Two conserved epigenetic regulators prevent healthy ageing.

It has long been assumed that lifespan and healthspan correlate strongly, yet the two can be clearly dissociated1-6. Although there has been a global increase in human life expectancy, increasing longevity is rarely accompanied by an extended healthspan4,7. Thus, understanding the origin of healthy behaviours in old people remains an important and challenging task. Here we report a conserved epigenetic mechanism underlying healthy ageing. Through genome-wide RNA-interference-based screening of genes that regulate behavioural deterioration in ageing Caenorhabditis elegans, we identify 59 genes as potential modulators of the rate of age-related behavioural deterioration. Among these modulators, we found that a neuronal epigenetic reader, BAZ-2, and a neuronal histone 3 lysine 9 methyltransferase, SET-6, accelerate behavioural deterioration in C. elegans by reducing mitochondrial function, repressing the expression of nuclear-encoded mitochondrial proteins. This mechanism is conserved in cultured mouse neurons and human cells. Examination of human databases8,9 shows that expression of the human orthologues of these C. elegans regulators, BAZ2B and EHMT1, in the frontal cortex increases with age and correlates positively with the progression of Alzheimer's disease. Furthermore, ablation of Baz2b, the mouse orthologue of BAZ-2, attenuates age-dependent body-weight gain and prevents cognitive decline in ageing mice. Thus our genome-wide RNA-interference screen in C. elegans has unravelled conserved epigenetic negative regulators of ageing, suggesting possible ways to achieve healthy ageing.

VP2 residue N142 of coxsackievirus A10 is critical for the interaction with KREMEN1 receptor and neutralizing antibodies and the pathogenicity in mice.

Coxsackievirus A10 (CVA10) has recently emerged as one of the major causative agents of hand, foot, and mouth disease. CVA10 may also cause a variety of complications. No approved vaccine or drug is currently available for CVA10. The residues of CVA10 critical for viral attachment, infectivity and in vivo pathogenicity have not been identified by experiment. Here, we report the identification of CVA10 residues important for binding to cellular receptor KREMEN1. We identified VP2 N142 as a key receptor-binding residue by screening of CVA10 mutants resistant to neutralization by soluble KREMEN1 protein. The receptor-binding residue N142 is exposed on the canyon rim but highly conserved in all naturally occurring CVA10 strains, which provides a counterexample to the canyon hypothesis. Residue N142 when mutated drastically reduced receptor-binding activity, resulting in decreased viral attachment and infection in cell culture. More importantly, residue N142 when mutated reduced viral replication in limb muscle and spinal cord of infected mice, leading to lower mortality and less severe clinical symptoms. Additionally, residue N142 when mutated could decrease viral binding affinity to anti-CVA10 polyclonal antibodies and a neutralizing monoclonal antibody and render CVA10 resistant to neutralization by the anti-CVA10 antibodies. Overall, our study highlights the essential role of VP2 residue N142 of CVA10 in the interactions with KREMEN1 receptor and neutralizing antibodies and viral virulence in mice, facilitating the understanding of the molecular mechanisms of CVA10 infection and immunity. Our study also provides important information for rational development of antibody-based treatment and vaccines against CVA10 infection.

Rheumatoid arthritis patients harbour aberrant enteric bacteriophages with autoimmunity-provoking potential: a paired sibling study.

OBJECTIVES: Viruses have been considered as important participants in the development of rheumatoid arthritis (RA). However, the profile of enteric virome and its role in RA remains elusive. This study aimed to investigate the atlas and involvement of virome in RA pathogenesis. METHODS: Faecal samples from 30 pairs of RA and healthy siblings that minimise genetic interferences were collected for metagenomic sequencing. The α and ß diversity of the virome and the virome-bacteriome interaction were analysed. The differential bacteriophages were identified, and their correlations with clinical and immunological features of RA were analysed. The potential involvement of these differential bacteriophages in RA pathogenesis was further investigated by auxiliary metabolic gene annotation and molecular mimicry study. The responses of CD4+ T cells and B cells to the mimotopes derived from the differential bacteriophages were systemically studied. RESULTS: The composition of the enteric bacteriophageome was distorted in RA. The differentially presented bacteriophages correlated with the immunological features of RA, including anti-CCP autoantibody and HLA-DR shared epitope. Intriguingly, the glycerolipid and purine metabolic genes were highly active in the bacteriophages from RA. Moreover, peptides of RA-enriched phages, in particular Prevotella phage and Oscillibacter phage could provoke the autoimmune responses in CD4+ T cells and plasma cells via molecular mimicry of the disease-associated autoantigen epitopes, especially those of Bip. CONCLUSIONS: This study provides new insights into enteric bacteriophageome in RA development. In particular, the aberrant bacteriophages demonstrated autoimmunity-provoking potential that would promote the occurrence of the disease.

Immunological profile of lactylation-related genes in Crohn's disease: a comprehensive analysis based on bulk and single-cell RNA sequencing data.

BACKGROUND: Crohn's disease (CD) is a disease characterized by intestinal immune dysfunction, often accompanied by metabolic abnormalities. Disturbances in lactate metabolism have been found in the intestine of patients with CD, but studies on the role of lactate and related Lactylation in the pathogenesis of CD are still unknown. METHODS: We identified the core genes associated with Lactylation by downloading and merging three CD-related datasets (GSE16879, GSE75214, and GSE112366) from the GEO database, and analyzed the functions associated with the hub genes and the correlation between their expression levels and immune infiltration through comprehensive analysis. We explored the Lactylation levels of different immune cells using single-cell data and further analyzed the differences in Lactylation levels between inflammatory and non-inflammatory sites. RESULTS: We identified six Lactylation-related hub genes that are highly associated with CD. Further analysis revealed that these six hub genes were highly correlated with the level of immune cell infiltration. To further clarify the effect of Lactylation on immune cells, we analyzed single-cell sequencing data of immune cells from inflammatory and non-inflammatory sites in CD patients and found that there were significant differences in the levels of Lactylation between different types of immune cells, and that the levels of Lactylation were significantly higher in immune cells from inflammatory sites. CONCLUSIONS: These results suggest that Lactylation-related genes and their functions are closely associated with changes in inflammatory cells in CD patients.

Autonomously Assembled Living Capsules by Microbial Coculture for Enhanced Bacteriotherapy of Inflammatory Bowel Disease.

Microorganism-mediated self-assembling of living formulations holds great promise for disease therapy. Here, we constructed a prebiotic-probiotic living capsule (PPLC) by coculturing probiotics (EcN) with Gluconacetobacter xylinus (G. xylinus) in a prebiotic-containing fermentation broth. Through shaking the culture, G. xylinus secretes cellulose fibrils that can spontaneously encapsulate EcN to form microcapsules under shear forces. Additionally, the prebiotic present in the fermentation broth is incorporated into the bacterial cellulose network through van der Waals forces and hydrogen bonding. Afterward, the microcapsules were transferred to a selective LB medium, which facilitated the colonization of dense probiotic colonies within them. The in vivo study demonstrated that PPLC-containing dense colonies of EcN can antagonize intestinal pathogens and restore microbiota homeostasis by showing excellent therapeutic performance in treating enteritis mice. The in situ self-assembly of probiotics and prebiotics-based living materials provides a promising platform for the treatment of inflammatory bowel disease.

Foxp1 is critical for the maintenance of regulatory T-cell homeostasis and suppressive function.

Regulatory T (Treg) cells play central roles in maintaining immune homeostasis and self-tolerance. However, the molecular mechanisms underlying Treg cell homeostasis and suppressive function are still not fully understood. Here, we report that the deletion of another P subfamily members of the forkhead box (Foxp) subfamily member Foxp1 in Treg cells led to increased numbers of activated Treg (aTreg) cells at the expense of quiescent Treg cells, and also resulted in impaired Treg suppressive function. Mice with Foxp1-deficient Treg cells developed spontaneous inflammatory disease with age; they also had more severe inflammatory disease in colitis and experimental autoimmune encephalomyelitis (EAE) models. Mechanistically, we found that Foxp1 bound to the conserved noncoding sequence 2 (CNS2) element of the Foxp3 locus and helped maintain Treg suppressive function by stabilizing the Foxp3 expression. Furthermore, we found that Foxp1 and Foxp3 coordinated the regulation of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) expression levels. Taken together, our study demonstrates that Foxp1 plays critical roles in both maintaining Treg cell quiescence during homeostasis and regulating Treg suppressive function.

Correlation of CT-derived pectoralis muscle status and COVID-19 induced lung injury in elderly patients.

OBJECTIVES: To explore the association between CT-derived pectoralis muscle index (PMI) and COVID-19 induced lung injury. METHODS: We enrolled 116 elderly COVID-19 patients linked to the COVID-19 outbreak in Nanjing Lukou international airport. We extracted three sessions of their CT data, including one upon admission (T1), one during the first 2 weeks when lung injury peaked (T2) and one on day 14 ± 2 (T3). Lung injury was assessed by CT severity score (CTSS) and pulmonary opacity score (POS). Pneumonia evolution was evaluated by changes of CT scores at T2 from T1(Δ). RESULTS: The maximum CT scores in low PMI patients were higher than those of normal PMI patients, including CTSS1 (7, IQR 6-10 vs. 5, IQR 3-6, p < 0.001), CTSS2 (8, IQR 7-11 vs. 5, IQR 4-7, p < 0.001) and POS (2, IQR 1-2.5 vs. 1, IQR 1-2, p < 0.001). Comorbidity (OR = 6.15, p = 0.023) and the presence of low PMI (OR = 5.43, p = 0.001) were predictors of lung injury aggravation with ΔCTSS1 > 4. The presence of low PMI (OR = 5.98, p < 0.001) was the predictor of lung injury aggravation with ΔCTSS2 > 4. Meanwhile, presence of low PMI (OR = 2.82, p = 0.042) and incrementally increasing D-dimer (OR = 0.088, p = 0.024) were predictors of lung injury aggravation with ΔPOS = 2. CONCLUSIONS: PMI can be easily assessed on chest CT images and can potentially be used as one of the markers to predict the severity of lung injury in elderly COVID-19 patients.

Long-term high-risk drinking does not change effective doses of propofol for successful insertion of gastroscope in Chinese male patients.

BACKGROUND: Available literature indicates that long-term drinkers demand a higher dose of propofol for induction of anesthesia than non-drinkers. However, there is no study having assessed the influence of long-term high-risk drinking (LTHRD) on the effective doses of propofol for successful insertion of gastroscope with sedation. This study was designed to compare the effective doses of propofol for successful insertion of gastroscope between LTHRD and non-drinking (ND) Chinese male patients. METHODS: Thirty-one LTHRD patients and 29 ND male patients undergoing elective gastroscopy with propofol sedation were enrolled. The modified Dixon's up-and-down method was applied to determine the calculated median effective dose (ED50) of propofol for successful insertion of gastroscope. Furthermore, the isotonic regression analysis was used to establish the dose-response curve of propofol and assess the effective doses of propofol where 50% (ED50) and 95% (ED95) of gastroscope insertions were successful. RESULTS: The calculated ED50 of propofol for successful insertion of gastroscope was 1.55 ± 0.10 mg/kg and 1.44 ± 0.11 mg/kg in the LTHRD and ND patients. The isotonic regression analysis further showed that ED50 and ED95 of propofol for successful insertion of gastroscope was 1.50 mg/kg (95%CI, 1.40-1.63) and 1.80 mg/kg (95%CI, 1.74-1.90) in the LTHRD patients, respectively; 1.40 mg/kg (95% CI, 1.27-1.57) and 1.60 mg/kg (95%CI, 1.56-1.65) in the ND patients. The ED50 of propofol for successful insertion of gastroscope was not significantly different between LTHRD and ND patients. CONCLUSIONS: This study demonstrates that the difference in the estimated ED50 of propofol for successful insertion of gastroscope between LTHRD and ND Chinese male patients was not statistically significant. TRIAL REGISTRATION: The study was registered on November 28, 2020 ( ChiCTR2000040382 ) in the Chinese Clinical Trial Registry.

scSensitiveGeneDefine: sensitive gene detection in single-cell RNA sequencing data by Shannon entropy.

BACKGROUND: Single-cell RNA sequencing (scRNA-seq) is the most widely used technique to obtain gene expression profiles from complex tissues. Cell subsets and developmental states are often identified via differential gene expression patterns. Most of the single-cell tools utilized highly variable genes to annotate cell subsets and states. However, we have discovered that a group of genes, which sensitively respond to environmental stimuli with high coefficients of variation (CV), might impose overwhelming influences on the cell type annotation. RESULT: In this research, we developed a method, based on the CV-rank and Shannon entropy, to identify these noise genes, and termed them as "sensitive genes". To validate the reliability of our methods, we applied our tools in 11 single-cell data sets from different human tissues. The results showed that most of the sensitive genes were enriched pathways related to cellular stress response. Furthermore, we noticed that the unsupervised result was closer to the ground-truth cell labels, after removing the sensitive genes detected by our tools. CONCLUSION: Our study revealed the prevalence of stochastic gene expression patterns in most types of cells, compared the differences among cell marker genes, housekeeping genes (HK genes), and sensitive genes, demonstrated the similarities of functions of sensitive genes in various scRNA-seq data sets, and improved the results of unsupervised clustering towards the ground-truth labels. We hope our method would provide new insights into the reduction of data noise in scRNA-seq data analysis and contribute to the development of better scRNA-seq unsupervised clustering algorithms in the future.

Molecular simulation of SARS-CoV-2 spike protein binding to pangolin ACE2 or human ACE2 natural variants reveals altered susceptibility to infection.

We constructed complex models of SARS-CoV-2 spike protein binding to pangolin or human ACE2, the receptor for virus transmission, and estimated the binding free energy changes using molecular dynamics simulation. SARS-CoV-2 can bind to both pangolin and human ACE2, but has a significantly lower binding affinity for pangolin ACE2 due to the increased binding free energy (9.5 kcal mol-1). Human ACE2 is among the most polymorphous genes, for which we identified 317 missense single-nucleotide variations (SNVs) from the dbSNP database. Three SNVs, E329G (rs143936283), M82I (rs267606406) and K26R (rs4646116), had a significant reduction in binding free energy, which indicated higher binding affinity than wild-type ACE2 and greater susceptibility to SARS-CoV-2 infection for people with them. Three other SNVs, D355N (rs961360700), E37K (rs146676783) and I21T (rs1244687367), had a significant increase in binding free energy, which indicated lower binding affinity and reduced susceptibility to SARS-CoV-2 infection.

Implementation of the CRISPR-Cas13a system in fission yeast and its repurposing for precise RNA editing.

In contrast to genome editing, which introduces genetic changes at the DNA level, disrupting or editing gene transcripts provides a distinct approach to perturbing a genetic system, offering benefits complementary to classic genetic approaches. To develop a new toolset for manipulating RNA, we first implemented a member of the type VI CRISPR systems, Cas13a from Leptotrichia shahii (LshCas13a), in Schizosaccharomyces pombe, an important model organism employed by biologists to study key cellular mechanisms conserved from yeast to humans. This approach was shown to knock down targeted endogenous gene transcripts with different efficiencies. Second, we engineered an RNA editing system by tethering an inactive form of LshCas13a (dCas13) to the catalytic domain of human adenosine deaminase acting on RNA type 2 (hADAR2d), which was shown to be programmable with crRNA to target messenger RNAs and precisely edit specific nucleotide residues. We optimized system parameters using a dual-fluorescence reporter and demonstrated the utility of the system in editing randomly selected endogenous gene transcripts. We further used it to restore the transposition of retrotransposon Tf1 mutants in fission yeast, providing a potential novel toolset for retrovirus manipulation and interference.

Veratramine modulates AP-1-dependent gene transcription by directly binding to programmable DNA.

Because the transcription factor activator protein-1 (AP-1) regulates a variety of protein-encoding genes, it is a participant in many cellular functions, including proliferation, transformation, epithelial mesenchymal transition (EMT), and apoptosis. Inhibitors targeting AP-1 have potential use in the treatment of cancer and other inflammatory diseases. Here, we identify veratramine as a potent natural modulator of AP-1, which selectively binds to a specific site (TRE 5'-TGACTCA-3') of the AP-1 target DNA sequence and regulates AP-1-dependent gene transcription without interfering with cystosolic signaling cascades that might lead to AP-1 activation. Moreover, RNA-seq experiments demonstrate that veratramine does not act on the Hedgehog signaling pathway in contrast to its analogue, cyclopamine, and likely does not harbor the same teratogenicity and toxicity. Additionally, veratramine effectively suppresses EGF-induced AP-1 transactivation and transformation of JB6 P+ cells. Finally, we demonstrate that veratramine inhibits solar-ultraviolet-induced AP-1 activation in mice. The identification of veratramine and new findings in its specific regulation of AP-1 down stream genes pave ways to discovering and designing regulators to regulate transcription factor.

Microbiota in the apical root canal system of tooth with apical periodontitis.

BACKGROUND: Apical periodontitis (AP) is essentially an inflammatory disease of microbial etiology primarily caused by infection of the pulp and root canal system. Variation of the bacterial communities caused by AP, as well as their changes responding to dental therapy, are of utmost importance to understand the pathogensis of the apical periodontitis and establishing effective antimicrobial therapeutic strategies. This study aims to uncover the composition and diversity of microbiota associated to the root apex to identify the relevant bacteria highly involved in AP, with the consideration of root apex samples from the infected teeth (with/without root canal treatment), healthy teeth as well as the healthy oral. METHODS: Four groups of specimens are considered, the apical part of root from diseased teeth with and without root canal treatment, and wisdom teeth extracted to avoid being impacted (tooth healthy control), as well as an additional healthy oral control from biofilm of the buccal mucosa. DNA was extracted from these specimens and the microbiome was examined through focusing on the V3-V4 hypervariable region of the 16S rRNA gene using sequencing on Illumina MiSeq platform. Composition and diversity of the bacterial community were tested for individual samples, and between-group comparisons were done through differential analysis to identify the significant changes. RESULTS: We observed reduced community richness and diversity in microbiota samples from diseased teeth compared to healthy controls. Through differential analysis between AP teeth and healthy teeth, we identified 49 OTUs significantly down-regulated as well as 40 up-regulated OTUs for AP. CONCLUSION: This study provides a global view of the microbial community of the AP associated cohorts, and revealed that AP involved not only bacteria accumulated with a high abundance, but also those significantly reduced ones due to microbial infection.

Comparative interactome analysis reveals distinct and overlapping properties of Raf family kinases.

The three mammalian Raf proteins (A-Raf, B-Raf, and C-Raf) are key components of the MAPK pathway. Although diverse functions have been proposed for Raf kinases, it is still not clear how interacting proteins contribute to differences in the signaling functions of the three Raf kinases. Here, we report the comparative interactomes of the three Raf kinases under serum-starved and EGF-stimulated conditions. We identified nearly 400 novel interacting proteins; some interacted with all three isoforms while others interacted exclusively with one or two. Comparing the interactomes of the three Raf kinases under different conditions revealed Raf proteins perform distinct functions through specific interactions. Our interactome data help define the differences between the three Raf kinases and may uncover new functions or regulatory mechanisms. Knowledge of Raf kinase protein-protein interactions will help us to investigate the function of specific pathways in the future.

Modelling BioNano optical data and simulation study of genome map assembly.

Motivation: The launch of the BioNano next-generation mapping system has greatly enhanced the performance of physical map construction, thus rapidly expanding the application of optical mapping in genome research. Data biases have profound implications for downstream applications. However, very little is known about the properties and biases of BioNano data, and the very factors that contribute to whole-genome optical map assembly. Results: We generated BioNano molecule data from eight organisms with diverse base compositions. We first characterized the properties/biases of BioNano molecule data, i.e. molecule length distribution, false labelling signal, variation of optical resolution and coverage distribution bias, and their inducing factors such as chimeric molecules, fragile sites and DNA molecule stretching. Second, we developed the BioNano Molecule SIMulator (BMSIM), a novel computer simulation program for optical data. BMSIM, is of great use for future genome mapping projects. Third, we evaluated the experimental variables that impact whole-genome optical map assembly. Specifically, the effects of coverage depth, molecule length, false-positive and false-negative labelling signals, chimeric molecules and nicking enzyme and nick site density were investigated. Our simulation study provides the empirical findings on how to control experimental variables and gauge analytical parameters to maximize benefit and minimize cost on whole-genome optical map assembly. Availability and implementation: BMSIM is freely available on: https://github.com/pingchen09990102/BMSIM. Supplementary information: Supplementary data are available at Bioinformatics online.

Lupus-associated atypical memory B cells are mTORC1-hyperactivated and functionally dysregulated.

OBJECTIVES: A population of atypical memory B cells (AtMs) are greatly expanded in patients with active lupus, but their generation and pathophysiological roles are poorly defined. The aim of this study was to comprehensively characterise lupus AtMs with a purpose to identify therapeutic clues to target this B cell population in lupus. METHODS: Peripheral B cell subsets were measured by flow cytometry. Sorting-purified B cell subsets were subject to RNA sequencing and functional studies. Plasma cytokines and secreted immunoglobulins were detected by Luminex or ELISA. In situ renal B cells were detected by multiplexed immunohistochemistry. RESULTS: CD24-CD20hi AtMs were strongly increased in two Chinese cohorts of patients with treatment-naïve lupus. Gene expression profile indicated that B cell signalling and activation, lipid/saccharide metabolism and endocytosis pathways were abnormally upregulated in lupus AtMs. In addition, the mammalian target of rapamycin complex 1 (mTORC1) pathway was remarkably activated in lupus AtMs, and blocking mTORC1 signalling by rapamycin abolished the generation of T-bet+ B cells and terminal differentiation of lupus AtMs. Furthermore, lupus AtMs displayed a dysfunctional phenotype, underwent accelerated apoptosis, poorly co-stimulated T cells and produced proinflammatory cytokines. Interestingly, lupus AtMs were in a paradoxically differentiated status with markers pro and against terminal differentiation and enriched with antinucleosome reactivity. Finally, AtMs were accumulated in the kidneys of patients with lupus nephritis and associated with disease severity. CONCLUSIONS: These findings demonstrated that mTORC1-overactivated lupus AtMs are abnormally differentiated with metabolic and functional dysregulations. Inhibiting mTORC1 signalling might be an attractive option to target AtMs and to improve therapeutic effectiveness in patients with lupus.

The Landscape of A-to-I RNA Editome Is Shaped by Both Positive and Purifying Selection.

The hydrolytic deamination of adenosine to inosine (A-to-I editing) in precursor mRNA induces variable gene products at the post-transcription level. How and to what extent A-to-I RNA editing diversifies transcriptome is not fully characterized in the evolution, and very little is known about the selective constraints that drive the evolution of RNA editing events. Here we present a study on A-to-I RNA editing, by generating a global profile of A-to-I editing for a phylogeny of seven Drosophila species, a model system spanning an evolutionary timeframe of approximately 45 million years. Of totally 9281 editing events identified, 5150 (55.5%) are located in the coding sequences (CDS) of 2734 genes. Phylogenetic analysis places these genes into 1,526 homologous families, about 5% of total gene families in the fly lineages. Based on conservation of the editing sites, the editing events in CDS are categorized into three distinct types, representing events on singleton genes (type I), and events not conserved (type II) or conserved (type III) within multi-gene families. While both type I and II events are subject to purifying selection, notably type III events are positively selected, and highly enriched in the components and functions of the nervous system. The tissue profiles are documented for three editing types, and their critical roles are further implicated by their shifting patterns during holometabolous development and in post-mating response. In conclusion, three A-to-I RNA editing types are found to have distinct evolutionary dynamics. It appears that nervous system functions are mainly tested to determine if an A-to-I editing is beneficial for an organism. The coding plasticity enabled by A-to-I editing creates a new class of binary variations, which is a superior alternative to maintain heterozygosity of expressed genes in a diploid mating system.

A survey on cellular RNA editing activity in response to Candida albicans infections.

BACKGROUND: Adenosine-to-Inosine (A-to-I) RNA editing is catalyzed by the adenosine deaminase acting on RNA (ADAR) family of enzymes, which induces alterations in mRNA sequence. It has been shown that A-to-I RNA editing events are of significance in the cell's innate immunity and cellular response to viral infections. However, whether RNA editing plays a role in cellular response to microorganism/fungi infection has not been determined. Candida albicans, one of the most prevalent human pathogenic fungi, usually act as a commensal on skin and superficial mucosal, but has been found to cause candidiasis in immunosuppression patients. Previously, we have revealed the up-regulation of A-to-I RNA editing activity in response to different types of influenza virus infections. The current work is designed to study the effect of microorganism/fungi infection on the activity of A-to-I RNA editing in infected hosts. RESULTS: We first detected and characterized the A-to-I RNA editing events in oral epithelial cells (OKF6) and primary human umbilical vein endothelial cells (HUVEC), under normal growth condition or with C. albicans infection. Eighty nine thousand six hundred forty eight and 60,872 A-to-I editing sites were detected in normal OKF6 and HUVEC cells, respectively. They were validated against the RNA editing databases, DARNED, RADAR, and REDIportal with 50, 80, and 80% success rates, respectively. While over 95% editing sites were detected in Alu regions, among the rest of the editing sites in non repetitive regions, the majority was located in introns and UTRs. The distributions of A-to-I editing activity and editing depth were analyzed during the course of C. albicans infection. While the normalized editing levels of common editing sites exhibited a significant increase, especially in Alu regions, no significant change in the expression of ADAR1 or ADAR2 was observed. Second, we performed further analysis on data from in vivo mouse study with C. albicans infection. One thousand one hundred thirty three and 955 A-to-I editing sites were identified in mouse tongue and kidney tissues, respectively. The number of A-to-I editing events was much smaller than in human epithelial or endothelial cells, due to the lack of Alu elements in mouse genome. Furthermore, during the course of C. albicans infection we observed stable level of A-to-I editing activity in 131 and 190 common editing sites in the mouse tongue and kidney tissues, and found no significant change in ADAR1 or ADAR2 expression (with the exception of ADAR2 displaying a significant increase at 12 h after infection in mouse kidney tissue before returning to normal). CONCLUSIONS: This work represents the first comprehensive analysis of A-to-I RNA editome in human epithelial and endothelial cells. C. albicans infection of human epithelial and endothelial cells led to the up-regulation of A-to-I editing activities, through a mechanism different from that of viral infections in human hosts. However, the in vivo mouse model with C. albicans infection did not show significant changes in A-to-I editing activities in tongue and kidney tissues. The different results in the mouse model were likely due to the presence of more complex in vivo environments, e.g. circulation and mixed cell types.

A comprehensive study on cellular RNA editing activity in response to infections with different subtypes of influenza a viruses.

BACKGROUND: RNA editing is an important mechanism that expands the diversity and complexity of genetic codes. The conversions of adenosine (A) to inosine (I) and cytosine (C) to uridine (U) are two prominent types of RNA editing in animals. The roles of RNA editing events have been implicated in important biological pathways. Cellular RNA editing activity in response to influenza A virus infection has not been fully characterized in human and avian hosts. This study was designed as a big data analysis to investigate the role and response of RNA editing in epithelial cells during the course of infection with various subtypes of influenza A viruses. RESULTS: Using a bioinformatics pipeline modified from our previous study, we characterized the profiles of A-to-I and C-to-U RNA editing events in human epithelial cells during the course of influenza A virus infection. Our results revealed a striking diversity of A-to-I RNA editing activities in human epithelial cells in responses to different subtypes of influenza A viruses. The infection of H1N1 and H3N2 significantly up-regulated normalized A-to-I RNA editing levels in human epithelial cells, whereas that of H5N1 did not change it and H7N9 infection significantly down-regulated normalized A-to-I editing level in A549 cells. Next, the expression levels of ADAR and APOBEC enzymes responsible for A-to-I and C-to-U RNA editing during the course of virus infection were examined. The increase of A-to-I RNA editing activities in infections with some influenza A viruses (H1N1 and H3N2) is linked to the up-regulation of ADAR1 but not ADAR2. Further, the pattern recognition receptors of human epithelial cells infected with H1N1, H3N2, H5N1 and H7N9 were examined. Variable responsive changes in gene expression were observed with RIG-I like receptors and Toll like receptors. Finally, the effect of influenza A virus infection on cellular RNA editing activity was also analyzed in avian hosts. CONCLUSION: This work represents the first comprehensive study of cellular RNA editing activity in response to different influenza A virus infections in human and avian hosts, highlighting the critical role of RNA editing in innate immune response and the pathogenicity of different subtypes of influenza A viruses.

[Research progress on pathophysiological function of SOS1 protein].

Son of sevenless homolog 1 (SOS1) protein is a ubiquitously expressed adapter. As a key protein in intracellular signaling, SOS1 plays an important role in many signal transduction pathways, such as Ras and Rac signaling pathways. The abnormal expression or mutation of SOS1 is closely related to clinical diseases. In this article, we review research progress on SOS1 functions and its roles in physiology and pathophysiology.