Biology subjects

Liu, L.

Publications and source records attributed to Liu, L..

At least 325 records · Page 18Linked to original sources

bioRxiv2024

A secondary β-hydroxybutyrate metabolic pathway linked to energy balance

{beta}-hydroxybutyrate (BHB) is an abundant ketone body. To date, all known pathways of BHB metabolism involve interconversion of BHB and primary energy intermediates. Here we show that CNDP2 controls a previously undescribed secondary BHB metabolic pathway via enzymatic conjugation of BHB and free amino acids. This BHB-ylation reaction produces a family of endogenous ketone metabolites, the BHB-amino acids. Genetic ablation of CNDP2 in mice eliminates tissue amino acid BHB-ylation activity and reduces BHB-amino acid levels. Administration of BHB-Phe, the most abundant BHB-amino acid, to obese mice activates neural populations in the hypothalamus and brainstem and suppresses feeding and body weight. Conversely, CNDP2-KO mice exhibit increased food intake and body weight upon ketosis stimuli. CNDP2-dependent amino acid BHB-ylation and BHB-amino acid metabolites are also conserved in humans. Therefore, the metabolic pathways of BHB extend beyond primary metabolism and include secondary ketone metabolites linked to energy balance.

biochemistry↗

bioRxiv2024

Deciphering the Cell Specific Transcript Heterogeneity and Alternative Splicing during the Early Embryonic Development of Zebrafish

Cell fate determination during early embryonic development is a complex process modulated by gene expression. The intricate interplay of transcriptional and post-transcriptional regulation is integral to the developmental trajectory of embryogenesis, yet how RNA processing may contribute to early development programming is largely elusive. Leveraging recent technological advances in single-molecule nanopore sequencing, we developed a single-cell long-read transcriptome sequencing technology, allowing a clear view of transcript diversity during zebrafish embryogenesis during pre- and post-zygotic genome activation (ZGA). A closer examination of the dynamic transcript usage and potential alternative splicing revealed that abundant stage-specific transcripts with differential coding potentials are involved in distinct biological functions. Specifically, we identified two cell populations at the onset of ZGA based on isoform diversity instead of gene profiling, which followed divergent developmental trajectories toward the ectoderm and the presumptive ectoderm. These two populations of cells were characterized by divergent splicing regulations linked to differential RNA-binding proteins, including SNRPA and SFPQ. Altogether, using the single-cell long-read transcriptome sequencing strategy, we work has revealed the cell-specific transcriptome dynamics contributing to the cell fate determination during embryogenesis.

developmental biology↗

bioRxiv2024

Targeted protein degradation in lysosome utilizing naturally produced bifunctional antibodies with high levels of mannose 6-phosphate glycans

Novel antibodies have been created for targeted degradation of extracellular and membrane proteins in the lysosome. The mechanism of degradation of target proteins for these antibodies has involved either chemical conjugation of synthetic mannose 6-phosphate (M6P) or engineered bispecific antibodies. Currently, recombinant antibodies cannot be produced with naturally phosphorylated N-glycans. Here, we report the development of a novel platform technology for producing bifunctional therapeutic antibodies with high levels of M6P-bearing glycans directly from producing cells. The antibodies designated as phosphorylated N-glycosylated peptide chimeric antibodies (PNCA) maintain their affinity for antigens with concurrent high affinity binding to cell surface cation-independent mannose-6-phosphate receptors that facilitate internalization and delivery of antibody/antigen complexes to lysosomes for efficient degradation of both target extracellular soluble and membrane proteins. This PNCA approach provides a simple, scalable, and viable approach for producing naturally phosphorylated bifunctional antibodies from production cell lines for targeted protein degradation in lysosomes.

biochemistry↗

bioRxiv2024

Natural genetic and transcriptomic variation in photosynthesis associated pathways contribute to adaptive traits variation in worldwide Arabidopsis thaliana population

Photosynthesis is the most important reaction underlying carbon fixation. Despite its potential in boosting carbon assimilation, nature variations underlying genes in photosynthesis pathway and their role in adaptive traits variation remains elusive. In this study, we investigated the genetic, transcriptomic variation of 1103 genes in photosynthesis associated pathways, including 82 photosynthesis core genes, 24 plastid-encoded RNA polymerase related genes, 2 nucleus-encoded RNA polymerase-related genes, 34 photomorphogenesis-related genes, 40 genes involved in transcription and translation (TAC) and 938 other nuclear-encoded chloroplast-targeted genes. By de novo assembling the chloroplast genomes of 28 representative accessions and leveraging whole-genome, transcriptome sequencing data from the 1001 Genome Project, we revealed extensive natural genetic and transcriptome variations these genes in worldwide Arabidopsis thaliana population. 34.0% of them were identified with regulatory variations in expression quantitative locus mapping (eQTL) mapping, including key components of Rubisco (RBCS1B, RBCS2B), and Rubisco activase (RCA). Genome-wide and transcriptome-wide association analysis (GWAS/TWAS) showed that these genetic and transcriptomic variations made considerable contribution to variation of adaptive traits. Overall, our study provides insight into the natural genetic variation of these genes among worldwide Arabidopsis thaliana accessions and their role in complex traits variation and adaptation.

plant biology↗

bioRxiv2024

Identification of a new ORF3a-E fusion subgenomic RNA of SARS-CoV-2 and its biological features in the infection process

Subgenomic RNAs (sgRNAs) are discontinuous transcription products of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that are involved in viral gene expression and replication, but their exact functions are still being studied. Here, we report the identification of a new type of sgRNA, the fusion ORF3a-E-sgRNA, involved in the infection process of SARS-CoV-2. This sgRNA codes both ORF3a and E and can be detected throughout the viral life cycle in SARS-CoV-2-infected cells with high copy numbers. ORF3a-E-sgRNA guides more ORF3a translation and promotes the expression of cellular ribosomal protein S3 (RPS3) and the binding of eukaryotic translation initiation factor 4E (eIF4E). Single-cell sequencing of a SARS-CoV-2-infected human bronchial epithelial cell line (16HBE) revealed that maintenance of this stable translational environment by ORF3a-E-sgRNA is important for the SARS-CoV-2 assembly and release capabilities and is also beneficial for viral evasion of host innate immunity. More importantly, the transcription level of ORF3a-E-sgRNA contributes to differences in infection processes between the Wuhan strain and XBB strain of SARS-CoV-2.

microbiology↗

bioRxiv2024

Pipeline for Assessing Tumor Immune Status Using Superplex Immunostaining and Spatial Immune Interaction Analysis

The characteristics of the tumor microenvironment (TME) are closely linked to tumor progression and treatment response. The TME comprises various cell types, their spatial distribution, cell-cell interactions, and their organization into cellular niches or neighborhoods. To capture this complexity, several spatial profiling technologies have been developed. However, challenges such as low throughput, high costs, and complicated data analysis have limited their widespread use in immune research. In this study, we introduce the Cyclic-multiplex TSA (CmTSA) staining platform, a high-throughput superplex staining technology based on tyramide signal amplification (TSA) immunostaining combined with an efficient fluorophore recycling method. The CmTSA platform allows for the labeling of 30-60 antigens across multiple parallel formalin-fixed paraffin-embedded (FFPE) slides. Furthermore, the automated CmTSA workflow requires only standard histological equipment and conventional immunohistochemistry (IHC) primary antibodies (Abs), significantly reducing costs. While the superplex images produced contain extensive multidimensional information, extracting the spatial features of the TME from raw pixel data can be challenging. To address this, we present a computer vision-based analysis pipeline, which begins with deep learning-based algorithms to segment individual cells and identify cell types based on defined annotation rules. It then evaluates the spatial distribution tendencies of each cell type, the interaction intensity between paired cells, and the multicellular functional niches. This comprehensive approach enables researchers to visualize and quantify the types, states, and levels of immune activities within the TME effectively, advancing tumor immunology research and precision immune medicine.

cancer biology↗

bioRxiv2024

SIRT5-mediated GLS and GDH desuccinylation attenuates autophagy in MAC-T cells induced by ammonia

Our previous research revealed that NH3 regulated autophagy dependent on SIRT5 in MAC-T cells. Interestingly, SIRT5 reduced the content of NH3 and glutamate by inhibiting GLS activity, ADP/ATP value also declined. In this study, SIRT5 interacted with endogenous GLS and GDH, and had no effect on endogenous GLS and GDH expression. SIRT5 declined significantly the succinylation levels of GLS and GDH, and further reduced the enzymatic activity of GLS and GDH. SIRT5 declined the glutamine metabolism, which attenuated ammonia release in MAC-T cells, accompanying with cellular autophagy decline, reducing the formation of autophagosome. Deletion of SIRT5 increased the content of NH3 and glutamate, as well as promotes autophagy, which could be alleviated by SIRT5 overexpression. SIRT5 KO was associated with increased succinylation and activity of GLS and GDH, as well as autophagy response in MAC-T cells. Furthermore, SIRT5 promoted the maintenance of mitochondria homeostasis. Mechanistically, SIRT5 modulated the succinylation levels and enzymatic activities of GLS and GDH in mitochondria and promoted the maintenance of mitochondria homeostasis, further attenuating ammonia-stimulated autophagy in MAC-T cells. HighlightsO_LISIRT5 catalyzed lysine desuccinylation of GLS and GDH. C_LIO_LIGLS and GDH enzymatic activity were enhanced by lysine succinylation. C_LIO_LIGLS and GDH were required for SIRT5 to regulate ammonia-induced cellular autophagy. C_LIO_LISIRT5 promoted the maintenance of mitochondrial homeostasis C_LI

physiology↗

bioRxiv2024

A single-molecule nanopore sequencing platform

Nanopore sequencing, a third-generation sequencing technology, has revolutionized the gene sequencing industry with its advantages of long reads, fast speed, real-time sequencing and analysis, and potential in detecting base modifications. This technology allows researchers to sequence longer DNA fragments in a single read, providing more comprehensive genomic information compared to previous methods. Nanopore sequencing operates on electrical signals generated by a nanopore embedded in a membrane separating two electrolyte-filled chambers. When single-stranded DNA (ssDNA) passes through the nanopore, it creates variations in the current that correspond to different DNA bases. By analyzing these current fluctuations with machine learning algorithms, the DNA sequence can be determined. In this study, we introduced several improvements to nanopore sequencing, including nanopore local chemistry sequencing, novel motor and pore proteins, chip design, and basecalling algorithms. Our new nanopore sequencing platform, CycloneSEQ, demonstrated long-duration sequencing (107 hours) on a single chip with high yield (>50 Gb). In human genomic DNA sequencing, CycloneSEQ was able to produce long reads with N50 33.6 kb and modal identity 97.0%. Preliminary findings on human whole-genome de novo assembly, variant calling, metagenomics sequencing, and single-cell RNA sequencing have further highlighted CycloneSEQs potential across different areas of genomics.

genomics↗

bioRxiv2024

Three-dimension transcriptomics maps of whole mouse embryo during organogenesis

Understanding mammalian development heavily relies on classical animal models like the house mouse (Mus musculus). Advanced spatial transcriptomics has enabled biologists to break new ground in studies of molecular dynamics and cellular patterning during embryonic development with spatiotemporal resolution. To construct a comprehensive developmental trajectory, current three-dimensional (3D) spatial transcriptomic profiling leverages mouse embryos from gastrulation (E5.5) to organogenesis (E13.5) in continuity. However, a crucial phase for early organogenesis between E9.5 and E11.5 was deficient. To unveil the mystery of this stage, we present the 3D transcriptomics of mouse embryos at E9.5 and E11.5, with a widely applicable reconstruction workflow that bypasses sophisticated bioinformatic calculations. As our 3D atlas is generated at single-cell resolution, we demonstrate how organogenetic processes can be interpreted at different levels of granularity, from local cellular interactions to whole embryonic regionalization. We release the open-access database MOSTA3D (Mouse Organogenesis Spatiotemporal Transcriptomic Atlas in Three-dimensional) and hope a broader community will contribute to extending this framework from conception to senility in the near future.

developmental biology↗

bioRxiv2024

The danger zone: the joint trap of incomplete lineage sorting and long-branch attraction in placing Rafflesiaceae

Two key factors have been implicated as major impediments to phylogenomic inference: incomplete lineage sorting (ILS)--especially in cases where clades are in the so-called anomaly zone--and erroneous gene tree estimation--commonly manifested by long- branch attraction in the Felsenstein zone. Rafflesiaceae (Malpighiales) is an iconic parasitic plant clade whose species occur west of Wallaces line in tropical Southeast Asia. This clade has been notoriously difficult to place phylogenetically and is nested within an explosive ancient radiation, rendering the Malpighiales one of the thorniest nodes across the angiosperm Tree of Life. The parasitic family Apodanthaceae has recently been positioned as sister to Rafflesiaceae, offering the hope to stabilize their placements. Here, using a dataset of 2,135 genes and complex species tree inference methods, the monophyletic Rafflesiaceae+Apodanthaceae clade is variously placed with Euphorbiaceae, Peraceae, Putranjivaceae, and Pandaceae. Such unstable placements appear to be the result of excessive levels of rate heterogeneity and ILS, which contribute to a phylogenetic "danger zone" where simulation suggests that current methods and genomic data will never provide a tidy phylogenetic resolution for species trees alike. Despite the topological uncertainty, however, our divergence time estimation identifies a mid-Cretaceous origin of stem group Rafflesiaceae and Apodanthaceae, not only making them the oldest parasitic plant lineage reported to date, but also suggests a likely Gondwana vicariance scenario to explain their disjunct distribution in South America, Africa, Australia, and Northern India.

evolutionary biology↗

bioRxiv2024

CD131 Contributes to Ulcerative Colitis Pathogenesis by Promoting Macrophage Infiltration

BackgroundUlcerative colitis (UC) is a group of chronic inflammatory bowel disease (IBD) mainly affecting the colon. The exact etiology of ulcerative colitis remains elusive. CD131 is a receptor subunit mediating the effects of hematopoietic growth factors GM-CSF and IL-3, which regulate various inflammatory responses. The pleiotropic effects of the cytokines on intestinal inflammation suggest that additional factors influence their overall function, where the receptor may play a role. MethodsIn the present study, we investigated the role of CD131 in the pathogenesis of ulcerative colitis, with the use of murine colitis model established by administration of DSS in the drinking water. ResultsBy comparing the immune and inflammatory responses between wt and CD131-deficient mice, we found that CD131 contributed to DSS-induced murine colitis, which functioned in synergy with tissue- infiltrating macrophages. Besides, CD131 may have promoted the chemotaxis of macrophages and T cells into the colon through CCL4. In addition, we analyzed clinical data and pathology specimens from ulcerative colitis patients and found that CD131 was associated with the endoscopic and pathological severity of intestinal inflammation. ConclusionsThe present study provides a novel way to the understanding of the mechanisms of GM-CSF and IL-3 effects in the intestine, which will benefit the development of therapeutic approaches.

immunology↗

bioRxiv2024

SARM1 orthosteric base exchange inhibitors cause subinhibitory SARM1 activation

SARM1, an octameric NADase, is a key regulator of axon degeneration and an emerging target in small molecule drug discovery to treat a wide range of neurodegenerative diseases. Recently, a structurally diverse series of adduct-forming, orthosteric SARM1 inhibitors have been discovered. Here, we show that subinhibitory concentrations of these orthosteric inhibitors, under mildly SARM1 activating conditions, cause sustained SARM1 activation. This synergistic adverse effect leads to increased nicotinamide adenine dinucleotide (NAD) consumption, neurodegeneration and release of the biomarker neurofilament-light (NfL) in cultured cortical neurons. In two distinct animal models, we found that low-dose treatment with these orthosteric SARM1 inhibitors results in increased plasma NfL and adverse events when combined with cellular stress or injury conditions. This may present a critical liability for orthosteric SARM1 inhibitors in certain patient populations.

neuroscience↗

bioRxiv2024

Two TAL effectors of Xanthomonas citri pv. malvacearum target GhSWEET15 as the susceptibility genes for bacterial blight of cotton

Bacterial Blight of Cotton (BBC) caused by Xanthomonas citri pv. malvacearum (Xcm) is an important and destructive disease affecting cotton plants. Transcription activator-like effectors (TALEs) released by the pathogen regulate cotton resistance to the susceptibility. In this study, we sequenced the whole genome of Xcm Xss-V2-18 and identified eight tal genes; seven on the plasmids and one on the chromosome. Deletion and complementation experiments of Xss-V2-18 tal genes demonstrated that Tal1b is required for full virulence on cotton. Transcriptome profiling coupled with TALE-binding element prediction revealed that Tal1b targets GhSWEET15A04/D04 and GhSWEET15D02 simultaneously. Expression analysis confirmed the independent inducibility of GhSWEET15A04/D04 and GhSWEET15D02 by Tal1b, whereas GhSWEET15A04/D04 is additionally targeted by Tal1. Moreover, GUS ({beta}-glucuronidase) and Xa10-mediated HR (hypersensitive response) assays indicated that the EBEs are required for the direct and specific activation of the candidate targets by Tal1 and Ta1b. These findings may advance our understanding of the dynamics between TALEs and EBEs, and decipher a simple and effective DNA-binding mechanism that could lead to the development of more efficient methods for gene editing and transgenic research.

pathology↗

bioRxiv2024

Transcriptional regulation of adipocyte lipolysis by IRF2BP2

Adipocyte lipolysis controls systemic energy levels and metabolic homeostasis. Lipolysis is regulated by post-translational modifications of key lipolytic enzymes. However, less is known about the transcriptional mechanisms that regulate lipolysis. Here, we identify the transcriptional factor interferon regulatory factor-2 binding protein 2 (IRF2BP2) as a repressor of adipocyte lipolysis. Deletion of IRF2BP2 in primary human adipocytes increases lipolysis without affecting glucose uptake, whereas IRF2BP2 overexpression decreases lipolysis. RNA-seq and ChIP-seq analyses reveal that IRF2BP2 directly represses several lipolysis-related genes, including LIPE (HSL, hormone sensitive lipase), which encodes the rate-limiting enzyme in lipolysis. Adipocyte-selective deletion of Irf2bp2 in mice increases Lipe expression and free fatty acid levels, resulting in elevated adipose tissue inflammation and glucose intolerance. Altogether, these findings demonstrate that IRF2BP2 restrains adipocyte lipolysis and opens new avenues to target lipolysis for the treatment of metabolic disease.

molecular biology↗

bioRxiv2024

Efficient generation of CAR NK cells from human umbilical cord blood CD34+ stem and progenitors for democratizing affordable immunotherapy

Chimeric antigen receptor (CAR) natural killer cells (CAR NK) cells, leveraging safety and not requiring HLA match in adoptive infusion, have emerged as promising alternative cells to CAR-T cells for immunotherapies. High and multiple doses of CAR NK cell infusions are essential to maintain therapeutic efficacy in clinical trials. This requires efficient methods for generating large-scale CAR NK cells and significantly reducing CAR engineering costs. In this study, we develop a three-step strategy to generate highly high yields of induced NK (iNK) and CAR iNK cells from human umbilical cord blood CD34+ hematopoietic stem and progenitor cells (CD34+ HSPCs). Starting from a single umbilical cord blood CD34+ HSPC, our reliable method efficiently produces 14-83 million mature iNK cells or 7-32 million CAR iNK cells with high expression levels of CD16 and zero T cell contaminations. Introducing CAR expression elements at the HSPC level reduces the quantities of CAR pseudoviruses to 1 / 140.000 - 1 / 600,000 compared to engineering CARs in mature NK cells. The iNK and CAR iNK cells, including fresh cells and thawed cells from cryopreserved conditions, demonstrate remarkable tumoricidal activities against various human cancer cells and significantly prolong the survival of human tumor-bearing animals. The high yields of CAR NK cells and negligible costs of CAR engineering of our method support the broad applications of CAR NK cells for treating cancer patients.

cell biology↗

bioRxiv2024

A nuclear RNA degradation code for eukaryotic transcriptome surveillance

The RNA exosome plays critical roles in eukaryotic RNA degradation, but it remains unclear how the exosome specifically recognizes its targets. The PAXT connection is an adaptor that recruits the exosome to polyadenylated RNAs in the nucleus, especially transcripts polyadenylated at intronic poly(A) sites. Here we show that PAXT-mediated RNA degradation is induced by the combination of a 5' splice site and a poly(A) junction, but not by either sequence alone. These sequences are bound by U1 snRNP and cleavage/polyadenylation factors, which in turn cooperatively recruit PAXT. As the 5' splice site-poly(A) junction combination is typically not found on correctly processed full-length RNAs, we propose that it functions as a "nuclear RNA degradation code" (NRDC). Importantly, disease-associated single nucleotide polymorphisms that create novel 5' splice sites in 3' untranslated regions can induce aberrant mRNA degradation via the NRDC mechanism. Together our study identified the first NRDC, revealed its recognition mechanism, and characterized its role in human diseases.

molecular biology↗

bioRxiv2024

Different Roles of D1/D2 Medium Spiny Neurons in the Nucleus Accumbens in Pair Bond Formation of Male Mandarin Voles

The mesolimbic dopamine (DA) system has been implicated in pair bond formation. However, involvements of DA release, real time activities, and electrophysiological activities of D1/D2 medium spiny neurons (MSNs) in the nucleus accumbens (NAc) shell in pair bonding remain unclear. This work verified that male mandarin voles after pair bonding released higher levels of DA in the NAc shell and displayed higher levels of D1 MSNs activity and lower levels of D2 MSNs activity upon sniffing their partners compared to upon sniffing an unknown female. Moreover, pair bonding induced differential alterations in both synaptic plasticity and neuronal intrinsic excitability in both D1 MSNs and D2 MSNs. In addition, chemogenetic inhibition of ventral pallidum (VP) -projecting D2 MSNs in the NAc shell enhanced pair bond formation, while chemogenetic activation of VP-projecting D2 MSNs in the NAc shell inhibited pair bond formation. These findings suggest that different neuronal activity of NAc shell D1 MSNs / D2 MSNs regulated by increasing DA release after pair bonding may be a neurobiological mechanism underlying pair bond formation.

neuroscience↗

bioRxiv2024

Promotion of RNF168-Mediated Nucleosomal H2A Ubiquitylation by Structurally-defined K63-Polyubiquitylated Linker Histone H1

The chemical synthesis of histones with homogeneous modifications is a potent approach for quantitatively deciphering the functional crosstalk between different post-translational modifications (PTMs). Here, we developed an expedient site-specific (poly)ubiquitylation strategy (CAEPL, Cysteine-Aminoethylation coupled with Enzymatic Protein Ligation), which integrates the Cys-aminoethylation reaction with the process of ubiquitin-activating enzyme UBA1-assisted native chemical ligation. Using this strategy, we successfully prepared monoubiquitylated and K63-linked di- and tri-ubiquitylated linker histone H1.0 proteins, which were incorporated into individual chromatosomes. Quantitative biochemical analysis of different RNF168 constructs on ubiquitylated chromatosomes with different ubiquitin lengths demonstrated that K63-linked polyubiquitylated H1.0 could directly stimulate RNF168 ubiquitylation activity by enhancing the affinity between RNF168 and chromatosome. Subsequent cryo-EM structural analysis of the RNF168/UbcH5c-Ub/H1.0-K63-Ub3 chromatosome complex revealed the potential recruitment orientation between RNF168 UDM1 domain and K63-linked ubiquitin chain on H1.0. Finally, we explored the impact of H1.0 ubiquitylation on RNF168 activity in the context of asymmetric H1.0-K63-Ub3 di-nucleosome substrate, revealing a comparable stimulation effect of both the inter- and intra-nucleosomal crosstalk. Overall, our study highlights the significance of access to structurally-defined polyubiquitylated H1.0 by CAEPL strategy, enabling in-depth mechanistic investigations of in-trans PTM crosstalk between linker histone H1.0 and core histone H2A ubiquitylation.

biochemistry↗