Biology subjects

Feng, Q.

Publications and source records attributed to Feng, Q..

At least 55 records · Page 3Linked to original sources

bioRxiv2023

GenBank genomics highlight the genomic features, genetic diversity and regulation of morphological, metabolic and disease-resistance traits in Nicotiana tabacum

Nicotiana tabacum is a model organism in plant molecular and pathogenic research and has significant potential in the production of biofuels and active pharmaceutical compounds in synthetic biology. Because of the large allotetraploid genome of tobacco, its genomic features, genetic diversity and genetic regulation of many complex traits remain unknown. In this study, we present a nearly complete chromosome-scale assembly of N. tabacum and provide evidence that homoeologous exchange between subgenomes and epigenetic remodelling are likely mechanisms of genome stabilization and subgenome coordination following polyploidization. By leveraging GenBank-scale sequencing and phenotyping data from 5196 lines, geography at the continent scale, rather than types assigned on the basis of curing crop practices, was found to be the most important correlate of genetic structure. Using 178 marker{square}trait associations detected in genome-wide association analysis, a reference genotype-to-phenotype map was built for 39 morphological, developmental, and disease-resistance traits. A novel gene, auxin response factor 9 (Arf9), associated with wider leaves after being knocked out, was fine-mapped to a single nucleotide polymorphism (SNP). This point mutation alters the translated amino acid from Ala203 to Pro203, likely preventing homodimer formation during DNA binding. Our analysis also revealed signatures of positive and polygenic selection for multiple traits during the process of selective breeding. Overall, this study demonstrated the power of leveraging GenBank genomics to gain insights into the genomic features, genetic diversity, and regulation of complex traits in N. tabacum, laying a foundation for future research on plant functional genomics, crop breeding, and the production of biopharmaceuticals and biofuels.

genetics↗

bioRxiv2023

DNA 5-methylcytosine regulates genome-wide formation of G-quadruplex structures

G-quadruplex structures (G4s) have been identified in genomes of multiple organisms and proven to play important epigenetic regulatory roles in various cellular functions. However, the G4 formation mechanism remains largely unknown. Here, we found a negative correlation between DNA 5mC methylation and G4 abundance. The abundance of genomic G4s significantly increased when the whole-genome methylation level was reduced in DNMT1-knockout cells. This increase was then suppressed by DNMT1 over-expression. And more G4s were detected in the hypomethylated cancer cell line HepG2 and rectal cancer tissues. Besides, 5mC modification significantly inhibited G4 formation of the potential G-quadruplex sequences (PQSs). The transcription of genes with 5mC modification sites in their promoter PQSs was affected after treatment with G4 stabilizer pyridostatin or methylation inhibitor 5-aza-dC. The global reduction of genomic methylation elevates gene transcription levels through increased G4s. Taken together, DNA 5mC methylation prevents PQSs from folding into G4s in genomes.

molecular biology↗

bioRxiv2022

Splicing quality control mediated by DHX15 and itsG-patch activator, SUGP1

Pre-mRNA splicing is surveilled at different stages by quality control (QC) mechanisms. The leukemia-associated DExH-box family helicase hDHX15/scPrp43, is known to disassemble spliceosomes after splicing. Here, using rapid protein depletion and analysis of nascent and mature RNA to enrich for direct effects, we identified a widespread splicing QC function for DHX15 in human cells, consistent with recent in vitro studies. We found that suboptimal introns with weak splice sites, multiple branch points, and cryptic introns are repressed by DHX15, suggesting a general role in promoting splicing fidelity. We identified SUGP1 as a G-patch factor that activates DHX15s splicing QC function. This interaction is dependent on both DHX15s ATPase activity and on SUGP1s ULM domain. Together, our results support a model in which DHX15 plays a major role in splicing QC when recruited and activated by SUGP1.

molecular biology↗

bioRxiv2022

Simulations reveal slow detachment and fast reattachment of kinesin and dynein in antagonistic pairs

Intracellular transport is propelled by kinesin and cytoplasmic dynein motors that carry membrane-bound vesicles and organelles bidirectionally along microtubule tracks. Much is known about these motors at the molecular scale, but many questions remain regarding how kinesin and dynein cooperate and compete during bidirectional cargo transport at the cellular level. The goal of the present study was to use a stochastic stepping model constructed by using published load-dependent properties of kinesin-1 and dynein-dynactin-BicD2 (DDB) to identify specific motor properties that determine the speed, directionality, and transport dynamics of a cargo carried by one kinesin and one dynein motor. Model performance was evaluated by comparing simulations to recently published experiments of kinesin-DDB pairs connected by complementary oligonucleotide linkers. Plotting the instantaneous velocity distributions from kinesin-DDB experiments revealed a single peak centered around zero velocity. In contrast, velocity distributions from simulations displayed a central peak around 100 nm/s, along with two side peaks corresponding to the unloaded kinesin and DDB velocities. We hypothesized that frequent motor detachment events and relatively slow motor reattachment rates resulted in periods in which only one motor is attached. To investigate this hypothesis, we varied specific model parameters and compared the resulting instantaneous velocity distributions, and we confirmed this systematic investigation using a machine learning approach that minimized the residual sum of squares between the experimental and simulation velocity distributions. The experimental data were best recapitulated by a model in which the kinesin and dynein stall forces are matched, motor detachment rates are independent of load, and the kinesin-1 reattachment rate is 50 s-1. These results provide new insights into motor dynamics during bidirectional transport and put forth hypotheses that can be tested by future experiments. Statement of significanceBidirectional transport of vesicles along microtubules is vital for cellular function, particularly in the highly elongated axons and dendrites of neurons, and transport defects are linked to neurodegenerative diseases. For developing future therapeutic strategies, a better understanding is needed for how motors, cargo adapters, and accessory proteins coordinate their activities to transport cargo to their proper cellular locations. We approached this problem by simulating how antagonistic kinesin and dynein motors compete in pairs. We constrain our simulations by recent experimental results and conclude that the motors spend nearly all their time attached to the microtubule and competing against one another. This behavior is not predicted by existing single-molecule experiments and thus provides new insights into bidirectional transport.

biophysics↗

bioRxiv2022

Kinesin-1, -2 and -3 motors use family-specific mechanochemical strategies to effectively compete with dynein during bidirectional transport

Bidirectional cargo transport in neurons requires competing activity of motors from the kinesin-1, -2 and -3 superfamilies against cytoplasmic dynein-1. Previous studies demonstrated that when kinesin-1 attached to dynein-dynactin-BicD2 (DDB) complex, the tethered motors move slowly with a slight plus-end bias, suggesting kinesin-1 overpowers DDB but DDB generates a substantial hindering load. Compared to kinesin-1, motors from the kinesin-2 and -3 families display a higher sensitivity to load in single-molecule assays and are thus predicted to be overpowered by dynein complexes in cargo transport. To test this prediction, we used a DNA scaffold to pair DDB with members of the kinesin-1, -2 and -3 families to recreate bidirectional transport in vitro, and tracked the motor pairs using two-channel TIRF microscopy. Unexpectedly, we find that when both kinesin and dynein are engaged and stepping on the microtubule, kinesin-1, -2, and -3 motors are able to effectively withstand hindering loads generated by DDB. Stochastic stepping simulations reveal that kinesin-2 and -3 motors compensate for their faster detachment rates under load with faster reattachment kinetics. The similar performance between the three kinesin transport families highlights how motor kinetics play critical roles in balancing forces between kinesin and dynein, and emphasizes the importance of motor regulation by cargo adaptors, regulatory proteins, and the microtubule track for tuning the speed and directionality of cargo transport in cells.

cell biology↗

bioRxiv2022

Full-length optic nerve regeneration in the absence of genetic manipulations

The inability of mature retinal ganglion cells (RGCs) to regenerate axons after optic nerve injury can be partially reversed by manipulating cell-autonomous and/or -non-autonomous factors, among which are neuroimmune interactions. We report here that preconditioning resulting from a mild lens injury (conditioning LI, cLI) prior to optic nerve damage induces far greater axon regeneration than LI or the pro-inflammatory agent zymosan after nerve injury or preconditioning with Zymosan. Unlike other instances of immune-supported regeneration, cLI is unaltered by depleting mature neutrophils, T cells or blocking receptors for identified inflammation-associated growth factors (Oncomodulin, SDF1, CCL5), and is only partially diminished by suppressing peripheral monocyte recruitment. Repeated LI leads to full-length optic nerve regeneration, and pharmacological removal of local resident macrophages with the colony stimulating factor 1 receptor (CSF-1R) inhibitor PLX5622 enables some axons to re-innervate the brain in just 6 weeks. Thus, cell non-autonomous interventions not involving genetic manipulations can induce high levels of optic nerve regeneration, paving the way to uncover potent, translatable therapeutic targets for CNS repair.

neuroscience↗

bioRxiv2022

Biochemical characterization of a Mycobacterium tuberculosis prolyl dipeptidyl peptidase that displays a remarkable thermostability

Dipeptidyl peptidases constitute a class of non-classical serine proteases that regulate an array of biological functions, making them pharmacologically attractive enzymes. With this work, we identified and characterized a dipeptidyl peptidase from Mycobacterium tuberculosis (MtDPP) displaying a strong preference for proline residues at the P1 substrate position and an unexpectedly high thermal stability. MtDPP was also characterized with alanine replacements of residues of its active site that yielded, for the most part, loss of catalysis. We show that MtDPP catalytic activity is inhibited by well-known human DPP4 inhibitors. Using MALDI-TOF mass spectrometry we also describe that in vitro, MtDPP mediates the truncation of the C-X-C motif chemokine ligand 10, indicating a plausible role in immune modulation for this mycobacterial enzyme.

biochemistry↗

bioRxiv2022

Regulation of protein translation by TRIM21

AbstractRegulation of translation initiation is essential for maintenance of protein homeostasis and typically involves the phosphorylation of translation initiation factor eIF2 in eukaryotes. In response to stressors, cells employ eIF2-dependent signaling to control translation initiation, which regulates multiple biological and physiological processes. However, the precise regulatory mechanism remains unclear. In this study, we focus on the role of TRIM21 in the regulation of protein translation mediated by protein kinase R (PKR), one of the classic kinases that phosphorylates eIF2. TRIM21 deficiency enhances the activation of PKR under different types of stress. TRIM21 interacts with PKR, and the E3 ligase activity of TRIM21 is crucial for stress-triggered PKR inactivation. TRIM21 interacts with the PKR phosphatase PP1 and promotes K6-linked polyubiquitination of PP1 under stresses. Ubiquitination of PP1 augments its interaction with PKR, causing PKR inactivation and subsequent dephosphorylation of eIF2, initiating protein synthesis. Moreover, TRIM21 constitutively restricts viral infection by reversing PKR-mediated inhibition of the protein synthesis of intrinsic antiviral genes. The TRIM21-PP1 axis acts as a newly discovered program that regulates PKR-associated protein synthesis and broadens our knowledge of antiviral genes. Moreover, TRIM21-mediated regulation of PKR activation provides evidence that TRIM21 may anticipate the interferon-dependent immunotherapy. Our study highlights the essential role of TRIM21 in regulating protein translation and may provide a novel target for the treatment of translation-associated diseases.

immunology↗

bioRxiv2022

An immune-lncRNA risk model to predict prognosis for patients with head and neck squamous cell carcinoma

Backgroundlong noncoding RNA (lncRNA) are closely correlated with the occurrence and development of tumors. The purpose of this research is to construct a risk model of immune-related lncRNAs that can be used for predicting the survival and prognosis of head and neck squamous cell carcinoma (HNSCC) patients and further exploring the immune function of immune-lncRNAs. Methodsobtained detailed transcriptional data and clinical information for 545 cases of HNSCC from The Cancer Genome Atlas (TCGA). Combined lncRNAs and the immune gene sets from the Molecular Signatures Database (MSigDB) were employed to construct co{square}expression networks, the significant correlation of immune-lncRNAs obtained from the results of Cox regression analysis were used to build the model. Survival analysis and QRT-PCR were used to confirm the expression of immune-lncRNAs and optimize the risk model. Then single-cell RNA Sequencing (scRNA-seq) dataset analysis of laryngeal squamous cell carcinoma (LSCC), co-expression analysis, correlation analysis and immunohistochemistry were used to explore the immune function of immune-lncRNAs. ResultsA total of 13 immune-lncRNAs including AC104083.1AC004148.2AL357033.4AC116914.2AC024075.1AC008115.3PCED1B-AS1RAB11B-AS1AC004687.1 AL450992.2EP300-AS1AC024075.2AC136475.2 were identified to construct the risk model. In this model, low-risk patients had higher overall survival (OS, P=1.923e-12, hazard ratio=2.104, 95% CI: 1.622-2.730). AC004687.1 and PCED1B-AS1 were overexpressed in T cells and were closely related to the genes encoding major histocompatibility complex II (MHC II) molecules. And the results of QRT-PCR and immunohistochemistry showed the expression significant positively correlated with HLA-DR which is one of the MHC II classical molecules. Conclusionthe immune-associated risk model constructed by 13 lncRNAs has good prognostic value for HNSCC. AC004687.1 and PCED1B-AS1 are significant correlating to clinical characteristics and MHC II, we provide a new insight into the immune function of lncRNAs.

bioinformatics↗

bioRxiv2022

The infiltration pattern of microenvironmental cells and different immune escape mechanisms in colorectal cancer

BackgroundThe tumour microenvironment (TME) plays a crucial role in tumour progression and metastasis. However, the infiltration pattern of TME cells in CRC samples and the immune escape mechanism underneath have not been studied sufficiently. MethodsTranscriptomic data from public datasets were retrieved online. In total, 1802 samples from the microarray dataset and 619 samples from the TCGA dataset were enrolled. The ssGSEA algorithm and unsupervised clustering were used for TME cells infiltration speculation and infiltration pattern recognition. ResultsCRC samples can be classified into three distinct TME cell subtypes. Subtype 1, the immune-active subtype, was characterised by high infiltration of activated adaptive immune cells. Subtype 2, the immune-desert subtype, featured high tumour purity and low infiltration of immune and stromal cells. And subtype 3, stroma-rich subtype, had high infiltration of stromal cells. The stroma-rich subtype conferred a significantly worse prognosis. Three subtypes had different immune escape mechanisms. The immune-active subtype has the highest immune checkpoint expression level. In comparison, the immune-desert subtype had the lowest immunogenicity and the defective antigen presentation. And the stroma-rich subtype lacked activated immune cells. ConclusionsDistinct TME cell subtypes and immune escape mechanisms may provide inspiration and direction for further researches on CRC immunotherapy.

cancer biology↗

bioRxiv2022

Autophagy promotes programmed cell death and corpse clearance in specific cell types of the Arabidopsis root cap

Autophagy is a conserved quality control pathway that mediates the degradation of unnecessary or dysfunctional cellular components by targeting them to the lysosomes or central vacuoles. Autophagy has been implicated in the regulation or execution of regulated cell death processes in a wide range of eukaryotes. However, its function in developmentally controlled programmed cell death (dPCD) in plants remains little studied and controversial. Here, we investigated the role of autophagy in dPCD using the Arabidopsis root cap as an accessible and genetically tractable model system. We show that autophagic flux is induced prior to dPCD execution in both root cap tissues, the columella and the lateral root cap (LRC), and impaired in autophagy-deficient mutants. These mutants show a strongly delayed cell death and an absence of corpse clearance in the columella during and after their shedding into the rhizosphere. However, autophagy deficiency does not affect dPCD execution or corpse clearance in LRC cells at the distal end of the root cap. Our results demonstrate that autophagy promotes dPCD in a highly cell-type specific manner, and present the root cap as a powerful model system to study organ-specific autophagy in vivo.

plant biology↗

bioRxiv2022

Construct a variable-length fragment library for de novo protein structure prediction

Although remarkable achievements, such as AlphaFold2, have been made in end-to-end structure prediction, fragment libraries remain essential for de novo protein structure prediction, which can help explore and understand the protein-folding mechanism. In this work, we developed a variable-length fragment library (VFlib). In VFlib, a master structure database was first constructed from the Protein Data Bank through sequence clustering. The Hidden Markov Model (HMM) profile of each protein in the master structure database was generated by HHsuite, and the secondary structure of each protein was calculated by DSSP. For the query sequence, the HMM-profile was first constructed. Then, variable-length fragments were retrieved from the master structure database through dynamically variable-length profile-profile comparison. A complete method for chopping the query HMM-profile during this process was proposed to obtain fragments with increased diversity. Finally, secondary structure information was used to further screen the retrieved fragments to generate the final fragment library of specific query sequence. The experimental results obtained with a set of 120 nonredundant proteins showed that the global precision and coverage of the fragment library generated by VFlib were 55.04% and 94.95% at the RMSD cutoff of 1.5 [A], respectively. Compared to the benchmark method of NNMake, the global precision of our fragment library had increased by 62.89% with equivalent coverage. Furthermore, the fragments generated by VFlib and NNMake were used to predict structure models through fragment assembly. Controlled experimental results demonstrated that the average TM-score of VFlib was 16.00% higher than that of NNMake.

bioinformatics↗

bioRxiv2021

A multi-layer functional genomic analysis to understand noncoding genetic variation in lipids

A major challenge of genome-wide association studies (GWAS) is to translate phenotypic associations into biological insights. Here, we integrate a large GWAS on blood lipids involving 1.6 million individuals from five ancestries with a wide array of functional genomic datasets to discover regulatory mechanisms underlying lipid associations. We first prioritize lipid-associated genes with expression quantitative trait locus (eQTL) colocalizations, and then add chromatin interaction data to narrow the search for functional genes. Polygenic enrichment analysis across 697 annotations from a host of tissues and cell types confirms the central role of the liver in lipid levels, and highlights the selective enrichment of adipose-specific chromatin marks in high-density lipoprotein cholesterol and triglycerides. Overlapping transcription factor (TF) binding sites with lipid-associated loci identifies TFs relevant in lipid biology. In addition, we present an integrative framework to prioritize causal variants at GWAS loci, producing a comprehensive list of candidate causal genes and variants with multiple layers of functional evidence. Two prioritized genes, CREBRF and RRBP1, show convergent evidence across functional datasets supporting their roles in lipid biology.

genomics↗

bioRxiv2021

CFIm25 regulates human stem cell function independently of its role in mRNA alternative polyadenylation

It has recently been shown that CFIm25, a canonical mRNA 3 processing factor, could play a variety of physiological roles through its molecular function in the regulation of mRNA alternative polyadenylation (APA). Here, we used CRISPR/Cas9-mediated gene editing approach in human embryonic stem cells (hESCs) for CFIm25, and obtained three gene knockdown/mutant cell lines. CFIm25 gene editing resulted in higher proliferation rate and impaired differentiation potential for hESCs, with these effects likely to be directly regulated by the target genes, including the pluripotency factor rex1. Mechanistically, we unexpected found that perturbation in CFIm25 gene expression did not significantly affect cellular mRNA 3 processing efficiency and APA profile. Rather, we provided evidences that CFIm25 may impact RNA polymerase II (RNAPII) occupancy at the body of transcribed genes, and promote the expression level of a group of transcripts associated with cellular proliferation and/or differentiation. Further study indicated that CFIm25 association with LEO1, an RNAPII associated factor, might contribute to the effect. Taken together, these results reveal novel mechanisms underlying CFIm25s modulation in determination of cell fate, and provide evidence that the process of mammalian gene transcription may be regulated by an mRNA 3 processing factor.

molecular biology↗

bioRxiv2021

Genome context influences evolutionary flexibility of nearly identical type III effectors in two phytopathogenic Pseudomonads

Integrative Conjugative Elements (ICEs) are replicons that can insert and excise from chromosomal locations in a site specific manner, can conjugate across strains, and which often carry a variety of genes useful for bacterial growth and survival under specific conditions. Although ICEs have been identified and vetted within certain clades of the agricultural pathogen Pseudomonas syringae, the impact of ICE carriage and transfer across the entire P. syringae species complex remains underexplored. Here we identify and vet an ICE (PmaICE-DQ) from P. syringae pv. maculicola ES4326, a strain commonly used for laboratory virulence experiments, demonstrate that this element can excise and conjugate across strains, and contains loci encoding multiple type III effector proteins. Moreover, genome context suggests that another ICE (PmaICE-AOAB) is highly similar in comparison with and found immediately adjacent to PmaICE-DQ within the chromosome of strain ES4326, and also contains multiple type III effectors. Lastly, we present passage data from in planta experiments that suggests that genomic plasticity associated with ICEs may enable strains to more rapidly lose type III effectors that trigger R-gene mediated resistance in comparison to strains where nearly isogenic effectors are not present in ICEs. Taken together, our study sheds light on a set of ICE elements from P. syringae pv. maculicola ES4326 and highlights how genomic context may lead to different evolutionary dynamics for shared virulence genes between strains.

microbiology↗

bioRxiv2021

Mitochondria transplantation between living cells

Mitochondria and the complex endomembrane system are hallmarks of eukaryotic cells. To date, it has been difficult to manipulate organelle structures within single live cells. We developed a FluidFM-based approach to extract, inject and transplant organelles from and into living cells with subcellular spatial resolution. The approach enabled the transfer of controlled quantities of mitochondria into cells while maintaining their viability and monitoring their fate in new host cells. Transplantation of healthy and drug-impaired mitochondria into primary keratinocytes allowed real-time tracking of mitochondrial subpopulation rescue. Fusion with the mitochondrial network of recipient cells occurred 20 min after transplantation and continued for over 16 hours. After transfer of mitochondria and cell propagation over generations, we show that donor mtDNA was replicated in recipient cells without the need for selection pressure. The approach opens new prospects for the study of organelle physiology and homeostasis, but also for mechanobiology, synthetic biology, and therapy.

cell biology↗

bioRxiv2021

OsMADS58 stabilizes gene regulatory circuits during rice stamen development

Rice (Oryza sativa) OsMADS58 is a C-class MADS box protein, and characterization of a transposon insertion mutant osmads58 suggested that OsMADS58 plays a role in stamen development. However, as no null mutation has been obtained, its role has remained unclear. Here, we report that the CRISPR knockout mutant osmads58 exhibits complex altered phenotypes, including anomalous diploid germ cell differentiation, aberrant meiosis, and delayed tapetum degeneration. This CRISPR mutant line exhibited stronger changes in expression of OsMADS58 target genes compared with the osmads58 dSpm (transposon insertion) line, along with changes in multiple pathways related to early stamen development. Notably, transcriptional regulatory circuits in young panicles covering the stamen at stages 4-6 were substantially altered in the CRISPR line compared to the dSpm line. These findings strongly suggest that the pleiotropic effects of OsMADS58 on stamen development derive from a potential role in stabilizing gene regulatory circuits during early stamen development. Thus, this work opens new avenues for viewing and deciphering the regulatory mechanisms of early stamen development from a network perspective.

plant biology↗

bioRxiv2021

Lactate Increases Stemness of CD8+ T Cells to Augment Anti-Tumor Immunity

Nutrients and metabolites play important roles in immune functions. Recent studies show lactate instead of glucose can serve as a primary carbon fuel source for most tissues. The role of lactate in tumor immunity is not well understood with immune suppressive functions reported for lactic acid, the conjugate acid form of lactate. In this study, we report lactate increases the stemness of CD8+ T cells and augments anti-tumor immunity. Subcutaneous administration of lactate but not glucose shows CD8+ T cell-dependent tumor growth inhibition. Single cell transcriptomics analysis revealed lactate treatment increased a subpopulation of stem-like TCF-1-expressing CD8+ T cells, which is further validated by ex vivo culture of CD8+ T cells from mouse splenocytes and human peripheral blood mononuclear cells. The inhibition of histone deacetylase activity by lactate increased acetylation in the histone H3K27 site at the Tcf7 super enhancer locus and increased the gene expression of Tcf7. Adoptive transfer of CD8+ T cells pretreated with lactate in vitro showed potent tumor growth inhibition in vivo. Our results elucidate the immune protective role of lactate in anti-tumor immunity without the masking effect of acid. These results may have broad implications for T cell therapy and the understanding of lactate in immune metabolism.

immunology↗