Biology subjects

Yu, X.

Publications and source records attributed to Yu, X..

At least 379 records · Page 21Linked to original sources

bioRxiv2021

Salt-induced first-order structural transition in a DNA-interacting protein

Thermodynamics and structural transitions on protein surfaces remain relatively understudied and poorly understood. Wrapping of DNA on proteins provides a paradigm for studying protein surfaces. We used magnetic tweezers to investigate a prototypical DNA-interacting protein, i.e., the single-stranded DNA binding protein (SSB). SSB binds DNA with distinct binding modes the mechanism of which is still elusive. The measured thermodynamic parameters relevant to the SSB-DNA complex are salt-dependent and discontinuous at the bind-mode transitions. Our data indicate that free SSB undergoes salt-induced first-order structural transitions. The conclusion was supported by the infrared spectroscopy of SSB in salt solutions. Ultrafast infrared spectroscopy further suggests that the transitions are correlated with surface salt bridges. Our work not only unravels a long-standing mystery of the different binding site sizes of SSB, but also would inspire interests in thermodynamics of protein surfaces.

biophysics↗

bioRxiv2021

The PD-L1 and TLR7 dual-targeting nanobody-drug conjugate exerts potent antitumor efficacy by orchestrating innate and adaptive immune responses

A variety of tumors are insensitive to immune checkpoint blockade (ICB) therapy. We propose that ICB therapy alone is insufficient to fully reactivate antitumor T cells, while effective mobilization of antigen-presenting cells (APCs) to assist adaptive immune cell activation can lead to potent antitumor effects with broad responsiveness. The Toll-like receptor 7 (TLR7) agonist SZU-101 we developed can induce the innate immune response against tumors and increase the immunogenicity of tumors. Interestingly, SZU-101-induced upregulation of programmed death ligand 1 (PD-L1) expression in tumor tissues can further enhance the response rate of the PD-L1 antibody. In addition, PD-L1 nanobodies have better solid tumor penetration ability, and because of this ability, they can be used to precisely deliver SZU-101 to tumor tissues. Therefore, a PD-L1 and TLR7 dual-targeting nanobody-drug conjugate (NDC), a novel drug molecule, was developed. We found that TLR7 agonists and PD-L1 nanobodies act synergistically and that NDC treatment reshapes the tumor immune microenvironment, activates both innate and adaptive immune cells, and exerts antitumor effects in both "hot" and "cold" tumors primarily through CD8+ T cells and natural killer (NK) cells. Our data show that a PD-L1 and TLR7 dual-targeting NDC can exhibit potent antitumor efficacy by orchestrating innate and adaptive immune responses and shows good prospects for clinical development. One Sentence SummaryBased on results showing that TLR7 agonists and PD-L1 nanobodies exert synergistic antitumor effects, a PD-L1 and TLR7 dual-targeting nanobody-drug conjugate that we developed shows good prospects for clinical development because it can orchestrate innate and adaptive immune responses, reshape the tumor immune microenvironment, and exert potent antitumor effects against both "hot" and "cold" tumors.

immunology↗

bioRxiv2021

Genome-wide survey of the F-box/Kelch (FBK) members and molecular identification of a novel FBK gene TaAFR in wheat

F-box proteins play critical roles in plant responses to biotic/abiotic stresses. In the present study, a total of 68 wheat F-box/Kelch (TaFBK) gene sequences encoding for 74 proteins were obtained in a genome-wide survey against EnsemblPlants. The 74 TaFBK proteins were divided into 5 categories based on their domain structures. The FBK proteins from wheat, Arabidopsis, and three other cereal species were grouped into 7 clades, and the number of Kelch domains present was their key clustering criterion. Sixty-eight TaFBK genes were unevenly distributed on 21 chromosomes. Most of TaFBKs were predicted to localize in the nucleus and cytoplasm. In silico analysis of a digital PCR revealed that TaFBKs were expressed at multiple developmental stages and tissues, and in response to drought and/or heat stresses. The TaFBK19 gene, a homologous to the Attenuated Far-Red Response (AFR) genes in other plant species, and hence named TaAFR, was selected for further analysis. The gene was isolated from the wheat line TcLr15 and its expression evaluated by quantitative real-time PCR. TaAFR transcripts were primarily detected in wheat leaves, and its expression was found to be regulated by various abiotic and biotic stresses as well as plant signaling hormones. Of particular interest, TaAFR expression was differentially regulated in the compatible vs incompatible wheat leaf rust reaction. Subcellular localization studies showed that TaAFR accumulates in the nucleus and cytoplasm. Three TaAFR-interacting proteins were identified experimentally: Skp1/ASK1-like protein (Skp1), ADP-ribosylation factor 2-like isoform X1 (ARL2) and phenylalanine ammonia-lyase (PAL). Further analysis revealed that the Skp1 protein interacted specifically with the F-box domain of TaAFR, while ARL2 and PAL were recognized by the Kelch domain. The data presented herein provides a solid foundation from which the function and metabolic network of TaAFR and other wheat FBKs can be further explored.

molecular biology↗

bioRxiv2021

Focal fMRI signal enhancement with implantable inductively coupled detectors

Despite extensive efforts to increase the signal-to-noise ratio (SNR) of fMRI images for brain-wide mapping, technical advances of focal brain signal enhancement are lacking, in particular, for animal brain imaging. Emerging studies have combined fMRI with fiber optic-based optogenetics to decipher circuit-specific neuromodulation from meso to macroscales. Acquiring fMRI signal with high spatiotemporal resolution is needed to bridge cross-scale functional dynamics, but SNR of targeted cortical regions is a limiting factor. We have developed a multi-modal fMRI imaging platform with an implanted inductive coil detector. This detector boosts the tSNR of MRI images, showing a 2-3 fold sensitivity gain over conventional coil configuration. In contrast to the cryoprobe or array coils with limited spaces for implanted brain interface, this setup offers a unique advantage to study brain circuit connectivity with optogenetic stimulation and can be further extended to other multi-modal fMRI mapping schemes.

neuroscience↗

bioRxiv2021

Macrophage-derived cholesterol contributes to therapeutic resistance in prostate cancer

Tumor-associated macrophages are key immune cells associated with cancer progression. Here we sought to determine the role of macrophages in castration-resistant prostate cancer (CRPC) using a syngeneic model that reflected the mutational landscape of the disease. A transcriptomic analysis of CRPC tumors following macrophage depletion revealed lower molecular signatures for steroid and bile acid synthesis, indicating potential perturbation of cholesterol metabolism. Since cholesterol is the precursor of the five major classes of steroid hormones, we reasoned that macrophages were regulating androgen biosynthesis within the prostate tumor microenvironment. Indeed, macrophage depletion reduced the levels of androgens within prostate tumors and restricted androgen receptor (AR) nuclear localization in vitro and in vivo. Macrophages were cholesterol rich and had the ability to transfer cholesterol to tumor cells in vitro, and AR nuclear translocation was inhibited by activation of Liver X Receptor (LXR)-{beta}, the master regulator of cholesterol homeostasis. Finally, combining macrophage depletion with androgen deprivation therapy increased survival, supporting the therapeutic potential of targeting macrophages in CRPC.

cancer biology↗

bioRxiv2021

Laminar-specific interhemispheric connectivity mapping with bilateral line-scanning fMRI

Despite extensive studies detecting blood-oxygen-level-dependent (BOLD) fMRI signals across two hemispheres to present cognitive processes in normal and diseased brains, the role of corpus callosum (CC) to mediate interhemispheric functional connectivity remains controversial. Several studies show maintaining low-frequency fluctuation of resting-state (rs)-fMRI signals in homotopic brain areas of acallosal humans and post-callosotomy animals, raising the question: how can we specify the circuit-specific rs-fMRI signal fluctuation from other sources? To address this question, we have developed a bilateral line-scanning fMRI (BiLS) method to detect bilateral laminar BOLD fMRI signals from symmetric cortical regions with high spatial (100 m) and temporal (100 ms) resolution in rodents under anesthesia. In addition to ultra-slow oscillation (0.01-0.02 Hz) patterns across all cortical layers, a layer-specific bilateral coherence pattern was observed with a peak at Layer (L)2/3, where callosal projection neurons are primarily located and reciprocal transcallosal projections are received. In particular, the L2/3-specific coherence pattern showed a peak at 0.05 Hz based on the stimulation paradigm, depending on the interhemispheric CC activation. Meanwhile, the L2/3-specific rs-fMRI coherence was peaked at 0.08-0.1Hz which was independent of the varied ultra-slow oscillation patterns (0.01-0.02 Hz) presumably involved with global neuromodulation. This work provides a unique laminar fMRI mapping scheme to characterize the CC-mediated evoked fMRI and frequency-dependent rs-fMRI responses, presenting crucial evidence to distinguish the circuit-specific fMRI signal fluctuations across two hemispheres. Significance statementLaminar fMRI is a promising method to better understand neuronal circuit contribution to functional connectivity (FC) across cortical layers. Here, we developed a bilateral line-scanning fMRI method, allowing the detection of laminar-specific BOLD-fMRI signals from homologous cortical regions in rodents with high spatial and temporal resolution. Laminar coherence patterns of both evoked and rs-fMRI signals revealed that CC-dependent interhemispheric FC is significantly strong at Layer 2/3, where callosal projection neurons are primarily located. The Layer 2/3-specific rs-fMRI coherence is independent of ultra-slow oscillation based on global neuromodulation, distinguishing the circuit-specific rs-fMRI signal fluctuation from different regulatory sources.

neuroscience↗

bioRxiv2021

Laminar-specific functional connectivity mapping with multi-slice line-scanning fMRI

Laminar BOLD-fMRI has been applied to better depict the neuronal input and output circuitry and functional connectivity across cortical layers by measuring local hemodynamic changes. Despite extensive studies detecting laminar fMRI signals to illustrate the canonical microcircuit, the spatiotemporal characteristics of laminar-specific information flow across different cortical regions remain to be fully investigated in both evoked and resting states. Here, we developed a multi-slice line-scanning fMRI (MS-LS) method to detect laminar fMRI signals in adjacent cortical regions with high spatial (50 {micro}m) and temporal resolution (100 ms) in anesthetized rats. Across different scanning trials, we detected both laminar-specific positive and negative BOLD responses in the surrounding cortical region adjacent to the most activated cortex under evoked condition. Specifically, in contrast to the typical Layer (L) 4 correlation across different regions due to the thalamocortical projections for trials with positive BOLD, a strong correlation pattern specific in L2/3 was detected for the trials with negative BOLD in adjacent regions, which indicate a brain state-dependent laminar-fMRI responses based on cortiocotical interaction from different trials. Also, we acquired the laminar-specific rs-fMRI signals across different cortical regions, of which the high spatiotemporal resolution allows us to estimate lag times based on the maximal cross-correlation of laminar-specific rs-fMRI signals. In contrast to the larger variability of lag times in L1 and 6, robust lag time differences in L2/3, 4, and 5 across multiple cortices represented the low-frequency rs-fMRI signal propagation from the caudal to the rostral slice. In summary, our work provides a unique laminar fMRI mapping scheme to better characterize trial-specific intra- and inter-laminar functional connectivity with MS-LS, presenting layer-specific spatiotemporal variation of both evoked and rs-fMRI signals.

neuroscience↗

bioRxiv2021

Intrinsic cardiac adrenergic cell contributes to septic cardiomyopathy

Occurring independently of cardiac sympathetic nervous system, the intrinsic cardiac adrenergic (ICA) cells have been identified as an important regulator in both of developing and adult cardiac physiological and pathological processes. However, its role in septic cardiomyopathy remains unknown. Herein, we report that lipopolysaccharide (LPS) dose- and time-dependently increased norepinephrine (NE) release from ICA cells, which aggravates myocardial TNF- production and dysfunction. Inhibition of NE synthesis in ICA cells alleviated LPS-elicited cardiac dysfunction as well as TNF- production in Langendorff perfusing hearts. Mechanistically, ICA cell expressed Toll-like receptor 4 (TLR4), activated by LPS, to increase the expression of tyrosine hydroxylase, a key enzyme responsible for NE biosynthesis, via AP-1 binding to its promoter. Surprisingly, LPS-TLR4 signaling triggered no TNF- production in ICA cells due to the elevated Nfkbia and Tnfaip6 expression. In LPS-treated co-culture of ICA cells and cardiomyocytes, the raised NE from ICA cells activated cardiomyocyte {beta}1-adrenergic receptor ({beta}1-AR), driving Ca2+/calmodulin-dependent protein kinase II (CaMKII) to increase the activities of NF-{kappa}B and mitogen-activated protein kinase pathways, which were mimicked by dobutamine. Our findings reveal a cell type-specific TLR4 function triggering NE synthesis, but not TNF- production in inflammatory pathogenesis, and identify ICA cell-derived NE as a paracrine signal in the cross talk among different cardiac cells to enhance myocardial injury during LPS challenge, suggesting that targeting ICA cell-derived NE may be a potential therapeutic strategy for septic cardiomyopathy.

immunology↗

bioRxiv2021

Decoding the brain state-dependent relationship between pupil dynamics and resting state fMRI signal fluctuation

Pupil dynamics serve as a physiological indicator of cognitive processes and arousal states of the brain across a diverse range of behavioral experiments. Pupil diameter changes reflect brain state fluctuations driven by neuromodulatory systems. Resting state fMRI (rs-fMRI) has been used to identify global patterns of neuronal correlation with pupil diameter changes, however, the linkage between distinct brain state-dependent activation patterns of neuromodulatory nuclei with pupil dynamics remains to be explored. Here, we identified four clusters of trials with unique activity patterns related to pupil diameter changes in anesthetized rat brains. Going beyond the typical rs-fMRI correlation analysis with pupil dynamics, we decomposed spatiotemporal patterns of rs-fMRI with principal components analysis (PCA) and characterized the cluster-specific pupil-fMRI relationships by optimizing the PCA component weighting via decoding methods. This work shows that pupil dynamics are tightly coupled with different neuromodulatory centers in different trials, presenting a novel PCA-based decoding method to study the brain state-dependent pupil-fMRI relationship.

neuroscience↗

bioRxiv2021

Aggregation-induced emission dots assisted non-invasive fluorescence hysterography in near-infrared IIb window

Uterine diseases seriously threaten the physical and mental health of women. The main principle, when clinicians adopt examinations, is to achieve efficient diagnosis without negative effect on the physical function including fertility. Hysterography in near-infrared (NIR) IIb window (1500-1700 nm) presents perceptibly enhanced signal to background ratio (SBR) and higher penetration capability compared with those beyond 1000 nm and 1300 nm, but lays down high requirements for the biosafety of fluorophores at the same time. Assisted by the biologically excretable aggregation-induced emission (AIE) dots, non-invasive NIR-IIb fluorescence hysterography visualized typical Y-shaped uteruses, real-time uterine peristalsis or the uterine lesions (mimetic disease statuses in clinic) in mouse models. Significantly, after intrauterine perfusion, the reproductive capacity was unimpaired via fertility assessment and histological analysis. This work could inspire some new ideas for non-invasive clinical diagnosis of uterine diseases and effectively promote the clinical translation of AIE dots.

bioengineering↗

bioRxiv2021

Regulation of NMDA receptor trafficking and gating by activity-dependent CaMKIIα phosphorylation of the GluN2A subunit

NMDAR-dependent Ca2+ influx underpins multiple forms of synaptic plasticity. In the adult forebrain, the majority of synaptic NMDAR currents are mediated by GluN2A-containing NMDARs. These receptors are rapidly inserted into synapses during LTP; however, the underlying molecular mechanisms remain poorly understood. Here we show that GluN2A is phosphorylated at Ser-1459 by CaMKII in response to glycine stimulation that mimics LTP in primary neurons. Phosphorylation of Ser-1459 promotes GluN2A interaction with the SNX27-retromer complex, therefore enhancing the endosomal recycling of NMDARs. Loss of SNX27 or CaMKII function blocks the glycine-induced increase in GluN2A-NMDARs on the neuronal membrane. Interestingly, mutations of Ser-1459, including the rare S1459G human epilepsy variant, prolong decay times of NMDAR-mediated synaptic currents in heterosynapses by increasing the active duration of channel openings. Taken together, these findings not only identify a critical role of Ser-1459 phosphorylation in regulating the function of NMDARs, but also explain how the S1459G epilepsy variant dysregulates NMDAR function.

neuroscience↗

bioRxiv2021

Resolving the graft ischemia-reperfusion injury during liver transplantation at the single cell resolution

Ischemia-reperfusion injury (IRI) remains the major reason for impaired donor graft function and increased mortality post-liver transplantation. The mechanism of IRI involves multiple pathophysiological processes and numerous types of cells. However, a systematic and comprehensive single-cell transcriptional profile of intrahepatic cells during liver transplantation is still unclear. We performed a single-cell transcriptome analysis of 14,313 cells from liver tissues collected from pre-procurement, at the end of preservation and 2 h post-reperfusion. We made detailed annotations of mononuclear phagocyte, endothelial cell, NK/T, B and plasma cell clusters, and we described the dynamic changes of the transcriptome of these clusters during IRI and the interaction between mononuclear phagocyte clusters and other cell clusters. In addition, we found that TNFAIP3 interacting protein 3 (TNIP3), specifically and highly expressed in Kupffer cell clusters post-reperfusion, may have a protective effect on IRI. In summary, our study provides the first dynamic transcriptome map of intrahepatic cell clusters during liver transplantation at single-cell resolution.

cell biology↗

bioRxiv2020

Autonomous sensing the insulin peptide by an olfactory G protein coupled receptor modulates glucose metabolism

Along with functionally intact insulin, diabetes-associated insulin peptides are secreted by {beta} cells(1-3). By screening the expression and functional characterization of olfactory receptors in pancreatic islets, we identified Olfr109 as the receptor to detect insulin peptides. Engagement of one insulin peptide, insB:9-23, with Olfr109 diminished insulin secretion through Gi-cAMP signalling and promoted macrophage proliferation. Remarkably, Olfr109 deficiency alleviated intra-islet inflammatory responses and improved glucose homeostasis in Akita- and HFD-fed mice. We further determined the binding mode between the insB:9-23 and Olfr109. A pepducin-based Olfr109 antagonist improved glucose homeostasis in diabetic and obese mouse models. Collectively, we found that pancreatic {beta} cells use Olfr109 to autonomously detect self-secreted insulin peptides and this detection arrests insulin secretion and crosstalk with macrophages to increase intra-islet inflammation.

physiology↗

bioRxiv2020

Astrocytes amplify cerebral blood flow elevation to sustained cortical activation in the awake mouse

Brain requires increased local cerebral blood flow (CBF) for as long as necessary during neuronal activation to match O2 and glucose supply with demand - termed functional hyperemia. Ca2+ elevation in astrocytes can drive arteriole dilation to increase CBF, yet affirmative evidence for the necessity of astrocytes in functional hyperemia in vivo is lacking. In awake and active mice, we discovered that functional hyperemia is bimodal with a distinct early and late component whereby arteriole dilation progresses as sensory stimulation is sustained. Clamping astrocyte Ca2+ signaling in vivo by expressing a high-affinity plasma membrane Ca2+ ATPase (CalEx) reduces sustained but not brief sensory-evoked arteriole dilation. Reciprocally, elevating astrocyte free Ca2+ using chemogenetics selectively augments sustained but not brief hyperemia. Neither locomotion, arousal, nor changes in neuronal signaling account for the selective effect of astrocyte Ca2+ on the late phase of the CBF response. Antagonizing NMDA-receptors or epoxyeicosatrienoic acid production reduces only the late component of functional hyperemia, leaving brief increases in CBF to sensory stimulation intact. We propose that a fundamental role of astrocyte Ca2+ is to amplify functional hyperemia when neuronal activation is prolonged.

neuroscience↗

bioRxiv2020

Microbial Species Abundance Distributions Guide Human Population Size Estimation from Sewage Metagenomes

The metagenome embedded in urban sewage is an attractive new data source to understand urban ecology and assess human health status at scales beyond a single host. Analyzing the viral fraction of wastewater in the ongoing COVID-19 pandemic has shown the potential of wastewater as aggregated samples for early detection, prevalence monitoring, and variant identification of human diseases in large populations. However, using census-based population size instead of real-time population estimates can mislead the interpretation of data acquired from sewage, hindering assessment of representativeness, inference of prevalence, or comparisons of taxa across sites. Here, we show that taxon abundance and sub-species diversisty in gut-associated microbiomes are new feature space to utilize for human population estimation. Using a population-scale human gut microbiome sample of over 1,100 people, we found that taxon-abundance distributions of gut-associated multi-person microbiomes exhibited generalizable relationships with respect to human population size. Here and throughout this paper, the human population size is essentially the sample size from the wastewater sample. We present a new algorithm, MicrobiomeCensus, for estimating human population size from sewage samples. MicrobiomeCensus harnesses the inter-individual variability in human gut microbiomes and performs maximum likelihood estimation based on simultaneous deviation of multiple taxas relative abundances from their population means. MicrobiomeCensus outperformed generic algorithms in data-driven simulation benchmarks and detected population size differences in field data. New theorems are provided to justify our approach. This research provides a mathematical framework for inferring population sizes in real time from sewage samples, paving the way for more accurate ecological and public health studies utilizing the sewage metagenome. Author summaryWastewater-based epidemiology (WBE) is an emerging field that employs sewage as aggregated samples of human populations. This approach is particularly promising for tracking diseases that can spread asymptomatically in large populations, such as the COVID-19. As a new type of biological data, sewage has its own unique challenges to utilize. While wastewater samples are usually assumed to represent large populations, it is not guaranteed, because of stochasticity in toilet flushes; unlike epidemiological experiments collecting data from individuals, sample size, i.e., the human population size represented by a wastewater sample, is a fundamental yet difficult-to-characterize parameter for sewage samples. Researchers would need to aggregate data from large areas and week-long collection to stabilize data, during which, important spikes in small areas or short time scales may be lost. It also remains challenging to turn viral titers into case prevalences, evaluating representativeness, or comparing measurements across sites/studies. This study provides a framework to estimate human population size from sewage utilizing human gut-associated microorganisms. Through analysis, we demonstrate that variance of taxon abundances and single-nucleotide polymorphism as two variables that change with population size. We provide a new tool MicrobiomeCensus that performs population size estimation from microbial taxon abundances. MicrobiomeCensus outperforms generic algorithms in terms of computational efficiency while at comparable or better accuracy. Using MicrobiomeCensus, we detected population size differences in sewage samples taken in Cambridge, MA, under two sampling approaches, i.e., "grab" or "composite" sampling. This study provides a framework to utilize individual-level microbiomes to learn from sewage, paving the way to prevalence estimation and improved spatio-temporal resolutions in WBE..

bioinformatics↗

bioRxiv2020

Widespread premature transcription termination of Arabidopsis thaliana NLR genes by the spen protein FPA

Genes involved in disease resistance are some of the fastest evolving and most diverse components of genomes. Large numbers of nucleotide-binding, leucine-rich repeat receptor (NLR) genes are found in plant genomes and are required for disease resistance. However, NLRs can trigger autoimmunity, disrupt beneficial microbiota or reduce fitness. It is therefore crucial to understand how NLRs are controlled. Here we show that the RNA-binding protein FPA mediates widespread premature cleavage and polyadenylation of NLR transcripts, thereby controlling their functional expression and impacting immunity. Using long-read Nanopore direct RNA sequencing, we resolved the complexity of NLR transcript processing and gene annotation. Our results uncover a co-transcriptional layer of NLR control with implications for understanding the regulatory and evolutionary dynamics of NLRs in the immune responses of plants.

molecular biology↗

bioRxiv2020

Efficient Inhibition of O-glycan biosynthesis using the hexosamine analog Ac5GalNTGc

There is a critical need to develop small molecule inhibitors of mucin-type O-linked glycosylation. The best known reagent currently is peracetylated benzyl-GalNAc, but it is only effective at millimolar concentrations. This manuscript demonstrates that Ac5GalNTGc, a peracetylated C-2 sulfhydryl substituted GalNAc, fulfills this unmet need. When added to cultured leukocytes, breast and prostate cells, Ac5GalNTGc increased cell surface VVA-binding by ~10-fold, indicating truncation of O-glycan biosynthesis. Cytometry, mass spectrometry and Western blot analysis of HL-60 promyelocytes demonstrate that 50-80M Ac5GalNTGc prevented elaboration of 30-60% of the O-glycans beyond the Tn-antigen (GalNAc1-Ser/Thr) stage. The effect of the compound on N-glycans and glycosphingolipids was small. Glycan inhibition induced by Ac5GalNTGc resulted in 50-80% reduction in leukocyte sialyl-Lewis-X expression, and L-/P-selectin mediated rolling under flow. Ac5GalNTGc was pharmacologically active in mouse. It reduced neutrophil infiltration to sites of inflammation by ~60%. Overall, Ac5GalNTGc may find diverse applications as a potent inhibitor of O-glycosylation.

biochemistry↗

bioRxiv2020

Novel gene-specific translation mechanism of dysregulated, chronic inflammation reveals promising, multifaceted COVID-19 therapeutics

Hyperinflammation and lymphopenia provoked by SARS-CoV-2-activated macrophages contribute to the high mortality of Coronavirus Disease 2019 (COVID-19) patients. Thus, defining host pathways aberrantly activated in patient macrophages is critical for developing effective therapeutics. We discovered that G9a, a histone methyltransferase that is overexpressed in COVID-19 patients with high viral load, activates translation of specific genes that induce hyperinflammation and impairment of T cell function or lymphopenia. This noncanonical, pro-translation activity of G9a contrasts with its canonical epigenetic function. In endotoxin-tolerant (ET) macrophages that mimic conditions which render patients with pre-existing chronic inflammatory diseases vulnerable to severe symptoms, our chemoproteomic approach with a biotinylated inhibitor of G9a identified multiple G9a-associated translation regulatory pathways that were upregulated by SARS-CoV-2 infection. Further, quantitative translatome analysis of ET macrophages treated progressively with the G9a inhibitor profiled G9a-translated proteins that unite the networks associated with viral replication and the SARS-CoV-2-induced host response in severe patients. Accordingly, inhibition of G9a-associated pathways produced multifaceted, systematic effects, namely, restoration of T cell function, mitigation of hyperinflammation, and suppression of viral replication. Importantly, as a host-directed mechanism, this G9a-targeted, combined therapeutics is refractory to emerging antiviral-resistant mutants of SARS-CoV-2, or any virus, that hijacks host responses.

systems biology↗