bioRxiv Science⌕ Search

Biology subjects

Yang, G.

Publications and source records attributed to Yang, G..

At least 199 records · Page 11Linked to original sources
bioRxiv2019

Leptin deficient rats develop nonalcoholic steatohepatitis with unique disease progression

Nonalcoholic steatohepatitis (NASH) is an aggressive liver disease threatening public health, however its natural history is poorly understood. Unlike ob/ob mice, Lep{triangleup}I14/{triangleup}I14 rats develop unique NASH phenotype with steatosis, lymphocyte infiltration and ballooning after postnatal week 16. Using Lep{triangleup}I14/{triangleup}I14 rats as NASH model, we studied the natural history of NASH progression by performing an integrated analysis of hepatic transcriptome from postnatal week 4 to 48. Leptin deficiency results in a robust increase in expression of genes encoding 9 rate-limiting enzymes in lipid metabolism such as ACC and FASN. However, genes in positive regulation of inflammatory response are highly expressed at week 16 and then remain the steady elevated expression till week 48. The high expression of cytokines and chemokines including CCL2, TNF, IL6 and IL1{beta} is correlated with the phosphorylation of several key molecules in pathways such as JNK and NF-{kappa}B. Meanwhile, we observed cell infiltration of MPO+ neutrophils, CD8+ T cells, CD68+ hepatic macrophages and CCR2+ inflammatory monocyte-derived macrophages, together with macrophage polarization from M2 to M1. Importantly, Lep{triangleup}I14/{triangleup}I14 rats share more homologous genes with NASH patients than previously established mouse models and crab eating monkeys with spontaneous hepatic steatosis. Transcriptomic analysis showed that many drug targets in clinical trials can be evaluated in Lep{triangleup}I14/{triangleup}I14 rats.\n\nConclusionWe characterize Lep{triangleup}I14/{triangleup}I14 rats as a unique NASH model by performing a long-term (i.e., 4 to 48 postnatal weeks) integrated transcriptomic analysis. This work reveal the temporal dynamics of hepatic gene expression in lipid metabolism and inflammation, and shed light on understanding the natural history of NASH in human beings.

pathology↗
bioRxiv2019

Contraction of the ROS scavenging enzyme glutathione S-transferase gene family in cetaceans

Cetaceans are a group of marine mammals whose ancestors were adaptated for life on land. Life in an aquatic environment poses many challenges for air-breathing mammals. Diving marine mammals have adapted to rapid reoxygenation and reactive oxygen species (ROS)-mediated reperfusion injury. Here, we considered the evolution of the glutathione transferase (GST) gene family which has important roles in the detoxification of endogenously-derived ROS and environmental pollutants. We characterized the cytosolic GST gene family in 21 mammalian species; cetaceans, sirenians, pinnipeds, and their terrestrial relatives. All seven GST classes were identified, showing that GSTs are ubiquitous in mammals. Some GST genes are the product of lineage-specific duplications and losses, in line with a birth-and-death evolutionary model. We detected sites with signatures of positive selection that possibly influence GST structure and function, suggesting that adaptive evolution of GST genes is important for defending mammals from various types of noxious environmental compounds. We also found evidence for loss of alpha and mu GST subclass genes in cetacean lineages. Notably, cetaceans have retained a homolog of at least one of the genes GSTA1, GSTA4, and GSTM1; GSTs that are present in both the cytosol and mitochondria. The observed variation in number and selection pressure on GST genes suggest that the gene family structure is dynamic within cetaceans. Taken together, our results indicate that the cytosolic GST family in cetaceans reflects unique evolutionary dynamics related to oxygen-poor aquatic environments.

evolutionary biology↗
bioRxiv2019

LonP1 Orchestrates UPRmt and UPRER and Mitochondrial Dynamics to Regulate Heart Function

Protein quality control is pivotal to cellular homeostasis and integrity of cardiomyocytes for maintenance of normal heart function. The unfolded protein response (UPR) is an adaptive process to modulate protein quality control in the endoplasmic reticulum (ER) and mitochondria, and is accordingly termed UPRER and UPRmt, respectively. Lon protease (LonP1) is a highly conserved mitochondrial protease to modulate UPRmt, which is involved in regulating metabolism, mitophagy, and stress response. However, whether LonP1 regulates UPRER remains elusive. To investigate the regulation of protein quality control in cardiomyocytes, we generated cardiac-specific LonP1 deletion mice. Our findings show that LonP1 deficiency caused impaired mitochondrial respiratory function and fragmentation. Surprisingly, both UPRER and UPRmt is substantially induced in LonP1-deletion heart suggesting of LonP1 as a novel regulator of UPRER; however, the activation of UPRER occurs earlier than UPRmt in response to LonP1 deletion. Consequently, cardiac-specific LonP1 deficiency causes aberrant metabolic reprogramming of cardiomyocytes, pathological heart remodeling, as well as impeded heart function. Thus, we uncovered the novel function of LonP1 as an UPRmt mediator, and reciprocal orchestration of UPRmt and UPRER and mitochondrial dynamics regulated by LonP1 in the cardiomyocytes that is critical to maintain heart function, which offers exciting new insights into the potential therapeutic strategy for heart failure.

cell biology↗
bioRxiv2019

Photorhabdus Virulence Cassettes: extracellular multi-protein needle complexes for delivery of small protein effectors into host cells.

Photorhabdus is a highly effective insect pathogen and symbiont of insecticidal nematodes. To exert its potent insecticidal effects, it elaborates a myriad of toxins and small molecule effectors. Among these, the Photorhabdus Virulence Cassettes (PVCs) represent an elegant self-contained delivery mechanism for diverse protein toxins. Importantly, these self-contained nanosyringes overcome host cell membrane barriers, and act independently, at a distance from the bacteria itself. In this study, we demonstrate that Pnf, a PVC needle complex associated toxin, is a Rho-GTPase, which acts via deamidation and transglutamination to disrupt the cytoskeleton. TEM and Western blots have shown a physical association between Pnf and its cognate PVC delivery mechanism. We demonstrate that for Pnf to exert its effect, translocation across the cell membrane is absolutely essential. SIGNIFICANCE STATEMENTHere we provide an up to date analysis of the nano-scale syringe-like molecular devices that Photorhabdus use to manipulate invertebrate hosts, the PVC system. They are related to the Serratia Anti-Feeding Prophage and the Psuedoalteromonas MAC system. All these systems are in turn more distantly related to the well characterized Type VI secretion system currently receiving a great deal of attention. We demonstrate for the first time that the PVC nanosyringes are physically "loaded" with an effector protein payload before being freely released. The PVCs therefore represent bacterial molecular machines that are used as "long-range" protein delivery systems. This widespread class of toxin delivery system will likely prove of great significance in understanding many diverse bacteria/host interactions in future.

microbiology↗
bioRxiv2019

Characteristics of executive control network function based on a lateralized version of the ANT-R test in athletes from open skill sports: An fNIRS study

The purpose of the study was to investigate the executive control network function characteristics of interceptive and strategic sports athletes from open skill sports. In order to do so, we used a revised lateralized attention network task to measure executive control efficiency and activation related to flanker interference changes on the right frontoparietal network using functional near-infrared spectroscopy in athletes from different sport sub-categories. Strategic athletes had higher accuracy and lower flanker conflict effects on accuracy, as well as longer reaction time and stronger conflict effects under the valid cue and invalid cue conditions. This was accompanied by higher activity in the right inferior frontal gyrus. These results extend the evidence suggesting that differences among interceptive sports and strategic sports athletes are due to the former using higher velocities to solve conflicts, and the latter using higher accuracy in the same tasks. These effects are attributed to differences in the right frontoparietal network.

physiology↗
bioRxiv2018

Higher-order epistatic networks underlie the evolutionary fitness landscape of a xenobiotic- degrading enzyme

Characterizing the adaptive landscapes that encompass the emergence of novel enzyme functions can provide molecular insights into both enzymatic and evolutionary mechanisms. Here, we combine ancestral protein reconstruction with biochemical, structural, and mutational analyses to characterize the functional evolution of methyl-parathion hydrolase (MPH), a xenobiotic organophosphate-degrading enzyme. We identify five mutations that are necessary and sufficient for the evolution of MPH from an ancestral dihydrocoumarin hydrolase. In-depth analyses of the adaptive landscapes encompassing this evolutionary transition revealed that a complex interaction network, defined in part by higher-order epistasis, determined the adaptive pathways that were available. By also characterizing the adaptive landscapes in terms of their functional activity towards three other OP substrates, we reveal that subtle differences in substrate substituents drastically alter the enzymes epistatic network by changing its intramolecular interactions. Our work suggests that the mutations function collectively to enable substrate recognition via subtle structural repositioning.

biochemistry↗
bioRxiv2018

Comparative genomics reveals contraction in cytosolic glutathione transferase genes in cetaceans: implications for oxidative stress adaptation

Cetaceans, a highly specialized group of aquatic mammals, experience oxidative stress induced by reactive oxygen species (ROS) production associated with the apnea/reoxygenation. The glutathione transferases (GST) family possesses multiple functions in detoxification and antioxidant defenses. However, the molecular evolution of GST family in cetaceans is still poorly investigated. Here, we characterized the GST gene family across 21 mammalian genomes including cetaceans and terrestrial relatives. Overall, 7 GST classes were identified, showing GSTs are ubiquitous and conservative to all mammals. Some of GSTs are lineage-specific duplication and loss, in line with a birth-and-death evolutionary model. We detected positive selection sites that possibly influence GST structure and function, suggesting adaptive evolution of GSTs is important for defending mammals from various types of noxious environmental compounds. There is evidence for loss of alpha and mu GST class in cetacean lineages when compared to their terrestrial relatives, consisting with the lower GST activities observed in cetaceans. Notably, we find that retained GSTA1, GSTA4 and GSTM1 in cetaceans, indicating a vital role in against lipid peroxidation and superoxide. Besides, variation in gene number, enzyme activity and selection pressure of GSTs between marine mammals suggests there is a divergent evolution of GSTs in aquatic species that might be associated to diving ability and oxidative status with different habitats. Summarily, our findings demonstrate that the GST family in cetaceans has been subject to evolutionary dynamics as response for their adaptations to oxidative stress, and highlighted the differential selection associated with different life history traits among mammals.

evolutionary biology↗
bioRxiv2018

A new model on DNA structure and thermal denaturation

A quantum model on DNA structure is proposed. By introducing the self-consistent harmonic potential in the X-Y plane vertical to helix axis (z-direction) and the periodic potential along the z-axis we obtain the wave function for the single nucleotide and the many-nucleotide system. The helix distribution of bases is deduced from the solution of wave function under the self-consistent potential. The variation of DNA structure (polymorphism) is related to the periodicity of the potential in Z-axis, the quantum state occurring in harmonic potential and the interaction between helix strands. As Watson-Crick (W-C) interaction is introduced between double helices, the quasi-particle transformation is utilized to solve the interacting many-body problem for DNA. It is proved that the phase-transition (thermal denaturation) temperature is related to the frequency {omega} of harmonic potential. Through comparison with experimental data a simple relation [Formula] (N means number of base pairs and V the W-C coupling) is deduced. For a DNA sequence of 1000 bp {omega} is predicted about (0.9-1.2)x1017/sec. Such a high frequency is necessary for nucleotides of each strand located on a narrow tube. The large temperature fluctuation experimentally observed during DNA thermal denaturation is interpreted by the collective motion of nucleotides.

biophysics↗
bioRxiv2018

Dynamic plant height QTL revealed in maize through remote sensing phenotyping using a high-throughput unmanned aerial vehicle (UAV)

Plant height is the key factor for plant architecture, biomass and yield in maize (Zea mays). In this study, plant height was investigated using unmanned aerial vehicle high-throughput phenotypic platforms (UAV-HTPPs) for maize diversity inbred lines at four important growth stages. Using an automated pipeline, we extracted accurate plant heights. We found that in temperate regions, from sowing to the jointing period, the growth rate for temperate maize was faster than tropical maize. However, from jointing to flowering stage, tropical maize maintained a vigorous growth state, and finally resulted in a taller plant than temperate lines. Genome-wide association study for temperate, tropical and both groups identified a total of 238 quantitative trait locus (QTLs) for the 16 plant height related traits over four growth periods. And, we found that plant height at different stages were controlled by different genes, for example, PIN1 controlled plant height at the early stage and PIN11 at the flowering stages. In this study, the plant height data collected by the UAV-HTTPs were credible and the genetic mapping power is high, indicating that the application of this UAV-HTTPs into the study of plant height will have great prospects.\n\nHighlightWe used UAV-based sensing platform to investigate plant height over 4 growth stages for different maize populations, and detected numbers of reliable QTLs using GWAS.

genetics↗
bioRxiv2018

A particle-filter framework for robust cryoEM 3D reconstruction

Electron cryo-microscopy (cryoEM) is now a powerful tool in determining atomic structures of biological macromolecules under nearly natural conditions. The major task of single-particle cryoEM is to estimate a set of parameters for each input particle image to reconstruct the three-dimensional structure of the macromolecules. As future large-scale applications require increasingly higher resolution and automation, robust high-dimensional parameter estimation algorithms need to be developed in the presence of various image qualities. In this paper, we introduced a particle-filter algorithm for cryoEM, which was a sequential Monte Carlo method for robust and fast high-dimensional parameter estimation. The cryoEM parameter estimation problem was described by a probability density function of the estimated parameters. The particle filter uses a set of random and weighted support points to represent such a probability density function. The statistical properties of the support points not only enhance the parameter estimation with self-adaptive accuracy but also provide the belief of estimated parameters, which is essential for the reconstruction phase. The implementation of these features showed strong tolerance to bad particles and enabled robust defocus refinement, demonstrated by the remarkable resolution improvement at the atomic level.

biophysics↗
bioRxiv2018

White spot syndrome virus infection induces Caspase 1-mediated antiviral cell death in crustacean

In vertebrates, pyroptosis is an intensely inflammatory form of programmed cell death which is dependent on Caspase 1 activation and release of cytoplasmic cytokines including IL-1{beta}. This death pathway is critical for controlling pathogenic infection by mobilizing immune cells and stimulating the development of adaptive immune response. In invertebrates, however, due to the lack of adaptive immune response, it is still elusive whether Caspase 1-dependent cell death pathway exists. In this study, our data showed that Caspase 1-mediated cell death was activated by white spot syndrome virus (WSSV) infection to control the virus in shrimp. Caspase 1 had a higher expression level in hemocytes and lymphoid-like organ in shrimp and WSSV infection was significantly promoted upon the inhibition of Caspase 1 enzymatic activity. IL-1{beta}-like protein was identified as the substrate of Caspase 1 and its interaction with Caspase 1 was validated ectopically and endogenously. Moreover, IL-1{beta} like protein was released into extracellular contents under WSSV infection and Prophenoloxidase system was activated, resulting in the reduction of WSSV copies in vivo. Our data unraveled a previously unidentified mechanism through which Caspase 1-dependent cell death controlled virus infection in shrimp. Therefore, our study opened the possibility that an invertebrate cytokine network might be operative and regulate host defenses against virus infection as in vertebrates.\n\nAuthor SummaryThe elimination of infected cells by programmed cell death is considered as one of the most important anti-pathogen responses. Pyroptosis is one form of programmed cell death, which is mediated by Caspase 1 activation. Activated Caspase 1 can process the inactive precursors of interleukin 1{beta} (IL-1{beta}) into mature inflammatory cytokines to induce potent immune responses. Meanwhile, pyroptosis also induces morphologic changes, DNA fragmentation and chromatin condensation to destroy infected cells. However, due to the lack of efficient adaptive immune responses, it is still unclear whether Caspase 1-mediated cell death also exits and plays such an important role in defending hosts from pathogen invasion in invertebrates. In our data, Caspase 1 gene was characterized and Caspase 1-mediated cell death pathway was validated in shrimp. The Caspase 1-mediated cell death pathway was enhanced by white spot syndrome virus (WSSV) infection to control the virus in shrimp. IL-1{beta}-like protein was cleaved by Caspase 1 and released into extracellular contents under WSSV infection to activate Prophenoloxidase system, leading to the reduction of WSSV copies in shrimp in vivo. On the other hand, silencing of Caspase 1 or IL-1{beta}-like gene facilitated virus infection in shrimp. Our study indicated that Casapase-1-mediated cell death played an important antiviral role in shrimp against WSSV infection and opened the possibility that an invertebrate cytokine network might be operative.

immunology↗
bioRxiv2018

Comprehensive Glycoproteomic Analysis of Chinese Hamster Ovary Cells

The Chinese hamster ovary (CHO) cell line is a major expression system for the production of therapeutic proteins, the majority of which are glycoproteins, such as antibodies and erythropoietin (EPO). The characterization of the glycosylation profiles is critical to understand the important role of glycosylation on therapeutic glycoproteins from CHO cells. In this study, a large scale glycoproteomic workflow was established and applied to CHO-K1 cells expressing EPO. The workflow includes enrichment of intact glycopeptides from CHO-K1 cell lysate and medium using hydrophilic enrichment, fractionation of the obtained intact glycopeptides (IGPs) by basic reversed phase liquid chromatography (bRPLC), analyzing the glycopeptides using LC-MS/MS, and annotating the results by GPQuest 2.0. A total of 10,338 N-linked glycosite-containing IGPs were identified, representing 1,162 unique glycosites in 530 glycoproteins, including 71 unique atypical N-linked IGPs on 18 atypical N-glycosylation sequons with an overrepresentation of the N-X-C motifs. Moreover, we compared the glycoproteins from CHO cell lysate with those from medium using the in-depth N-linked glycoproteome data. The obtained large scale glycoproteomic data from intact N-linked glycopeptides in this study is complementary to the genomic, proteomic, and N-linked glycomic data previously reported for CHO cells. Our method has the potential to accelerate the production of recombinant therapeutic glycoproteins.

biochemistry↗
bioRxiv2018

Cullin1 represses systematic inflammasome activation by binding and catalyzing NLRP3 ubiquitination

Activation of the NLRP3 inflammasome is a key process of host immune response, the first line of defense against cellular stresses and pathogen infections. However, excessive inflammasome activation damages the hosts, and thus it must be precisely controlled. The mechanism underlying the repression of systematic inflammasome activation remains largely unknown. This study reveals that CUL1, a key component of the SCF E3 ligase, plays a critical role in regulation of the inflammasome. CUL1 suppresses the inflammasome activation in HEK293T cells, inhibits endogenous NLRP3 in macrophages, and represses inflammatory responses in C57BL/6 mice. Under normal physiological conditions, CUL1 interacts with NLRP3 to disrupt the inflammasome assembly, and catalyzes NLRP3 ubiquitination to repress the inflammasome activation. In response to inflammatory stimuli, CUL1 disassociates from NLRP3 to release the repression of NLRP3 inflammasome activation. This work reveals a distinct mechanism underlying the repression of inflammasome activation under physiological conditions and the induction of inflammasome activation in response to inflammatory stimuli, and thus provides insights into the prevention and treatment of infectious and inflammatory diseases.

immunology↗
bioRxiv2018

Structural and functional influences of urban and rural childhoods on the medial prefrontal cortex

Global increases in urbanization have brought dramatic economic, environmental and social changes. However, less is understood about how these may influence disease-related brain mechanisms underlying epidemiological observations that urban birth and childhoods may increase the risk for neuropsychiatric disorders, including increased social stress and depression. In a genetically homogeneous Han Chinese adult population with divergent urban and rural birth and childhoods, we examined the structural and functional MRI neural correlates of childhood urbanicity, focusing on behavioral traits responding to social status threats, and polygenic risk for depression. Subjects with divergent rural and urban childhoods were similar in adult socioeconomic status and were genetically homogeneous. Urban childhoods, however, were associated with higher trait anxiety-depression. On structural MRI, urban childhoods were associated with relatively reduced medial prefrontal gray matter volumes. Functional medial prefrontal engagement under social status threat during working memory correlated with trait anxiety-depression in subjects with urban childhoods, to a significantly greater extent than in their rural counterparts, implicating an exaggerated physiological response to the threat context. Stress-associated medial prefrontal engagement also interacted with polygenic risk for depression, significantly predicting a differential response in individuals with urban but not rural childhoods. Developmental urbanicity thus differentially influenced medial prefrontal structure and function, at least in part through mechanisms associated with the neural processing of social status threat, trait anxiety, and genetic risk for depression, which may be factors in the association of urbanicity with adult psychopathology.\n\nSignificance StatementUrban living has been associated with social inequalities and stress. However, less is understood about the neural underpinnings by which these stressors affect disease risk, and in particular, genetic risk for depression. Leveraging urbanization in China, we studied adults with diverse urban and rural upbringings, who were genetically homogeneous and with similar current socioeconomic status, to isolate the effects of childhood urbanicity. At medial prefrontal cortex, a region critical for processing emotional stressors and social status, genetic risk for depression resulted in more deleterious function under stress in individuals with urban, but not rural childhoods. This implicates medial prefrontal cortexs critical role in brain development, integrating genetic mechanisms of stress and depression with the childhood environment.

neuroscience↗
bioRxiv2018

Target Control in Logical Models Using the Domain of Influence of Nodes

Dynamical models of biomolecular networks are successfully used to understand the mechanisms underlying complex diseases and to design therapeutic strategies. Network control, and its special case of target control, is a promising avenue toward developing disease therapies. In target control it is assumed that a small subset of nodes is most relevant to the systems state and the goal is to drive the target nodes into their desired states. An example of target control would be driving a cell to commit to apoptosis (programmed cell death). From the experimental perspective, gene knockout, pharmacological inhibition of proteins and providing sustained external signals are among practical intervention techniques. We identify methodologies to use the stabilizing effect of sustained interventions for target control in logical models of biomolecular networks. Specifically, we define the domain of influence of a node (in a certain state) to be the nodes (and their corresponding states) that will be ultimately stabilized by the sustained state of this node regardless of the initial state of the system. We also define the related concept of the logical domain of influence of a node, and develop an algorithm for its identification using an auxiliary network that incorporates the regulatory logic. This way a solution to the target control problem is a set of nodes whose domain of influence can cover the desired target node states. We perform greedy randomized adaptive search in state space to find such solutions. We apply our strategy to several biological networks to demonstrate its effectiveness.

systems biology↗
bioRxiv2017

Cryptic genetic variation defines the adaptive evolutionary potential of enzymes

Genetic variation among orthologous proteins can cause cryptic phenotypic properties that only manifest in changing environments. Such variation may also impact the evolutionary potential of proteins, but the molecular basis for this remains unclear. Here we perform comparative directed evolution in which four orthologous metallo-{beta}-lactamases were evolved toward a new function. We found that genetic variation between these enzymes resulted in distinct evolutionary outcomes. The ortholog with the lower initial activity reached a 20-fold higher fitness plateau exclusively via increasing catalytic activity. By contrast, the ortholog with the highest initial activity evolved to a less-optimal and phenotypically distinct outcome through changes in expression, oligomerization and activity. We show that the cryptic molecular properties and conformational variation of residues in the initial genotypes cause epistasis, thereby constraining evolutionary outcomes. Our work highlights that understanding the molecular details relating genetic variation to protein functions is essential to predicting the evolution of proteins.

evolutionary biology↗
bioRxiv2017

Optogenetics reprogramming of planktonic cells for biofilm formation

Single-cell behaviors play essential roles during early-stage biofilms formation. In this study, we evaluated whether biofilm formation could be guided by precisely manipulating single cells behaviors. Thus, we established an illumination method to precisely manipulate the type IV pili (TFP) mediated motility and microcolony formation of Pseudomonas aeruginosa by using a combination of a high-throughput bacterial tracking algorithm, optogenetic manipulation and adaptive microscopy. We termed this method as Adaptive Tracking Illumination (ATI). We reported that ATI enables the precise manipulation of TFP mediated motility and microcolony formation during biofilm formation by manipulating bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) levels in single cells. Moreover, we showed that the spatial organization of single cells in mature biofilms can be controlled using ATI. Thus, the established method (i.e., ATI) can markedly promote ongoing studies of biofilms.

microbiology↗