Project description:We developed a novel approach, m1A-seq, for high-resolution mapping of the transcriptome-wide m1A landscape, based on antibody-mediated capture followed by massively parallel sequencing. Using this method we performed immunodepletion of methylated transcipts to assess the average methylation level Immunodepletion of m1A modified transcripts in human compared to the input, allows for estimation of the fraction of methylated transcripts. We compared the expression levels of sup (immunodepleted) and input methylated transcripts to deduce the fraction of m1A methylation.
Project description:The Ets transcription factor, ERG, plays a central role in definitive hematopoiesis and its overexpression in acute myeloid leukemia is associated with a stem cell signature and bad prognosis. However, little is known about the underlying mechanism by which ERG causes leukemia. Therefore we sought to identify ERG targets that participate in development of leukemia by integration of expression arrays and Chromatin immunoprecipitation. Bone marrow was collected from three transgenic ERG mice harboring a myeloid leukemia and twelve wild type mice. Nine wild type bone marrow samples were lineage depleted and pooled into 3 samples (each one consisting of three lineage negative wild type bone marrows). The resulting 9 samples were used for RNA extraction and hybridization on affymetrix microarrays.
Project description:DS children have a 500-fold increased risk for developing acute megakaryoblastic leukemia (AMKL). Around 10% of DS newborns have a transient myeloproliferative disorder (TMD) that resolves spontaneously. Somatic mutations acquired during fetal hematopoiesis in the GATA1 transcription factor are detected in megakaryoblasts from all the DS TMDs or AMKLs. GATA1 is an X chromosome transcription factor essential for the development of multiple hematopoietic lineages. Loss of GATA1 results in embryonic lethality due to severe anemia. The GATA1 mutations result in the expression of a shorter isoform, GATA1s. Replacement of GATA1 with GATA1s causes transient proliferation of immature fetal megakaryocytic progenitors. The Hsa21 ETS transcription factor, ERG, is expressed in megakaryocytes and erythrocytes and is involved in several types of cancer. Mutation in GATA1 gene leading to expression of the short isoform (GATA1s) that occurs on the background of trisomy 21 is regarded as one of the driving forces for megakaryocytic expansion observed in DS fetal livers. ERG, which is located on chromosome 21, is considered one of the leading candidates to cooperate with GATA1 mutation in the generation of DS AMKL. To study the in vivo cooperation between ERG and GATA1 isoforms, we crossed the ERG transgenic mice with the GATA1s Knock-in mice (GATA null background). We found that males expressing both ERG and the short isoform of GATA1(GATA1s) died in uterus between embryonic days E121/2 and E141/2.We studied erythropoiesis and megakaryopoiesis in fetal livers from the different genotypes generated from our cross. We used expression array to study the specific interaction of ERG with the different GATA1 isoforms in fetal livers from E121/2 and E141/2 and identify ERG, GATA1 and GATA1s target genes by comparing sets of genes that are activated or repressed in the presence of ERG and the two isoforms of GATA1.
Project description:Alternative mRNA splicing is a major mechanism for gene regulation and transcriptome diversity. Despite the extent of the phenomenon, the regulation and specificity of the splicing machinery are only partially understood. Adenosine-to-inosine (A-to-I) RNA editing of pre-mRNA by ADAR enzymes has been linked to splicing regulation in several cases. Here we used bioinformatics approaches, RNA-seq and exon-specific microarray of ADAR knockdown cells to globally examine how ADAR and its A-to-I RNA editing activity influence alternative mRNA splicing. Although A-to-I RNA editing only rarely targets canonical splicing acceptor, donor, and branch sites, it was found to affect splicing regulatory elements (SREs) within exons. Cassette exons were found to be significantly enriched with A-to-I RNA editing sites compared with constitutive exons. RNA-seq and exon-specific microarray revealed that ADAR knockdown in hepatocarcinoma and myelogenous leukemia cell lines leads to global changes in gene expression, with hundreds of genes changing their splicing patterns in both cell lines. This global change in splicing pattern cannot be explained by putative editing sites alone. Genes showing significant changes in their splicing pattern are frequently involved in RNA processing and splicing activity. Analysis of recently published RNA-seq data from glioblastoma cell lines showed similar results. Our global analysis reveals that ADAR plays a major role in splicing regulation. Although direct editing of the splicing motifs does occur, we suggest it is not likely to be the primary mechanism for ADAR-mediated regulation of alternative splicing. Rather, this regulation is achieved by modulating trans-acting factors involved in the splicing machinery. HepG2 and K562 cell lines were stably transfected with plasmids containing siRNA designed to specifically knock down ADAR expression (ADAR KD). This in order to examine how ADAR affects alternative splicing globally.
Project description:NCAM1+ subpopulation of adult human kidney epithelial cells (hKEpC) can be specifically activated in vitro to stem-like cells that de-differentiate and recapitulate embryogenesis. We used microarrays to detail the global programme of gene expression in the NCAM1+ sub-population in comparison to NCAM1-.
Project description:NCAM1+ subpopulation of fetal human kidneyl cells are nephron progenitors We used microarrays to detail the global programme of gene expression in the NCAM1+ sub-population in comparison to total culture.
Project description:SMCs must undergo specialzed patterning during blood vessel stabilization. We used microarray analysis to identify differentially expressed genes as smooth muscle cells were induced to assemble into a network of elongated cords. Two time points (Day 0 and Day 8) and three biological replicates for each, using Affymetrix HGU133A and HGU133B arrays for each sample.
Project description:Integrin-?3 plays a central role in the interplay of cells, morphogens and ECM, required for proper nephrogenesis, thus adding ITGA3 to the list of CAKUT (congenital anomalies of the kidney and urinary tract)-causing genes. we used renal tissue originally obtained from a patient with an ITGA3 mutation and assessed its gene expression profile as compared to controls
Project description:Cell-based approaches utilizing autologous human renal cells require their isolation, expansion in vitro and reintroduction back into the host for renal tissue regeneration. Nevertheless, human kidney epithelial cells (hKEpC) lose their phenotype, dedifferentiate and assume the appearance of fibroblasts after relatively few passages in culture. We hypothesized that growth conditions may influence hKEpC phenotype and function. hKEpC retrieved from human nephrectomy tissue samples showed the ability to reproducibly form kidney-spheres when grown in suspension culture developed in non-adherent conditions. Genetic labeling and time-lapse microscopy indicated, at least in part, the aggregation of hKEpC into 3D-spheroids rather than formation of pure clonally expanded spheres. Characterization of hKEpC spheroids by real-time PCR and FACS analysis showed up-regulation of some renal developmental and 'stemness' markers compared to monolayer and mostly an EpCAM+CD24+CD133+CD44+ spheroid cell phenotype. Oligonucleotide microarrays which were used to identify global transcriptional changes accompanying spheroid formation, showed predominantly up-regulation of cell matrix/cell contact molecules and cellular biogenesis processes and down-regulation of cell cycle, growth and locomotion. Accordingly, hKEpC spheroids proliferated slowly as indicated by low Ki-67 staining, but when grafted in low cell numbers onto the chorioallantoic membrane (CAM) of the chick embryo, they exclusively reconstituted various renal tubular epithelia. Moreover, efficient generation of kidney spheroids was observed after long-term monolayer culture resulting in re-establishment of tubulogenic capacity upon CAM grafting. Thus, generation of a specialized quiescent niche in hKEpC spheroids may provide a functional benefit for kidney-derived cells in vivo. 6 samples, 3 adherent and 3 spheroids samples