Biology subjects

Yuan, X.

Publications and source records attributed to Yuan, X..

At least 145 records · Page 8Linked to original sources

bioRxiv2020

Attention Modulates Automatic Movements

The majority of human behaviors are composed of automatic movements (e.g., walking or finger-tapping) which are learned during nurturing and can be performed simultaneously without interfering with other tasks. One critical and yet to be examined assumption is that the attention system has the innate capacity to modulate automatic movements. The present study tests this assumption. Setting no deliberate goals for movement, we required sixteen participants to perform personalized and well-practiced finger-tapping movements in three experiments while focusing their attention on either different component fingers or away from movements. Using cutting-edge pose estimation techniques to quantify tapping trajectory, we showed that attention to movement can disrupt movement automaticity, as indicated by decreased inter-finger and inter-trial temporal coherence; facilitate the attended and inhibit the unattended movements in terms of tapping amplitude; and re-organize the action sequence into distinctive patterns according to the focus of attention. These findings demonstrate compelling evidence that attention can modulate automatic movements and provide an empirical foundation for theories based on such modulation in controlling human behavior.

neuroscience↗

bioRxiv2020

Swine Promyelocytic Leukemia Isoform II Inhibits Pseudorabies Virus Infection by Suppressing Viral Gene Transcription in PML-NBs

Promyelocytic leukaemia nuclear bodies (PML-NBs) possess an important intrinsic antiviral activity against -herpesvirus infection. PML is the structural backbone of NBs, comprising different isoforms. However, the contribution of each isoform to -herpesvirus restriction is not well understood. Here, we report the role of PML-NBs and swine PML (sPML) isoforms in pseudorabies virus (PRV) infection in its natural host swine cells. We found that sPML-NBs exhibit an anti-PRV activity in the context of increasing the expression level of endogenous sPML. Of four sPML isoforms cloned and examined, only isoform sPML-II/IIa, not sPML-I and IVa, expressed in a sPML knockout cells inhibits PRV infection. Both the unique 7b region of sPML-II and sumoylation-dependent normal formation of PML-NBs are required. 7b possesses a transcriptional repression activity and suppresses viral gene transcription during PRV infection with the cysteine residue 589 and 599 being critically involved. We conclude that sPML-NBs inhibit PRV infection by repressing viral gene transcription through the 7b region of sPML-II. IMPORTANCEPML-NBs are nuclear sites that mediate the antiviral restriction of -herpesvirus gene expression and replication. However, the contrition of each PML isoform to this activity of PML-NBs is not well characterized. Using PRV and its natural host swine cells as a system, we have discovered that the unique C-terminus of sPML isoform II is required for PML-NBs to inhibit PRV infection by directly engaging in repression of viral gene transcription. Our study not only confirms in swine cells that PML-NBs have an anti-viral function, but also presents a mechanism to suggest that PML-NBs inhibit viral infection in an isoform specific manner.

immunology↗

bioRxiv2020

Aberrant sorting of hippocampal complex pyramidal cells in Type I Lissencephaly alters topological innervation

Layering has been a long-appreciated feature of higher order mammalian brain structures but the extent to which it plays an instructive role in synaptic specification remains unknown. Here we examine the formation of synaptic circuitry under cellular heterotopia in hippocampal CA1, using a mouse model of the human neurodevelopmental disorder Type I Lissencephaly. We identify calbindin-expressing principal cells which are mispositioned under cellular heterotopia. Ectopic calbindin-expressing principal cells develop relatively normal morphological features and stunted intrinsic physiological features. Regarding network development, a connectivity preference for cholecystokinin-expressing interneurons to target calbindin expressing principal cells is diminished. Moreover, in vitro gamma oscillatory activity is less synchronous across heterotopic bands and mutants are less responsive to pharmacological antagonism of cholecystokinin-containing interneurons. This study will aid not only in our understanding of how cellular networks form but highlight vulnerable cellular circuit motifs that might be generalized across disease states.

neuroscience↗

bioRxiv2020

Identification of CDH11 as an ASD risk gene by matched-gene co-expression analysis and mouse behavioral studies

A large number of putative risk genes of autism spectrum disorder (ASD) have been reported. The functions of most of these susceptibility genes in developing brains remain unknown, and a causal relationship between their variations and autism traits has not been established. The aim of this study is to predict putative risk genes at the whole-genome level based on the analysis of gene co-expression with a group of high confidence ASD risk genes (hcASDs). Results showed that three gene features, including gene size, mRNA abundance, and guanine-cytosine content, affect genome-wide co-expression profiles of hcASDs. To circumvent the interference of these gene features on gene co-expression analysis (GCA), we developed a method to determine whether a gene is significantly co-expressed with hcASDs by statistically comparing the co-expression profile of this gene with hcASDs to that of this gene with permuted gene sets of feature-matched genes. This method is referred to as "matched-gene co-expression analysis" (MGCA). With MGCA, we demonstrated the convergence in developmental expression profiles of hcASDs and improved the efficacy of risk gene prediction. Results of analysis of two recently reported ASD candidate genes, CDH11 and CDH9, suggested the involvement of CDH11, but not CDH9, in ASD. Consistent with this prediction, behavioral studies showed that Cdh11-null mice, but not Cdh9-null mice, have multiple autism-like behavioral alterations. This study highlighted the power of MGCA in revealing ASD-associated genes and the potential role of CDH11 in ASD.

neuroscience↗

bioRxiv2019

Viral manipulation of functionally distinct neurons from mice to humans

Recent success in identifying gene regulatory elements in the context of recombinant adeno-associated virus vectors have enabled cell type-restricted gene expression. However, within the cerebral cortex these tools are presently limited to broad classes of neurons. To overcome this limitation, we developed a strategy that led to the identification of multiple novel enhancers to target functionally distinct neuronal subtypes. By investigating the regulatory landscape of the disease gene Scn1a, we identified enhancers that target the breadth of its expression, including two that are selective for parvalbumin and vasoactive intestinal peptide cortical interneurons. Demonstrating the functional utility of these elements, we found that the PV-specific enhancer allowed for the selective targeting and manipulation of these neurons across species, from mice to humans. Finally, we demonstrate that our selection method is generalizable to other genes and characterize four additional PV-specific enhancers with exquisite specificity for distinct regions of the brain. Altogether, these viral tools can be used for cell-type specific circuit manipulation and hold considerable promise for use in therapeutic interventions.

neuroscience↗

bioRxiv2019

LncRNA MIR4435-2HG mediates cisplatin resistance in HCT116 cells by regulating Nrf2 and HO-1

PURPOSECisplatin resistance is still a serious problem in clinic. However, the underlying mechanism remains unclear. In this study investigated the drug resistance of cisplatin by the cisplatin resistance cell line HCT116R.\n\nRESULTSIn this study, we found that LncRNA MIR4435-2HG level dramatically increased in the cisplatin resistance cell line HCT116R. Knockdown of MIR4435-2HG in HCR116R significantly restored the sensitivity to cisplatin, inhibited cell proliferation and promoted cell apoptosis. Furthermore, Nrf2 and HO-1 mRNA level, as the critical molecular of the oxidative stress pathway, was inhibited by the siRNA targeting to MIR4435-2HG, displaying MIR4435-2HG-mediated cisplatin resistance through the Nrf2/HO-1 pathway.\n\nCONCLUSIONOur findings demonstrated that LncRNA MIR4435-2HG as a main factor could drive the cisplatin resistance of HCT116.

cancer biology↗

bioRxiv2019

2D-HELS-AA MS Seq: Direct sequencing of tRNA reveals its different isoforms and multiple dynamic base modifications

We report a direct method for sequencing tRNAPhe without cDNA by combining 2-dimensional hydrophobic RNA end-labeling with an anchor-based algorithm in mass spectrometry-based sequencing (2D-HELS-AA MS Seq). The entire tRNAPhe was sequenced and the identity, location and abundance of all 11 base modifications were determined. Changes in ratios of wybutosine and its depurinated form under different conditions were quantified, pointing to the ability of our technology to determine dynamic changes of nucleotide modifications. Two truncated isoforms at 3CCA tail of the tRNAPhe (75 nt CC, 80% and 74 nt C, 3%) were identified in addition to the 76 nt tRNAPhe with a full-length 3CCA tail (17%). We also discovered a new isoform with A-G transitions at both the 44 and 45 positions in the tRNAPhe variable loop.\n\nOne Sentence SummaryDirect 2D-HELS-AA MS Seq of tRNA reveals different isoforms and base modifications

biochemistry↗

bioRxiv2019

A general LC/MS-based RNA sequencing method for direct analysis of multiple-base modifications in RNA mixtures

A complete understanding of the structural and functional potential of RNA requires understanding of chemical modifications and noncanonical bases; this in turn requires advances in current sequencing methods to be able to sequence not only canonical ribonucleotides, but at the same time directly sequence these nonstandard moieties. Here, we present the first direct and modification type-independent RNA sequencing method via integration of a hydrophobic end-labeling strategy with of 2-D mass-retention time LC/MS analysis to allow de novo sequencing of RNA mixtures and enhance sample usage efficiency. Our method can directly read out the complete sequence, while identifying, locating, and quantifying base modifications accurately in both single and mixed RNA samples containing multiple different modifications at single-base resolution. Our method can also quantify stoichiometry/percentage of modified RNA vs. its canonical counterpart RNA, simulating a real biological sample where modifications exist but may not be 100% at a particular site of the RNA. This method is a critical step towards fully sequencing real complex cellular RNA samples of any type and containing any modification types and can also be used in the quality control of modified therapeutic RNAs.

biochemistry↗

bioRxiv2019

Hemozoin produced by mammals confers heme tolerance

Free heme is cytotoxic as exemplified by hemolytic diseases and genetic deficiencies in heme recycling and detoxifying pathways. Thus, intracellular accumulation of heme has not been observed in mammalian cells to date. Here we show that mice deficient for the heme transporter HRG1 accumulate over ten-fold excess heme in reticuloendothelial macrophage lysosomes that are 10 to 100 times larger than normal. Macrophages tolerate these high concentrations of heme by polymerizing them into crystalline hemozoin, which heretofore has only been found in blood-feeding parasites. HRG1 deficiency results in impaired erythroid maturation and an inability to systemically respond to iron deficiency. Complete heme tolerance requires a fully-operational heme degradation pathway as haploinsufficiency of HMOX1 combined with HRG1 inactivation causes perinatal lethality demonstrating synthetic lethal interactions between heme transport and degradation. Our studies establish the formation of hemozoin by mammals as a previously unsuspected heme tolerance pathway.

pathology↗

bioRxiv2019

A Cys2/His2 zinc finger protein acts as a repressor of gibberellins biosynthesis by regulating SD1/OsGA20ox2 in rice (Oryza sativa L.)

Gibberellins (GAs) play important roles in the regulation of plant growth and development. The green evolution gene SD1 encoding gibberellin 20-oxidase 2 (GA20ox2) has been widely used in modern rice breeding. However, the molecular mechanism of how SD1/OsGA20ox2 expression is regulated remains unclear. Here we report a Cys2/His2 zinc finger protein ZFP207 acting as a transcriptional repressor of OsGA20ox2. ZFP207 was mainly accumulated in young tissues and more specifically in culm nodes. ZFP207-overexpression (ZFP207OE) plants displayed semi-dwarfism phenotype and small grains by modulating cell length. RNA interference of ZFP207 caused higher plant and longer grains. The endogenous bioactive GA levels were significantly reduced in ZFP207OE plants and application of exogenous GA3 rescued the semi-dwarf phenotype. The in vivo and in vitro studies showed that ZFP207 repressed the expression of OsGA20ox2 via binding to its promoter region. Together, ZFP207 acts as a transcriptional repressor of gibberellins biosynthesis and it may play a critical role in plant growth and development through fine-tuning GA biosynthesis in rice.

molecular biology↗

bioRxiv2019

A Pandas complex adapted for piRNA-guided transposon silencing

The repression of transposons by the Piwi-interacting RNA (piRNA) pathway is essential to protect animal germ cells. In Drosophila ovaries, Panoramix (Panx) enforces transcriptional silencing by binding to the target-engaged Piwi-piRNA complex, although the precise mechanisms by which this occurs remain elusive. Here, we show that Panx functions together with a germline specific paralogue of a nuclear export factor, dNxf2, and its cofactor dNxt1 (p15), as a ternary complex to suppress transposon expression. Structural and functional analyses demonstrate that dNxf2 binds Panx via its UBA domain, which plays an important role in transposon silencing. Unexpectedly, dNxf2 interacts directly with dNxf1 (TAP), a general nuclear export factor. As a result, dNxf2 prevents dNxf1 from binding to the FG repeats of the nuclear pore complex, a process required for proper RNA export. Transient tethering of dNxf2 to nascent transcripts leads to their nuclear retention. Therefore, we propose that dNxf2 may function as a Pandas (Panoramix-dNxf2 dependent TAP/p15 silencing) complex, which counteracts the canonical RNA exporting machinery and restricts transposons to the nuclear peripheries. Our findings may have broader implications for understanding how RNA metabolism modulates epigenetic gene silencing and heterochromatin formation.

molecular biology↗

bioRxiv2019

Cell-length heterogeneity: a population-level solution to growth/virulence trade-offs in the plant pathogen Dickeya dadantii

Necrotrophic plant pathogens acquire nutrients from dead plant cells, which requires the disintegration of the plant cell wall and tissue structures by the pathogen. Infected plants lose tissue integrity and functional immunity as a result, exposing the nutrient rich, decayed tissues to the environment. One challenge for the necrotrophs to successfully cause secondary infection (infection spread from an initially infected plant to the nearby uninfected plants) is to effectively utilize nutrients released from hosts towards building up a large population before other saprophytes come. In this study, we observed that the necrotrophic pathogen Dickeya dadantii exhibited heterogeneity in bacterial cell length in an isogenic population during infection of potato tuber. While some cells were regular rod-shape (<10m), the rest elongated into filamentous cells (>10m). Short cells tended to occur at the interface of healthy and diseased tissues, during the early stage of infection when active attacking and killing is occurring, while filamentous cells tended to form when large amount of nutrients were released at a later stage of infection. Short cells expressed all necessary virulence factors and motility, whereas filamentous cells did not engage in virulence, were non-mobile and more sensitive to environmental stress. However, compared to the short cells, the filamentous cells displayed elevated metabolism and faster growth, which may benefit the pathogens to build up a large population necessary for the secondary infection. The segregation of the two subpopulations was dependent on differential expression of the alarmone guanosine tetraphosphate (ppGpp). When exposed to fresh tuber tissues or freestanding water, filamentous cells quickly transformed to short virulent cells. The pathogen adaptation of cell length heterogeneity identified in this study presents a model for how some necrotrophs balance virulence and vegetative growth to maximize fitness during infection.

microbiology↗

bioRxiv2019

Spread of pathological α-synuclein from urogenital nerves initiates multiple system atrophy-like symptoms

Multiple system atrophy (MSA) is a fatal adult-onset movement disorder with autonomic failures, especially urogenital dysfunction. The neuropathological feature of MSA is the accumulation of misfolded -synuclein (-Syn) in the nervous system. Here, we show that misfolded -Syn exist in nerve terminals in detrusor (DET) and external urethral sphincter (EUS) of patients with MSA. Moreover, -Syn preformed fibrils inoculated into the EUS or DET in TgM83+/- mice initiated the transmission of misfolded -Syn from the lower urinary tract to brain, and these mice developed -Syn inclusion pathology through micturition reflex pathways along with urinary dysfunction and motor impairments. These findings indicate that spreading of misfolded -Syn from the autonomic control of the lower urinary tract to the brain via micturition reflex pathways induces autonomic failure and motor impairments. These results provide important new insights into the pathogenesis of MSA as well as highlight potential targets for early detection and therapeutics.

neuroscience↗

bioRxiv2018

The biochemical properties of a novel paraoxonase-like enzyme in Trichoderma atroviride strain T23 involved in the degradation of 2,2-dichlorovinyl dimethyl phosphate

Dichlorvos, is a broad-spectrum organophosphorus pesticide that is widely applied in the agricultural industry and considered a pollutant to fish and bees. T. atroviride strain T23, an efficient DDVP-degrading strain, could convert DDVP to dichloroacetic acid, 2,2-dichloroethanol and phosphoric acid through mineralization. RT-qPCR analysis showed TaPon1-like encoding an organophosphorus hydrolase, is continuously highly expressed in the process of degrading DDVP. TaPon1-like contained an open reading frame of 1317 bp, and the deduced amino acid sequence shared 21% homology with HuPON1, which also exhibits excellent hydrolysis of organophosphate-oxons compounds. By analysis of gene knockout, we found the {Delta}TaPon1-like knockout strain KO1 lost 35.6% of its DDVP-degradation capacity at 24 h, but this loss of degradation activity was recovered when the gene was complemented. Furthermore, the purified recombinant protein reTAPON1-LIKE, could transform DDVP only to dimethyl phosphate and showed significant paraoxonase activity (1028 U L-1). The reTAPON1-LIKE enzyme showed a broad degradation spectrum, degrading not only DDVP but also organophosphate-oxons and lactone. The kinetic parameters (Km and kcat) of the purified reTAPON1-LIKE were determined to be 0.23 mM and 204.3 s-1 for DDVP, respectively. The highest activity was obtained at 35 {degrees}C, and the optimal pH was 8.5. The activity of reTAPON1-LIKE was enhanced most significantly when 1.0 mM Ca2+ was added but declined when 1.0 mM Cu2+ was added. These results showed TAPON1-LIKE play an important role for DDVP degradation in the first step by T23 and provided clue to comprehensively understanding the degradation mechanism of organophosphate-oxons pesticides by filamentous fungi.\n\nImportanceThe large amounts of residues of organophosphate pesticides in agroecological system has become a great threat to the safety of environment and humans. Bioremediation in association with microbial is innovative technology having a potential to alleviate such pollution problems. The genus Trichoderma is genetically diverse with capabilities to degrade chemical pesticides among different strains with agricultural significance. As a typical organophosphorus pesticide, it is one of the most employed compounds of the family. Though it was classified as a highly toxic pesticide by WHO due to its hazardous properties, it plays an important role in the control of plant pests, food storage and homes, as well as to treat infections in livestock. Therefore, we use DDVP as a model of organophosphate pesticide to study the mechanism of Trichoderma degrading organophosphate pesticides, for the aim of globally understanding molecular mechanism of enzymatic degradation of organophosphate pesticides by beneficial fungi.

microbiology↗

bioRxiv2018

Diagnostic Whole Exome Sequencing in Patients with Short Stature

Short stature is among the most common reasons for children being referred to the pediatric endocrinology clinics. The cause of short stature is broad, in which genetic factors play a substantial role, especially in primary growth disorders. However, identifying the molecular causes for short stature remains as a challenge because of the high heterogeneity of the phenotypes. Here, whole exome sequencing (WES) was used to identify the genetic causes of short stature with unknown etiology for 20 patients aged from 1 to 16 years old. The genetic causes of short stature were identified in 9 of the 20 patients, corresponding to a molecular diagnostic rate of 45%. Notably, in 2 of the 9 patients identified with genetic causes, the diagnosed diseases based on WES are different from the original clinical diagnosis. Our results highlight the clinical utility of WES in the diagnosis of rare, high heterogeneity disorders.

genetics↗

bioRxiv2018

Cyclin B3 is specifically required for metaphase to anaphase transition in mouse oocyte meiosis I

Meiosis, a cell division to generate gametes for sexual reproduction in eukaryotes, executes a single round of DNA replication and two successive rounds of chromosome segregation [1]. The extraordinary reliability of the meiotic cycle requires the activities of cyclin-dependent kinases (Cdks) associated with specific cyclins [2-4]. Cyclins are the regulatory subunits of protein kinases, which are the main regulators of maturation promoting factor or mitosis promoting factor (MPF) [5, 6] and anaphase-promoting complex/cyclosome (APC/C) [7, 8] in eukaryotic cell division. But how cyclins collaborate to control meiosis is still largely unknown. Cyclin B3 (Ccnb3) shares homology with A- and B-type cyclins [9], and is conserved during higher eukaryote evolution [10-17]. Previous studies have shown that Ccnb3-deleted females are sterile with oocytes unable to complete meiosis I in Drosophila [18], implying that Ccnb3 may have a special role in meiosis. To clarify the function of Ccnb3 in meiosis in mammalian species, we generated Ccnb3 mutant mice by CRISPR/Cas9, and found that Ccnb3 mutation caused female infertility with the failure of metaphase-anaphase transition in meiosis I. Ccnb3 was necessary for APC/C activation to initiate anaphase I, but not required for oocytes maturation, meiosis II progression, or early embryonic development. Our study reveals the differential cell cycle regulation between meiosis I and meiosis II, as well as meiosis between males and females, which shed light on the cell cycle control of meiosis.\n\nHighlightsO_LIIdentification of a female meiosis-specific cyclin in mouse\nC_LIO_LICyclin B3 is required for metaphase-anaphase transition in oocyte meiosis I\nC_LIO_LICyclin B3 is not essential for oocyte maturation and sister chromosome segregation\nC_LIO_LICyclin B3 is necessary for APC/C activation and MPF kinase activity through Cdk1\nC_LI

cell biology↗

bioRxiv2018

Uric acid lowering treatment alleviates perivascular carotid collar placement induced neointimal lesions in Uricase knockout mice

Hyperuricemia (HU) is a cause of gout. Clinical studies show a link between HU and cardiovascular disease. However, the role of soluble serum urate on atherosclerosis development remains elusive. We aimed to use a new HU mouse model (Uricase/Uox knockout (KO)) to further investigate the relationship between HU and atherosclerosis. Mouse model of induced carotid atherosclerosis was established in the novel spontaneous HU Uox-KO mouse and their wild type littermates (C57BL/6J background). Mice were implanted with a perivascular collar placement around the right carotid artery in combination with a western-type diet. To investigate urate-lowering treatment (ULT) effects on intima, the mice were gavaged daily from the age of 6 weeks with allopurinol. Human umbilical vein endothelial cells (HUVECs) were co-incubated with soluble urate, with and without probenecid, to study the mechanism of urate-related atherosclerosis. The Uox-KO mice had significantly elevated serum urate levels combined with higher blood urea nitrogen and serum creatinine. Western blot analysis showed enhanced levels of atherosclerosis inflammatory response proteins. However, there were no other risk indicators for the pathogenesis of atherosclerosis, including increased fasting glucose, altered lipid and atherosclerosis characterized cardiovascular and histological manifestations. In contrast, collar placement Uox-KO mice showed severe neointimal changes in histology staining consistent with increases in intimal area and increases in proliferating cell nuclear antigen (PCNA) - and F4/80-positive cells. Allopurinol reduced neointimal areas induced by the perivascular collar in hyperuricemic mice accompanied by decreased expression of PCNA- and F4/80-positive cells (P< 0.05). ULT alleviated atherosclerosis inflammatory response factors and reactive oxygen species intensities in both collar placement Uox-KO mice and urate-stimulated HUVECs. In vitro results using HUVECs showed ROS was induced by urate and ROS induction was abrogated using antioxidants. These data demonstrate that urate per se does not trigger atherosclerosis intima lesions in mice. Urate worsens carotid neointimal lesions induced by the perivascular collar and urate-lowering therapy partially abrogates the effects. The current study warrants the further human based study on the possible benefits of urate-lowering therapy in atherosclerosis patients with HU.\n\nSummary statementWe generated a carotid collar placement atherosclerosis model in the novel spontaneous HU Uox-KO mouse and demonstrate that urate plays a contributing rather than a causal role in the carotid neointimal lesions, while urate-lowering treatment may bring additional benefits in this HU mouse model.

physiology↗

bioRxiv2018

PRL-1 is required for neuroprotection against olfactory CO2 stimulation in Drosophila

The Mammalian phosphatase of regenerating liver (PRL) family is primarily recognized for its oncogenic properties. Here we found that in Drosophila, loss of prl-1 resulted in CO2-induced brain disorder presented as irreversible wing hold up with enhancement of Ca2+ responses at the neuron synaptic terminals. Overexpression of Prl-1 in the nervous system could rescue the mutant phenotype. We show that Prl-1 is particularly expressed in CO2-responsive neural circuit and the higher brain centers. Ablation of the CO2 olfactory receptor, Gr21a, suppressed the mutant phenotype, suggesting that CO2 acts as a neuropathological substrate in absence of Prl-1. Further studies found that the wing hold up is an obvious consequence upon knockdown of Uex, a magnesium transporter, which directly interacts with Prl-1. Conditional expression of Uex in the nervous system could rescue the phenotype of prl-1 mutants. We demonstrate that Uex acts genetically downstream of Prl-1. Our findings provide important insights into mechanisms of Prl-1 protection against olfactory CO2 stimulation induced brain disorder at the level of detailed neural circuits and functional molecular connections.

neuroscience↗