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Shen, X.

Publications and source records attributed to Shen, X..

At least 181 records · Page 10Linked to original sources

Generative pretraining from large-scale transcriptomes: Implications for single-cell deciphering and clinical translation

Exponential accumulation of single-cell transcriptomes poses great challenge for efficient assimilation. Here, we present an approach entitled tGPT towards integration of 22.3 million single-cell transcriptomes by modeling gene expression rankings as generative pretraining task. tGPT is conceptually simple in that it autoregressively models the ranking of a gene in the context of its preceding neighbors. We demonstrated the high performance of tGPT on a range of fundamental single-cell analysis tasks and novel applications on bulk tissues. The single-cell clusters and cell lineage trajectories derived from tGPT are highly aligned with known cell labels and states. The feature patterns of tumor bulk tissues learned by tGPT are associated with a wide range of genomic alteration events, prognosis and treatment outcome of immunotherapy. tGPT represents a new analytical paradigm for integrating and deciphering massive amount of transcriptome data and it will facilitate the interpretation and clinical translation of single-cell transcriptomes.

bioinformatics↗

Mapping SARS-CoV-2 antigenic relationships and serological responses

During the SARS-CoV-2 pandemic, multiple variants escaping pre-existing immunity emerged, causing concerns about continued protection. Here, we use antigenic cartography to analyze patterns of cross-reactivity among a panel of 21 variants and 15 groups of human sera obtained following primary infection with 10 different variants or after mRNA-1273 or mRNA-1273.351 vaccination. We find antigenic differences among pre-Omicron variants caused by substitutions at spike protein positions 417, 452, 484, and 501. Quantifying changes in response breadth over time and with additional vaccine doses, our results show the largest increase between 4 weeks and >3 months post-2nd dose. We find changes in immunodominance of different spike regions depending on the variant an individual was first exposed to, with implications for variant risk assessment and vaccine strain selection. One sentence summaryAntigenic Cartography of SARS-CoV-2 variants reveals amino acid substitutions governing immune escape and immunodominance patterns.

immunology↗

Scale Bar of Aging Trajectories for Screening Personal Rejuvenation Treatments

Although aging is an increasingly severe healthy, economic, and social global problem, it is far from well-modeling aging due to the aging processs complexity. To promote the aging modeling, here we did the quantitative measurement based on aging blood transcriptome. Specifically, the aging blood transcriptome landscape was constructed through ensemble modeling in a cohort of 505 people, and 1138 age-related genes were identified. To assess the aging rate in the linear dimension of aging, we constructed a simplified linear aging clock, which distinguished fast-aging and slow-aging populations and showed the differences in the composition of immune cells. Meanwhile, the non-linear dimension of aging revealed the transcriptome fluctuations with a crest around the age of 40 and showed that this crest came earlier and was more vigorous in the fast-aging population. Moreover, the aging clock was applied to evaluate the rejuvenation effect of molecules in vitro, such as Nicotinamide Mononucleotide (NMN) and Metformin. In sum, this study developed a de novo aging clock to evaluate agedependent precise medicine by revealing its fluctuation nature based on comprehensively mining the aging blood transcriptome, promoting the development of personal aging monitoring and anti-aging therapies.

bioengineering↗

ASGR1 is a candidate receptor for SARS-CoV-2 that promotes infection of liver cells

Backgroud & AimsCurrently, the COVID-19 pandemic, caused by SARS-CoV-2 infection, represents a serious public health problem worldwide. Although it has been shown that ACE2 serves as the main receptor for SARS-CoV-2 entry into host cells, studies have shown that ACE2 is expressed at extremely low levels in various tissues, especially in some organs where virus particles have been found, such as the heart and liver. Therefore, these organs potentially express additional SARS-CoV-2 receptors that have not yet been discovered. Methods & ResultsHere, by a genome-wide CRISPR-Cas9 activation library screening, we found that ASGR1 promoted SARS-CoV-2 infection of 293T cells. In Huh-7 and HepG2 cell lines, simultaneous knock out of ACE2 and ASGR1 prevented SARS-CoV-2 pseudovirus infection. In the immortalized THLE-2 hepatocyte cell line and primary liver parenchymal cells, both of which hardly express ACE2, SARS-CoV-2 could successfully establish an infection. After treatment with ASGR1 antibody, the infection rate significantly reduced. This suggests that SARS-CoV-2 infects liver cells mainly through an ASGR1-dependent mechanism. Finally, we also found that the soluble ASGR1 could not only prevent the SARS-CoV-2 pseudovirus, which binds to the ASGR1 receptors, from infecting host liver cells, but also had a protective effect on those expressing ACE2, indicating that administration of soluble ASGR1 protein may represent a new treatment approach. ConclusionsColletively, these findings indicate that ASGR1 is a candidate receptor for SARS-CoV-2 that promotes infection of liver cells. Lay SummaryWe show that ASGR1 is a candidate receptor for SARS-CoV-2 to infect liver cells.

microbiology↗

Allogeneic gene-edited HIV-specific CAR-T cells secreting PD-1 blocking scFv enhance anti-HIV activity in vitro

HIV-specific chimeric antigen receptor (CAR) T cells have been developed to target latently infected CD4+ T cells that express virus either spontaneously or after intentional latency reversal. However, the T-cell exhaustion and the patient-specific autologous paradigm of CAR-T hurdled the clinical application. Here, we created HIV-specific CAR-T cells using human peripheral blood mononuclear cells and a 3BNC117-E27 CAR (3BE CAR) construct that enables the expression of PD-1 blocking scFv E27 and the single-chain variable fragment of the HIV-1-specific broadly neutralizing antibody 3BNC117 to target native HIV envelope glycoprotein (Env). In comparison with T cells expressing 3BNC117-CAR alone, 3BE CAR-T cells showed greater anti-HIV potency with stronger proliferation capability, higher killing efficiency (up to ~75%) and enhanced cytokine secretion in the presence of HIV envelope glycoprotein-expressing cells. Furthermore, our approach achieved high levels (over 97%) of the TCR-deficient 3BE CAR-T cells with the functional inactivation of endogenous TCR to avoid graft-versus-host disease without compromising their antiviral activity relative to standard anti-HIV CAR-T cells. These data suggest that we have provided a feasible approach to large-scale generation of "off-the-shelf" anti-HIV CAR-T cells in combination with antibody therapy of PD-1 blockade, which can be a powerful therapeutic candidate for the functional cure of HIV.

bioengineering↗

Long-lasting germinal center responses to a priming immunization with continuous proliferation and somatic mutation

Germinal centers (GCs) are the engines of antibody evolution. Using HIV Env protein immunogen priming in rhesus monkeys (RM) followed by a long period without further immunization, we demonstrate GC B cells (BGC) lasted at least 6 months (29 weeks), all the while maintaining rapid proliferation. A 186-fold BGC cell increase was present by week 10 compared to a conventional immunization. Single cell transcriptional profiling revealed that both light zone and dark zone GC states were sustained throughout the 6 months. Antibody somatic hypermutation (SHM) of BGC cells continued to accumulate throughout the 29 week priming period, with evidence of selective pressure. Additionally, Env-binding BGC cells were still 49-fold above baseline 29 weeks after immunization, suggesting that they could be active for significantly longer periods of time. High titers of HIV neutralizing antibodies were generated after a single booster immunization. Fully glycosylated HIV trimer protein is a complex antigen, posing significant immunodominance challenges for B cells, among other difficulties. Memory B cells (BMem) generated under these long priming conditions had higher levels of SHM, and both BMem cells and antibodies were more likely to recognize non-immunodominant epitopes. Numerous BGC cell lineage phylogenies spanning the >6-month GC period were identified, demonstrating continuous GC activity and selection for at least 191 days, with no additional antigen exposure. A long prime, adjuvanted, slow delivery (12-day) immunization approach holds promise for difficult vaccine targets, and suggests that patience can have great value for tuning GCs to maximize antibody responses.

immunology↗

Scalable batch-correction method for integrating large-scale single-cell transcriptomes

Integration of the evolving large-scale single-cell transcriptomes requires scalable batch-correction approaches. Here we propose a simple batch-correction method that is scalable for integrating super large-scale single-cell transcriptomes from diverse sources. The core idea of the method is encoding batch information of each cell as a trainable parameter and added to its expression profile; subsequently, a contrastive learning approach is used to learn feature representation of the additive expression profile. We demonstrate the scalability of the proposed method by integrating 18 million cells obtained from the Human Cell Atlas. Our benchmark comparisons with current state-of-the-art single-cell integration methods demonstrated that our method could achieve comparable data alignment and cluster preservation. Our study would facilitate the integration of super large-scale single-cell transcriptomes. The source code is available at https://github.com/xilinshen/Fugue.

bioinformatics↗

Myelin Imaging Using 3D Dual-echo Ultra-short Echo Time MRI with Rosette k-Space Pattern

PurposeThis study aimed to develop a new 3D dual-echo rosette k-space trajectory, specifically for ultra-short echo time (UTE) magnetic resonance imaging (MRI) applications. The direct imaging of the myelin bilayer, which has ultra-short transverse relaxation time (uT2), was acquired to test the performance of the proposed UTE sequence. Theory and MethodsThe rosette trajectory was developed based on rotations of a petal-like pattern in the kx-ky plane, with oscillated extensions in kz-direction for 3D coverage. Five healthy volunteers were recruited and underwent ten dual-echo 3D rosette UTE scans with various echo times (TEs). Dual-exponential complex model fitting was performed on the magnitude data to separate uT2 signals, with the output of uT2 fraction, uT2 value, and long T2 value. ResultsThe reconstructed images signal contrast between whiate matter (WM) and grey matter (GM) increased with longer TEs. The WM regions had higher uT2 fraction values than GM (10.9%{+/-}1.9% vs. 5.7%{+/-}2.4%). The uT2 value was approximately 0.15 milliseconds in WM. ConclusionThe higher uT2 fraction value in WM compared to GM demonstrated the ability of the proposed sequence to capture rapidly decaying signals.

neuroscience↗

Reward enhances memory via age-varying online and offline neural mechanisms across development

Reward motivation enhances memory through interactions between mesolimbic, hippocampal, and cortical systems -- both during and after encoding. Developmental changes in these distributed neural circuits may lead to age-related differences in reward-motivated memory and the underlying neural mechanisms. Converging evidence from cross-species studies suggests that subcortical dopamine signaling is increased during adolescence, which may lead to stronger memory representations of rewarding, relative to mundane, events and changes in the contributions of underlying subcortical and cortical brain mechanisms across age. Here, we used fMRI to examine how reward motivation influences the "online" encoding and "offline" post-encoding brain mechanisms that support long-term associative memory from childhood to adulthood in human participants of both sexes. We found that reward motivation led to both age-invariant enhancements and nonlinear age-related differences in associative memory after 24 hours. Furthermore, reward-related memory benefits were linked to age-varying neural mechanisms. During encoding, interactions between the prefrontal cortex and ventral tegmental area (VTA) were associated with better high-reward memory to a greater degree with increasing age. Pre- to post-encoding changes in functional connectivity between the anterior hippocampus and VTA were also associated with better high-reward memory, but more so at younger ages. Our findings suggest that there may be developmental differences in the contributions of offline subcortical and online cortical brain mechanisms supporting reward-motivated memory. Significance StatementA substantial body of research has examined the neural mechanisms through which reward influences memory formation in adults. However, despite extensive evidence that both reward processing and associative memory undergo dynamic change across development, few studies have examined age-related changes in these processes. We found both age-invariant and nonlinear age-related differences in reward-motivated memory. Moreover, our findings point to developmental differences in the processes through which reward modulates the prioritization of information in long-term memory - with greater early reliance on offline subcortical consolidation mechanisms and increased contribution of systems-level online encoding circuitry with increasing age. These results highlight dynamic developmental changes in the cognitive and neural mechanisms through which motivationally salient information is prioritized in memory from childhood to adulthood.

neuroscience↗

Mapping brain-wide excitatory projectome of primate prefrontal cortex at submicron resolution: relevance to diffusion tractography

Resolving trajectories of axonal pathways in the primate prefrontal cortex remains crucial to gain insights into higher-order processes of cognition and emotion, which requires a comprehensive map of axonal projections linking demarcated subdivisions of prefrontal cortex and the rest of brain. Here we report a mesoscale excitatory projectome issued from the ventrolateral prefrontal cortex (vlPFC) to the entire macaque brain by using viral-based genetic axonal tracing in tandem with high-throughput serial two-photon tomography, which demonstrated prominent monosynaptic projections to other prefrontal areas, temporal, limbic and subcortical areas, relatively weak projections to parietal and insular cortices but no projections directly to the occipital lobe. In a common 3D space, we quantitatively validated an atlas of diffusion tractography-derived vlPFC connections with correlative enhanced green fluorescent protein-labelled axonal tracing, and observed generally good agreement except a major difference in the posterior projections of inferior fronto-occipital fasciculus. These findings raise an intriguing question as to how neural information passes along long-range association fiber bundles in macaque brains, and call for the caution of using diffusion tractography to map the wiring diagram of brain circuits.

neuroscience↗

A TET1-PSPC1-Neat1 molecular axis modulates PRC2 functions in controlling stem cell bivalency

TET1 maintains hypomethylation at bivalent promoters through its catalytic activity in embryonic stem cells (ESCs). However, whether and how TET1 exerts catalytic activity-independent functions in regulating bivalent genes is not well understood. Using a proteomics approach, we mapped the TET1 interactome in mouse ESCs and identified PSPC1 as a novel TET1 partner. Genome-wide location analysis reveals that PSPC1 functionally associates with TET1 and Polycomb repressive complex-2 (PRC2) complex. We establish that PSPC1 and TET1 repress, and Neat1, the PSPC1 cognate lncRNA, activates the bivalent gene expression. In ESCs, Neat1 tethers the TET1-PSPC1 pair with PRC2 at bivalent promoters. During the ESC-to-formative epiblast-like stem cell (EpiLC) transition, PSPC1 and TET1 promote PRC2 chromatin occupancy at bivalent gene promoters while restricting Neat1 functions in facilitating PRC2 binding to bivalent gene transcripts. Our study uncovers a novel TET1-PSPC1-Neat1 molecular axis that modulates PRC2 binding affinity to chromatin and bivalent gene transcripts in controlling stem cell bivalency. In BriefTET1 is a transcriptional repressor for bivalent genes in pluripotent stem cells, but its mechanistic action on stem cell bivalency is unclear. Huang et al. use proteomics and genetic approaches to reveal that catalytic activity-independent functions of TET1, coordinated with the paraspeckle components PSPC1 and its cognate lncRNA Neat1, dynamically regulates stem cell bivalency by modulating PRC2 binding affinity to chromatin and bivalent gene transcripts in pluripotent state transition. HighlightsO_LIThe TET1 interactome identifies PSPC1 as a novel partner in ESCs C_LIO_LITET1 and PSPC1 repress bivalent genes by promoting PRC2 chromatin occupancy C_LIO_LINeat1 facilitates bivalent gene activation by promoting PRC2 binding to their mRNAs C_LIO_LINeat1 bridges the TET1-PSPC1 and PRC2 complexes in regulating bivalent gene transcription C_LI

developmental biology↗

A universal approach for integrating super large-scale single-cell transcriptomes by exploring gene rankings

Advancement in single-cell RNA sequencing leads to exponential accumulation of single-cell expression data. However, there is still lack of tools that could integrate these unlimited accumulation of single-cell expression data. Here, we presented a universal approach iSEEEK for integrating super large-scale single-cell expression via exploring expression rankings of top-expressing genes. We developed iSEEEK with 13.7 million single-cells. We demonstrated the efficiency of iSEEEK with canonical single-cell downstream tasks on five heterogenous datasets encompassing human and mouse samples. iSEEEK achieved good clustering performance benchmarked against well-annotated cell labels. In addition, iSEEEK could transfer its knowledge learned from large-scale expression data on new dataset that was not involved in its development. iSEEEK enables identification of gene-gene interaction networks that are characteristic of specific cell types. Our study presents a simple and yet effective method to integrate super large-scale single-cell transcriptomes and would facilitate translational single-cell research from bench to bedside.

bioinformatics↗

Perinatal maternal chronic exposure to dibutyl phthalate promotes visceral obesity in adult female offspring

IntroductionMaternal exposure to dibutyl phthalate (DBP) may result in glucolipid dysfunction in female offspring. However, the underlying mechanisms remain elusive. We hypothesized that chronic maternal DBP exposure could induce abnormal metabolism of glucolipid. Materials and methodsSprague-Dawley rats were intraperitoneally injected with different doses of DBP, estradiol, and corn oil from gestational day 7 until the end of lactation. The weights, visceral fat percentage, serum lipid, insulin and glucose, protein levels of PI3K signal pathway in muscle were detected in F1 female offspring. ResultsAlthough the birth weight of F1 female offspring was not different among groups, the weights were heavier in DBP groups from postnatal day 7 to adult (P<0.001). The visceral adipose percentage in adult female offspring was increased by perinatal exposure to DBP (P<0.001). Decreased serum levels of triglyceride (P<0.0001), fasting glucose (P=0.004), prolactin (P=0.006), HOMA-IR (P=0.014) were found in female offspring exposed to DBP, but no difference for fasting insulin, total cholesterol, adiponectin. Increased protein levels of p-AKT, but decreased PTEN and GPR30 were observed in muscle of female offspring in DBP group, but without significant difference. None difference was observed for the protein levels of PI3K, AKT, GLUT4, InsR and IRS-1. ConclusionMaternal perinatal exposure to DBP induced obesity and accumulation of visceral adipose tissue for the adult female offspring. Serum glucolipid and local signal transduction of PTEN/PI3K/AKT pathway in muscle were not adversely affected by perinatal exposure to DBP for adult female offspring.

pharmacology and toxicology↗

Changes at V2 apex of HIV-1 Clade C trimer enhance elicitation of autologous neutralizing and broad V1V2-scaffold antibodies

HIV-1 clade C envelope immunogens that elicit both neutralizing and non-neutralizing V1V2-scaffold specific antibodies (protective correlates from RV144 human trial) are urgently needed due to the prevalence of this clade in the most impacted regions worldwide. To achieve this, we introduced structure-guided changes followed by consensus-C sequence-guided optimizations at the V2-region to generate UFO-v2-RQH173 trimer. This improved the abundance of native-like trimers and carried an intrinsic dynamic V2-loop. Following immunization of rabbits, the wild-type protein failed to elicit any autologous neutralizing antibodies but UFO-v2-RQH173 elicited both autologous neutralizing and broad V1V2-scaffold antibodies. The variant with 173Y modification in V2-region, most prevalent among HIV-1 sequences, showed decreased ability in displaying native-like V1V2 epitope with time in-vitro and elicited antibodies with lower neutralizing and higher V1V2-scaffold activities. Our results identify a clade C C.1086-UFO-v2-RQH173 trimer capable of eliciting improved neutralizing and V1V2-scaffold antibodies, and reveal the importance of V2-region in tuning this.

immunology↗

Integration and comparison of multi-omics profiles of NGLY1 deficiency plasma and cellular models to identify clinically relevant molecular phenotypes

NGLY1 (N-glycanase 1) deficiency is a rare congenital recessive disorder of protein deglycosylation unaddressed by the current standard of care. Using combined metabolomics and proteomics profiling, we show that NGLY1 deficiency activates the immune response and disturbs lipid metabolism, biogenic amine synthesis, and glutathione metabolism. These alterations were also observed in NGLY1 deficient patient-derived induced pluripotent stem cells (iPSCs) and differentiated neural progenitor cells (NPCs), which serve as personalized cellular models of the disease. These findings provide molecular insight into the pathophysiology of NGLY1 deficiency and suggest potential therapeutic strategies.

systems biology↗

HIV-1 Nef and CycK:CDK13 antagonize SERINC5 for optimal viral infectivity

HIV-1 Nef antagonizes SERINC5 by redirecting this potent restriction factor to the endosomes and lysosomes for degradation. However, the precise mechanism remains unclear. Using affinity purification/mass spectrometry, we identified cyclin K and cyclin-dependent kinase 13 (CycK:CDK13) as a new Nef-associated kinase complex. CycK:CDK13 phosphorylates the serine at position 360 (S360) in SERINC5, which is required for Nef downregulation of SERINC5 from the cell surface and its counter activity of the SERINC5 antiviral activity. To understand the role of S360 phosphorylation, we created chimeric proteins between CD8 and SERINC5. Nef not only downregulates, but importantly, also binds to this chimera in a S360-dependent manner. Thus, S360 phosphorylation increases interactions between Nef and SERINC5 and initiates the destruction of SERINC5 by the endocytic machinery.

microbiology↗

Multi-omics characterization of mesenchymal stem/stromal cells for the identification of putative critical quality attributes

BackgroundMesenchymal stromal cells (MSCs) have shown great promise in the field of regenerative medicine as many studies have shown that MSCs possess immunomodulatory function. Despite this promise, no MSC therapies have been granted licensure from the FDA. This lack of successful clinical translation is due in part to MSC heterogeneity and a lack of critical quality attributes (CQAs). While MSC Indoleamine 2,3-dioxygnease (IDO) activity has been shown to correlate with MSC function, multiple CQAs may be needed to better predict MSC function. MethodsThree MSC lines (two bone marrow, one iPSC) were expanded to three passages. At the time of harvest for each passage, cell pellets were collected for nuclear magnetic resonance (NMR) and ultra-performance liquid chromatography mass spectrometry (UPLC-MS), and media was collected for cytokine profiling. Harvested cells were also cryopreserved for assessing function using T cell proliferation and IDO activity assays. Linear regression was performed on functional and multiomics data to reduce the number of important features, and partial least squares regression (PLSR) was used to obtain putative CQAs based on variable importance in projection (VIP) scores. ResultsSignificant functional heterogeneity (in terms of T cell suppression and IDO activity) was observed between the three MSC lines, as well as donor-dependent differences based on passage. Omics characterization revealed distinct differences between cell lines using principal component analysis (PCA). Cell lines separated along principal component 1 based on tissue source (bone marrow vs. iPSC-derived) for NMR, MS, and cytokine profiles. PLSR modeling of important features predicts MSC functional capacity with NMR (R2=0.86), MS (R2=0.83), cytokines (R2=0.70), and a combination of all features (R2=0.88). DiscussionThe work described here provides a platform for identifying putative CQAs for predicting MSC functional capacity using PLSR modeling that could be used as release criteria and guide future manufacturing strategies for MSCs and other cell therapies.

bioengineering↗

metID: A R package for automatable compound annotation for LC-MS-based data

SummaryAccurate and efficient compound annotation is a long-standing challenge for LC-MS-based data (e.g. untargeted metabolomics and exposomics). Substantial efforts have been devoted to overcoming this obstacle, whereas current tools are limited by the sources of spectral information used (in-house and public databases) and are not automated and streamlined. Therefore, we developed metID, an R package that combines information from all major databases for comprehensive and streamlined compound annotation. metID is a flexible, simple, and powerful tool that can be installed on all platforms, allowing the compound annotation process to be fully automatic and reproducible. A detailed tutorial and a case study are provided in Supplementary Materials. Availability and implementationhttps://jaspershen.github.io/metID/. Contactjiangzhu@sioc.ac.cn and mpsnyder@stanford.edu

bioinformatics↗