From phenotypical investigation to RNA-sequencing for gene expression analysis: a workflow for single and pooled rare cells
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE212814 | GEO | 2023/01/03
REPOSITORIES: GEO
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Project description:Fluorescence-activated cell sorting (FACS) is a sensitive and valuable technique to characterize cellular subpopulations and great advances have been made using this approach. Cells are often fixed with formaldehyde prior to the sorting process to preserve cell morphology and maintain the expression of surface molecules, as well as to ensure safety in the sorting of infected cells. It is widely recognized that formaldehyde fixation alters RNA and DNA structure and integrity, thus analyzing gene expression in these cells has been difficult. We therefore examined the effects of formaldehyde fixation on the stability and quantitation of nucleic acids in cell lines, primary leukocytes and also cells isolated from SIV-infected pigtailed macaques. We developed a method to extract RNA from fixed cells that yielded the same amount of RNA as our common method of RNA isolation from fresh cells. Quantitation of RNA by RT-qPCR in fixed cells was not always comparable with that in unfixed cells. In comparison, when RNA was measured by the probe-based NanoString system, there was no significant difference in RNA quantitation. In addition, we demonstrated that quantitation of proviral DNA in fixed cells by qPCR is comparable to that in unfixed cells when normalized by a single-copy cellular gene. These results provide a systematic procedure to quantitate gene expression in cells that have been fixed with formaldehyde and sorted by FACS. We compared RNA quantitation between unfixed and formaldehyde-fixed cells using the NanoString nCounter system. This analysis was performed using two cell lines, K562 and CEMx174, and human PBMCs. Three biological replicates were performed for each cell type. We also performed this comparison using human PBMCs sorted by FACS. For this analysis, we isolated PBMCs from two donors and performed two technical replicates for each donor sample.
2013-09-09 | E-GEOD-50690 | biostudies-arrayexpress
Project description:Fluorescence-activated cell sorting (FACS) is a sensitive and valuable technique to characterize cellular subpopulations and great advances have been made using this approach. Cells are often fixed with formaldehyde prior to the sorting process to preserve cell morphology and maintain the expression of surface molecules, as well as to ensure safety in the sorting of infected cells. It is widely recognized that formaldehyde fixation alters RNA and DNA structure and integrity, thus analyzing gene expression in these cells has been difficult. We therefore examined the effects of formaldehyde fixation on the stability and quantitation of nucleic acids in cell lines, primary leukocytes and also cells isolated from SIV-infected pigtailed macaques. We developed a method to extract RNA from fixed cells that yielded the same amount of RNA as our common method of RNA isolation from fresh cells. Quantitation of RNA by RT-qPCR in fixed cells was not always comparable with that in unfixed cells. In comparison, when RNA was measured by the probe-based NanoString system, there was no significant difference in RNA quantitation. In addition, we demonstrated that quantitation of proviral DNA in fixed cells by qPCR is comparable to that in unfixed cells when normalized by a single-copy cellular gene. These results provide a systematic procedure to quantitate gene expression in cells that have been fixed with formaldehyde and sorted by FACS.
2013-09-09 | GSE50690 | GEO
Project description:The human neocortex is created from diverse progenitors that are intermixed with multiple cell types in the prenatal germinal zones. These progenitors have been difficult to profile with unbiased transcriptomics since progenitors-particularly radial glia (RG)-are rare cell types, defined by a combination of intracellular markers, position and morphology. To circumvent these problems, we developed a method called FRSCR for transcriptome profiling of individual fixed, stained, and sorted cells. After validation of FRSCR with human embryonic stem cells, we profiled primary human RG that constitute only 1% of the mid-gestation cortex. These data showed that RG could be classified into ventricle zone-enriched RG (vRG) that expressed ANXA1 and CRYAB, and outer subventricular zone-localized RG (oRG) that expressed HOPX. Our study identified the first markers and molecular profiles of vRG and oRG cells, and provides an essential step for understanding molecular networks that control the development and lineage of human neocortical progenitors. Furthermore, FRSCR allows targeted single-cell transcriptomic profiling of many tissues that currently lack live-cell markers.
2015-10-02 | GSE71858 | GEO
Project description:From phenotypical investigation to RNA-sequencing for gene expression analysis: a workflow for single and pooled rare cells
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Project description:We show that high quality microarray gene expression profiles can be obtained following FACS sorting of cells using combinations of transcription factors. We use this transcription factor FACS (tfFACS) methodology to perform a genomic analysis of hESC-derived endodermal lineages marked by combinations of SOX17, GATA4, and CXCR4, and find that triple positive cells have a much stronger definitive endoderm signature than other combinations of these markers. Additionally, SOX17+GATA4+ cells can be obtained at a much earlier stage of differentiation, prior to expression of CXCR4+ cells, providing an important new tool to isolate this earlier definitive endoderm subtype. Overall, tfFACS represents an advancement in FACS technology which broadly crosses multiple disciplines, most notably in regenerative medicine to redefine cellular populations. 21 Total samples were analyzed. Samples collected after 5 days of hESC differentiation included SOX17+GATA4+ CXCR4+ cells, unfixed CXCR4+ cells, and unsorted fixed cells. Samples collected after 3 days of differentiation included SOX17+GATA4+ cells, SOX17-GATA- cells, and unsorted fixed cells. As controls, we analyzed both unfixed hESCs and fixed hESCs. All samples contained biological duplicates, triplicates or quadriplicates. We performed hierarchical clustering to demonstrate whether cellular fixation alone could change gene expression. We based this analysis on 1647 transcript clusters with coefficient of variation > 0.5 across the samples and expression values >= 500 in at least 2 out of the 21 samples. We found that fixation and staining steps did not cause distortions in gene expression measurements. This is supported by the fact that fixed and unfixed cells cluster together based upon differentiation stage, not based upon degree of fixation. Furthermore, using GSEA analysis, we found that the SOX17+GATA4+CXCR4+ day 5 cells and day 3 SOX17+GATA4+ were more enriched for compiled gold-standard endodermal genes than the CXCR4+ day 5 population.
2011-08-23 | E-GEOD-24135 | biostudies-arrayexpress
Project description:High-throughput sequencing technologies have enabled many biological discoveries; nevertheless, the resolution of bulk RNA sequencing is insufficient to elucidate the heterogeneity at the single-cell level. Single-cell RNA sequencing (scRNA-Seq) has emerged as a powerful tool for disentangling this complexity.. A major challenge in scRNA-Seq of blood is the analysis of granulocytes. These cells are pivotal to immunological responses but are recalcitrant to isolation from blood without inducing activation artifacts, thereby perturbing their transcriptomic integrity.. The difficulty of granulocyte handling for scRNA-Seq necessitate immediate processing of samples, a workflow incompatible with the logistical demands of large-scale, multi-centric studies. Innovations in commercial fixed scRNA-Seq methodologies promise to ameliorate these limitations by preserving RNA integrity post-fixation. Our investigation evaluates two such commercial kits for fixed scRNA-Seq. Our overall goal was to determine feasibility for distributed collection and centralised processing of fixed whole blood samples.
2024-05-06 | GSE266615 | GEO
Project description:RNA sequencing (RNA-seq) coupled with laser capture microdissection (LCM) is a powerful tool for transcriptomic analysis in unfixed fresh-frozen tissues. Fixation of ocular tissues for immunohistochemistry commonly involves the use of paraformaldehyde (PFA) followed by embedding in Optimal Cutting Temperature (OCT) medium for long-term cryopreservation. However, the quality of RNA derived from such archival PFA-fixed/OCT-embedded samples is often compromised, limiting its suitability for transcriptomic studies. In this study, we aimed to develop a methodology to extract high-quality RNA from PFA-fixed canine eyes by utilizing LCM to isolate retinal tissue. We demonstrate the efficacy of an optimized LCM and RNA purification protocol for transcriptomic profiling of PFA-fixed retinal specimens. We compared four pairs of canine retinal tissues, where one eye was subjected to PFA-fixation prior to OCT embedding, while the contralateral eye was embedded fresh frozen (FF) in OCT without fixation. Since the mRNA obtained from PFA-fixed retinas were contaminated with genomic DNA, we employed two rounds of DNase I treatment to obtain RNA suitable for RNA-seq. Notably, the quality of sequencing reads and gene sets identified from both PFA-fixed and FF tissues were nearly identical. In summary, our study introduces an optimized workflow for transcriptomic profiling from PFA-fixed archival retina. This refined methodology paves the way for improved transcriptomic analysis of preserved ocular tissue, bridging the gap between optimal sample preservation and high-quality RNA data acquisition.
2024-05-15 | GSE262625 | GEO
Project description:<p>The human neocortex is created from diverse intermixed progenitors in the prenatal germinal zones. These progenitors have been difficult to characterize since progenitors - particularly radial glia (RG) - are rare, and are defined by a combination of intracellular markers, position and morphology. To circumvent these problems we developed a method called FRISCR (Fixed and Recovered Intact Single Cell RNA) for transcriptome profiling of individual fixed, stained and sorted cells. We developed and validated FRISCR on human embryonic stem cells. We then profiled primary human RG (96 - 132 days post conception) that constitute only 1% of the mid-gestation cortex. These RG could be classified into ventricular zone-enriched RG (vRG) that express ANXA1 and CRYAB, and outer subventricular zone-localized RG (oRG) that express HOPX. Our study identifies the first markers and molecular profiles of vRG and oRG cells, and provides an essential step for understanding molecular networks driving the lineage of human neocortical progenitors.</p> <p><i>Reprinted from Thomsen et. al. Nature Methods (2015), with permission from Nature Publishing.</i></p> <p>Human embryonic stem cell data may be obtained through NCBI's GEO database, using accession number <a href="http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE71858">GSE71858</a>. Raw data from one human sample that was not consented to be released to dbGaP may be obtained directly from the authors of Thomsen et. al., 2015.</p>
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Project description:Proximity biotinylation is a commonly used method to identify the in vivo proximal proteome for proteins of interest. This technology typically relies on fusing a bait protein to a biotin ligase using overexpression or CRISPR-based tagging, thus prohibiting such assays in (primary) cell types that are difficult to transfect. We recently developed an ‘off the shelf’ proximity biotinylation method, which makes use of a recombinant enzyme consisting of the biotin ligase TurboID fused to the antibody-recognizing moiety Protein A. In this method, a bait specific antibody and the ProteinA-Turbo enzyme are consecutively added to permeabilized fixed or unfixed cells. Following incubation, during which ProteinA-Turbo-antibody-antigen complexes are formed, unbound molecules are washed away, after which bait-proximal biotinylation is triggered by the addition of exogenous biotin. Finally, biotinylated proteins are enriched from crude lysates using streptavidin beads followed by mass spectrometry-based protein identification. Here, we present a detailed protocol for this method
2022-10-17 | PXD030963 | Pride
Project description:RNA-Seq is an effective method to study the transcriptome, but can be difficult to apply to scarce or degraded RNA from fixed clinical samples, rare cell populations, or cadavers. Recent studies have proposed several methods for RNA-Seq of low quality and/or low quantity samples, but their relative merits have not been systematically analyzed. Here, we compare five such methods using a comprehensive set of metrics, relevant to applications such as transcriptome annotation, transcript discovery, and gene expression. Using a single human RNA sample, we constructed and deeply sequenced 10 libraries with these methods and two control libraries. We find that the RNase H method performed best for low quality RNA, and can even effectively replace oligo (dT) based methods for standard RNA-Seq. SMART and NuGEN had distinct strengths for low quantity RNA. Our analysis allows biologists to select the most suitable methods and provides a benchmark for future method development. Examination of 9 different RNA-Seq libraries starting from total RNA from 5 distinct methods; also 3 control RNA-Seq libraries
2013-05-15 | E-GEOD-40705 | biostudies-arrayexpress