A-To-I RNA Editing By ADAR1 Is Essential For Hematopoiesis

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1199-1199 ◽  
Author(s):  
Brian Liddicoat ◽  
Robert Piskol ◽  
Alistair Chalk ◽  
Miyoko Higuchi ◽  
Peter Seeburg ◽  
...  

Abstract The role of RNA and its regulation is becoming increasingly appreciated as a vital component of hematopoietic development. RNA editing by members of the Adenosine Deaminase Acting on RNA (ADAR) gene family is a form of post-transcriptional modification which converts genomically encoded adenosine to inosine (A-to-I) in double-stranded RNA. A-to-I editing by ADAR directly converts the sequence of the RNA substrate and can alter the structure, function, processing, and localization of the targeted RNA. ADAR1 is ubiquitously expressed and we have previously described essential roles in the development of hematopoietic and hepatic organs. Germline ablation of murine ADAR1 results in a significant upregulation of interferon (IFN) stimulated genes and embryonic death between E11.5 and E12.5 associated with fetal liver disintegration and failed hemopoiesis. To determine the biological importance of A-to-I editing by ADAR1, we generated an editing dead knock-in allele of ADAR1 (ADAR1E861A). Mice homozygous for the ADAR1E861A allele died in utero at ∼E13.5. The fetal liver (FL) was small and had significantly lower cellularity than in controls. Analysis of hemopoiesis demonstrated increased apoptosis and a loss of hematopoietic stem cells (HSC) and all mature lineages. Most notably erythropoiesis was severely impaired with ∼7-fold reduction across all erythrocyte progenitor populations compared to controls. These data are consistent with our previous findings that ADAR1 is essential for erythropoiesis (unpublished data) and suggest that the ADAR1E861A allele phenocopies the null allele in utero. To assess the requirement of A-to-I editing in adult hematopoiesis, we generated mice where we could somatically delete the wild-type ADAR1 allele and leave only ADAR1E861A expressed in HSCs (hScl-CreERAdar1fl/E861A). In comparison to hScl-CreERAdar1fl/+ controls, hScl-CreERAdar1fl/E861A mice were anemic and had severe leukopenia 20 days post tamoxifen treatment. Investigation of marrow hemopoiesis revealed a significant loss of all cells committed to the erythroid lineage in hScl-CreERAdar1fl/E861A mice, despite having elevated phenotypic HSCs. Upon withdrawal of tamoxifen diet, all blood parameters were restored to control levels within 12 weeks owing to strong selection against cells expressing only the ADAR1E861A allele. To understand the mechanism through which ADAR1 mediated A-to-I editing regulates hematopoiesis, RNA-seq was performed. Gene expression profiles showed that a loss of ADAR1 mediated A-to-I editing resulted in a significant upregulation of IFN signatures, consistent with the gene expression changes in ADAR1 null mice. To define substrates of ADAR1 we assessed A-to-I mismatches in the RNA-seq data sets. 3,560 previously known and 353 novel A-to-I editing sites were identified in our data set. However, no single editing substrate discovered could account for the IFN signature observed or the lethality of ADAR1E861A/E861A mice. These results demonstrate that ADAR1 mediated A-to-I editing is essential for the maintenance of both fetal and adult hemopoiesis in a cell-autonomous manner and a key suppressor of the IFN response in hematopoiesis. Furthermore the ADAR1E861A allele demonstrates the essential role of ADAR1 in vivo is A-to-I editing. Disclosures: Hartner: TaconicArtemis: Employment.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1231-1231
Author(s):  
Chih Long Liu ◽  
Bo Dai ◽  
Aaron M. Newman ◽  
Ravi Majeti ◽  
Ash A Alizadeh

Abstract Abstract 1231 Background: Current methods for defining and isolating human hematopoietic stem and progenitor cells using surface markers enrich for unique functional properties of these populations. However, significant functional heterogeneity in these compartments remains with important implications for understanding normal and altered hematopoiesis. Using flow sorting to enrich >10,000 cells as progenitor subpopulations, we previously characterized the gene expression signature of normal human HSC (Majetiet al 2009 PNAS 106(9):3396–3401). We hypothesized that interrogation of the transcriptomes of single cells from this compartment could resolve remaining heterogeneity and help identify and better define features of progenitor cells and hematopoietic stem cells (HSCs). Methods: Using normal human bone marrow aspirates and a FACS Aria II instrument equipped with a specialized single-cell sorting apparatus, we sorted cells enriched for HSCs based on expression of Lin-CD34+CD38-CD90+CD45RA− into 1-cell, 10-cell, 100-cell, and 40000-cell (bulk) representations. We used at least 5 replicates per group and verified single cell deposition by direct visualization. We amplified cDNA from these corresponding inputs using an exponential whole transcriptome amplification (WTA) scheme (Miltenyi SuperAmp), and evaluated gene expression profiles by two microarray platforms (Agilent/GE Healthcare 60K, and Affymetrix U133 plus 2.0), and by RNA-Seq (Illumina). We used gene expression correlation between replicates within and between microarrays as means of assessing methodological reproducibility and estimating population heterogeneity. Results: Whole transcriptome amplification yielded cDNA ranging from 0.2–1 kb for 10 and 100 cells, with significantly lower size distribution of amplified cDNA observed for single cells. Gene expression profiles had significantly better replicate reproducibility and array coverage with the Agilent microarray platform when compared with the Affymetrix U133 Plus 2.0 platform (gene coverage of 84 % for 100 cells, 73 % for 10 cells and 50% for 1 cell for Agilent vs 24 % for 100 cells, 11 % for 10 cells and 5.7% for 1 cell for Affymetrix). RNA-Seq profiling of the same populations is ongoing with major technical optimizations focused on reducing amplification of non-human templates while maintaining library complexity and representation. Using biological replicates for each input size, we observed high inter-replicate correlation levels for expression profiles obtained for bulk sorted HSCs from 8 healthy donors (∼40000-cells, average r=0.97) and for 100-cell and 10-cell inputs from a single donor (r=0.96–0.99, respectively). While intra-array concordance of replicate measurements (n=14642) was high (r>0.91) within each of 5 single cells from a single donor, comparison of 5-single cells from the same donor identified significant heterogeneity, when compared to the 10-cell and 100-cell sub-clusters (Figure 1). Individual genes characteristically expressed by these heterogeneous single cell populations are currently being investigated by FACS and Fluidigm arrays. A larger experiment characterizing 192 single progenitor cells, employing Agilent microarrays and RNA-Seq is currently in progress. Conclusions: Single cell transcriptome profiling is feasible, with best performance on 60-mer microarrays. Single cell transcriptomes exhibit lower, but reasonable levels of reproducibility (r>0.7) and precision as compared with higher cell numbers. Gene expression profiles of single cells capture gene expression heterogeneity in HSCs. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3843-3843
Author(s):  
Elina K Cook ◽  
Richard N Armstrong ◽  
Eshita Sharma ◽  
Brooke Snetsinger ◽  
Jacqueline Boultwood ◽  
...  

Abstract BACKGROUND: Clonal hematopoiesis of indeterminate potential (CHIP) involves the peripheral blood (PB) expansion of progeny of a hematopoietic stem or progenitor cell that is somatically mutated in a hematological cancer-associated gene (most often TET2 or DNMT3A). CHIP associates with comorbid diseases of aging such as cardiovascular disease. Murine knockout (Tet2 or Dnmt3a) and engraftment models of CHIP develop exacerbated cardiovascular disease and their mutated myeloid cells are more reactive to inflammatory stimuli. However, whether blood leukocytes in human CHIP are hyper-inflammatory remains speculative. We recently found people with CHIP have higher serum levels of certain pro-inflammatory cytokines and chemokines than controls (Cook et al, ASH 2017). Thus, we hypothesized that PB effector cells in people with CHIP will be enriched for pro-inflammatory gene expression and pathways. METHODS: The presence of CHIP (variant allele frequency, VAF>0.02) was determined in the whole PB of 30 hematologically healthy adults >65 years old at Baycrest and Sunnybrook Health Sciences Centers (Toronto, Canada) using Ion Proton DNA sequencing targeting 48 commonly mutated genes in myeloid neoplasms. RNA-Seq (HISeq 4000, Illumina, 75bp paired-end sequencing reads with a depth of >50 million/sample) was performed on corresponding ribo-depleted whole PB samples (PAXgene), reads were aligned with HISAT2, gene counts quantified with featureCount, and analyzed with DESeq2. FDR<0.1 was used as a cutoff for differential gene expression analyses. Correlations with clinical and comorbidity data were tested with logistic regressions. RESULTS: People with CHIP ("CHIP+", n: males=8, females=13; TET2=12, DNMT3A=8, SF3B1=1; VAF range=0.03-0.40) compared to those without CHIP ("CHIP-", n: males=3, females=6) had six significantly downregulated genes (e.g. GZMM) and 10 upregulated genes (e.g. DEFA4, LTF, MPO, see Figure 1A). Hierarchical clustering of these top genes yielded two groups, one consisting of most of the CHIP- cases (8/9 cases, in a cluster of 11, see Figure 1A). The three CHIP+ cases that clustered with CHIP- had VAFs lower than 0.15. Of the 16 differentially regulated genes between CHIP+ and CHIP-, nine were recognized by reactome, and most overlapped (≥6 genes) with pathways involving neutrophil degranulation and innate immunity (Figure 1B). DEFA4, LTF, CRISP3, BPI and MPO specifically encode components of neutrophil granules, with various anti-microbial and homeostatic functions. However, mean neutrophil counts (4.6±1.6 vs. 4.4±1.6 10^9/L for CHIP+ vs. CHIP-) and neutrophil to lymphocyte ratios (3.2±1.4 vs. 2.8±2.1 in CHIP+ vs. CHIP-) did not significantly differ between the groups. This suggests that mutations of CHIP may affect neutrophil/immune-related function or phenotype, potentially contributing to comorbid disease. For example, greater expression of alpha-defensins (i.e. DEFA4) in CHIP may involve dysregulated granulocyte maturation and inflammatory function as seen in myelodysplasia (Droin et al, 2010 Blood), suggesting a potential dysregulation of inflammation and immunity. Higher VAFs (>0.15) associated with higher ECOG scores (poorer overall daily functioning: odds ratio=44, 95% CI=4-500, p=0.002), suggesting that larger proportions of mutated cells may have greater effects on gene expression profiles. Accordingly, there were linear correlations between the VAFs of the mutated cell populations and the levels of differentially expressed genes (Figure 1C). CONCLUSIONS: The connection between mutant clones of CHIP and disease remains poorly elucidated. For the first time, to our knowledge, we studied gene expression in CHIP leukocytes. We report that the most prominent gene expression differences between people with CHIP and those without CHIP involve neutrophil degranulation and the innate immune system. Additionally, higher VAFs may have a greater influence on gene expression levels and health than lower VAFs. We plan to validate these candidate genes in a larger cohort. These novel data warrant further investigation of the cellular pathways perturbed by somatic mutations of CHIP. Disclosures Buckstein: Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 735-735
Author(s):  
Per Holmfeldt ◽  
Pardieck Jennifer ◽  
Shannon McKinney-Freeman

Abstract Hematopoietic stem cells (HSCs) are responsible for life-long maintenance of hematopoiesis. HSC transplantation represents one of the most heavily exploited cell based therapies, routinely used to treat a myriad of life threating disorders, such as leukemia and bone marrow failure. Identifying the molecular pathways that regulate HSC engraftment is crucial to further improving outcomes in patients that rely on HSC transplantation as a curative therapy. By examining the global gene expression profiles of highly purified HSC (Lineage-Sca-1+c-Kit+CD150+CD48-), we recently identified the following members of the Nfi gene family of transcription factors as highly expressed by HSC (McKinney-Freeman et al., Cell Stem Cell, 2012): Nfix, Nfia, and Nfic. These data suggest that Nfi genes may play a novel role in regulating HSC function. To test this hypothesis, HSCs were enriched from adult bone marrow (Lineage-, c-kit+, Sca-1+ (LSK) cells) and then transduced, individually, with lentiviruses carrying shRNAs targeting each Nfi gene. Twenty-four hours post-transduction, cells were injected into lethally irradiated mice along with untransduced bone marrow LSK competitor cells congenic at the CD45 allele. The peripheral blood of recipient mice was then analyzed periodically over 16 weeks for engraftment of the Nfi-depleted cells. Although shRNA mediated knockdown of Nfi gene expression had no effect on the in vitro cell growth or viability of LSK cells, Nfi-depleted HSCs displayed a significant loss of short- and long-term in vivo hematopoietic repopulating activity. This was true for Nfia-, Nfic-, and Nfix-deficient HSC. While Nfia and Nfic are only expressed by bone marrow HSC, Nfix is highly expressed by both bone marrow and fetal liver HSC. When Nfix was depleted by shRNAs from LSK cells purified from E14.5 fetal liver, a similar loss in competitive repopulating potential was seen. Lineage analysis of peripheral blood of recipients showed no significant differences in the distribution of the major blood lineages derived from LSK cells transduced with Nfi-specific shRNAs compared to controls. When the bone marrow of recipients transplanted with Nfix- depleted cells was examined 4 and 16 weeks post-transplant, a general loss of all hematopoietic stem- and progenitor compartments examined was seen relative to control. Thus, the observed decrease in repopulating activity occurs at the level of HSCs and multipotent progenitors. To confirm an essential role for an Nfi gene family member in the regulation of HSC engraftment post-transplant, LSK cells were purified from Nfix fl/fl mice, transduced with lentiviral Cre recombinase and subsequently introduced into lethally irradiated recipients alongside congenic competitor cells. Like LSK transduced with Nfix-specific shRNAs, Nfix-/- LSK cells failed to repopulate the peripheral blood of recipient mice as efficiently as control and similar trends were detected in all stem- and progenitor cell populations examined. Time-course experiments immediately following transplantation revealed that Nfix-depleted LSK cells establish themselves in the marrow of recipient mice as efficiently as control at 5 days post-transplant, but thereafter exhausted rapidly. Examination 10 days post-transplant revealed a 5-fold increase in apoptosis specifically in the LSK compartment, but not in its differentiated progeny, in recipients transplanted with Nfix-depleted LSK cells compared to control. The increase in apoptosis was not associated with any apparent change in the cell cycle status of the LSK cells. These data suggest that Nfi genes are necessary for the survival of HSC post-transplantation. In an effort to identify the molecular pathways regulated by Nfi genes in HSC, we acquired the global gene expression profiles of Nfix-depleted HSC. In agreement with our observation that Nfix-deficient HSC displays elevated levels of apoptosis following transplantation in vivo, we observed a significant decrease in multiple genes known to be important for HSC survival, such as Erg, Mecom and Mpl, in Nfix-depleted HSC. In summary, we have for the first time established a role for the Nfi gene family in HSC biology, as evident by a decrease in bone marrow repopulating activity in Nfi-depleted HSCs. By dissecting the precise role of Nfi genes in HSC biology, we will glean insights that could improve our understanding of graft failure in clinical bone marrow transplantations. Disclosures: No relevant conflicts of interest to declare.


Genes ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
He-Gang Chen ◽  
Xiong-Hui Zhou

Drug repurposing/repositioning, which aims to find novel indications for existing drugs, contributes to reducing the time and cost for drug development. For the recent decade, gene expression profiles of drug stimulating samples have been successfully used in drug repurposing. However, most of the existing methods neglect the gene modules and the interactions among the modules, although the cross-talks among pathways are common in drug response. It is essential to develop a method that utilizes the cross-talks information to predict the reliable candidate associations. In this study, we developed MNBDR (Module Network Based Drug Repositioning), a novel method that based on module network to screen drugs. It integrated protein–protein interactions and gene expression profile of human, to predict drug candidates for diseases. Specifically, the MNBDR mined dense modules through protein–protein interaction (PPI) network and constructed a module network to reveal cross-talks among modules. Then, together with the module network, based on existing gene expression data set of drug stimulation samples and disease samples, we used random walk algorithms to capture essential modules in disease development and proposed a new indicator to screen potential drugs for a given disease. Results showed MNBDR could provide better performance than popular methods. Moreover, functional analysis of the essential modules in the network indicated our method could reveal biological mechanism in drug response.


BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yanlei Yue ◽  
Ze Jiang ◽  
Enoch Sapey ◽  
Tingting Wu ◽  
Shi Sun ◽  
...  

Abstract Background In soybean, some circadian clock genes have been identified as loci for maturity traits. However, the effects of these genes on soybean circadian rhythmicity and their impacts on maturity are unclear. Results We used two geographically, phenotypically and genetically distinct cultivars, conventional juvenile Zhonghuang 24 (with functional J/GmELF3a, a homolog of the circadian clock indispensable component EARLY FLOWERING 3) and long juvenile Huaxia 3 (with dysfunctional j/Gmelf3a) to dissect the soybean circadian clock with time-series transcriptomal RNA-Seq analysis of unifoliate leaves on a day scale. The results showed that several known circadian clock components, including RVE1, GI, LUX and TOC1, phase differently in soybean than in Arabidopsis, demonstrating that the soybean circadian clock is obviously different from the canonical model in Arabidopsis. In contrast to the observation that ELF3 dysfunction results in clock arrhythmia in Arabidopsis, the circadian clock is conserved in soybean regardless of the functional status of J/GmELF3a. Soybean exhibits a circadian rhythmicity in both gene expression and alternative splicing. Genes can be grouped into six clusters, C1-C6, with different expression profiles. Many more genes are grouped into the night clusters (C4-C6) than in the day cluster (C2), showing that night is essential for gene expression and regulation. Moreover, soybean chromosomes are activated with a circadian rhythmicity, indicating that high-order chromosome structure might impact circadian rhythmicity. Interestingly, night time points were clustered in one group, while day time points were separated into two groups, morning and afternoon, demonstrating that morning and afternoon are representative of different environments for soybean growth and development. However, no genes were consistently differentially expressed over different time-points, indicating that it is necessary to perform a circadian rhythmicity analysis to more thoroughly dissect the function of a gene. Moreover, the analysis of the circadian rhythmicity of the GmFT family showed that GmELF3a might phase- and amplitude-modulate the GmFT family to regulate the juvenility and maturity traits of soybean. Conclusions These results and the resultant RNA-seq data should be helpful in understanding the soybean circadian clock and elucidating the connection between the circadian clock and soybean maturity.


Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 244 ◽  
Author(s):  
Antonio Victor Campos Coelho ◽  
Rossella Gratton ◽  
João Paulo Britto de Melo ◽  
José Leandro Andrade-Santos ◽  
Rafael Lima Guimarães ◽  
...  

HIV-1 infection elicits a complex dynamic of the expression various host genes. High throughput sequencing added an expressive amount of information regarding HIV-1 infections and pathogenesis. RNA sequencing (RNA-Seq) is currently the tool of choice to investigate gene expression in a several range of experimental setting. This study aims at performing a meta-analysis of RNA-Seq expression profiles in samples of HIV-1 infected CD4+ T cells compared to uninfected cells to assess consistently differentially expressed genes in the context of HIV-1 infection. We selected two studies (22 samples: 15 experimentally infected and 7 mock-infected). We found 208 differentially expressed genes in infected cells when compared to uninfected/mock-infected cells. This result had moderate overlap when compared to previous studies of HIV-1 infection transcriptomics, but we identified 64 genes already known to interact with HIV-1 according to the HIV-1 Human Interaction Database. A gene ontology (GO) analysis revealed enrichment of several pathways involved in immune response, cell adhesion, cell migration, inflammation, apoptosis, Wnt, Notch and ERK/MAPK signaling.


2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xiaoshan Su ◽  
Junjie Chen ◽  
Xiaoping Lin ◽  
Xiaoyang Chen ◽  
Zhixing Zhu ◽  
...  

Abstract Background Cigarette smoking is a major risk factor for chronic obstructive pulmonary disease (COPD) and lung cancer. Epithelial–mesenchymal transition (EMT) is an essential pathophysiological process in COPD and plays an important role in airway remodeling, fibrosis, and malignant transformation of COPD. Previous studies have indicated FERMT3 is downregulated and plays a tumor-suppressive role in lung cancer. However, the role of FERMT3 in COPD, including EMT, has not yet been investigated. Methods The present study aimed to explore the potential role of FERMT3 in COPD and its underlying molecular mechanisms. Three GEO datasets were utilized to analyse FERMT3 gene expression profiles in COPD. We then established EMT animal models and cell models through cigarette smoke (CS) or cigarette smoke extract (CSE) exposure to detect the expression of FERMT3 and EMT markers. RT-PCR, western blot, immunohistochemical, cell migration, and cell cycle were employed to investigate the potential regulatory effect of FERMT3 in CSE-induced EMT. Results Based on Gene Expression Omnibus (GEO) data set analysis, FERMT3 expression in bronchoalveolar lavage fluid was lower in COPD smokers than in non-smokers or smokers. Moreover, FERMT3 expression was significantly down-regulated in lung tissues of COPD GOLD 4 patients compared with the control group. Cigarette smoke exposure reduced the FERMT3 expression and induces EMT both in vivo and in vitro. The results showed that overexpression of FERMT3 could inhibit EMT induced by CSE in A549 cells. Furthermore, the CSE-induced cell migration and cell cycle progression were reversed by FERMT3 overexpression. Mechanistically, our study showed that overexpression of FERMT3 inhibited CSE-induced EMT through the Wnt/β-catenin signaling. Conclusions In summary, these data suggest FERMT3 regulates cigarette smoke-induced epithelial–mesenchymal transition through Wnt/β-catenin signaling. These findings indicated that FERMT3 was correlated with the development of COPD and may serve as a potential target for both COPD and lung cancer.


Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1610
Author(s):  
Mohammad Vatanparast ◽  
Youngjin Park

Solenopsis japonica, as a fire ant species, shows some predatory behavior towards earthworms and woodlice, and preys on the larvae of other ant species by tunneling into a neighboring colony’s brood chamber. This study focused on the molecular response process and gene expression profiles of S. japonica to low (9 °C)-temperature stress in comparison with normal temperature (25 °C) conditions. A total of 89,657 unigenes (the clustered non-redundant transcripts that are filtered from the longest assembled contigs) were obtained, of which 32,782 were annotated in the NR (nonredundant protein) database with gene ontology (GO) terms, gene descriptions, and metabolic pathways. The results were 81 GO subgroups and 18 EggNOG (evolutionary genealogy of genes: Non-supervised Orthologous Groups) keywords. Differentially expressed genes (DEGs) with log2fold change (FC) > 1 and log2FC < −1 with p-value ≤ 0.05 were screened for cold stress temperature. We found 215 unigenes up-regulated and 115 unigenes down-regulated. Comparing transcriptome profiles for differential gene expression resulted in various DE proteins and genes, including fatty acid synthases and lipid metabolism, which have previously been reported to be involved in cold resistance. We verified the RNA-seq data by qPCR on 20 up- and down-regulated DEGs. These findings facilitate the basis for the future understanding of the adaptation mechanisms of S. japonica and the molecular mechanisms underlying the response to low temperatures.


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