Project description:Hematopoietic stem cells (HSC) possess life-long self-renewal activity and generate a series of multipotent progenitors that differentiate into lineage-committed progenitors and subsequently mature cells. Recently, functionally distinct stem and progenitor cell types have been identified, however, a systems-wide understanding of the underlying gene regulation is lacking. Here, we present the global transcriptome of ex vivo isolated mouse multipotent hematopoietic stem cells (HSC) and multipotent progenitor cells (MPP1-MPP4) as revealed by next-generation sequencing (RNA-seq). A related high-throughput study with DNA methylome data was also conducted, with data deposited at NCBI Gene Expression Omnibus, under accession GSE52709 ( http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE52709 ). An imported copy of the methylome data set can also be found at ArrayExpress: http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-52709.
Project description:The transcription factor (TF), nuclear factor I-X (NFIX), is a positive regulator of hematopoietic stem and progenitor cell (HSPC) transplantation. Nfix-deficient HSPC exhibit a severe loss of repopulating activity, increased apoptosis and a loss of colony forming potential. However, the underlying mechanism remains elusive. Here, we performed cellular indexing of transcriptomes and epitopes by high-throughput sequencing (CITE-seq) on Nfix-deficient HSPC and observed loss of long-term hematopoietic stem cells (LT-HSC) and an accumulation of megakaryocyte and myelo-erythroid progenitors. The genome-wide binding profile of NFIX in primitive murine hematopoietic cells revealed its co-localization with other hematopoietic TFs such as PU.1. We confirmed the physical interaction between NFIX and PU.1 and unveiled that the two TFs co-occupy super-enhancers and regulate genes implicated in cellular respiration and hematopoietic differentiation. Our data support a model in which NFIX collaborates with PU.1 at super-enhancers to promote the differentiation of hematopoietic progenitors.
Project description:Combinatorial actions of relatively few transcription factors control hematopoietic differentiation. To investigate this process in erythro-megakaryopoiesis, we correlated the genome-wide chromatin occupancy signatures of four master hematopoietic transcription factors (GATA1, GATA2, SCL/TAL1 and FLI1) and three diagnostic histone modification marks with the gene expression changes that occur during development of primary megakaryocytes (MEG) and erythroblasts (ERY) from murine fetal liver hematopoietic stem/progenitor cells. We identified a robust, genome-wide mechanism of MEG-specific lineage priming by a previously described stem/progenitor cell-expressed transcription factor heptad (GATA2, LYL1, SCL/TAL1, FLI1, ERG, RUNX1, LMO2) binding to MEG-specific cis-regulatory modules in multipotential hematopoietic progenitors. This is followed by genome-wide GATA factor switching that mediates further induction of MEG-specific genes following lineage commitment. Interaction between GATA and ETS factors appears to be a key determinant of these processes. In contrast, ERY-specific lineage priming occurs is biased toward GATA2-independent mechanisms. In addition to its role in MEG lineage priming, GATA2 plays an extensive role in late megakaryopoiesis as a transcriptional repressor at loci defined by a specific DNA signature. Our findings reveal important new insights into how ERY and MEG lineages arise from a common bipotential precursor via overlapping and divergent functions of shared hematopoietic transcription factors. Gene expression changes during the development of primary megakaryocytes (MEG) and erythroblasts (ERY) from murine fetal liver hematopoietic stem/progenitor cells
Project description:We report the application of sequencing technology for high-throughput profiling of RUNX1 transcription factor occupancy in mouse EML cells. RUNX1 antibody was use for chromatin immunoprecipitation followed by high-throughput sequencing to reveal RUNX1 genome occupancy in hematopoietic stem/progenitor cells. Examination of RUNX1 transcription factor occupancy in EML cells.
Project description:Infections are associated with extensive consumption of blood platelets representing a high risk for health. How the hematopoietic system coordinates the rapid and efficient regeneration of this particular lineage during such stress scenarios remains unclear. Here we report that the phenotypic hematopoietic stem cell (HSC) compartment contains highly potent megakaryocyte-committed progenitors (hipMkPs), a cell population that shares many features with multipotent HSCs and serves as a lineage-restricted emergency pool for inflammatory insults. Our data show that during homeostasis, hipMkPs are maintained in a primed but quiescent state, thus contributing little to steady-state megakaryopoiesis. Moreover, homeostatic hipMkPs show expression of megakaryocyte lineage priming transcripts for which protein synthesis is suppressed. We demonstrate that acute inflammatory signaling instructs activation of hipMkPs, as well as Mk protein production from pre-existing transcripts and drives a rapid maturation of hipMkPs and other Mk progenitors. This results in an efficient regeneration of platelets that are lost during inflammatory insult. Thus, our study reveals an elegant emergency machinery that counteracts life-threating depletions in the platelet pool during acute inflammation.