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Lai, C.

Publications and source records attributed to Lai, C..

34 records · Page 2Linked to original sources

Long-read genome assemblies reveals a cis-regulatory landscape associated with phenotypic divergence in two sister Siniperca fishes

BackgroundDissecting the genetic basis of variation in the regulation of gene expression is essential for understanding phenotypic evolution. Structural variants intersecting the cis-regulatory elements are found to cause gene expression variation in several developmental genes, resulting in morphological divergence between species. Due to the difficulty of identifying structural variants accurately across the genome, a comprehensive study of impacts of structural variants in cis-regulatory divergence of closely related species, especially fish species, is still scarce. Recently identified broad H3K4me3 domains are essential for the regulation of genes involved in several biological processes. However, the role of broad H3K4me3 domains in phenotypic divergence remain poorly understood. Siniperca chuatsi and S. scherzeri are two closely related fish species diverge in several phenotypic traits, making them an ideal model to study cis-regulatory evolution in closely related species. ResultsWe generated chromosome-level genomes of S. chuatsi and S. scherzeri. The evolutionary histories of S. chuatsi and S. scherzeri were studied by inferring the dynamic changes in the ancestral population sizes. The genetic basis of adaptation in S. chuatsi and S. scherzeri was dissected by performing gene family expansion and contraction analysis and identifying positively selected genes (PSGs). To investigate the role of SVs in cis-regulatory divergence of closely related fish species, we identified high-quality SVs between S. chuatsi and S. scherzeri, as well as H3K27ac and H3K4me3 domains. Integrated analysis revealed that cis-regulatory divergence caused by SVs played an essential role in the differentiation of metabolism, skin pigmentation, and immunity between S. chuatsi and S. scherzeri. Additionally, divergent broad H3K4me3 domains were found to mostly associate with cancer-related genes in S. chuatsi and S. scherzeri and contribute to their phenotypic divergence. ConclusionsOur analysis reveals SVs play an essential role in cis-regulatory variation between the two sister fish species, which in turn contributes to their phenotypic divergence. The divergence of broad H3K4me3 domains contributes to phenotypic divergence between closely related species. Additionally, the association of broad H3K4me3 domains and cancer-related genes has an ancient origin.

genomics↗

Programmed cell death-1 receptor mediated regulation of Tbet+ NK1.1- Innate Lymphoid Cells within the Tumor Microenvironment

Innate Lymphoid Cells (ILCs) play a key role in tissue mediated immunity and can be controlled by co-receptor signaling. Here we define a subset of ILCs that are Tbet+NK1.1- and are present within the tumor microenvironment (TME). We show programmed death-1 receptor (PD-1) expression on ILCs within TME is found in Tbet+NK1.1-ILCs. PD-1 significantly controlled the proliferation and function of Tbet+NK1.1-ILCs in multiple murine and human tumors. We found tumor derived lactate enhanced PD-1 expression on Tbet+NK1.1-ILCs within the TME, which resulted in dampened mTOR signaling along with increased fatty acid uptake. In line with these metabolic changes, PD-1 deficient Tbet+NK1.1-ILCs expressed significantly increased IFN{gamma}, granzyme B and K. Furthermore, PD1 deficient Tbet+NK1.1- ILCs contributed towards diminished tumor growth in an experimental murine model of melanoma. These data demonstrate that PD-1 can regulate anti-tumor responses of Tbet+NK1.1-ILCs within the tumor microenvironment. HighlightsO_LITbet+NK1.1- ILCs are found in WT and PD1 ko mice C_LIO_LIPD-1 is expressed on Tbet+NK1.1- ILC1s within multiple TME C_LIO_LIPD-1 controls the proliferation and function of Tbet+NK1.1- ILCs within the tumor microenvironment by modulating fatty acid metabolism. C_LIO_LIPD-1 regulates the proliferation of human Tbet+ ILC1s in human cutaneous squamous cell carcinoma (cSCC) and melanoma tumor microenvironment. C_LI

immunology↗

CIRKO: A chemical-induced reversible gene knockout system for studying gene function in situ

Conditional loss and restoration of function are becoming important approaches for investigating gene function. Given that reversible conditional gene knockouts in cells required complicated manipulation, conditional inactivation and reactivation of a gene in primary somatic cells with limited proliferative capacity and in animal models remain difficult to achieve. Here, we first developed a reportable and reversible conditional intronic cassette (ReCOIN), wherein inactivation and reactivation of the gene are mediated via sequential expression of Cre and Flp recombinases, respectively. The expression pattern of the target gene can be monitored by direct visualization. To simply and tightly control temporal expression of the recombinases, on the basis of ReCOIN, we further presented a dual chemical-induced reversible gene knockout system (CIRKO) by insertion of reverse tetracycline transcriptional activator (rtTA) and tetracycline response element (TRE)-controlled Cre and FlpoERT2 recombinases cassettes into Rosa26 and Hipp11 loci of cells, respectively, in which transcription termination of the target gene can be induced at a specific stage in the presence of doxycycline, while gene restoration is achieved in the presence of doxycycline and tamoxifen simultaneously. This system provides a simple, rapid, and flexible gene switch for studying gene function in situ both in vitro and in vivo. Impact statementA novel chemical-induced reversible gene knockout system provides a simple, rapid, and flexible gene switch to facilitate the study of gene function in primary somatic cells in vitro, embryos in vitro or in vivo, and animals in vivo.

genetics↗

ROBUST AND EFFICIENT ACTIVE GENETICS GENE CONVERSION IN THE RAT AND MOUSE

The utility of Active Genetic (AG) gene conversion systems in rats and mice holds great promise for facilitating the production of complex strains harboring multiple humanizing genes. The practical application of such systems requires the identification of a robust, reusable, and highly efficient system. By characterizing twenty-eight different promoter and target site pairs we aimed to define the parameters needed to establish an efficient conversion system in male and female rats and mice. Using three specific meiosis prophase I active promoters to drive Cas9 expression. We studied several variables, including the number of Cas9 target sites, the distance between target sites, the cis versus trans configuration in linked pairs, and the effect of Cas9 copy number. In the rat, three of twelve tested configurations provided efficient AG gene conversion in the 22% - 67% range, and four others catalyzed AG in the 0.7-1% range. The rat Ddx4 (Vasa) promoter provides higher AG efficiency than the Sycp1 promoter. In mice, ten of sixteen tested configurations, using the Sycp1 and pSycp1 promoters, provided efficiency in the 0.3% - 3.2% range. In rats, Cas9 expression levels are remarkably well correlated with AG gene conversion efficiency. The rat cis rCyp3A1/rCyp3A2 locus was the most successful configuration, with gene conversion efficiencies of 0.7%-67%. This target site has a special property; the two Cas9 target sites are nearly perfectly homologous in the 100 bases around the gRNA target site. Our findings identify key parameters that improve AG efficiency, including the use of two Cas9 target sites, and efficient promoters that drive high levels of Cas9 expression that are correctly timed during gamete development. These findings also uncover the unexpected benefit of high homology at paired gRNA target sites to promote efficiency. We provide new data to guide future efforts to develop yet further improved AG systems.

genetics↗

Generating Functional Cells Through Enhanced Interspecies Chimerism with Human Pluripotent Stem Cells

Obtaining functional human cells through interspecies chimerism with human pluripotent stem cells (hPSCs) remains unsuccessful due to its extreamly low efficiency. Here, we show that hPSCs failed to differentiate and contribute teratoma in presence of mouse PSCs (mPSCs). While, MYCN, a pro-growth factor dramatically promotes hPSC contribution in teratoma co-formation by hPSCs/mPSCs. MYCN combined with BCL2 (M/B) greatly enhanced conventional hPSCs to integrate into preimplantation embryos of different species, such as mice, rabbits and pigs and substrantially contributed to mouse post-implantation chimera in embryonic and extra-embyonic tissues. Strikingly, M/B-hPSCs injected into preimplantation Flk-1+/- mouse embryos show further enhanced chimerism that allows obtaining live human CD34+ blood progenitor cells from chimeras through cell sorting. The chimera derived human CD34+ cells further gave rise to various subtype blood cells in typical colony forming unit(CFU) assay. Thus, we proof the concept to obtain functional human cells through enchanced interspecies chimerism with hPSCs.

cell biology↗

Tuning the sensitivity of genetically encoded fluorescent potassium indicators through structure-guided and genome mining strategies

Genetically encoded potassium indicators lack optimal binding affinity for monitoring intracellular dynamics in mammalian cells. Through structure-guided design and genome mining of potassium binding proteins, we developed green fluorescent potassium indicators with a broad range of binding affinities. KRaION1, based on the insertion of a potassium binding protein (Ec-Kbp) into the fluorescent protein mNeonGreen, exhibits an isotonically measured Kd of 69{+/-}10 (mM; mean {+/-} standard deviation used throughout). We identified Ec-Kbps binding site using NMR spectroscopy to detect protein-thallium scalar couplings and refined the structure of Ec-Kbp in its potassium-bound state. Guided by this structure, we modified KRaION1, yielding KRaION2, which exhibits an isotonically measured Kd of 96{+/-}9 (mM). We identified four Ec-Kbp homologs as potassium binding proteins, which yielded indicators with isotonically measured binding affinities in the 39-112 (mM) range. KRaIONs expressed and functioned in HeLa cells, but exhibited lower Kd values, which were mirrored by lower Kd values measured in vitro when holding sodium constant. Thus, potassium indicator Kd may need to be evaluated in the context of a given experimental goal.

bioengineering↗

Rapamycin attenuated zinc-induced tau phosphorylation and oxidative stress in animal model: Involvement of dual mTOR/p70S6K and Nrf2/HO-1 pathways

Alzheimers disease is pathologically featured by abnormal accumulation of amyloid-beta plaque, neurofibrillary tangles, oxidative stress, neuroinflammation, and neurodegeneration. Metal dysregulation including excessive zinc released by presynaptic neurons plays an important role in tau pathology and oxidase activation. The activities of mammalian target of rapamycin (mTOR)/ ribosomal S6 protein kinase (p70S6K) are elevated in the brains of patients with Alzheimers disease. Zinc induces tau hyperphosphorylation via mTOR/P70S6K activation in vitro. However, the involvement of mTOR/P70S6K pathway in zinc-induced oxidative stress, tau degeneration, synaptic and cognitive impairment, has not been fully elucidated in vivo. Here we assessed in the effect of pathological concentration of zinc in SH-SY5Y cells by using biochemical assays and immunofluorescence staining. Rats (n = 18, male) were lateral ventricularly-injected with zinc and treated with rapamycin (intraperitoneal injection) for one week and assessed using Morris water maze. Evaluation of the oxidative stress, tau phorsphylation and synaptic impairment were performed using the hippocampus tissue of the rats by biochemical assays and immunofluorescence staining. Results from Morris water maze showed that the capacity of spatial memory is impaired in zinc-treated rats. Zinc sulfate significantly increased the levels of P-mTOR Ser2448, P-p70S6K Thr389, and P-tau Ser356, and decreased levels of Nrf2 and HO{square}1 in SH-SY5Y cells and in zinc-treated rats compared with control groups. Increased expressions of reactive oxygen species were observed in zinc sulfate-induced SH-SY5Y cells as well as in the hippocampus of zinc-injected rats. Rapamycin, an inhibitor of mTOR, rescued the zinc-induced increases in mTOR/p70S6K activations, tau phosphorylation and oxidative stress, as well as Nrf2/HO{square}1 inactivation, cognitive impairment and synaptic impairment reduced the expression of synapse-related proteins in zinc-injected rats. In conclusion, our findings imply that rapamycin prevents zinc-induced cognitive impairment and protects neurons from tau pathology, oxidative stress and synaptic impairment, by decreasing mTOR/p70S6K hyperactivity and increasing Nrf2/HO {square} 1 activity.

neuroscience↗

AI for predicting chemical-effect associations at the universe level - deepFPlearn

Many chemicals are out there in our environment, and all living species are exposed. However, numerous chemicals pose risks, such as developing severe diseases, if they occur at the wrong time in the wrong place. For the majority of the chemicals, these risks are not known. Chemical risk assessment and subsequent regulation of use require efficient and systematic strategies. Lab-based methods - even if high throughput - are too slow to keep up with the pace of chemical innovation. Existing computational approaches are designed for specific chemical classes or sub-problems but not usable on a large scale. Further, the application range of these approaches is limited by the low amount of available labeled training data. We present the ready-to-use and stand-alone program deepFPlearn that predicts the association between chemical structures and effects on the gene/pathway level using a combined deep learning approach. deepFPlearn uses a deep autoencoder for feature reduction before training a deep feedforward neural network to predict the target association. We received good prediction qualities and showed that our feature compression preserves relevant chemical structural information. Using a vast chemical inventory (unlabeled data) as input for the autoencoder did not reduce our prediction quality but allowed capturing a much more comprehensive range of chemical structures. We predict meaningful - experimentally verified-associations of chemicals and effects on unseen data. deepFPlearn classifies hundreds of thousands of chemicals in seconds. We provide deepFPlearn as an open-source and flexible tool that can be easily retrained and customized to different application settings at https://github.com/yigbt/deepFPlearn. Supplementary informationSupplementary data are available at bioRxiv online. Contactjana.schor@ufz.de

bioinformatics↗

VGLL1-directed TEAD activation drives endocrine therapy resistance in estrogen receptor positive breast cancer

Resistance to endocrine therapies (ET) is common in estrogen receptor (ER) positive breast cancer and most relapsed patients die with ET-resistant disease. While genetic mutations provide explanations for some relapsed patients1, mechanisms of resistance remain undefined in many cases. Drug-induced epigenetic reprogramming provides possible routes to resistance2. By analysing histone H3 lysine 27 acetylation (H3K27ac) profiles in models of ET resistance, we discovered that selective ER down-regulators (SERDs) such as fulvestrant promote epigenetic activation of VGLL1, a co-activator for TEAD transcription factors. We show that VGLL1, acting via TEADs, promotes expression of genes that drive growth of fulvestrant-resistant breast cancer cells. Pharmacological disruption of VGLL1/TEAD4 interaction inhibits VGLL1/TEAD transcriptional programmes to block growth of the resistant cells and prevents growth. Among the VGLL1/TEAD-regulated genes, we identify EGFR, whereby VGLL1-directed EGFR upregulation sensitises fulvestrant-resistant breast cancer cells to EGFR inhibitors. Taken together, our findings identify VGLL1 as a transcriptional driver in ET resistance and advance new therapeutic possibilities for relapsed ER+ breast cancer patients.

cancer biology↗

A single-cell method to map higher-order 3D genome organization in thousands of individual cells reveals structural heterogeneity in mouse ES cells

In eukaryotes, the nucleus is organized into a three dimensional structure consisting of both local interactions such as those between enhancers and promoters, and long-range higher-order structures such as nuclear bodies. This organization is central to many aspects of nuclear function, including DNA replication, transcription, and cell cycle progression. Nuclear structure intrinsically occurs within single cells; however, measuring such a broad spectrum of 3D DNA interactions on a genome-wide scale and at the single cell level has been a great challenge. To address this, we developed single-cell split-pool recognition of interactions by tag extension (scSPRITE), a new method that enables measurements of genome-wide maps of 3D DNA structure in thousands of individual nuclei. scSPRITE maximizes the number of DNA contacts detected per cell enabling high-resolution genome structure maps within each cells and is easy-to-use and cost-effective. scSPRITE accurately detects chromosome territories, active and inactive compartments, topologically associating domains (TADs), and higher-order structures within single cells. In addition, scSPRITE measures cell-to-cell heterogeneity in genome structure at different levels of resolution and shows that TADs are dynamic units of genome organization that can vary between different cells within a population. scSPRITE will improve our understanding of nuclear architecture and its relationship to nuclear function within an individual nucleus from complex cell types and tissues containing a diverse population of cells.

molecular biology↗

Subanesthetic ketamine reactivates adult cortical plasticity to restore vision from amblyopia

Subanesthetic ketamine evokes rapid and long-lasting antidepressant effects in human patients. The mechanism for ketamines effects remains elusive, but ketamine may broadly modulate brain plasticity processes. We show that single-dose ketamine reactivates adult mouse visual cortical plasticity and promotes functional recovery of visual acuity defects from amblyopia. Ketamine specifically induces down-regulation of neuregulin-1 (NRG1) expression in parvalbumin-expressing (PV) inhibitory neurons in mouse visual cortex. NRG1 downregulation in PV neurons co-tracks both the fast onset and sustained decreases in synaptic inhibition to excitatory neurons, along with reduced synaptic excitation to PV neurons in vitro and in vivo following a single ketamine treatment. These effects are blocked by exogenous NRG1 as well as PV targeted receptor knockout. Thus ketamine reactivation of adult visual cortical plasticity is mediated through rapid and sustained cortical disinhibition via downregulation of PV-specific NRG1 signaling. Our findings reveal the neural plasticity-based mechanism for ketamine-mediated functional recovery from adult amblyopia. Highlights{circ} Disinhibition of excitatory cells by ketamine occurs in a fast and sustained manner {circ}Ketamine evokes NRG1 downregulation and excitatory input loss to PV cells {circ}Ketamine induced plasticity is blocked by exogenous NRG1 or its receptor knockout {circ}PV inhibitory cells are the initial functional locus underlying ketamines effects

neuroscience↗

TP53 abnormalities correlate with immune infiltration and are associated with response to flotetuzumab, an investigational immunotherapy, in acute myeloid leukemia

PurposeSomatic TP53 mutations and 17p deletions with genomic loss of TP53 occur in 37-46% of acute myeloid leukemia (AML) cases with adverse risk cytogenetics and are associated with primary induction failure (PIF), high risk of relapse and dismal prognosis. Herein, we aimed to characterize the immune landscape of TP53 mutated AML and to determine whether TP53 abnormalities identify a patient subgroup that may benefit from T-cell targeting immunotherapy approaches. Experimental DesignThe NanoString Pan-Cancer IO 360 assay was used for the immune transcriptomic analysis of 64 diagnostic bone marrow (BM) samples from adults with TP53 mutated AML (n=42) or TP53 wild type AML (n=22), and 35 BM samples from heavily pretreated patients with relapsed/refractory (R/R) AML (11 cases with TP53 mutations and/or 17p deletion with genomic loss of TP53) who received immunotherapy with flotetuzumab, an investigational CD123xCD3 bispecific DART(R) molecule (NCT02152956). In silico data series included The Cancer Genome Atlas (TCGA) cohort and a Dutch-Belgian Cooperative Trial Group for Hematology-Oncology (HOVON) cohort. ResultsAll TCGA cases with TP53 mutations (n=13) expressed higher levels of negative immune checkpoints, inflammatory chemokines, interferon (IFN)-{gamma}-inducible molecules, and had a higher tumor inflammation signature (TIS) score, compared with TCGA cases with other risk-defining molecular lesions. The comparison between TP53 mutated and TP53 wild type primary BM samples showed higher expression of IFNG, FoxP3, immune checkpoints and markers of exhaustion and senescence in the former cohort and allowed the computation of a 34-gene immune classifier prognostic for overall survival. In vitro modeling experiments with AML cell lines showed heightened expression of IFN-{gamma} and inflammation pathway genes in KG-1 cells (loss-of-function mutation of TP53) compared with Kasumi-1 cells (gain-of-function mutation of TP53). Finally, 5 out of 11 (45.5%) patients with R/R AML and TP53 abnormalities showed evidence of anti-leukemic activity of flotetuzumab immunotherapy and had higher TIS, FoxP3, CD8 T-cell abundance, inflammatory chemokine and PD1 gene expression scores at baseline compared with non-responders. ConclusionsThis study provides evidence for a correlation between IFN-{gamma}-dominant immune subtypes and TP53 abnormalities. The anti-leukemic activity with flotetuzumab encourages further study of this immunotherapeutic approach in this patient subgroup.

immunology↗

Long noncoding RNA AVAN promotes antiviral innate immunity by interacting with TRIM25 and enhancing the transcription of FOXO3a

Accumulating evidence has shown that long noncoding RNAs (lncRNAs) are involved in several biological processes, including immune responses. However, the role of lncRNAs in antiviral innate immune responses remains largely unexplored. Here, we identify an uncharacterized human lncRNA from influenza A virus (IAV) patients, antivirus and activate neutrophil (AVAN), that is significantly up-regulated upon virus infection. Mechanistically, nuclear lncRNA-AVAN positively regulates the transcription of forkhead box O3A (FOXO3a) by associating with its promoter and inducing chromatin remodeling to promote neutrophil chemotaxis. Furthermore, we also found that cytoplasmic lncRNA-AVAN directly binds tripartite motif containing 25 (TRIM25) and enhances the association of TRIM25 and Retinoic acid inducible gene-1 proteins (RIG-I) and the ubiquitylation of RIG-I, thereby promoting TRIM25- and RIG-I-mediated antiviral innate immune signaling. More importantly, we enforced the expression of AVAN in transgenic mice and found that it significantly alleviated IAV virulence and virus production. Collectively, these findings highlight the potential clinical implications of lncRNA-AVAN as a key positive regulator of the antiviral innate immune response and a promising target for developing broad antiviral therapeutics.

immunology↗

Molecular measurable residual disease testing of blood during AML cytotoxic therapy for early prediction of clinical response

AbstractO_ST_ABSPURPOSEC_ST_ABSMeasurable residual disease (MRD) testing after initial chemotherapy treatment can predict relapse and survival in AML. However, it has not been established if repeat molecular or genetic testing during chemotherapy can offer information regarding the chemotherapy sensitivity of the leukemic clone.\n\nPATIENTS AND METHODSBlood from 45 adult AML patients at day 1 and 4 of induction (n = 35) or salvage (n = 10) cytotoxic chemotherapy was collected for both quantitative real-time PCR (qPCR) assessment (WT1) and next generation sequencing (NGS, >500x depth) of 49 gene regions recurrently mutated in MDS/AML.\n\nRESULTSThe median age was 62 (23-78); 42% achieved a complete response. WT1 was overexpressed in most patients tested but was uninformative for very early MRD assessment. A median of 4 non-synonymous variants (range 0-7) were detected by DNA sequencing of blood on day 1 of therapy (median VAF: 29%). Only two patients had no variants detectable. All mutations remained detectable in blood on day 4 of intensive chemotherapy and remarkably the ratio of mutated to wild-type sequence was often maintained. This phenomenon was not limited to variants in DNMT3A, TET2 and ASXL1. The kinetics of NPM1 and TP53 variant burden early during chemotherapy appeared to be exceptions and exhibited consistent trends in this cohort.\n\nCONCLUSIONSMolecular testing of blood on day 4 of chemotherapy is not predictive of clinical response in AML. The observed stability in variant allele frequency suggests that cytotoxic therapy may have a limited therapeutic index for clones circulating in blood containing these mutations. Further validation is required to confirm the utility of monitoring NPM1 and TP53 kinetics in blood during cytotoxic therapy.

cancer biology↗

Human Bone Marrow Assessment by Single Cell RNA Sequencing, Mass Cytometry and Flow Cytometry

New techniques for single-cell analysis have led to insights into hematopoiesis and the immune system, but the ability of these techniques to cross-validate and reproducibly identify the biological variation in diverse human samples is currently unproven. We therefore performed a comprehensive assessment of human bone marrow cells using both single-cell RNA sequencing and multiparameter flow cytometry from twenty healthy adult human donors across a broad age range. These data characterize variation between healthy donors as well as age-associated changes in cell population frequencies. Direct comparison of techniques revealed discrepancy in the quantification of T lymphocyte and natural killer cell populations. Orthogonal validation of immunophenotyping using mass cytometry demonstrated good correlation with flow cytometry. Technical replicates using single-cell RNA sequencing matched robustly, while biological replicates showed variation. Given the increasing use of single-cell technologies in translational research, this resource serves as an important reference dataset and highlights opportunities for further refinement.

immunology↗

Real-time spike sorting platform for high-density extracellular probes with ground-truth validation and drift correction

Electrical recordings from a large array of electrodes give us access to neural population activity with single-cell, single-spike resolution. These recordings contain extracellular spikes which must be correctly detected and assigned to individual neurons. Despite numerous spike-sorting techniques developed in the past, a lack of high-quality ground-truth datasets hinders the validation of spike-sorting approaches. Furthermore, existing approaches requiring manual corrections are not scalable for hours of recordings exceeding 100 channels. To address these issues, we built a comprehensive spike-sorting pipeline that performs reliably under noise and probe drift by incorporating covariance-based features and unsupervised clustering based on fast density-peak finding. We validated performance of our workflow using multiple ground-truth datasets that recently became available. Our software scales linearly and processes up to 1000-channel recording in real-time using a single workstation. Accurate, real-time spike sorting from large recording arrays will enable more precise control of closed-loop feedback experiments and brain-computer interfaces.

neuroscience↗