Biology subjects

Zhang, T.

Publications and source records attributed to Zhang, T..

At least 613 records · Page 34Linked to original sources

bioRxiv2018

CDK12 loss in cancer cells affects DNA damage response genes through premature cleavage and polyadenylation

The cyclin-dependent kinase 12 (CDK12) modulates transcription elongation by phosphorylating the carboxy-terminal domain of RNA polymerase II and appears to selectively affect the expression of DNA damage response (DDR) and mRNA processing genes. Yet, the mechanism(s) by which it achieves this selectivity remains unclear. Using a highly selective CDK12/13 inhibitor, THZ531, and nascent RNA sequencing, we show that CDK12 inhibition results in gene length-dependent elongation defects, leading to premature cleavage and polyadenylation (PCPA) as well as loss of expression of long (>45 kb) genes, a substantial proportion of which participate in the DDR. This early termination phenotype correlated with an increased proportion of intronic polyadenylation sites, a feature that was especially prominent among DDR genes. Finally, phosphoproteomic analysis indicated that pre-mRNA processing factors, including those involved in PCPA, are direct phosphotargets of CDKs 12 and 13. These results support a model in which DDR genes are uniquely susceptible to CDK12 inhibition due primarily to their relatively longer lengths and lower ratios of U1 snRNP binding to intronic polyadenylation sites.

cancer biology↗

bioRxiv2018

Both Fallopian Tube and Ovarian Surface Epithelium Can Act as Cell-of-Origin for High Grade Serous Ovarian Carcinoma

The cell-of-origin of high grade serous ovarian carcinoma (HGSOC) remains controversial, with fallopian tube epithelium (FTE) and ovarian surface epithelium (OSE) each suggested as candidates. Here, by using genetically engineered mouse models and novel organoid systems, we assessed the tumor-forming capacity and properties of FTE and OSE harboring the same oncogenic abnormalities. Combined RB family inactivation (via T121 expression) and Tp53 mutation in Pax8+ FTE caused transformation to Serous Tubal Intraepithelial Carcinoma (STIC), which rapidly metastasized to the ovarian surface. This mouse model was recapitulated by FTE organoids, which, upon orthotopic injection, generated widely metastatic HGSOC. The same genetic lesions in Lgr5+ OSE cells or organoids also caused metastatic HGSOC, although with longer latency and lower penetrance. Comparative transcriptome analysis was consistent with different human HGSOCs arising from FTE and OSE. Furthermore, FTE- and OSE-derived organoids showed differential sensitivity to HGSOC chemotherapeutics. Our results comport with a dualistic origin for HGSOC and suggest the cell-of-origin could influence therapeutic response.\n\nSIGNIFICANCEThe cell-of-origin for high grade serous ovarian carcinoma (HGSOC) has been controversial. By generating novel GEMMs and organoid models with the same oncogenic defects, we demonstrate that HGSOC can originate from either fallopian tube epithelium (FTE) or ovarian surface epithelium (OSE). Importantly, FTE- and OSE-derived tumors differ significantly in biologic properties.

cancer biology↗

bioRxiv2018

From copy number alterations to structural variants: the evolutionary cascade of papillary renal cell carcinomas

Intratumor heterogeneity (ITH) and tumor evolution have been well described for clear cell renal cell carcinomas (ccRCC), but they are less studied for other kidney cancer subtypes. Here we investigate ITH and clonal evolution of papillary renal cell carcinoma (pRCC) and rarer kidney cancer subtypes, integrating whole-genome sequencing and DNA methylation data. In 29 tumors, up to 10 samples from the center to the periphery of each tumor, and metastatic samples in 2 cases, enable phylogenetic analysis of spatial features of clonal expansion, which shows congruent patterns of genomic and epigenomic evolution. In contrast to previous studies of ccRCC, in pRCC driver gene mutations and most arm-level somatic copy number alterations (SCNAs) are clonal. These findings suggest that a single biopsy would be sufficient to identify the important genetic drivers and targeting large-scale SCNAs may improve pRCC treatment, which is currently poor. While type 1 pRCC displays near absence of structural variants (SVs), the more aggressive type 2 pRCC and the rarer subtypes have numerous SVs, which should be pursued for prognostic significance.

genomics↗

bioRxiv2018

Systematic Allelic Analysis Defines the Interplay of Key Pathways in X Chromosome Inactivation

Xist RNA, the master regulator of X chromosome inactivation, acts in cis to induce chromosome silencing through the stepwise recruitment of factors that modify underlying chromatin structure. Whilst considerable progress has been made towards defining key silencing factors and the elements to which they bind, their relative contribution to silencing different genes, and their relationship with one another is poorly understood. Here we describe a systematic analysis of Xist-mediated allelic silencing in ES cell-based models. We show that Spen, recruited through the Xist A-repeat, plays a central role, being critical for silencing of all except a subset of weakly expressed genes. Polycomb, recruited through the Xist B/C-repeat, also plays a key role, favouring silencing of genes with pre-existing H3K27me3 chromatin. LBR and the Rbm15/ m6A-methyltransferase complex, previously proposed to have a central role, make at most a minor contribution to gene silencing. We integrate our findings in a comprehensive model for Xist-mediated chromosome silencing.

genetics↗

bioRxiv2018

Mouse Academy: high-throughput automated training and trial-by-trial behavioral analysis during learning

Progress in understanding how individual animals learn will require high-throughput standardized methods for behavioral training but also advances in the analysis of the resulting behavioral data. In the course of training with multiple trials, an animal may change its behavior abruptly, and capturing such events calls for a trial-by-trial analysis of the animals strategy. To address this challenge, we developed an integrated platform for automated animal training and analysis of behavioral data. A low-cost and space-efficient apparatus serves to train entire cohorts of mice on a decision-making task under identical conditions. A generalized linear model (GLM) analyzes each animals performance at single-trial resolution. This model infers the momentary decision-making strategy and can predict the animals choice on each trial with an accuracy of ~80%. We also assess the animals detailed trajectories and body poses within the apparatus. Unsupervised analysis of these features revealed unusual trajectories that represent hesitation in the response. This integrated hardware/software platform promises to accelerate the understanding of animal learning.

animal behavior and cognition↗

bioRxiv2018

Exploratory study of factors associated with human brucellosis in mainland China based on time-series-cross-section data from 2005 to 2016

ObjectiveMany studies focused on reasons behind the increasing incidence and the spread of human brucellosis in mainland China, yet most of them lacked comprehensive consideration with quantitative evidence. Hence, this study aimed to further investigate the epidemic mechanism and associated factors of human brucellosis in China so as to provide suggestions on more effective countermeasures.\n\nMethodsData of human brucellosis incidence and some associated factors in economy, animal husbandry, transportation and health were collected at provincial level from 2005-2016. Time series plot and cluster analysis were first used to visualize incidence levels and categorize provinces based on their incidence level and epidemic trend of human brucellosis. Furthermore, according to the characteristics of data, the dynamic panel data model in combination with supervised principal component analysis was proposed to explore the effects of associated factors on human brucellosis.\n\nResults[circled1] The incidence rate of human brucellosis has increased threefold (from 1.41 in 2005 to 4.22 in 2016) in mainland China. Incidence rates in the north have always been higher than those in the south, but the latter also experienced an upward trend especially in the recent five years. [circled2] The 31 provinces of mainland China were categorized into three clusters, and each cluster had its own characteristics of incidence level and epidemic trend. [circled3] Public health expenditure and rural medical expenditure proportion were potential protective factors of human brucellosis, with attribute risks of -0.74 and -1.04 respectively. Other factors (such as amount of sheep, total length of highways, etc.) exhibited relatively trivial effects.\n\nConclusionsThe epidemic status of human brucellosis has changed in both spatial and temporal dimensions in recent years. Apart from those traditional control measures, more attention should be paid to the improvement of medical healthcare especially in rural areas in order to strengthen the control effect.

epidemiology↗

bioRxiv2018

DNA-mediated self-assembly of gold nanoparticles on protein superhelix

Recent advances in protein engineering have enabled methods to control the self-assembly of protein on various length-scales. One attractive application for designed proteins is to direct the spatial arrangement of nanomaterials of interest. Until now, however, a reliable conjugation method is missing to facilitate site-specific positioning. In particular, bare inorganic nanoparticles tend to aggregate in the presence of buffer conditions that are often required for the formation of stable proteins. Here, we demonstrated a DNA mediated conjugation method to link gold nanoparticles with protein structures. To achieve this, we constructed de novo designed protein fibers based on previously published uniform alpha-helical units. DNA modification rendered gold nanoparticles with increased stability against ionic solutions and the use of complementary strands hybridization guaranteed the site-specific binding to the protein. The combination of high resolution placement of anchor points in designed protein assemblies with the increased control of covalent attachment through DNA binding can enable investigations of multilevel physical coupling events of nanocomponents on protein templates and expand the application of protein structures to material sciences.

biophysics↗

bioRxiv2018

Using pan RNA-seq analysis to reveal the ubiquitous existence of 5′ end and 3′ end small RNAs

In this study, we used pan RNA-seq analysis to reveal the ubiquitous existence of 5 end and 3 end small RNAs. 5 and 3 sRNAs alone can be used to annotate mitochondrial with 1-bp resolution and nuclear non-coding genes and identify new steady-state RNAs, which are usually from functional genes. Using 5, 3 and intronic sRNAs, we revealed that the enzymatic dsRNA cleavage and RNAi could involve in the RNA degradation and gene expression regulation of U1 snRNA in human. The further study of 5, 3 and intronic sRNAs help rediscover double-stranded RNA (dsRNA) cleavage, RNA interference (RNAi) and the regulation of gene expression, which challenges the classical theories. In this study, we provided a simple and cost effective way for the annotation of mitochondrial and nuclear non-coding genes and the identification of new steady-state RNAs, particularly long non-coding RNAs (lncRNAs). We also provided a different point of view for cancer and virus, based on the new discoveries of dsRNA cleavage, RNAi and the regulation of gene expression.

bioinformatics↗

bioRxiv2018

Flux-Balance Based Modeling of Biofilm Communities

Models of microbial community dynamics generally rely on a sub-scale model for microbial metabolisms. In systems such as distributed multispecies communities like biofilms, where it is not reasonable to simplify to a small number of limiting substrates, tracking the large number of active metabolites likely requires measurement or estimation of large numbers of kinetic and regulatory parameters. Alternatively, a largely kinetics-free methodology is proposed combining cellular level constrained, steady state metabolic flux analysis with macro scale microbial community models. The methodology easily allows coupling of macroscale information, including measurement data, with cell-scale metabolism. Illustrative examples are included.

microbiology↗

bioRxiv2018

Brg1 controls neurosensory cell fate commitment and differentiation in the mammalian inner ear

Otic ectoderm gives rise to almost all cell types of the inner ear; however, the mechanisms that link transcription factors, chromatin, lineage commitment and differentiation capacity are largely unknown. Here we show that Brg1 chromatin-remodeling factor is required for specifying neurosensory lineage in the otocyst and for inducing hair and supporting cell fates in the cochlear sensory epithelium. Brg1 interacts with the critical neurosensory-specific transcription factors Eya1/Six1, both of which simultaneously interact with BAF60a or BAF60c. Chromatin immunoprecipitation-sequencing (ChIP-seq) and ChIP assays demonstrate Brg1 association with discrete regulatory elements at the Eya1 and Six1 loci. Brg1-deficiency leads to markedly decreased Brg1 binding at these elements and loss of Eya1 and Six1 expression. Furthermore, ChIP-seq reveals Brg1-bound promoter-proximal and distal regions near genes essential for inner ear morphogenesis and cochlear sensory epithelium development. These findings uncover essential functions for chromatin-remodeling in the activation of neurosensory fates during inner ear development.

developmental biology↗

bioRxiv2018

Generation of human neural retina transcriptome atlas by single cell RNA sequencing

The retina is a highly specialized neural tissue that senses light and initiates image processing. Although the functional organisation of specific cells within the retina has been well-studied, the molecular profile of many cell types remains unclear in humans. To comprehensively profile cell types in the human retina, we performed single cell RNA-sequencing on 20,009 cells obtained post-mortem from three donors and compiled a reference transcriptome atlas. Using unsupervised clustering analysis, we identified 18 transcriptionally distinct clusters representing all known retinal cells: rod photoreceptors, cone photoreceptors, Muller glia cells, bipolar cells, amacrine cells, retinal ganglion cells, horizontal cells, retinal astrocytes and microglia. Notably, our data captured molecular profiles for healthy and early degenerating rod photoreceptors, and revealed a novel role of MALAT1 in putative rod degeneration. We also demonstrated the use of this retina transcriptome atlas to benchmark pluripotent stem cell-derived cone photoreceptors and an adult Muller glia cell line. This work provides an important reference with unprecedented insights into the transcriptional landscape of human retinal cells, which is fundamental to our understanding of retinal biology and disease.

systems biology↗

bioRxiv2018

New genetic variants associated with major adverse cardiovascular events in patients with acute coronary syndromes and treated with clopidogrel and aspirin

ImportanceAlthough a few studies have reported the effects of several polymorphisms on major adverse cardiovascular events (MACE) in patients with acute coronary syndromes (ACS) and those undergoing percutaneous coronary intervention (PCI), these genotypes account for only a small fraction of the variation and evidence is insufficient. This study aims to identify new genetic variants associated with MACE by large-scale sequencing data.\n\nObjectiveTo identify the genetic variants that caused MACE.\n\nDesignAll patients in this study were allocated to dual antiplatelet therapy for up to 12 months and have the follow-up duration of 18 months.\n\nSettingA two-stage association study was performed.\n\nParticipantsWe evaluated the associations of genetic variants and MACE in 1961 patients with ACS undergoing PCI (2009-2012), including high-depth whole exome sequencing of 168 patients in the discovery cohort and high-depth targeted sequencing of 1793 patients in the replication cohort.\n\nMain Outcomes and MeasureThe primary clinical efficacy endpoint was the major adverse cardiovascular events (MACE) composite endpoint, including cardiovascular death, myocardial infarction (MI), stroke (CT or MR scan confirmed) and repeated revascularization (RR).\n\nResultsWe discovered and confirmed six new genotypes associated with MACE in patients with ACS. Of which, rs17064642 at MYOM2 increased the risk of MACE (hazard ratio [HR] 2.76; P = 2.95 x 10-9) and reached genome-wide significance. The other five suggestive variants were KRTAP10-4 (rs201441480), WDR24 (rs11640115), ECHS1 (rs140410716), AGAP3 (rs75750968) and NECAB1 (rs74569896). Notably, the expressions of MYOM2 and ECHS1 are down-regulated in both animal models and patients with phenotypes related to MACE. Importantly, we developed the first superior classifier for predicting MACE and achieved high predictive accuracy (0.809).\n\nConclusions and RelevanceWe identified six new genotypes associated with MACE and developed a superior classifier for predicting MACE. Our findings shed light on the pathogenesis of cardiovascular outcomes and may help clinician to make decision on the therapeutic intervention for ACS patients.\n\nTrial RegistrationThis study has been registered in the Chinese Clinical Trial Registry (http://www.chictr.org.cn, Registration number: ChiCTR-OCH-11001198).

genetics↗

bioRxiv2018

Sequencing of the MHC region defines HLA-DQA1 as the major independent risk for anti-citrullinated protein antibodies (ACPA)-positive rheumatoid arthritis in Han population

The strong genetic contribution of the major histocompatibility complex (MHC) to rheumatoid arthritis (RA) susceptibility has been generally attributed to HLA-DRB1. However, due to the high linkage disequilibrium in the MHC region, it is difficult to define the real or/and additional independent genetic risks using the conventional HLA genotyping or chip-based microarray technology. By the capture sequencing of entire MHC region for discovery and HLA-typing for validation in 2,773 subjects of Han ancestry, we identified HLA-DQ1:160D as the strongest independent genetic risk for anti-citrullinated protein antibodies (ACPA)-positive RA in Han population (P = 6.16 x 10-36, OR=2.29). Further stepwise conditional analysis revealed that DR{beta}1:37N has an independent protective effect on ACPA-positive RA (P = 5.81 x 10-16, OR=0.49). The DQ1:160 coding allele DQA1*0303 displayed high impact on joint radiographic severity, especially in patients with early disease and smoking (P = 3.02 x 10-5). Interaction analysis by comparative molecular modeling revealed that the negative charge of DQ1:160D stabilizes the dimer of dimers, leading to an increased T cell activation. The electrostatic potential surface analysis indicated that the negative charged DR{beta}1:37N encoding alleles could bind with epitope P9 arginine, thus may result in a decreased RA susceptibility.\n\nIn this study, we provide the first evidence that HLA-DQA1, instead of HLA-DRB1, is the strongest and independent genetic risk for ACPA-positive RA in Chinese Han population. Our study also illustrates the value of MHC deep sequencing for fine mapping disease risk variants in the MHC region.

genetics↗

bioRxiv2018

e-workflow for recording of glycomic mass spectrometric data in compliance with reporting guidelines

Glycomics targets released glycans from proteins, lipids and proteoglycans. High throughput glycomics is based on mass spectrometry (MS) that increasingly depends on exchange of data with databases and the use of software. This requires an agreed format for accurately recording of experiments, developing consistent storage modules and granting public access to glycomic MS data. The introduction of the MIRAGE (Mimimum Requirement for A Glycomics Experiment) reporting standards for glycomics was the first step towards automating glycomic data recording. This report describes a glycomic e-infrastructure utilizing a well established glycomics recording format (GlycoWorkbench), and a dedicated web tool for submitting MIRAGE-compatible MS information into a public experimental repository, UniCarb-DR. The submission of data to UniCarb-DR should be a part of the submission process for publications with glycomics MSn that conform to the MIRAGE guidelines. The structure of this pipeline allows submission of most MS workflows used in glycomics.

bioinformatics↗

bioRxiv2018

Brain folding is initiated by mechanical constraints without a cellular pre-pattern

During human brain development the cerebellum and cerebral cortex fold into robust patterns that increase and compartmentalize neural circuits. Although differential expansion of elastic materials has been proposed to explain brain folding, the cellular and physical processes responsible at the time of folding have not been defined. Here we used the murine cerebellum, with 8-10 folds, as a tractable model to study brain folding. At folding initiation we considered the cerebellum as a bilayer system with a fluidlike outer layer of proliferating precursors and an incompressible core. We discovered that there is no obvious cellular pre-pattern for folding, since when folding initiates, the precursors within the outer layer have uniform sizes, shapes and proliferation, as well as a distribution of glial fibers. Furthermore, although differential expansion is created by the outer layer expanding faster than the core at folding initiation, thickness variations arise in the outer layer that are inconsistent with elastic material models. A multiphase model was applied that includes radial and circumferential tension and mechanical constraints derived from in vivo measurements. Our results demonstrate that cerebellar folding emerges from mechanical forces generated by uniform cell behaviors. We discuss how our findings apply to human cerebral cortex folding.

developmental biology↗

bioRxiv2018

The distribution of large floating seagrass (Zostera marina) clumps in northern temperate zones of Bohai Bay in the Bohai Sea, China

Seagrass meadows (Zostera marina) are important coastal ecosystems with high levels of productivity and biodiversity. They are subject to considerable natural and anthropogenic threats in China, such as oyster and snail aquaculture, wastewater discharge, electro-fishing, shellfish collection, typhoons and floods. When seagrass communities are disturbed, they can become removed from the sediment and converted into floating clumps, which then serve as marine hot spots attracting a variety of marine organisms that then inhabit them. They are important nursery habitats for many economic fish such as red drum (Sciaenops ocellatus), Atlantic cod (Gadus morhua), queen conch (Strombus gigas), and blue crab (Callinectes sapidus). Thus, it is necessary to study the distribution and biological characteristics of these floating seagrass clumps. In September 2016 we observed large scale floating Z. marina clumps in the northernmost area of Bohai Bay (38{degrees}571.14\"-39{degrees} 041.28\" N, 118{degrees}4523.22\"-118{degrees}476.96\" E), in the Bohai Sea, China. We observed characteristics that precluded their origination from the nearby Caofeidian seagrass meadows. Two research cruises were undertaken, during which we did not observe other marine organisms accompanying these floating Z. marina clumps. The dominant frond lengths were 40-50 cm, with less than 5% of the total number of fronds found in larger size categories (80-90 and 90-100 cm). We aim to pursue future research into the breakdown and dislodgement characteristics of Z. marina clumps and the processes whereby they sink and integrate with the sediment.

ecology↗

bioRxiv2018

Identifying Lineage-specific Targets of Darwinian Selection by a Bayesian Analysis of Genomic Polymorphisms and Divergence from Multiple Species

We present a method that jointly analyzes the polymorphism and divergence sites in genomic sequences of multiple species to identify the genes under positive or negative selection and pinpoints the occurrence time of selection to a specific lineage of the species phylogeny. This method integrates population genetics models using the Bayesian Poisson random field framework and combines information over all gene loci to boost the power to detect selection. The method provides posterior distributions of the fitness effects of each gene along with parameters associated with the evolutionary history, including the species divergence times and effective population sizes of external species. A simulation is performed, and the results demonstrate that our method provides accurate estimates of these population genetic parameters.\n\nThe proposed method is applied to genomic sequences of humans, chimpanzees, gorillas and orangutans, and a spatial and temporal map is constructed of the natural selection that occurred during the evolutionary history of the four Hominidae species. In addition to FOXP2 and other known genes, we identify a new list of lineage-specific targets of Darwinian selection. The positively selected genes in the human lineage are enriched in pathways of gene expression regulation, immune system, metabolism etc. Interestingly, some pathways, such as gene expression, are significantly enriched with positively selected genes, whereas other pathways, such as metabolism, are enriched with both positively and negatively selected genes. Our analysis provides insights into Darwinian evolution in the coding regions of humans and great apes and thus serves as a basis for further molecular and functional studies.

genomics↗

bioRxiv2018

Impaired hematopoiesis and leukemia development in mice with a \"knock-in\" allele of U2af1(S34F)

Mutations affecting the spliceosomal protein U2AF1 are commonly found in myelodysplastic syndromes (MDS) and secondary acute myeloid leukemia (sAML). We have generated mice that carry Cre-dependent \"knock-in\" alleles of U2af1(S34F), the murine version of the most common mutant allele of U2AF1 encountered in human cancers. Cre-mediated recombination in murine hematopoietic lineages caused changes in RNA splicing, as well as multilineage cytopenia, macrocytic anemia, decreased hematopoietic stem and progenitor cells, low-grade dysplasias, and impaired transplantability, but without lifespan shortening or leukemia development. In an attempt to identify U2af1(S34F)-cooperating changes that promote leukemogenesis, we combined U2af1(S34F) with Runx1 deficiency in mice and further treated the mice with a mutagen, N-Ethyl-N-Nitrosourea (ENU). Overall, three of sixteen ENU-treated compound transgenic mice developed AML. However, AML did not arise in mice with other genotypes or without ENU treatment. Sequencing DNA from the three AMLs revealed somatic mutations homologous to those considered to be drivers of human AML, including predicted loss-or gain-of-function mutations in Tet2, Gata2, Idh1, and Ikzfl. However, the engineered U2af1(S34F) missense mutation reverted to wild type (WT) in two of the three AML cases, implying that U2af1(S34F) is dispensable, or even selected against, once leukemia is established.\n\nSIGNIFICANCE STATEMENTSomatic mutations in four splicing factor genes (U2AF1, SRSF2, SF3B1, and ZRSR2) are found in MDS and MDS-related AML, blood cancers with few effective treatment options. However, the pathophysiological effects of these mutations remain poorly characterized, in part due to the paucity of disease-relevant models. Here, we report the establishment of mouse models to study the most common U2AF1 mutation, U2af1(S34F). Production of the mutant protein specifically in the murine hematopoietic compartment disrupts hematopoiesis in ways resembling human MDS. We further identified deletion of the Runx1 gene and other known oncogenic mutations as changes that might collaborate with U2af1(S34F) to give rise to frank AML in mice.

cancer biology↗