Project description:The formation of hematopoietic cells relies on the chromatin remodeling activities of ISWI ATPase SMARCA5 (SNF2H) and its complexes. The Smarca5 null and conditional alleles have been used to study its functions in embryonic and organ development in mice. These mouse model phenotypes vary from embryonic lethality of constitutive knockout to less severe phenotypes observed in tissue-specific Smarca5 deletions, e.g., in the hematopoietic system. Here we show that, in a gene dosage-dependent manner, the hypomorphic allele of SMARCA5 (S5tg) can rescue not only the developmental arrest in hematopoiesis in the hCD2iCre model but also the lethal phenotypes associated with constitutive Smarca5 deletion or Vav1iCre-driven conditional knockout in hematopoietic progenitor cells. Interestingly, the latter model also provided evidence for the role of SMARCA5 expression level in hematopoietic stem cells, as the Vav1iCre S5tg animals accumulate stem and progenitor cells. Furthermore, their hematopoietic stem cells exhibited impaired lymphoid lineage entry and differentiation. This observation contrasts with the myeloid lineage which is developing without significant disturbances. Our findings indicate that animals with low expression of SMARCA5 exhibit normal embryonic development with altered lymphoid entry within the hematopoietic stem cell compartment.
Project description:The transcription factor c-Myb a key regulator in proliferation and differentiation of hematopoietic progenitor cells, is precisely regulated during essential cellular processes. Overexpression and rearrangement of c-myb has been reported in human tumors including myeloid leukemia, but exact regulatory mechanisms have remained elusive. Here, we identified, using 4C assay with the c-myb promoter as an anchor, the interaction site at -34k region upstream of c-myb gene that are involved in c-myb expression. Furthermore, we found that the long-range interactions changed with c-myb being down-regulated on differentiation progress in human myeloid leukemia cell lines. Taken together, our date revealed that a potential c-myb enhancer-promoter interactions may be a particularly important regulatory mechanism for c-myb gene expression in human myeloid leukemia cells.
Project description:MYB is well recognized to be a key regulator of definitive hematopoiesis that plays an important role in the maintenance and multilineage differentiation of hematopoietic stem cells (HSCs). In the vertebrate developmental context, MYB is widely regarded dispensable for primitive hematopoiesis but critically required for the development of definitive hematopoiesis. To explore the role of MYB in human hematopoietic development we have inactivated the gene by bi-allelic TALEN-supported gene targeting in several lines of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), and subjected these cells to hematopoietic differentiation in well-defined cell culture conditions. Venus gene reporter was inserted into the knock-in allele to monitor MYB expression during the course of the hESC/iPSC differentiation. The gene reporter system showed that MYB is specifically expressed during hematopoietic commitment in the earliest primitive blood cells. Moreover, the level of MYB expression was highest at the commitment stage of differentiation and significantly decreased at the maturations stage. We found that MYB was not required for initial hematopoietic commitment of nascent mesoderm and emergence of primitive, yolk sac-type human hematopoietic progenitors. However, inactivation of MYB severely abrogated proliferation of the primitive erythroid and mixed erythroid-macrophage-megakaryocyte progenitors. In addition, MYB-negative hESC/iPSC lines demonstrated major defects in myeloid cell development and completely failed to generate mature granulocytes. Transposon-mediated rescue of MYB expression in MYB-null cells efficiently restored both the primitive hematopoietic progenitors and immature myeloid cells. Our data indicate that in contrast to its previously attributed exclusive role in definitive hematopoiesis, MYB is indispensable for primitive human hematopoiesis.
Project description:The B-myb (MYBL2) gene is a member of the MYB family of transcription factors and is involved in cell cycle regulation, DNA replication and maintenance of genomic integrity. However, its function during adult development and hematopoiesis is unknown. We show here that conditional inactivation of B-myb in vivo results in depletion of the HSC pool, leading to profound reductions in mature lymphoid, erythroid and myeloid cells. This defect is autonomous to the bone marrow and is first evident in the HSCs, which accumulate in the S and G2/M phases. B-myb inactivation also causes defects in the myeloid progenitor compartment and results in an accumulation of GMPs. Microarray studies indicate that B-myb null LKS+ cells differentially express genes that direct myeloid lineage development and commitment, suggesting that B-myb is a key player in controlling cell fate. Collectively, these studies demonstrate that B-myb is essential for HSC and progenitor maintenance and survival during hematopoiesis. Total RNA was isolated from FACS purified LKS+ cells isolated from pIpC-treated control and B-myb floxed-MxCre mice. Each sample is derived from a pool of 3-5 mice. 2 samples were analyzed for each genotype.
Project description:The transcription factor c-Myb has been well characterized as an oncogene in several human tumor types, and its expression in the hematopoietic stem/progenitor cell population is essential for proper hematopoiesis. However, the role of c-Myb in mammopoeisis and breast tumorigenesis is poorly understood, despite its high expression in the majority of breast cancer cases (60-80%). We find that c-Myb high expression in human breast tumors correlates with the luminal/ER+ phenotype and a good prognosis. RNAi knock-down of endogenous c-Myb levels in the MCF7 luminal breast tumor cell line increases tumorigenesis both in vitro and in vivo, suggesting a tumor suppressor role in luminal breast cancer. We created a mammary-derived c-Myb expression signature and found it to be highly correlated with a published mature luminal mammary cell signature and least correlated with a mammary stem/progenitor lineage gene signature. These data describe, for the first time, a tumor suppressor role for the c-Myb proto-oncogene in breast cancer that has implications for understanding luminal tumorigenesis and for guiding treatment. refXsample
Project description:Recurring chromosomal translocation t(10;17)(p15;q21) present in a subset of human acute myeloid leukemia (AML) patients creates an aberrant fusion gene termed ZMYND11-MBTD1 (ZM); however, its function remains undetermined. Here, we show that ZM confers primary murine hematopoietic stem/progenitor cells indefinite self-renewal capability ex vivo and causes AML in vivo. Genomics profilings reveal that ZM directly binds to and maintains high expression of pro-leukemic genes including Hoxa, Meis1, Myb, Myc and Sox4. Mechanistically, ZM recruits NuA4/Tip60 histone acetyltransferase complex to cis-regulatory elements, sustaining an active chromatin state enriched in histone acetylation and devoid of repressive histone marks. Systematic mutagenesis of ZM demonstrates essential requirements of Tip60 interaction and an H3K36me3-binding PWWP domain for oncogenesis. Inhibitor of histone acetylation-‘reading’ bromodomain proteins, which act downstream of ZM, is efficacious in treating ZM-induced AML. Collectively, this study demonstrates AML-causing effects of ZM, examines its gene-regulatory roles, and reports an attractive mechanism-guided therapeutic strategy.
Project description:The B-myb (MYBL2) gene is a member of the MYB family of transcription factors and is involved in cell cycle regulation, DNA replication and maintenance of genomic integrity. However, its function during adult development and hematopoiesis is unknown. We show here that conditional inactivation of B-myb in vivo results in depletion of the HSC pool, leading to profound reductions in mature lymphoid, erythroid and myeloid cells. This defect is autonomous to the bone marrow and is first evident in the HSCs, which accumulate in the S and G2/M phases. B-myb inactivation also causes defects in the myeloid progenitor compartment and results in an accumulation of GMPs. Microarray studies indicate that B-myb null LKS+ cells differentially express genes that direct myeloid lineage development and commitment, suggesting that B-myb is a key player in controlling cell fate. Collectively, these studies demonstrate that B-myb is essential for HSC and progenitor maintenance and survival during hematopoiesis. Total RNA was isolated from FACS purified LKS+ cells isolated from pIpC-treated control and B-myb floxed-MxCre mice.
Project description:The comparative characterization of hematopoietic stem cells from healthy stem cell donors and patients with acute myeloid leukemia on a proteome level has the potential to reveal differentially regulated proteins which might be candidates for specific immunotherapy target molecules. Exemplarily, we analyzed the proteome of the cytosolic and the membrane fraction of CD34 and CD123 co-expressing FACS-sorted leukemic progenitors from five patients with acute myeloid leukemia employing mass spectrometry. As a reference, CD34+CD123+ normal hematopoietic progenitor cells from five healthy stem cell donors were analyzed. In this TMT 10-plex labeling based approach 2068 proteins were identified with 256 proteins differentially regulated in one or both cellular compartments. This study demonstrates the feasibility of a mass spectrometry based proteomic approach to detect differentially expressed proteins in two compartment fractions of leukemic stem cells as compared to their healthy stem cell counterparts.
Project description:Collombet2016 - Lymphoid and myeloid cell
specification and transdifferentiation
This model is described in the article:
Logical modeling of lymphoid
and myeloid cell specification and transdifferentiation
Samuel Collombet, Chris van Oevelen,
Jose Luis Sardina Ortega, Wassim Abou-Jaoudé, Bruno Di
Stefano, Morgane Thomas-Chollier, Thomas Graf, and Denis
Thieffry
Proceedings of the National Academy of
Sciences of the United States of America
Abstract:
Blood cells are derived from a common set of hematopoietic
stem cells, which differentiate into more specific progenitors
of the myeloid and lymphoid lineages, ultimately leading to
differentiated cells. This developmental process is controlled
by a complex regulatory network involving cytokines and their
receptors, transcription factors, and chromatin remodelers.
Using public data and data from our own molecular genetic
experiments (quantitative PCR, Western blot, EMSA) or
genome-wide assays (RNA-sequencing, ChIP-sequencing), we have
assembled a comprehensive regulatory network encompassing the
main transcription factors and signaling components involved in
myeloid and lymphoid development. Focusing on B-cell and
macrophage development, we defined a qualitative dynamical
model recapitulating cytokine-induced differentiation of common
progenitors, the effect of various reported gene knockdowns,
and the reprogramming of pre-B cells into macrophages induced
by the ectopic expression of specific transcription factors.
The resulting network model can be used as a template for the
integration of new hematopoietic differentiation and
transdifferentiation data to foster our understanding of
lymphoid/myeloid cell-fate decisions.
This model is hosted on
BioModels Database
and identified by:
MODEL1610240000.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.