Biology subjects

Geng, Y.

Publications and source records attributed to Geng, Y..

At least 55 records · Page 3Linked to original sources

bioRxiv2021

Lateral plate mesoderm cell-based organoid system for NK cell regeneration from human pluripotent stem cells

Human pluripotent stem cell (hPSC)-induced NK (iNK) cells are a promising "off-the-shelf" cell product for universal immune therapy. Conventional methods for iNK cell regeneration from hPSCs include embryonic body-formation and feeder-based expansion steps, which bring instability, time-consuming, and high costs for manufacture. In this study, we develop an embryonic body-free, organoid aggregate method for NK cell regeneration from hPSCs. In a short time window of 27-day induction, millions of hPSC input can produce over billions of iNK cells without the necessity of NK cell-expansion feeders. The iNK cells highly express classical toxic granule proteins, apoptosis-inducing ligands, as well as abundant activating and inhibitory receptors. Functionally, the iNK cells eradicate human tumor cells by mechanisms of direct cytotoxity, apoptosis, and antibody-dependent cellular cytotoxicity. This study provides a reliable scale-up method for regenerating human NK cells from hPSCs, which promotes the universal availability of NK cell products for immune therapy.

immunology↗

bioRxiv2021

Hoxb5 reprograms murine multipotent blood progenitors into hematopoietic stem cell-like cells

The expression of transcription factor Hoxb5 specifically marks the functional hematopoietic stem cells (HSC) in mice. However, our recent work demonstrated that ectopic expression of Hoxb5 exerted little effect on HSC but could convert B cell progenitors into functional T cells in vivo. Thus, cell type- and development stage-specific roles of Hoxb5 in hematopoietic hierarchy await more extensive exploration. Here, with a mouse strain engineered with conditional expression of Hoxb5, we unveiled that induced expression of Hoxb5 in mouse multipotent progenitor cells (MPP) led to the generation of a de novo Sca1+cKit+Mac1+CD48+ (Mac1+CD48+SK) cell type, which has the ability to repopulate long-term multi-lineage hematopoiesis in serial transplant recipients. RNA-seq analyses showed that Mac1+CD48+SK cells exhibited an acquired machinery of DNA replication and cell division, which resembled nature fetal liver HSC cells (FL HSC). In short, our current study uncovers that Hoxb5 is able to empower MPP with self-renewal potential, thereby providing new strategies to reprogram blood progenitor cells into HSC-like cells.

cell biology↗

bioRxiv2021

Unsupervised deep learning reveals a stimulative effect of dopamine D3 receptor agonists on zebrafish sociality

It has been a major challenge to systematically evaluate and compare how pharmacological perturbations influence social behavioral outcomes. Although some pharmacological agents are known to alter social behavior, precise description and quantification of such effects have proven difficult. The complexity of brain functions regulating sociality makes it challenging to predict drug effects on social behavior without testing in live animals, and most existing behavioral assays are low-throughput and provide only unidimensional readouts of social function. To achieve richer characterization of drug effects on sociality, we developed a scalable social behavioral assay for zebrafish named ZeChat based on unsupervised deep learning. High-dimensional and dynamic social behavioral phenotypes are automatically classified using this method. By screening a neuroactive compound library, we found that different classes of chemicals evoke distinct patterns of social behavioral fingerprints. By examining these patterns, we discovered that dopamine D3 agonists possess a social stimulative effect on zebrafish. The D3 agonists pramipexole, piribedil, and 7-hydroxy-DPAT-HBr rescued social deficits in a valproic acid-induced zebrafish autism model. The ZeChat platform provides a promising approach for dissecting the pharmacology of social behavior and discovering novel social-modulatory compounds.

animal behavior and cognition↗

bioRxiv2021

Top2a promotes the development of social behavior via PRC2 and H3K27me3

Human infants exhibit innate social behaviors at birth, yet little is understood about the embryonic development of sociality. We screened 1120 known drugs and found that embryonic inhibition of topoisomerase II (Top2a) resulted in lasting social deficits in zebrafish. In mice, prenatal Top2 inhibition caused behavioral defects related to core symptoms of autism, including impairments in social interaction and communication. Mutation of Top2a in zebrafish caused downregulation of a set of genes highly enriched for genes associated with autism in humans. Both the Top2a-regulated and autism-associated gene sets possess binding sites for polycomb repressive complex 2 (PRC2), a regulatory complex responsible for H3K27 trimethylation. Moreover, both gene sets are highly enriched for H3K27me3. Inhibition of PRC2 component Ezh2 rescued social deficits caused by Top2 inhibition. Therefore, Top2a is a key component of an evolutionarily conserved pathway that promotes the development of social behavior through PRC2 and H3K27me3.

animal behavior and cognition↗

bioRxiv2021

Regeneration of humoral immunity from pluripotent stem cells by defined transcription factors

Regeneration of humoral immunity from pluripotent stem cells (PSCs) is a crucial aim in translational medicine. However, reconstitution of complete, sustained, and functional B lymphopoiesis from PSCs has not yet been developed. Here, we successfully achieved regenerative B lymphopoiesis in B-cell deficient animals transplanted with PSC-derived hematopoietic progenitors (iHPCs) guided by synergistic expression of Runx1, Hoxa9, and Lhx2. Upon transplantation, the iHPCs immediately gave rise to pro/pre-B cells in recipients bone marrow, which were able to further differentiate into the entire B cell lineages, including innate B-1a, B-1b, MZ B cells, as well as adaptive FO B cells. In responding to antigen stimuli, the regenerative B cells produced adaptive humoral immune responses, sustained a prolonged antigen-specific antibody production, and formed immune-memory. Particularly, the regenerative B cells in spleen showed developing patterns of immunoglobulin chain-switch and hyper-mutation via a cross-talk with the host T follicular helper cells, which eventually formed T cell-dependent humoral responses. This study provides de novo evidence that B lymphopoiesis can be regenerated from PSCs via a HSC-independent approach, which provides insights into treating B-cell related humoral deficiencies using PSCs as unlimited cell resource.

immunology↗

bioRxiv2021

Structural insights into the activation of human calcium-sensing receptor

Human calcium-sensing receptor (CaSR) is a G-protein-coupled receptor that maintains Ca2+ homeostasis in serum. Here, we present the cryo-electron microscopy structures of the CaSR in the inactive and active states. Complemented with previously reported crystal structures of CaSR extracellular domains, it suggests that there are three distinct conformations: inactive, intermediate and active state during the activation. We used a negative allosteric nanobody to stabilize the CaSR in the fully inactive state and found a new binding site for Ca2+ ion that acts as a composite agonist with L-amino acid to stabilize the closure of active Venus flytraps. Our data shows that the agonist binding leads to the compaction of the dimer, the proximity of the cysteine-rich domains, the large-scale transitions of 7-transmembrane domains, and the inter-and intrasubunit conformational changes of 7-transmembrane domains to accommodate the downstream transducers. Our results reveal the structural basis for activation mechanisms of the CaSR.

biophysics↗

bioRxiv2020

Beyond fear centers: a distributed fMRI-based neuromarker for the subjective experience of fear

The specific neural systems underlying the subjective feeling of fear remain vigorously debated in affective neuroscience. Here, we combined functional MRI with machine learning to identify and evaluate a sensitive and generalizable neural signature predictive of the momentary self-reported subjective fear experience across discovery (n=67), validation (n=20) and generalization (n=31) cohorts. We systematically demonstrate that accurate fear prediction crucially requires distributed brain systems, with important contributions from cortical (e.g., prefrontal, midcingulate and insular cortices) and subcortical (e.g., thalamus, periaqueductal gray, basal forebrain and amygdala) regions. We further demonstrate that the neural representation of subjective fear is distinguishable from the representation of conditioned threat and general negative affect. Overall, our findings suggest that subjective fear, which exhibits distinct neural representation with some other aversive states, is encoded in distributed systems rather than isolated fear centers. This signature provides a neuromarker for monitoring fear-related neuropathology and evaluating novel treatments targeting pathological fear.

neuroscience↗

bioRxiv2020

Alisertib exerts KRAS allele specific anticancer effects in colorectal cancer

Colorectal cancer (CRC) is a common cancer causing substantial mortality and morbidity worldwide. Oncogene RAS mutations occur notably in [~]45% of CRCs, associated with a poor prognosis. KRAS is subject to multiple tiers of regulation, including kinase. Aurora kinases has been implicated in many types of tumor onsets and progression, making them as a promising therapeutic targets. Alisertib (ALS), selectively inhibits Aurora kinase A (AURKA) and exerts potent anticancer activities in vitro and in vivo studies, but the latent anticancer effect of ALS on CRC remains unclear in the context of different KRAS mutations. This study aimed to assess the effects of ALS on RAS signaling pathway in a panel of CRC lines expressing different KRAS alleles, including Caco-2 (KRAS WT), Colo-678 (KRAS G12D), SK-CO-1 (KRAS G12V), HCT116 (KRAS G13D), CCCL-18 (KRAS A146T), and HT29 (BRAF V600E). The results showed that ALS modulated the active form of KRAS in a RAS allele specific manner across the panel of CRC lines; ALS differentially regulated RAS signal via PI3K/Akt and MAPK pathways; and ALS induced apoptosis and autophagy in a RAS allele specific manner. Of note, in combination of ALS and MEK inhibitor, selumetinib, enhanced ALS regulatory effects in CRC lines in a RAS allele specific manner on apoptosis, autophagy, and cell growth. Taken together, this study suggests that ALS differentially regulates RAS signaling pathway and manipulates cell apoptosis and autophagy in RAS allele specific manner. The combinatorial approach of ALS and MEK inhibitor may represent a new therapeutic strategy for precision therapy of CRC in a RAS allele manner.

cancer biology↗

bioRxiv2020

CAS-LiveFISH: Simple and versatile imaging of genomic loci in live mammalian cells and early pre-implantation embryos

Visualizing the 4D genome in live cells is essential for understanding its regulation. Programmable DNA-binding probes, such as fluorescent clustered regularly interspaced short palindromic repeats (CRISPR) and transcription activator-like effector (TALE) proteins have recently emerged as powerful tools for imaging specific genomic loci in live cells. However, many such systems rely on genetically-encoded components, often requiring multiple constructs that each must be separately optimized, thus limiting their use. Here we develop efficient and versatile systems, based on in vitro transcribed single-guide-RNAs (sgRNAs) and fluorescently-tagged recombinant, catalytically-inactivated Cas9 (dCas9) proteins. Controlled cell delivery of pre-assembled dCas9-sgRNA ribonucleoprotein (RNP) complexes enables robust genomic imaging in live cells and in early mouse embryos. We further demonstrate multiplex tagging of up to 3 genes, tracking detailed movements of chromatin segments and imaging spatial relationships between a distal enhancer and a target gene, with nanometer resolution in live cells. This simple and effective approach should facilitate visualizing chromatin dynamics and nuclear architecture in various living systems.

cell biology↗

bioRxiv2020

Loss of Nupr1 promotes engraftment by tuning the dormancy threshold of hematopoietic stem cell repository via regulating p53-checkpoint pathway

Hematopoietic stem cells (HSCs) are dominantly quiescent under homeostasis, which is a key mechanism of maintaining the HSC pool for life-long hematopoiesis. Dormant HSCs poise to be immediately activated on urgent conditions and can return to quiescence after regaining homeostasis. To date, the molecular networks of regulating the threshold of HSC dormancy, if exist, remain largely unknown. Here, we unveiled that deletion of Nupr1, a gene preferentially expressed in HSCs, activated the quiescence HSCs under homeostatic status, which conferred engraftment competitive advantage on HSCs without compromising their stemness and multi-lineage differentiation abilities in serial transplantation settings. Following an expansion protocol, the Nupr1-/- HSCs proliferate more robustly than their wild type counterparts in vitro. Nupr1 inhibits the expression of p53 and the rescue of which offsets the engraftment advantage. Our data unveil the de novo role of Nupr1 as an HSC quiescence-regulator, which provides insights into accelerating the engraftment efficacy of HSC transplantation by targeting the HSC quiescence-controlling network.

cell biology↗

bioRxiv2020

Intrinsic, dynamic and effective connectivity among large-scale brain networks modulated by oxytocin

The neuropeptide oxytocin is a key modulator of social-emotional behavior and its intranasal administration can influence the functional connectivity of brain networks involved in the control of attention, emotion and reward reported in humans. However, no studies have systematically investigated the effects oxytocin on dynamic or directional aspects of functional connectivity. The present study employed a novel computational framework to investigate these latter aspects in 15 oxytocin-sensitive regions using data from randomized placebo-controlled between-subject resting state functional MRI studies incorporating 200 healthy subjects. Results showed that oxytocin extensively modulated effective connectivity both between and within emotion, reward, salience and social cognition processing networks and their interactions with the default mode network, but had no effect on the frequency of dynamic changes. Top-down control over emotional processing regions such as the amygdala was particularly affected. Oxytocin effects were also sex-dependent, being more extensive in males. Overall, these findings suggest that modulatory effects of oxytocin on both within- and between-network interactions may underlie its functional influence on social-emotional behaviors, although in a sex-dependent manner. Furthermore, they demonstrate a useful approach to determining pharmacological influences on resting state effective connectivity and support oxytocins potential therapeutic use in psychiatric disorders.

neuroscience↗

bioRxiv2020

Generation of cardiac valve endocardial like cells from human pluripotent stem cells

The cardiac valvular endothelial cells (VECs) are an ideal cell source that could be used for the fabrication of the next generation tissue-engineered cardiac valves (TEVs). However, few studies have been focused on the derivation of this important cell type. Here we describe a chemically defined xeno-free method for generating VEC-like cells from human pluripotent stem cells (hPSCs) through an intermediate endocardium stage. HPSCs were initially specified to KDR+/ISL1+ multipotent cardiac progenitor cells (CPCs), followed by differentiation into endocardial progenitors under the combined treatment with VEGFA, BMP4 and bFGF. In the presence of VEGFA, BMP4 and TGFb, valve endocardial progenitor cells (VEPs) were efficiently derived from endocardial progenitors without a sorting step. Mechanistically, administration of TGFb and BMP4 may specify the VEP fate by facilitating the expression of key transcription factors ETV2 and NFATc1 at the immediate early stage and by activating Notch signaling at the later stage. Notch activation is likely an important part of VEP induction. HPSC-derived VEPs exhibited morphological, molecular and functional similarities to that of the primary VECs isolated from normal human aortic valves. When hPSC-derived VEPs were seeded onto the surface of the de-cellularized porcine aortic valve (DCV) matrix scaffolds, they exhibited higher proliferation and survival potential than the primary VECs. Our results suggest that hPSC-derived VEPs could serve as as a potential platform for the study of valve development, and as starting materials for the construction of the next generation TEVs. HighlightsO_LIValve endocardial progenitor cells (VEPs) could be efficiently derived from hPSCs without a sorting step C_LIO_LIThe combined treatment with TGFb and BMP4 induce VEP fate by enhancing the expression of ETV2 and NFATc1 C_LIO_LIHPSC-derived VEPs resemble the isolated primary VECs molecularly, morphologically and functionally C_LIO_LIHPSC-derived VEPs exhibit proliferative and functional potential similar to the primary VECs when seeded onto the DCVs C_LI

developmental biology↗

bioRxiv2020

Coupling of Ca2+ and voltage activation in BK channels through the αB helix/voltage sensor interface

Large conductance Ca2+ and voltage activated K+ (BK) channels control membrane excitability in many cell types. BK channels are tetrameric. Each subunit is comprised of a voltage sensor domain (VSD), a central pore gate domain, and a large cytoplasmic domain (CTD) that contains the Ca2+ sensors. While it is known that BK channels are activated by voltage and Ca2+, and that voltage and Ca2+ activations interact, less is known about the mechanisms involved. We now explore mechanism by examining the gating contribution of an interface formed between the VSDs and the B helices located at the top of the CTDs. Proline mutations in the B helix greatly decreased voltage activation while having negligible effects on gating currents. Analysis with the HCA model indicated a decreased coupling between voltage sensors and pore gate. Proline mutations decreased Ca2+ activation for both Ca2+ bowl and RCK1 Ca2+ sites, suggesting that both high affinity Ca2+ sites transduce their effect, at least in part, through the B helix. Mg2+ activation was also decreased. The crystal structure of the CTD with proline mutation L390P showed a flattening of the first helical turn in the B helix compared to WT, without other notable differences in the CTD, indicating structural change from the mutation was confined to the B helix. These findings indicate that an intact B helix/VSD interface is required for effective coupling of Ca2+ binding and voltage depolarization to pore opening, and that shared Ca2+ and voltage transduction pathways involving the B helix may be involved. SignificanceLarge conductance BK (Slo1) K+ channels are activated by voltage, Ca2+, and Mg2+ to modulate membrane excitability in neurons, muscle, and other cells. BK channels are of modular design, with pore-gate and voltage sensors as transmembrane domains and a large cytoplasmic domain CTD containing the Ca2+ sensors. Previous observations suggest that voltage and Ca2+ sensors interact, but less is known about this interaction and its involvement in the gating process. We show that a previously identified structural interface between the CTD and voltage sensors is required for effective activation by both voltage and Ca2+, suggesting that these processes may share common allosteric activation pathways. Such knowledge should help explain disease processes associated with BK channel dysfunction.

neuroscience↗

bioRxiv2019

T Lymphopoiesis from Pluripotent Stem Cells by Defined Transcription Factors at Single Cell Resolution

Achievement of immunocompetent and therapeutic T lymphopoiesis from pluripotent stem cells is a central aim in T cell regenerative medicine. To date, preferentially regenerating T lymphopoiesis in vivo from pluripotent stem cells (PSC) remains a practical challenge. Here we documented that synergistic and transient expression of Runx1 and Hoxa9 restricted in the time window of endothelial to hematopoietic transition and hematopoietic maturation stages induced in vitro from PSC (iR9-PSC) preferentially generated engraftable hematopoietic progenitors capable of homing to thymus and developing into mature T (iT) cells in primary and secondary immunodeficient recipients. Single-cell transcriptome and functional analyses illustrated the cellular trajectory of T lineage induction from PSC, unveiling the T-lineage specification determined at as early as hemogenic endothelial cell stage and identifying the bona fide pre-thymic progenitors. The iT cells distributed normally in central and peripheral lymphoid organs and exhibited abundant TCR{beta} repertoire. The regenerative T lymphopoiesis rescued the immune-surveillance ability in immunodeficient mice. Furthermore, gene-edited iR9-PSC produced tumor-specific-T cells in vivo that effectively eradicated tumor cells. This study provides insight into universal generation of functional and therapeutic T lymphopoiesis from the unlimited and editable PSC source.

immunology↗

bioRxiv2019

Mesenchymal stem cells restore local microenvironment and systemically suppress leukemia via reprogramming macrophages

Bone marrow (BM) mesenchymal stem cells (MSCs) are critical components of the BM microenvironment and play an essential role in supporting hematopoiesis. Dysfunction of MSCs is associated with the impaired BM microenvironment that promotes leukemia development. However, whether and how restoration of the impaired BM microenvironment can inhibit leukemia development remain unknown. Using an established leukemia model and the RNA-seq analysis, we discovered functional degeneration of MSCs during leukemia progression. Importantly, intra-BM instead of systemic transfusion of donor healthy MSCs restored the BM microenvironment, thus systemically altering cytokine expression patterns, improving normal hematopoiesis, reducing tumor burden, and ultimately prolonging survival of the leukemia-bearing mice. Donor MSC treatment restored the function of host MSCs and reprogrammed host macrophages to fulfill tissue-repair function. Transfusion of MSC-reprogrammed macrophages largely recapitulated the therapeutic effects of MSCs. Further, we found that donor MSCs reprogrammed macrophages to reduce leukemia burden through autocrine of IL-6. Taken together, our study reveals that donor MSCs reprogram host macrophages to restore the BM microenvironment and inhibit leukemia development, thus offering rationales for local MSC administration as a potentially effective therapy for leukemia.\n\nKey PointsKey Point 1: Intra-BM transfusion of MSCs restores the BM microenvironment, improves thrombopoiesis, and suppresses MDS/MPN initiated by Nras mutation.\n\nKey Point 2: Donor MSCs reprogram macrophages to restore the BM microenvironment, improve thrombopoiesis, and suppress leukemia.

cancer biology↗

bioRxiv2019

Human extinction learning is accelerated by an angiotensin antagonist via ventromedial prefrontal cortex and its connections with basolateral amygdala

Recent translational research suggests a role of the renin-angiotensin (RA) system in threat extinction and underlying neuroplasticity; however, whether and how pharmacological modulation of the RA system influences physiological and neural manifestations of threat during extinction learning in humans is unclear. Here we report that pre-extinction administration of losartan, an angiotensin II type 1 receptor antagonist, accelerated attenuation of physiological threat expression. During early extinction, losartan enhanced threat-signal specific ventromedial prefrontal cortex (vmPFC) activation and its coupling with the basolateral amygdala. Multivoxel pattern analysis revealed that losartan reduced whole brain, particularly vmPFC, threat expression and voxel-wise mediation analyses further confirmed that losartan-accelerated extinction crucially involved vmPFC processing. Overall the results provide initial evidence for a critical role of the RA system in extinction learning in humans and suggest that adjunct losartan administration may facilitate the efficacy of extinction-based therapies. ClinicalTrials.gov, Identifier: NCT03396523

clinical trials↗

bioRxiv2018

Oxytocin modulates the intrinsic dynamics between attention-related large scale networks

Attention and salience processing have been linked to the intrinsic between- and within-network dynamics of large scale networks engaged in internal (default mode network, DN) and external attention allocation (dorsal attention, DAN, salience network, SN). The central oxytocin (OXT) system appears ideally organized to modulate widely distributed neural systems and to regulate the switch between internal attention and salient stimuli in the environment. The current randomized placebo (PLC) controlled between-subject pharmacological resting-state fMRI study in N = 187 (OXT, n = 94; n = 93; single-dose intranasal administration) healthy male and female participants employed an independent component analysis (ICA) approach to determine the modulatory effects of OXT on the within- and between-network dynamics of the DAN-SN-DN triple network system. OXT increased the functional integration between subsystems within SN and DN and increased functional segregation of the DN with the SN and DAN engaged in attentional control. Whereas no sex differences were observed, OXT effects on the DN-SN interaction were modulated by autism traits. Together, the findings suggest that OXT may facilitate efficient attentional allocation towards social cues by modulating the intrinsic functional dynamics between DN components engaged in social processing and large-scale networks involved in external attentional demands (SN, DAN).

neuroscience↗

bioRxiv2018

Oxytocin facilitates empathic- and self-embarrassment ratings by attenuating amygdala and anterior insula responses

The hypothalamic neuropeptide oxytocin has been reported to enhance emotional empathy in association with reduced amygdala activation, although to date studies have not investigated empathy for individuals expressing self-conscious, moral emotions which engage mentalizing as well as emotion processing networks. In the current randomized, double-blind placebo controlled functional MRI experiment on 70 male and female subjects we have therefore investigated the effects of intranasal oxytocin (40 IU) on behavioral and neural responses to embarrassment experienced by others or by self. Results showed that oxytocin significantly increased ratings of both empathic and self-embarrassment and concomitantly decreased skin conductance response and activation in the right amygdala and insula but not in the medial prefrontal cortex. The amygdala effects of oxytocin were associated with the magnitude of the skin conductance response and trait anxiety scores. Overall our results demonstrate that oxytocin increases ratings of self- and other embarrassment and that this is associated with reduced physiological arousal and activity in neural circuitry involved in emotional arousal. The neural effects of oxytocin are also stronger in individuals with high trait anxiety suggesting that it may particularly reduce their anxiety in embarrassing situations.

neuroscience↗