Project description:Here we addressed the mRNA transcriptome of Long-Term Hematopoietic Stem Cells (LT-HSC) and Multipotent Progenitor (MPP) -3 and -4 purified from WT and Helios KO mice. By analyzing the differentially expressed genes among WT and KO condition we found that Helios deletion affects transcription mostly in the LT-HSC compartment and favor a megakaryocyte mRNA lineage priming at the expense of the lymphoid one.
Project description:Our understanding of cell fate decisions in hematopoietic stem cells is incomplete. Here, we show that the transcription factor Helios is highly expressed in murine hematopoietic stem and progenitor cells (HSPCs), where it is required to suppress the separation of the platelet/megakaryocyte lineage from the HSPC pool. Helios acts mainly in quiescent cells, where it directly represses the megakaryocyte gene expression program in cells as early as the stem cell stage. Helios binding promotes chromatin compaction, notably at the regulatory regions of platelet-specific genes recognized by the Gata2 and Runx1 transcriptional activators, implicated in megakaryocyte priming. Helios null HSPCs are biased toward the megakaryocyte lineage at the expense of the lymphoid and partially resemble cells of aging animals. We propose that Helios acts as a guardian of HSPC pluripotency by continuously repressing the megakaryocyte fate, which in turn allows downstream lymphoid priming to take place. These results highlight the importance of negative and positive priming events in lineage commitment.
Project description:Our understanding of cell fate decisions in hematopoietic stem cells is incomplete. Here, we show that the transcription factor Helios is highly expressed in murine hematopoietic stem and progenitor cells (HSPCs), where it is required to suppress the separation of the platelet/megakaryocyte lineage from the HSPC pool. Helios acts mainly in quiescent cells, where it directly represses the megakaryocyte gene expression program in cells as early as the stem cell stage. Helios binding promotes chromatin compaction, notably at the regulatory regions of platelet-specific genes recognized by the Gata2 and Runx1 transcriptional activators, implicated in megakaryocyte priming. Helios null HSPCs are biased toward the megakaryocyte lineage at the expense of the lymphoid and partially resemble cells of aging animals. We propose that Helios acts as a guardian of HSPC pluripotency by continuously repressing the megakaryocyte fate, which in turn allows downstream lymphoid priming to take place. These results highlight the importance of negative and positive priming events in lineage commitment.
Project description:This experiment aimed to determine Helios contribution in chromatin accessibility in hematopoietic stem and progenitor cells. Thus, we examined the change in chromatin accessibility in purified hematopoietic stem cells (LSK, Lin-Sca1+ckit+) from 10 weeks old WT and Helios deficient mice using the ATAC-seq approach. We found that Helios null LSK an affected Open Chromatin Region (OCR) landscape, overall in the proximity of genes regulating platelets functions.
Project description:We newly identified prospectively-isolatable unipotent megakaryocyte progenitor population (MegP) as the major source of megakaryocytes, which emerges directly from early stage of hematopoiesis bypassing megakaryocyte-erythroid lineage bifurcation and contributes to physiological and pathological human megakaryopoiesis. To explore gene expression signature of hematopoietic stem/progenitor populrations miroarry-based whole transcriptome analysis was performed. As a result, gene expression signature of MegP clearly reflected its differentiation potential.
Project description:To further address the mechanism by which excessive c-MYC represses self-replication and induces apoptosis, microarray analysis of iPSC-derived megakaryocyte progenitor cell lines(MKCLs) with high or low level of c-MYC expression were examined.
Project description:It has been known that aberrant isoforms of Ikaros family ptoteins are expressed in malignant cells. We identified that PBMC of ATL (acute T-cell leukemia) patients expresses different patterns of Helios isoforms compared with normal PBMC. In order to investigate the biological impact of ATL-type Helios isoform, we conducted complehensive gene expression analyses in Jurkat cells overexpressing ATL-type Helios. Also, we investigated the influence of WT-Helios or WT-Ikaros knockdown on the gene expression profile and compared with that of the cells with ATL-type Helios overexpression. Total RNA samples from Jurkat cells were subjected to Cy-3 labeling followed by human whole genome gene expression microarray analyses.
Project description:Here we addressed the genome-wide DNA binding profile of Helios transcription factor in early hematopoietic progenitor cells. We reported Helios DNA target sites by performing Chromatin Immuno-Precipitation (ChIP) assay on genomic DNA from the early hematopoietic progenitor cells line HPC7.
Project description:It has been known that aberrant isoforms of Ikaros family ptoteins are expressed in malignant cells. We identified that PBMC of ATL (acute T-cell leukemia) patients expresses different patterns of Helios isoforms compared with normal PBMC. In order to investigate the biological impact of ATL-type Helios isoform, we conducted complehensive gene expression analyses in Jurkat cells overexpressing ATL-type Helios. Also, we investigated the influence of WT-Helios or WT-Ikaros knockdown on the gene expression profile and compared with that of the cells with ATL-type Helios overexpression.