Biology subjects

Liang, J.

Publications and source records attributed to Liang, J..

At least 127 records · Page 7Linked to original sources

bioRxiv2023

Selective Mitochondrial Respiratory Complex I Subunit Deficiency Causes Tumor Immunogenicity

Targeting of specific metabolic pathways in tumor cells has the potential to sensitize them to immune-mediated attack. Here we provide evidence for a specific means of mitochondrial respiratory Complex I (CI) inhibition that improves tumor immunogenicity and sensitivity to immune checkpoint blockade (ICB). Targeted genetic deletion of the CI subunits Ndufs4 and Ndufs6, but not other subunits, induces an immune-dependent tumor growth attenuation in mouse melanoma models. We show that deletion of Ndufs4 induces expression of the transcription factor Nlrc5 and genes in the MHC class I antigen presentation and processing pathway. This induction of MHC-related genes is driven by an accumulation of pyruvate dehydrogenase-dependent mitochondrial acetyl-CoA downstream of CI subunit deletion. This work provides a novel functional modality by which selective CI inhibition restricts tumor growth, suggesting that specific targeting of Ndufs4, or related CI subunits, increases T-cell mediated immunity and sensitivity to ICB.

cancer biology↗

bioRxiv2023

Int&in: a machine learning-based web server for split site identification in inteins

Inteins are proteins that excise themselves out of host proteins and ligate the flanking polypeptides in an auto-catalytic process called protein splicing. They are gaining momentum in synthetic biology for their ability to post-translationally modify proteins of interest. In nature, inteins are either contiguous or split, in which case the two intein fragments must first form a complex for the splicing to occur. So far, heuristic methods have been employed whenever a new split site in an intein had to be identified. To make the process of split site identification in inteins faster, easier and less costly, we developed Int&in, a web server that uses a gaussian Naive Bayes machine learning model to predict active and inactive split sites with high accuracy. The model was trained on a data set generated by us and validated using a large diverse data set from the literature, resulting in an accuracy of 0.76. Int&in will facilitate the engineering of novel split inteins for applications in biotechnology and synthetic biology.

synthetic biology↗

bioRxiv2023

Assessing the role of mitonuclear interactions on mitochondrial function and organismal fitness in natural Drosophila populations

Mitochondrial metabolism is regulated by a series of enzyme complexes, whose function depends on effective interactions between proteins and RNA encoded by the mitochondrial and nuclear genomes. These epistatic interactions are in turn highly sensitive to the environment. Many studies have found that mitochondrial haplotype frequencies of various taxa associate with latitude or altitude, leading to the hypothesis that mitochondrial genomes may respond to thermal selection and contribute to local adaptation. We used a Drosophila melanogaster panel comprising native (coadapted) populations from the extremes of the Australian east-coast cline, and generated mitonuclear cybrid populations. Our results indicate a strong phenotypic impact of mitonuclear interactions in cybrid lines, involving an apparent trade-off between aerobic capacity and key fitness aspects such as reproduction, growth, and survival. Overall, our study shows that naturally-occurring mitonuclear disruptions can have a meaningful impact on phenotypes, potentially influencing future ecological adaptation and population persistence.

evolutionary biology↗

bioRxiv2023

Structural insights into abscisic acid exporter AtABCG25

Cellular hormone homeostasis is essential for the precise spatial and temporal signaling responses and plant fitness. Abscisic acid (ABA) plays pivotal roles in orchestrating various developmental and stress responses and confers fitness benefits over ecological and evolutionary timescales in terrestrial plants. Cellular ABA levels is regulated by complex processes including biosynthesis, catabolism, and transport. AtABCG25 is the first identified ABA exporter through genetic screen which affects diverse ABA responses. Resolving the structure basis of ABCG25 in ABA exporting is critical for further manipulating ABA homeostasis and plant fitness. We utilized cryo-electron microscopy to elucidate the structural dynamics of AtABCG25, and successfully characterized different states including apo AtABCG25, ABA-bound AtABCG25 and ATP-bound AtABCG25(E232Q). Notably, AtABCG25 forms a homodimer, featuring a deep, slit-like cavity in the transmembrane domain. The critical residues in the cavity where ABA binds are precisely characterized. Moreover, ATP binding triggers the closure of nucleotide-binding domains and conformational transitions in the transmembrane domains. Collectively, these findings provide valuable insights into the intricate substrate recognition and transport mechanisms of ABA exporter ABCG25, paving the way towards genetical manipulating of ABA homeostasis and plant fitness.

plant biology↗

bioRxiv2023

Rationally designed multimeric nanovaccines using icosahedral DNA origami for molecularly controlled display of SARS-CoV-2 receptor binding domain

Multivalent antigen display on nanoparticles can enhance the immunogenicity of nanovaccines targeting viral moieties, such as the receptor binding domain (RBD) of SARS-CoV-2. However, particle morphology and size of current nanovaccines are significantly different from those of SARS-CoV-2. Additionally, surface antigen patterns are not controllable to enable the optimization of B cell activation. Herein, we employed an icosahedral DNA origami (ICO) as a display particle for SARS-CoV-2 RBD nanovaccines. The morphology and diameter of the particles were close to those of the virus (91 {+/-} 11 nm). The surface addressability of the DNA origami permitted facile modification of the ICO surface with numerous RBD antigen clusters (ICO-RBD) to form various antigen patterns. Using an in vitro screening system, we demonstrate that the antigen spacing, antigen copies within clusters and cluster number parameters of the surface antigen pattern all impact the ability of the nanovaccines to activate B cells. Importantly, the optimized ICO-RBD nanovaccines evoked stronger and more enduring humoral and T cell immune responses in mouse models compared to soluble RBD antigens. Our vaccines activated similar humoral immunity and slightly stronger cellular immunity compared to mRNA vaccines. These results provide reference principles for the rational design of nanovaccines and exemplify the utility of DNA origami as a display platform for vaccines against infectious disease.

bioengineering↗

bioRxiv2023

CDK19 and CDK8 Mediator kinases drive androgen-independent in vivo growth of castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) remains incurable due to its high plasticity. We found that Mediator kinases CDK8 and CDK19, pleiotropic regulators of transcriptional reprogramming, are differentially affected by androgen, which downregulates CDK8 and upregulates CDK19. Accordingly, expression of CDK8 decreases while CDK19 increases during prostate carcinogenesis, but both CDK19 and CDK8 are upregulated in metastatic CRPC. Genetic inactivation of CDK8 and CDK19 suppresses CRPC tumor growth in castrated male mice and renders CRPC responsive to androgen deprivation. Restoration of active CDK19 or CDK8 kinases reverses this phenotype, indicating that CRPC becomes dependent on Mediator kinase activity for in vivo growth under the conditions of androgen deprivation. Selective CDK8/19 inhibitors suppress androgen-independent growth of cell line-based and patient-derived CRPC xenografts, whereas prolonged inhibitor treatment induces tumor regression and even leads to cures. Mediator kinase activity was found to affect tumor and stromal gene expression preferentially in castrated mice, orchestrating castration-induced transcriptional reprogramming. These results warrant the exploration of Mediator kinase inhibitors for CRPC therapy.

cancer biology↗

bioRxiv2023

BL-Hi-C reveals the 3D genome structure of Brassica crops with high efficiency and sensitivity

High-throughput chromatin conformation capture (Hi-C) technologies can be used to investigate the three-dimensional genomic structure of plants. However, complex protocol and high background noise in Hi-C hinder its practical application in plant 3D genomics. Here, we took the approach of modified Bridge Linker Hi-C technology (BL-Hi-C) to explore plant 3D landscape. We modified the BL-Hi-C method by simplifing nuclei extraction step. By using Brassica rapa and Brassica oleracea, BL-Hi-C showed higher signal value and lower background noise than Hi-C. The high sensitivity of BL-Hi-C was further demonstrated by its capacity to identify gene loops involving BrFLC1, BrFLC2 and BrFLC3 which were undetectable in Hi-C. BL-Hi-C also showed promising performance with input as low as 100 mg leaf tissue. By analyzing of the generated data from BL-Hi-C, we found that the simulated 3D genome structure of B. rapa leaf cells was Bouquet configuration. Our results showed that the modified BL-Hi-C is a powerful tool for the investigation of plants genomic organization, gene regulation, and genome assembly. IN A NUTSHELL Background3D genome structure play a critical role in regulating spatiotemporal gene expression. However, there is a lack of simple, efficient and sensitive Hi-C technique in plants. QuestionHow to study plant 3D genomics more simple and efficientHow to detect plant chromatin loops more sensitive? FindingsWe showed that BL-Hi-C is more simple, efficient and sensitive than coventional Hi-C by using Brassica rapa and Brassica oleracea. Furthermore, BL-Hi-C demonstrated its high sensitivity by detecting gene loops involving BrFLC1, BrFLC2, and BrFLC3 which could not be detected by Hi-C. In addition, BL-Hi-C demonstrated promising performance with inputs as low as 100 mg leaf tissue. By analyzing BL-Hi-C data, we found that the simulated 3D genome structure of B. rapa leaf cells was Bouquet configuration. Next stepsHow chromatin loops are formed and regulated gene expression are key questions to be answered in plants. Our dataset of BL-Hi-C will enable future investigations to improve our understanding of chromatin loops.

genomics↗

bioRxiv2023

Variations in Homoeologous Dosage and Epigenomics Mark the Early Evolution of Synthetic Brassica Tetraploids

Polyploidization is important in plant evolution and is becoming increasingly important in crop breeding and material creation. Studies have provided evidence for structural variations and epigenomic repatterning in synthetic polyploidizations, but the relationships between structural and epigenomic variations, as well as their effects on gene expression and phenotypic variations are unknown. Here, we investigated the genome-wide large deletion/duplication regions (DelDups) and genomic methylation dynamics, in the leaf organ as a representative, of progenies from eight generations that derived from the synthetic tetraploidization between Brassica rapa and Brassica oleracea. We found that half or complete deletion/duplication of fragments ranging in size from 400 kb to 65.85 Mb, with a mean size of 5.70 Mb, occurred frequently from the first generation of selfing and thereafter. The genes located in these DelDups expressed at levels expected for a positive dosage effect, as indicated by the positive association between expression and the copy number of these genes. Plants containing these DelDups also showed distinct phenotypic variations. The whole genome methylation level experienced significant fluctuations in different generations and eventually decreased in the latter generations. Moreover, the DelDups did not show methylation changes from other individuals of the same generation, and the local regions with methylation alterations did not affect gene expression. Our findings provide new insights into the early evolution of polyploid genomes and guide the use of synthetic polyploidizations in breeding.

genomics↗

bioRxiv2023

Divergence of TORC1-mediated Stress Response Leads to Novel Acquired Stress Resistance in a Pathogenic Yeast

Acquired stress resistance (ASR) enables organisms to prepare for environmental changes that occur after an initial stressor. However, the genetic basis for ASR and how the underlying network evolved remain poorly understood. In this study, we discovered that a short phosphate starvation induces oxidative stress response (OSR) genes in the pathogenic yeast C. glabrata and protects it against a severe H2O2 stress; the same treatment, however, provides little benefit in the low pathogenic-potential relative, S. cerevisiae. This ASR involves the same transcription factors (TFs) as the OSR, but with different combinatorial logics. We show that Target-of- Rapamycin Complex 1 (TORC1) is differentially inhibited by phosphate starvation in the two species and contributes to the ASR via its proximal effector, Sch9. Therefore, evolution of the phosphate starvation-induced ASR involves the rewiring of TORC1s response to phosphate limitation and the repurposing of TF-target gene networks for the OSR using new regulatory logics.

microbiology↗

bioRxiv2023

A transcriptional cell atlas identifies the decline in the AT2 niche in aged human lungs

Aging poses a global public health challenge, associated with molecular and physiological changes in the lungs. It increases susceptibility to acute and chronic lung diseases, yet the underlying molecular and cellular drivers in aged populations are not fully appreciated. To systematically profile the genetic changes associated with age, we present a single-cell transcriptional atlas comprising nearly half a million cells from the healthy lungs of human subjects spanning various ages, sexes, and smoking statuses. Most annotated cell lineages in aged lungs exhibit dysregulated genetic programs. Specifically, the aged alveolar epithelial cells, including both alveolar type II (AT2) and type I (AT1) cells, demonstrate loss of epithelial identities, heightened inflammaging characterized by increased expression of AP-1 transcription factor and chemokine genes, and significantly increased cellular senescence. Furthermore, the aged mesenchymal cells display a remarkable decrease in Collagen and Elastin transcription. The decline of the AT2 niche is further exacerbated by a weakened endothelial cell phenotype and a dysregulated genetic program in macrophages. These findings highlight the dysregulation observed in both AT2 stem cells and their supportive niche cells, potentially contributing to the increased susceptibility of aged populations to lung diseases.

cell biology↗

bioRxiv2023

Automated cell annotation in multi-cell images using an improved CRF_ID algorithm

Cell identification is an important yet difficult process in data analysis of biological images. Previously, we developed an automated cell identification method called CRF_ID and demonstrated its high performance in C. elegans whole-brain images (Chaudhary et al, 2021). However, because the method was optimized for whole-brain imaging, comparable performance could not be guaranteed for application in commonly used C. elegans multi-cell images that display a subpopulation of cells. Here, we present an advance CRF_ID 2.0 that expands the generalizability of the method to multi-cell imaging beyond whole-brain imaging. To illustrate the application of the advance, we show the characterization of CRF_ID 2.0 in multi-cell imaging and cell-specific gene expression analysis in C. elegans. This work demonstrates that high accuracy automated cell annotation in multi-cell imaging can expedite cell identification and reduce its subjectivity in C. elegans and potentially other biological images of various origins.

bioengineering↗

bioRxiv2023

Opposing implications of co-evolutionary lineages and traits of gut microbiome on human health status

Little is known about the co-evolutionary history of the human gut microbe and its relevance to host physiology. Here, we constructed a gut prokaryotic genomic database of wild primates (pSGBs) and compared it with the human gut prokaryotic database (hSGBs) to define shared co-evolutionary clusters (SCEC-hSGBs) and co-evolutionary traits of hSGBs. We analyzed the evolutionary trends of specific functions like carbohydrate-active enzymes and antibiotic resistance in hSGBs and uncovered host-jumping events and genome reduction tendencies in SCEC-hSGBs. Intriguingly, the SCEC-hSGBs and the super enrichers of the traits (SUEN-hSGBs), which are putatively partially derived from carnivores, showed opposite implications for host health status. Specifically, SUEN-hSGBs are enriched in various diseases, showing a negative correlation with gut biodiversity and disproportionate contributions to the known health-negative marker taxa and metabolite. Our study provides insight into the origin and adaptability of human gut microbes and references for developing probiotics and microbiome-based host health prediction.

microbiology↗

bioRxiv2023

Defining a critical role of an essential membrane protein in mycolic acid transport in mycobacteria

A major feature of the mycobacterial outer membrane (OM) is the presence of long, branched chain mycolic acids (MAs), which render the OM hydrophobic and impervious against various noxious substances, including antibiotics. While the biosynthesis of MA is well studied, the mechanisms governing its transport from the inner membrane to the OM remain largely elusive. In this study, we characterized the function of MSMEG_0317 in Mycobacterium smegmatis, a membrane protein encoded within a conserved genetic locus that has been implicated in MA metabolism and/or transport. Using a conditional knockout mutant, we demonstrate that msmeg_0317 is essential for mycobacterial growth. Depleting msmeg_0317 from cells blocks the formation of MA species found at the OM, establishing a critical function in MA transport across the cell envelope. We further reveal that MSMEG_0317 exists as stable dimers in vitro that require the presence of its N- and C-terminal transmembrane helices, both of which are important for functionality in cells. Our work defines the essential role of MSMEG_0317 in MA metabolism and/or transport, and offers new insights into cell envelope biogenesis in mycobacteria.

biochemistry↗

bioRxiv2023

Development of heat shock resistance in L. pneumophila modeled by experimental evolution

Because it can grow in buildings with complex hot water distribution systems (HWDS), healthcare facilities recognize the waterborne bacterium Legionella pneumophila as a major nosocomial infection threat and often try to clear the systems with a pasteurization process known as superheat-and-flush. After this treatment, many facilities find that the contaminating populations slowly recover, suggesting the possibility of in situ evolution favouring increased survival in high temperature conditions. To mimic this process in a controlled environment, an adaptive laboratory evolution (ALE) model was used to select a wild-type strain of L. pneumophila for survival to transient exposures to temperatures characteristic of routine hot water use or failed pasteurization processes in HWDS. Over their evolution, these populations became insensitive to exposure to 55 {degrees}C and innovated the ability to survive short exposures to 59 {degrees}C heat shock. Heat-adapted lineages maintained a higher expression of heat shock genes during low-temperature incubation in freshwater, suggesting a pre-adaptation to heat stress. Although there were distinct mutation profiles in each of the heat-adapted lineages, each acquired multiple mutations in the DnaJ/DnaK/ClpB disaggregase complex, as well as mutations in chaperone htpG and protease clpX. These mutations were specific to heat shock survival and were not seen in control lineages included in the ALE without exposure to heat shock. This study supports in situ observations of adaptation to heat stress and demonstrate the potential of L. pneumophila to develop resistance to control measures. ImportanceAs a bacterium that thrives in warm water ecosystems, Legionella pneumophila is a key factor motivating regulations on hot water systems. Two major measures intended to control Legionella are the maintenance of high circulating temperatures to curtail growth and the use of superheat-and-flush pasteurization processes to eliminate established populations. Although hospitals are particularly vulnerable to nosocomial pneumoniae caused by Legionella, they recurrently experience recolonization of their hot water systems after treatment. To understand these long-term survivors, we have used an experimental evolution model to replicate this process. We find major differences between the mutational profiles of heat-adapted and heat-naive L. pneumophila populations, including mutations in major heat shock genes like chaperones and proteases. This model demonstrates the value of appropriate heat treatment of L. pneumophila contaminated systems and - in an analogue to antibiotic resistance - the importance of complete eradication of the resident population to prevent selection for more persistent bacteria.

microbiology↗

bioRxiv2023

Myocardial IGF2R is a critical mediator of inflammation and fibrosis after ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injury is a common occurrence in various surgical procedures used to treat heart diseases. However, the role of insulin-like growth factor 2 receptor (IGF2R) during the process of myocardial I/R remains unclear. Therefore, this study aims to investigate the expression, distribution, and functionality of IGF2R in various I/R-associated models (such as reoxygenation, revascularization, and heart transplant). Loss-of-function studies (including myocardial conditional knockout and CRISPR interference) were performed to clarify the role of IGF2R in I/R injuries. Following hypoxia, IGF2R expression increased, but this effect was reversed upon restoration of oxygen levels. Loss of myocardial IGF2R was found to enhance the cardiac contractile functions, and reduced cell infiltration or cardiac fibrosis of I/R mouse models compared to the genotype control. CRISPR-inhibition of IGF2R decreased cell apoptotic death under hypoxia. RNA sequencing analysis indicated that myocardial IGF2R played a critical role in regulating the inflammatory response, innate immune response, and apoptotic process following I/R. Integrated analysis of the mRNA profiling, pulldown assays, and mass spectrometry identified granulocyte-specific factors as potential targets of myocardial IGF2R in the injured heart. In conclusion, myocardial IGF2R emerges as a promising therapeutic target to ameliorate inflammation or fibrosis following I/R injuries.

cell biology↗

bioRxiv2023

GTP signaling links metabolism, DNA repair, and responses to genotoxic stress

How cell metabolism regulates DNA repair is incompletely understood. Here, we define a GTP-mediated signaling cascade that links metabolism to DNA repair and has significant therapeutic implications. GTP, but not other nucleotides, regulates the activity of Rac1, a G protein, that promotes the dephosphorylation of serine 323 on Abl-interactor 1 (Abi-1) by protein phosphatase 5 (PP5). Dephosphorylated Abi-1, a protein previously not known to activate DNA repair, promotes non-homologous end joining. In patients and mouse models of glioblastoma, Rac1 and dephosphorylated Abi-1 mediate DNA repair and resistance to standard of care genotoxic treatments. The GTP-Rac1-PP5-Abi-1 signaling axis is not limited to brain cancer, as GTP supplementation promotes DNA repair and Abi-1-S323 dephosphorylation in non-malignant cells and protects mouse tissues from genotoxic insult. This unexpected ability of GTP to regulate DNA repair independently of deoxynucleotide pools has important implications for normal physiology and cancer treatment.

cancer biology↗

bioRxiv2023

Semiconductor augumented valuable chemical photosynthesis from Rhodospirillum rubrum and mechanism study

Photosynthetic biohybrid systems based on purple bacteria and semiconducting nanomaterials are promising platforms for sustainable solar-powered chemical production. However, these types of biohybrid systems have not been fully developed to date, and their energy utilization and electron transfer mechanisms are not well understood. Herein, a Rhodospirillum rubrum-CdS biohybrid system was successfully constructed. The photosynthetic activity and photoelectrochemical properties of biohybrid system were analyzed. Chromatographic and spectroscopic studies confirmed the metabolic activities of R. rubrum cells were effectively augmented by surface-deposited CdS nanoparticles and validated with increased H2 evolution, polyhydroxybutyric acid (PHB) production, and solid biomass accumulation. Energy consumption and metabolic profiles of R. rubrum-CdS biohybrid system exhibited a growth phase-dependent behaviour. Photoelectrochemical study confirmed that light-excited electrons from CdS enhanced photosynthetic electron flow of R. rubrum cells. Monochromatic light modulated photoexcitation of biohybrid system was utilized to explore interfacial electron transfer between CdS and R. rubrum cells, and the results showed that CdS enhanced the utilization of blue light by R. rubrum cells. This work investigated the feasibility and prospect of utilizing R. rubrum in semi-artificial photosynthesis of valuable products, and offered insights into the energy utilization and the electron transfer mechanism between nanomaterials and purple bacteria.

microbiology↗

bioRxiv2023

Single-cell RNA-sequencing identifies a novel subset of CD9+ reparative macrophages modulated by CCN2 derived from Nlrx1 deficient cardiomyocytes in the infarcted heart

RationaleNlrx1, a pattern recognition receptor belonging to the NLR family, is highly expressed in the heart and is significantly increased after myocardial infarction in vivo, however, the role of Nlrx1 in post-infarction inflammation and healing is poorly understood. Although the effects of infiltrating macrophages on survival of cardiomyocytes and healing of injured hearts have been intensely studied, whether or not and how surviving cardiomyocytes might influence the phenotype and function of macrophages in the infarcted hearts was largely unexplored. ObjectiveTo investigate the role of Nlrx1 in post-infarction inflammation and healing and to dissect the underlying mechanism. Methods and resultsSingle cell RNA-sequencing of 23,805 cells isolated from infarcted hearts revealed 7 clusters of infarct macrophages including CCR2+, Isg+, Mki67+ proliferative, and LYVE1+ cardiac resident macrophages, and identified a novel subset of CD9+Il1rn+ macrophages, which were characterized by high expression of Cd9, Il1rn, Gpnmb and Spp1, and downregulation of proinflammatory cytokines and chemokines. CD9+Il1rn+ macrophages were largely found in infarcted hearts of Nlrx1KO mice, and were transcriptionally unique with reparative phenotype. Loss of Nlrx1 attenuated ventricular dysfunction and adverse remodeling, and decreased post-infarction mortality. Flow cytometry analysis showed markedly increased number of CD9+ macrophages and higher mean fluorescence intensity of CD9 in Nlrx1KO mice. RNA-seq analysis revealed that CD9+ macrophages of Nlrx1KO infarcted hearts exhibited a reparative and anti-inflammatory phenotype as featured by upregulation of wound healing-associated genes including CD9, Spp1 and Fn1, and downregulation of proinflammatory genes. Conditioned medium from Nlrx1 deficient cardiomyocytes upon hypoxia stimulation skewed macrophage polarization towards a reparative and inflammation-suppressed phenotype. Gain-and loss-of function of Nlrx1 combined with RNA-seq analysis identified CCN2, whose expression and secretion were significantly increased in Nlrx1 deficient cardiomyocytes upon hypoxia, as a cardiomyocytes-derived mediator responsible, at least partly, for reprograming macrophage towards a reparative phenotype. In vivo, CCN2 expression was markedly elevated in Nlrx1KO infarcted hearts. Moreover, exogenous CCN2 partially mediated macrophage transition towards a reparative phenotype. ConclusionsCD9+ IL1rn+ macrophages modulated by Nlrx1 deficient cardiomyocytes-derived CCN2, is a novel subset of reparative macrophages contributing to infarct healing. Inhibition of myocardial Nlrx1 and/or activation of CCN2 to boost CD9+ IL1rn+ reparative macrophages may represent new therapeutics for infarct healing following ischemic injury.

immunology↗