Single-cell RNA sequencing (scRNA-seq) offers new possibilities to address biological and medical questions. However, systematic comparisons of the performance of diverse scRNA-seq protocols are lacking. We generated data from 583 mouse embryonic stem cells to evaluate six prominent scRNA-seq methods: CEL-seq2, Drop-seq, MARS-seq, SCRB-seq, Smart-seq and Smart-seq2. While Smart-seq2 detected the most genes per cell and across cells, CEL-seq2, Drop-seq, MARS-seq and SCRB-seq quantified mRNA levels with less amplification noise due to the use of unique molecular identifiers (UMIs). Power simulations at different sequencing depths showed that Drop-seq is more cost-efficient for transcriptome quantification of large numbers of cells, while MARS-seq, SCRB-seq and Smart-seq2 are more efficient when analyzing fewer cells. Our quantitative comparison offers the basis for an informed choice among six prominent scRNA-seq methods and provides a framework for benchmarking further improvements of scRNA-seq protocols. Overall design: J1 mESC in two replicates per library preparation method.
A systematic evaluation of single cell RNA-seq analysis pipelines.
Cell line, Subject
View SamplesBackground Single-cell RNA-sequencing (scRNA-seq) experiments typically analyze hundreds or thousands of cells after amplification of the cDNA. The high throughput is made possible by the early introduction of sample-specific bar codes (BCs), and the amplification bias is alleviated by unique molecular identifiers (UMIs). Thus, the ideal analysis pipeline for scRNA-seq data needs to efficiently tabulate reads according to both BC and UMI. Findings zUMIs is a pipeline that can handle both known and random BCs and also efficiently collapse UMIs, either just for exon mapping reads or for both exon and intron mapping reads. If BC annotation is missing, zUMIs can accurately detect intact cells from the distribution of sequencing reads. Another unique feature of zUMIs is the adaptive downsampling function that facilitates dealing with hugely varying library sizes but also allows the user to evaluate whether the library has been sequenced to saturation. To illustrate the utility of zUMIs, we analyzed a single-nucleus RNA-seq dataset and show that more than 35% of all reads map to introns. Also, we show that these intronic reads are informative about expression levels, significantly increasing the number of detected genes and improving the cluster resolution. Conclusions zUMIs flexibility makes if possible to accommodate data generated with any of the major scRNA-seq protocols that use BCs and UMIs and is the most feature-rich, fast, and user-friendly pipeline to process such scRNA-seq data. Overall design: HEK293T cells were sequenced using the mcSCRB-seq protocol (Bagnoli et al., 2017)
zUMIs - A fast and flexible pipeline to process RNA sequencing data with UMIs.
Cell line, Subject
View SamplesMany library preparation methods are available for gene expression quantification. Here, we sequenced and analysed Universal Human Reference RNA (UHRR) prepared using Smart-Seq2, TruSeq (public data) and a protocol using unique molecular identifiers (UMIs) that all include the ERCC spike-in mRNAs to investigate the effects of amplification bias on expression quantification. Overall design: UHRR 10 and 12 replicates for Smart-seq2 and UMI-seq library preparation methods, respectively.
The impact of amplification on differential expression analyses by RNA-seq.
No sample metadata fields
View SamplesMicroarray technologies allow the identification of large numbers of expression differences within and between species. Although environmental and physiological stimuli are clearly responsible for changes in the expression levels of many genes, it is not known whether the majority of changes of gene expression fixed during evolution between species and between various tissues within a species are caused by Darwinian selection or by stochastic processes. We find the following: (1) expression differences between species accumulate approximately linearly with time; (2) gene expression variation among individuals within a species correlates positively with expression divergence between species; (3) rates of expression divergence between species do not differ significantly between intact genes and expressed pseudogenes; (4) expression differences between brain regions within a species have accumulated approximately linearly with time since these regions emerged during evolution. These results suggest that the majority of expression differences observed between species are selectively neutral or nearly neutral and likely to be of little or no functional significance. Therefore, the identification of gene expression differences between species fixed by selection should be based on null hypotheses assuming functional neutrality. Furthermore, it may be possible to apply a molecular clock based on expression differences to infer the evolutionary history of tissues.
A neutral model of transcriptome evolution.
Sex, Age, Specimen part, Disease, Disease stage
View SamplesPurpose: Foxp2 is the first and for now the only gene connected to speech and language in humans. Two aminoacid substitutions took place in this protein during recent human evolution, after our split from the last common ancestor with chimpanzees, and are most likely to have undergone positive selection in human lineage (Enard et al., 2002). Methods: Transgenic mice in which the wild-type (murine) version of Foxp2 was replaced with the one bearing two human-specific amino acid substitutions (i.e. "humanized" Foxp2) - Foxp2hum/hum, have been compared to their wild-type (WT) counterparts in terms of behavior, electrophysiology and striatal gene expression. The latter was analyzed through RNA-sequencing performed on pooled indexed libraries on three flow cells on Illumina GAIIx. The reads were mapped to mouse genome (mm9) by TopHat 1.4.1 and were counted using Bedtools. mRNA profiles were obtained with more than 20 million reads for every sample. Differential gene expression was analyzed with DESeq using multifactor model (Anders and Huber, 2010). Results: Wild-type and Foxp2hum/hum mice did not show any significant differences in expression at individual gene level, neither in dorsomedial nor in dorsolateral striatum. However, when genes were grouped into functional categories and analyzed accordingly, this revealed a significant downregulation of functional categories related to synaptic signalling and plasticity in dorsomedial striatum of Foxp2hum/hum mice. Overall design: RNA-sequencing was performed on dorsomedial and dorsolateral striatum of wild-type and Foxp2hum/hum mice, on three flow cells Illumina GAIIx. The libraries from each sample were indexed and pooled together.
Humanized Foxp2 accelerates learning by enhancing transitions from declarative to procedural performance.
No sample metadata fields
View SamplesDifferentiation of haematopoietic stem cells followsa hierarchical program of transcription-factor regulated events. Early myeloid cell differentiation is dependent on PU.1 and CEBPA (CCAAT/enhancer binding protein alpha), late myeloid differentiation is orchestrated by CEBPE (CCAAT/enhancer binding protein epsilon). The influence of SWI/SNF (SWItch/Sucrose Non-Fermentable) chromatin remodelling factors as novel master regulators of haematopoietic differentiation is only beginning to be explored. Here, we identified three homozygous loss-of-function mutations in SMARCD2 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily d, member 2), a member of the SWI/SNF complex, in three unrelated pedigrees. We find that SMARCD2-deficient hematopoiesis results in dysfunctional neutrophil granulocytes, characterized by specific granule deficiency, myelodysplasia, and an excess of blast cells. We can show that SMARCD2 controls early steps in the differentiation of myeloid-erythroid progenitor cells in mice and zebra fish. In vitro SMARCD2 interacts with the transcription factor CEBPE. Furthermore, we find that SMARCD2 controls expression of neutrophil proteins stored in specific granules and leads to transcriptional and chromatin changes in AML cells. Hence, we identify SMARCD2 as a key factor controlling myelopoiesis and as a potential tumour suppressor in leukemia. Overall design: We analyzed CD45.2+ Lin- Mac+/low Sca1+ cKit+ (LSK) cells from Smarcd2 wild-type, heterozygous and mutant foetal livers in at least 5 replicates Additionally, we analysed three different progenitor populations from Smarcd2 wild-type and homozygous knock-out foetal livers: CD45+Lin-Sca-1-CD177+CD34lowCD16/32 (FCGR)low(MEP) CD45+Lin-Sca-1-CD177+CD34+CD16/32(FCGR)int (CMP) CD45+Lin-Sca-1-CD177+CD34+CD16/32(FCGR)high (GMP)
Chromatin-remodeling factor SMARCD2 regulates transcriptional networks controlling differentiation of neutrophil granulocytes.
Sex, Specimen part, Cell line, Subject
View SamplesThe interaction between cancer and stroma plays a key role in tumor progression. Inactivation of p53 is often observed in stromal cells surrounding in cancer, suggesting that p53 in fibroblasts is involved in tumor progression.
TSPAN12 is a critical factor for cancer-fibroblast cell contact-mediated cancer invasion.
Sex, Specimen part, Cell line
View SamplesWe here show that the niche regulates the quality of the hematopoietic stem cells (HSCs) that are regenerated after transplantation. We find that a reduced level of Wnt5a in the niche regenerates dysfunctional HSCs, which do not successfully engraft secondary recipients. In particular, RNA sequencing shows a dysregulated Zeb1-associated gene expression of multiple genes involved in the small GTPase-dependent actin polymerization pathway. Misexpression of these genes results in reduced ability to direct polarized F-actin localization, leading to defects in adhesion, migratory behavior and homing to the bone marrow of secondary recipients. Our study further shows that the Wnt5a-haploinsufficient environment similarly affects BCR-ABLp185+ cells, which, in 42% of the studied recipients, fail to generate leukemia and, in the remaining cases, fail to transfer leukemia to secondary hosts. Thus, we show that Wnt5a in the niche is required to regenerate HSCs and leukemic cells with functional ability to rearrange the actin cytoskeleton which is required for successful engraftment. Overall design: Hematopoietic stem cells are regenerated in WT or Wnt5a-haploinsufficient niches. We profile LSK hematopoiteic stem cells after transplantation and three cell populations from the niche environment: endothelial cells (EC), osteoblastic cells (OBC), and mesenchymal cells (MSC)
Niche WNT5A regulates the actin cytoskeleton during regeneration of hematopoietic stem cells.
Cell line, Subject
View SamplesTumor relapse is associated with dismal prognosis, but responsible biological principles remain incompletely understood. To isolate and characterize relapse-inducing cells, we used genetic engineering and proliferation-sensitive dyes in patient-derived xenografts of acute lymphoblastic leukemia (ALL). We identified a rare subpopulation that resembled relapse-inducing cells with combined properties of long-term dormancy, treatment resistance, and stemness. Single-cell and bulk expression profiling revealed their similarity to primary ALL cells isolated from pediatric and adult patients at minimal residual disease (MRD). Therapeutically adverse characteristics were reversible, as resistant, dormant cells became sensitive to treatment and started proliferating when dissociated from the in vivo environment. Our data suggest that ALL patients might profit from therapeutic strategies that release MRD cells from the niche. Overall design: Gene expression profiles from two PDX ALL Samples (ALL-199 & ALL-265) were generated for either dormant (LRC) vs. dividing (non-LRC) cells or drug treated vs. non-treated cells. For single cell analysis one mouse were analyzed for each condition.
Characterization of Rare, Dormant, and Therapy-Resistant Cells in Acute Lymphoblastic Leukemia.
Specimen part, Treatment, Subject
View SamplesIn lung cancer progression, p53 mutations are more often observed in invasive tumors than in non-invasive tumors, suggesting that p53 is involved in tumor invasion and metastasis. To understand the nature of p53 function as a tumor suppressor, it is crucial to elucidate the detailed mechanism of the alteration in epithelial cells, the main origin of solid tumors, following p53 inactivation.
TSPAN2 is involved in cell invasion and motility during lung cancer progression.
Sex, Age, Specimen part, Treatment
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