Project description:To further understand the similaries and differences between 3 types of arterial cells (adult cells, fetal cells, and arterial cells derived from pluripotent stem cells, we analyzed the gene expression. We were able to confirm the specific gene expression hallmark of arterial endothelial cells and also to identify which are the genes that make the difference between fetal and derived endothelial cells.
Project description:Human pluripotent stem cells (hPSCs) provide a powerful platform for studying the dynamic molecular network towards hematopoiesis. To date, a comprehensive roadmap at single-cell resolution for hPSC-derived hematopoietic differentiation has not been established. Here, we performed extensive single-cell transcriptomic analyses to map fate choices and gene expression programs during hematopoietic differentiation of hPSCs and identified strategies to improve the quantity and quality of hPSC-derived hematopoietic cells. By focusing specifically on cell populations and molecular events involved in endothelial-to-hematopoietic transition (EHT), the EHT was identified accompanying by a decline in aerobic metabolism and providing hypoxia in vitro enhances arterial and hematopoietic differentiation. Furthermore, arterial endothelial cells are validated as a critical regulator of definitive hematopoietic progenitor specification. Collectively, our study provides benchmark datasets to understand the origins of human hematopoiesis and presents an advance for guiding the generation of functional hematopietic cells in vitro for clinical applications.
Project description:To characterize the genetic basis of hybrid male sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven ‘hotspots,’ seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL - but not cis eQTL - were substantially lower when mapping was restricted to a ‘fertile’ subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility.
Project description:During embryonic development, blood cells emerge from a subset of specialized endothelial cells, named hemogenic endothelial cells (HECs), via a process known as endothelial-to-hematopoietic transition (EHT). A thorough characterization of HECs and their EHT is essential to guide the efforts to derive this population from human pluripotent stem cells (hPSCs), a critical step to generate therapeutic blood products in vitro. However, current known markers used to isolate HECs are insufficient as they also enrich for arterial endothelial cells that are associated with HECs. To identify specific human HEC markers, we performed transcriptomic analysis of 28-32-day human embryos, a developmental stage characterized by active EHT. We observed that the expression of FCGR2B, encoding for the Fc receptor CD32 previously associated with other specialized endothelia, is highly enriched in the ACE+CD34+ endothelial cell population that contains HECs. Functional ex vivo analyses confirmed that multilineage hematopoietic potential is highly enriched in CD32+ endothelial cells isolated from the aorta-gonad-mesonephros region and yolk sac of human embryos. In addition, CD32 emerged as selective marker for hPSC-derived HECs across different hematopoietic programs. Remarkably, our analyses showed that CD32 expression identifies HECs that are irreversibly bound to undergo EHT. As such, CD32 expression enriches for cells with hemogenic potential with a higher specificity for hPSC-derived HECs than other known HEC markers. These findings provide a simple method for isolating HECs from human embryos and hPSC cultures, allowing the efficient generation of hematopoietic cells in vitro.
Project description:During embryonic development, blood cells emerge from a subset of specialized endothelial cells, named hemogenic endothelial cells (HECs), via a process known as endothelial-to-hematopoietic transition (EHT). A thorough characterization of HECs and their EHT is essential to guide the efforts to derive this population from human pluripotent stem cells (hPSCs), a critical step to generate therapeutic blood products in vitro. However, current known markers used to isolate HECs are insufficient as they also enrich for arterial endothelial cells that are associated with HECs. To identify specific human HEC markers, we performed transcriptomic analysis of 28-32-day human embryos, a developmental stage characterized by active EHT. We observed that the expression of FCGR2B, encoding for the Fc receptor CD32 previously associated with other specialized endothelia, is highly enriched in the ACE+CD34+ endothelial cell population that contains HECs. Functional ex vivo analyses confirmed that multilineage hematopoietic potential is highly enriched in CD32+ endothelial cells isolated from the aorta-gonad-mesonephros region and yolk sac of human embryos. In addition, CD32 emerged as selective marker for hPSC-derived HECs across different hematopoietic programs. Remarkably, our analyses showed that CD32 expression identifies HECs that are irreversibly bound to undergo EHT. As such, CD32 expression enriches for cells with hemogenic potential with a higher specificity for hPSC-derived HECs than other known HEC markers. These findings provide a simple method for isolating HECs from human embryos and hPSC cultures, allowing the efficient generation of hematopoietic cells in vitro.
Project description:Chavez2009 - a core regulatory network of OCT4 in human embryonic stem cells
A core OCT4-regulated network has been identified as a test case, to analyase stem cell characteristics and cellular differentiation.
This model is described in the article:
In silico identification of a core regulatory network of OCT4 in human embryonic stem cells using an integrated approach.
Chavez L, Bais AS, Vingron M, Lehrach H, Adjaye J, Herwig R
BMC Genomics, 2009, 10:314
Abstract:
BACKGROUND: The transcription factor OCT4 is highly expressed in pluripotent embryonic stem cells which are derived from the inner cell mass of mammalian blastocysts. Pluripotency and self renewal are controlled by a transcription regulatory network governed by the transcription factors OCT4, SOX2 and NANOG. Recent studies on reprogramming somatic cells to induced pluripotent stem cells highlight OCT4 as a key regulator of pluripotency.
RESULTS: We have carried out an integrated analysis of high-throughput data (ChIP-on-chip and RNAi experiments along with promoter sequence analysis of putative target genes) and identified a core OCT4 regulatory network in human embryonic stem cells consisting of 33 target genes. Enrichment analysis with these target genes revealed that this integrative analysis increases the functional information content by factors of 1.3 - 4.7 compared to the individual studies. In order to identify potential regulatory co-factors of OCT4, we performed a de novo motif analysis. In addition to known validated OCT4 motifs we obtained binding sites similar to motifs recognized by further regulators of pluripotency and development; e.g. the heterodimer of the transcription factors C-MYC and MAX, a prerequisite for C-MYC transcriptional activity that leads to cell growth and proliferation.
CONCLUSION: Our analysis shows how heterogeneous functional information can be integrated in order to reconstruct gene regulatory networks. As a test case we identified a core OCT4-regulated network that is important for the analysis of stem cell characteristics and cellular differentiation. Functional information is largely enriched using different experimental results. The de novo motif discovery identified well-known regulators closely connected to the OCT4 network as well as potential new regulators of pluripotency and differentiation. These results provide the basis for further targeted functional studies.
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Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from seven Mus musculus tissues (Heart, Brain, Liver, Lung, Kidney, Skeletal Muscle, Thymus)