Project description:We performed an experimental Cas13d-SARScov2 genome-wide screen to identify gRNAs that would allow Cas13d to degrade the viral RNA. We built mCherry reporter plasmids that express mCherry with a 3kb 3'UTR deriving from the SARScov2 genome. In total we designed 11 reporters covering the entire plus strand of the viral genome and 11 other reporters covering the entire minus strand. Each of the 22 mCherry reporter plasmids carries a U6 expression cassette containing a Cas13d gRNA that targets the 3'UTR of the mCherry reporter. Each reporter is represented by a pool of reporters each containing a different gRNA that targets mCherry 3'UTR for a total average of ~300 gRNA per 3'UTR. The entire pool of 22 reporters, each with a pool of ~300 different gRNAs constitutes a comprehensive set ~6,500 reporters (~ 6,500 different gRNAs) that allowed us to interrogate the entire SARScov2 plus and minus strand viral RNA for regions of vulnerability and targetability. In order to specifically interrogate Cas13d activity an remove the biases that would be introduced in the reporter expression by the presence of a large 3kb 3'UTR we used a case (presence of Cas13d) control (absence of Cas13d) design. Briefly, the ~6,500 reporters were lentiviral transduced in RKO cells, the cells were split in 2 populations, 1 population was transduced with Cas13d and the other serving as control did not. The population expressing Cas13d was FACS sorted in low mCherry (efficient gRNAs) and high mCherry (un-efficient gRNAs) in 2 biological replicates and the genomic DNA of these populations was extracted, gRNAs were PCR amplified and sequenced. For the population that did not express Cas13d, a low mCherry, one high mCherry and unsorted population were sequenced as control libraries.
Project description:The transcriptome of LT-HSC (CD34+CD38-CD45RA+CD90+CD49f+) and ST-HSC (CD34+CD38-CD45RA+CD90-CD49f-) from healthy adult human Bone Marrow Cells were assessed by RNA-seq.
Project description:It is widely accepted that hematopoietic progenitor cells (HPC) are tightly associated with discrete niches within the bone marrow. This molecular environment supports and regulates their self renewal and differentiation. AFT024 is a cell line derived from murine fetal liver that has been demonstrated to maintain human hematopoietic progenitors in an undifferentiated state in vitro. While various functional and genomic studies of this and other stromal layers have already been reported, the influence of the cellular microenvironment on the gene expression of HPC has not yet been systematically analyzed.<br> <br> The CD34+/CD38- fraction of human umbilical cord blood was parted and either cultivated on AFT024 [kindly provided by I. Lemischka] or without stromal feeder layer for 16h, 20h, 48h or 72h. Both fractions were then harvested and separated by vigorous pipetting and FACS sorted again to separate the HPC from AFT024. Global gene expression profiles were determined using a novel Human Genome cDNA Microarray of over 51,145 ESTs of the UnigenSet-RZPD3. In analogy, we have compared the gene expression profiles of CD34+/CD38- cells versus AFT024 to exclude that differential gene expression resulted from contaminating feeder layer cells.
Project description:Homodimerization of Mpl can also be accomplished in the absence of Tpo, by binding of a synthetic ligand (Chemical inducer of dimerization, CID) to a constitutively expressed fusion protein F36VMpl consisting of a ligand binding domain (F36V) and the intracellular signaling domain of Mpl. In contrast to Tpo stimulation, F36VMpl dimerization in human CD34+ progenitor cells generates robust erythropoiesis. Microarray gene expression profiling of progenitors demonstrated that F36VMpl dimerization, but not Tpo, results in upregulation of critical erythroid genes. CD34+ cord blood cells were transduced with F36VMpl-GFP (GFP reporter gene) and cultured on MS-5 stroma for 7 days in the presence of CID, Tpo, Epo or no factors (no CID, negative control). CD34+GFP+ cells were sorted on day 7 and subjected to microarray (n=3 independent experiments).
Project description:The occurrence of clonal perturbations and leukemia in patients transplanted with retrovirally-transduced autologous hematopoietic stem and progenitor cells (HSPCs) has stimulated extensive investigation, demonstrating that proviral insertions perturb adjacent proto-oncogene expression. Although enhancer-deleted lentiviruses are less likely to result in insertional oncogenesis, there is evidence that they may perturb transcript splicing, and one patient with a benign clonal expansion of lentivirally-transduced HPSC has been reported. The rhesus macaque model provides an opportunity for informative long-term analysis to ask whether transduction impacts on long-term HSPC properties. We utilized two techniques to examine whether lentivirally-transduced HSPCs from eight rhesus macaques transplanted 1-13.5 years previously are perturbed at a population level, comparing telomere length as a measure of replicative history and gene expression profile of vector positive versus vector negative cells. There were no differences in telomere lengths between sorted GFP+ and GFP- blood cells, suggesting that lentiviral transduction did not globally disrupt replicative patterns. Bone marrow GFP+ and GFP- CD34+ cells showed no differences in gene expression using unsupervised and principal component analysis. These studies did not uncover any global long-term perturbation of proliferation, differentiation, or other important functional parameters of transduced HSPCs in the rhesus macaque model. CD34+ hematopoietic stem and progenitor cells were purified from bone marrow aspirates obtained from 4 rhesus macaques 3-9 years following transplantation with lentivirally-transduced autologous hematopoietic stem and progenitor cells. All lentiviral vectors contained the GFP marker gene. The CD34+ cells from each animal were sorted via flow cytometry into GFP+ and GFP- fractions, and RNA from these cells was used for Affymetrix gene expression analysis as detailed below. There were two samples, GFP+ and GFP-, from each of 4 animals.