptor (ER) activation results in the formation of DNA double strand breaks (DSB), which promote genomic instability and tumour heterogeneity in ER-positive breast cancers. The single-stranded DNA (ssDNA) cytosine deaminase APOBEC3B (A3B) regulates ER activity by inducing DSB at ER enhancers. To delineate how A3B recognises its substrates and unveil the underlying mechanism leading to the formation of ER-induced DSB, we sampled A3B-mediated deamination sites using whole genome sequencing in a human breast cancer cell model lacking base excision repair function. Our genome-wide analysis revealed that C>U conversions carried out by A3B in R-loop structures are processed into DSB in the vicinity of ER promoters or enhancers. A mechanism which required both the processing of A3B-editing sites and R-loops by distinct DNA damage repair mechanisms. In addition, using BioID-enabled mass-spectroscopy proteomics, we identified TDRD3 as a key A3B-binding partner directing the activity of A3B to ER-induced R-loops. This study suggests a function for A3B in sustaining tumour evolution as an adaptive response at the transcriptional and epigenetic level and supports A3B as a promising target to control ER activity in cancer.

cancer biology↗

A human DCC variant causing mirror movement disorder reveals an essential role for the Wave regulatory complex in Netrin/DCC signaling

The axon guidance cue, Netrin-1, signals through its receptor DCC to attract commissural axons to the midline. Pathogenic variants in DCC frequently lead to congenital mirror movements (CMM), but how these variants impact DCC function is largely unknown. Screening of DCC in individuals with CMM recently revealed a novel variant located in a conserved motif in the cytoplasmic tail of DCC that is predicted to bind to a central actin nucleation promoting factor, the WAVE regulatory complex (WRC). Here, we use biochemical and axon guidance assays to show that this CMM-associated DCC variant is pathogenic by disrupting the interaction between DCC and the WRC. This DCC-WRC interaction is evolutionarily conserved and is required for Netrin-1 mediated commissural axon outgrowth and guidance. Together, we identify the WRC as a pivotal component of Netrin-1/DCC signaling and further provide a molecular mechanism explaining how genetic variants in DCC may lead to CMM.

neuroscience↗

Cardiac MAO-A inhibition protects against catecholamine-induced ventricular arrhythmias via enhanced diastolic calcium control

BackgroundPeople with clinical depression exhibit increased risk for cardiac arrhythmias that could be related to differences in catecholamine metabolism. Emerging studies have implicated a pathophysiologic role for monoamine oxidase (MAO-A), which catalyzes catecholamine metabolism in the heart. MAO-A is the pharmacological target of some classes of anti-depressants. Here, we investigated the relationship between MAO-A activity and arrhythmogenesis. Methods & ResultsTriNetX database analysis of adult patients with depression (n=11,533) revealed that MAO inhibitor (MAOI) treatment is associated with significantly lower risk of arrhythmias compared with selective serotonin reuptake inhibitor (SSRI) treatment (16.7% vs 18.6%, p=0.0002). To determine a mechanistic link between MAO activity and arrhythmia, we utilized a genetically modified mouse model with cardiomyocyte-specific MAO-A deficiency (cMAO-Adef). Compared with wild-type (WT) mice, cMAO-Adef mice had a significant reduction in the incidence (38.9% vs. 77.8%, p=0.0409) and duration (55.33 {+/-} 26.21s vs.163.1 {+/-} 56.38s, p=0.0360) of catecholamine stress-induced ventricular tachyarrhythmias (VT). Reduced VT risk and duration were associated with altered cardiomyocyte Ca2+ handling in the cMAO-Adef hearts, including a marked increase in Ca2+ reuptake rate, decreased diastolic Ca2+ levels, decreased SR Ca2+ load and reduced Ca2+ spark activity following catecholamine stimulation relative to WT. Further analysis of molecular mechanisms revealed that altered Ca2+ handling in the cMAO-Adef hearts was related to decreased catecholamine-induced phosphorylation of Ca2+/calmodulin-dependent kinase II (CaMKII) and ryanodine receptor 2 (RyR2), and increased phosphorylation of phospholamban (PLB). ConclusionsThese findings suggest that MAO-A inhibition in cardiomyocytes mitigates arrhythmogenesis via enhanced Ca2+ reuptake that lowers diastolic Ca2+ levels thereby diminishing arrhythmic triggers following catecholamine stimulation. Thus, cardiac MAO-A represents a potential target for antiarrhythmic therapy.

physiology↗

PINK1 supports colorectal cancer growth by regulating the labile iron pool.

Mitophagy is a cargo-specific autophagic process that recycles damaged mitochondria to promote mitochondrial turnover. PTEN-induced putative kinase 1 (PINK1) mediates the canonical mitophagic pathway. We show that PINK1 expression is positively correlated with decreased colon cancer survival, and mitophagy is required for colon cancer growth following nutrient stress. However, the mechanism by which PINK1 maintains colon cancer growth remains equivocal. Inducible knockdown (KD) of PINK1 in a panel of colon cancer cell lines inhibited colon cancer cell proliferation, whereas disruption of other mitophagy receptors did not similarly impact cellular proliferation. Mechanistically, we observed a decrease in mitochondrial respiration, membrane hyperpolarization, accumulation of mitochondrial DNA, and depletion of antioxidant glutathione following PINK1 KD. Mitochondria are important hubs for storing iron and synthesizing iron-dependent cofactors such as heme and iron sulfur clusters. An increase iron storage protein ferritin and a decrease labile iron pool was observed in PINK1 KD cells. However, neither total cellular iron nor markers of iron starvation/overload were affected. Cellular iron storage and the labile iron pool are maintained via autophagic degradation of ferritin (ferritinophagy). Overexpressing nuclear receptor coactivator 4 (NCOA4), a key adaptor for ferritinophagy, rescued cell growth and the labile iron pool in PINK1 KD cells. We demonstrate that PINK1 regulates intracellular iron availability by integrating mitophagy to ferritinophagy. In conclusion, these results indicate that PINK1 is essential for maintaining intracellular iron homeostasis to support survival and growth in colorectal cancer cells.

cancer biology↗

Improve the Protein Complex Prediction with Protein Language Models

AlphaFold-Multimer has greatly improved protein complex structure prediction, but its accuracy also depends on the quality of the multiple sequence alignment (MSA) formed by the interacting homologs (i.e., interologs) of the complex under prediction. Here we propose a novel method, denoted as ESMPair, that can identify interologs of a complex by making use of protein language models (PLMs). We show that ESMPair can generate better interologs than the default MSA generation method in AlphaFold-Multimer. Our method results in better complex structure prediction than AlphaFold-Multimer by a large margin (+10.7% in terms of the Top-5 best DockQ), especially when the predicted complex structures have low confidence. We further show that by combining several MSA generation methods, we may yield even better complex structure prediction accuracy than Alphafold-Multimer (+22% in terms of the Top-5 best DockQ). We systematically analyze the impact factors of our algorithm and find out the diversity of MSA of interologs significantly affects the prediction accuracy. Moreover, we show that ESMPair performs particularly well on complexes in eucaryotes.

bioinformatics↗