Project description:Hematopoietic stem cells (HSCs) are located in the bone marrow in a specific microenvironment referred as the hematopoietic stem cell niche, where HSCs interact with a variety of stromal cells. Though several components of the stem cell niche have been identified, the regulatory mechanisms through which such components regulate the stem cell fate are still unknown. In order to address this issue, we investigated how osteoblasts (OBs) can affect the molecular and functional phenotype of HSCs and vice versa. Our data showed that CD34+ cells cultured with OBs give rise to higher total cell numbers, produce more CFU and maintain a higher percentage of CD34+CD38- cells compared to control culture. Moreover, clonogenic assay and long-term culture results showed that OBs enhance HSC differentiation towards the mono/macrophage lineage at the expense of the granulocytic and erythroid ones. Finally, GEP analysis allowed us to identify several cytokine-receptor networks, such as WNT pathway, and transcription factors, as TWIST1 and FOXC1, that could be activated by co-culture with OBs and could be responsible for the biological effects reported above. Altogether our results indicate that OBs are able to affect both HPC maintenance and differentiation capacity by modulating mono/macrophage and erythroid commitment. We set up a co-culture system composed of human CD34+ cells in culture with human OBs. After coculture, CD34+ cells and the hematopoietic cell fraction were separated from OBs and analyzed by gene expression profiling (GEP), clonogenic assay and long-term culture.
Project description:The transcription factor c-Myb plays a key role in human primary CD34+ hematopoietic progenitor cells (HPCs) lineage choice, by enhancing erythropoiesis at the expense of megakaryopoiesis. We previously demonstrated that c-Myb affects erythroid versus megakaryocyte lineage decision in part by transactivating KLF1 and LMO2 expression. To further unravel the molecular mechanisms through which c-myb affects lineage fate decision, we profiled the miRNA and mRNA changes in myb-silenced CD34+ HPCs. The integrative analysis of miRNA/mRNA expression changes upon c-myb silencing in human CD34+ HPCs highlighted a set of 19 miRNA with 150 anticorrelated putative target mRNAs. Among the miRNAs downregulated in myb-silenced progenitors with the highest number of predicted target mRNAs, we selected hsa-miR-486-3p based on the in vitro effects of its overexpression on HPCs commitment. Indeed, morphological and flow cytometric analyses after liquid culture showed that hsa-miR-486-3p overexpression in HPCs enhanced erythroid and granulocyte differentiation while restraining megakaryocyte and macrophage differentiation. Moreover, collagen-based clonogenic assay demonstrated a strong impairement megakaryocyte commitment upon hsa-miR-486-3p overexpression in CD34+ cells. Moreover, in order to identify the mRNA target through which hsa-miR-486-3p affects lineage fate decision, we profiled the mRNA changes in mimic transfected CD34+ HPC by means of Affymetrix GeneAtlas U219 strip array. Gene expression profiling of hsa-miR-486-3p overexpressing CD34+ cells enabled us to identify a set of 8 genes downregulated and computationally predicted, putative hsa-miR-486-3p targets. Among them, we selected c-maf transcript as upregulated upon myb silencing. Worth of note, c-maf silencing in CD34+ progenitor cells was able to reverse the affects of myb silencing on erythroid versus megakaryocyte lineage choice. Integrative miRNA/mRNA analysis highlighted a set of miRNAs and anticorrelated putative target mRNAs modulated upon myb silencing, therefore potential players in myb-driven HPCs lineage choice. Among them, we demonstrated the hsa-miR-486-3p/c-maf pair as partially contributing to the effects of myb on HPCs commitment. Therefore, our data collectively identified myb-driven hsa-miR-486-3p upregulation and subsequent c-maf downregulation as a new molecular mechanism through which cMyb favours erythropoiesis while restraining megakaryopoiesis. Gene expression profile (GEP) was performed on total RNA derived from three independent experiments at 24h after the last nucleofection.
Project description:The transcription factor cMyb plays a key role in human primary CD34+ hematopoietic progenitor cells (HPCs) lineage choice, by enhancing erythropoiesis at the expense of megakaryopoiesis. We previously demonstrated that cMyb affects erythroid versus megakaryocyte lineage decision in part by transactivating KLF1 and LMO2 expression. To further unravel the molecular mechanisms through which cmyb affects lineage fate decision, we profiled the miRNA and mRNA changes in myb-silenced CD34+ HPCs. mRNA and miRNA expression for each sample were profiled by Affymetrix GeneAtlas U219 strip array and Exiqon Human miRNome PCR Panel, respectively. miRNA/mRNA data were integrated by Ingenuity Pathway Analysis. The integrative analysis of miRNA/mRNA expression changes upon c-myb silencing in human CD34+ HPCs highlighted a set of 19 miRNA with 150 anticorrelated putative target mRNAs. Among the miRNAs downregulated in myb-silenced progenitors with the highest number of predicted target mRNAs, we selected hsa-miR-486-3p based on the in vitro effects of its overexpression on HPCs commitment. Indeed, morphological and flow cytometric analyses after liquid culture showed that hsa-miR-486-3p overexpression in HPCs enhanced erythroid and granulocyte differentiation while restraining megakaryocyte and macrophage differentiation. Moreover, collagen-based clonogenic assay demonstrated a strong impairement megakaryocyte commitment upon hsa-miR-486-3p overexpression in CD34+ cells. Gene expression profiling of hsa-miR-486-3p overexpressing CD34+ cells enabled us to identify a set of 8 genes downregulated and computationally predicted, putative hsa-miR-486-3p targets. Among them, we selected c-maf transcript as upregulated upon myb silencing. Worth of note, c-maf silencing in CD34+ progenitor cells was able to reverse the affects of myb silencing on erythroid versus megakaryocyte lineage choice. Integrative miRNA/mRNA analysis highlighted a set of miRNAs and anticorrelated putative target mRNAs modulated upon myb silencing, therefore potential players in myb-driven HPCs lineage choice. Among them, we demonstrated the hsa-miR-486-3p/c-maf pair as partially contributing to the effects of myb on HPCs commitment. Therefore, our data collectively identified myb-driven hsa-miR-486-3p upregulation and subsequent c-maf downregulation as a new molecular mechanism through which cMyb favours erythropoiesis while restraining megakaryopoiesis. RNA from CD34+ HPCs transfected with c-myb-targeting/non targeting control (NegCTR) synthetic siRNAs was collected 24 hours post-Nucleofection for a set of 5 independent experiments.
Project description:The transcription factor cMyb plays a key role in human primary CD34+ hematopoietic progenitor cells (HPCs) lineage choice, by enhancing erythropoiesis at the expense of megakaryopoiesis. We previously demonstrated that cMyb affects erythroid versus megakaryocyte lineage decision in part by transactivating KLF1 and LMO2 expression. To further unravel the molecular mechanisms through which cmyb affects lineage fate decision, we profiled the miRNA and mRNA changes in myb-silenced CD34+ HPCs. mRNA and miRNA expression for each sample were profiled by Affymetrix GeneAtlas U219 strip array and Exiqon Human miRNome PCR Panel, respectively. miRNA/mRNA data were integrated by Ingenuity Pathway Analysis. The integrative analysis of miRNA/mRNA expression changes upon c-myb silencing in human CD34+ HPCs highlighted a set of 19 miRNA with 150 anticorrelated putative target mRNAs. Among the miRNAs downregulated in myb-silenced progenitors with the highest number of predicted target mRNAs, we selected hsa-miR-486-3p based on the in vitro effects of its overexpression on HPCs commitment. Indeed, morphological and flow cytometric analyses after liquid culture showed that hsa-miR-486-3p overexpression in HPCs enhanced erythroid and granulocyte differentiation while restraining megakaryocyte and macrophage differentiation. Moreover, collagen-based clonogenic assay demonstrated a strong impairement megakaryocyte commitment upon hsa-miR-486-3p overexpression in CD34+ cells. Gene expression profiling of hsa-miR-486-3p overexpressing CD34+ cells enabled us to identify a set of 8 genes downregulated and computationally predicted, putative hsa-miR-486-3p targets. Among them, we selected c-maf transcript as upregulated upon myb silencing. Worth of note, c-maf silencing in CD34+ progenitor cells was able to reverse the affects of myb silencing on erythroid versus megakaryocyte lineage choice. Integrative miRNA/mRNA analysis highlighted a set of miRNAs and anticorrelated putative target mRNAs modulated upon myb silencing, therefore potential players in myb-driven HPCs lineage choice. Among them, we demonstrated the hsa-miR-486-3p/c-maf pair as partially contributing to the effects of myb on HPCs commitment. Therefore, our data collectively identified myb-driven hsa-miR-486-3p upregulation and subsequent c-maf downregulation as a new molecular mechanism through which cMyb favours erythropoiesis while restraining megakaryopoiesis. RNA from CD34+ HPCs transfected once/twice/3 times with c-myb-targeting/non targeting control siRNAs was collected for a set of 5 independent experiments.
Project description:Hematopoietic stem cells (HSCs) are located in the bone marrow in a specific microenvironment referred as the hematopoietic stem cell niche, where HSCs interact with a variety of stromal cells. Though several components of the stem cell niche have been identified, the regulatory mechanisms through which such components regulate the stem cell fate are still unknown. In order to address this issue, we investigated how osteoblasts (OBs) can affect the molecular and functional phenotype of HSCs and vice versa. Our data showed that CD34+ cells cultured with OBs give rise to higher total cell numbers, produce more CFU and maintain a higher percentage of CD34+CD38- cells compared to control culture. Moreover, clonogenic assay and long-term culture results showed that OBs enhance HSC differentiation towards the mono/macrophage lineage at the expense of the granulocytic and erythroid ones. Finally, GEP analysis allowed us to identify several cytokine-receptor networks, such as WNT pathway, and transcription factors, as TWIST1 and FOXC1, that could be activated by co-culture with OBs and could be responsible for the biological effects reported above. Altogether our results indicate that OBs are able to affect both HPC maintenance and differentiation capacity by modulating mono/macrophage and erythroid commitment.
Project description:The transcription factor c-Myb plays a key role in human primary CD34+ hematopoietic progenitor cells (HPCs) lineage choice, by enhancing erythropoiesis at the expense of megakaryopoiesis. We previously demonstrated that c-Myb affects erythroid versus megakaryocyte lineage decision in part by transactivating KLF1 and LMO2 expression. To further unravel the molecular mechanisms through which c-myb affects lineage fate decision, we profiled the miRNA and mRNA changes in myb-silenced CD34+ HPCs. The integrative analysis of miRNA/mRNA expression changes upon c-myb silencing in human CD34+ HPCs highlighted a set of 19 miRNA with 150 anticorrelated putative target mRNAs. Among the miRNAs downregulated in myb-silenced progenitors with the highest number of predicted target mRNAs, we selected hsa-miR-486-3p based on the in vitro effects of its overexpression on HPCs commitment. Indeed, morphological and flow cytometric analyses after liquid culture showed that hsa-miR-486-3p overexpression in HPCs enhanced erythroid and granulocyte differentiation while restraining megakaryocyte and macrophage differentiation. Moreover, collagen-based clonogenic assay demonstrated a strong impairement megakaryocyte commitment upon hsa-miR-486-3p overexpression in CD34+ cells. Moreover, in order to identify the mRNA target through which hsa-miR-486-3p affects lineage fate decision, we profiled the mRNA changes in mimic transfected CD34+ HPC by means of Affymetrix GeneAtlas U219 strip array. Gene expression profiling of hsa-miR-486-3p overexpressing CD34+ cells enabled us to identify a set of 8 genes downregulated and computationally predicted, putative hsa-miR-486-3p targets. Among them, we selected c-maf transcript as upregulated upon myb silencing. Worth of note, c-maf silencing in CD34+ progenitor cells was able to reverse the affects of myb silencing on erythroid versus megakaryocyte lineage choice. Integrative miRNA/mRNA analysis highlighted a set of miRNAs and anticorrelated putative target mRNAs modulated upon myb silencing, therefore potential players in myb-driven HPCs lineage choice. Among them, we demonstrated the hsa-miR-486-3p/c-maf pair as partially contributing to the effects of myb on HPCs commitment. Therefore, our data collectively identified myb-driven hsa-miR-486-3p upregulation and subsequent c-maf downregulation as a new molecular mechanism through which cMyb favours erythropoiesis while restraining megakaryopoiesis.
Project description:The transcription factor cMyb plays a key role in human primary CD34+ hematopoietic progenitor cells (HPCs) lineage choice, by enhancing erythropoiesis at the expense of megakaryopoiesis. We previously demonstrated that cMyb affects erythroid versus megakaryocyte lineage decision in part by transactivating KLF1 and LMO2 expression. To further unravel the molecular mechanisms through which cmyb affects lineage fate decision, we profiled the miRNA and mRNA changes in myb-silenced CD34+ HPCs. mRNA and miRNA expression for each sample were profiled by Affymetrix GeneAtlas U219 strip array and Exiqon Human miRNome PCR Panel, respectively. miRNA/mRNA data were integrated by Ingenuity Pathway Analysis. The integrative analysis of miRNA/mRNA expression changes upon c-myb silencing in human CD34+ HPCs highlighted a set of 19 miRNA with 150 anticorrelated putative target mRNAs. Among the miRNAs downregulated in myb-silenced progenitors with the highest number of predicted target mRNAs, we selected hsa-miR-486-3p based on the in vitro effects of its overexpression on HPCs commitment. Indeed, morphological and flow cytometric analyses after liquid culture showed that hsa-miR-486-3p overexpression in HPCs enhanced erythroid and granulocyte differentiation while restraining megakaryocyte and macrophage differentiation. Moreover, collagen-based clonogenic assay demonstrated a strong impairement megakaryocyte commitment upon hsa-miR-486-3p overexpression in CD34+ cells. Gene expression profiling of hsa-miR-486-3p overexpressing CD34+ cells enabled us to identify a set of 8 genes downregulated and computationally predicted, putative hsa-miR-486-3p targets. Among them, we selected c-maf transcript as upregulated upon myb silencing. Worth of note, c-maf silencing in CD34+ progenitor cells was able to reverse the affects of myb silencing on erythroid versus megakaryocyte lineage choice. Integrative miRNA/mRNA analysis highlighted a set of miRNAs and anticorrelated putative target mRNAs modulated upon myb silencing, therefore potential players in myb-driven HPCs lineage choice. Among them, we demonstrated the hsa-miR-486-3p/c-maf pair as partially contributing to the effects of myb on HPCs commitment. Therefore, our data collectively identified myb-driven hsa-miR-486-3p upregulation and subsequent c-maf downregulation as a new molecular mechanism through which cMyb favours erythropoiesis while restraining megakaryopoiesis.
Project description:The transcription factor cMyb plays a key role in human primary CD34+ hematopoietic progenitor cells (HPCs) lineage choice, by enhancing erythropoiesis at the expense of megakaryopoiesis. We previously demonstrated that cMyb affects erythroid versus megakaryocyte lineage decision in part by transactivating KLF1 and LMO2 expression. To further unravel the molecular mechanisms through which cmyb affects lineage fate decision, we profiled the miRNA and mRNA changes in myb-silenced CD34+ HPCs. mRNA and miRNA expression for each sample were profiled by Affymetrix GeneAtlas U219 strip array and Exiqon Human miRNome PCR Panel, respectively. miRNA/mRNA data were integrated by Ingenuity Pathway Analysis. The integrative analysis of miRNA/mRNA expression changes upon c-myb silencing in human CD34+ HPCs highlighted a set of 19 miRNA with 150 anticorrelated putative target mRNAs. Among the miRNAs downregulated in myb-silenced progenitors with the highest number of predicted target mRNAs, we selected hsa-miR-486-3p based on the in vitro effects of its overexpression on HPCs commitment. Indeed, morphological and flow cytometric analyses after liquid culture showed that hsa-miR-486-3p overexpression in HPCs enhanced erythroid and granulocyte differentiation while restraining megakaryocyte and macrophage differentiation. Moreover, collagen-based clonogenic assay demonstrated a strong impairement megakaryocyte commitment upon hsa-miR-486-3p overexpression in CD34+ cells. Gene expression profiling of hsa-miR-486-3p overexpressing CD34+ cells enabled us to identify a set of 8 genes downregulated and computationally predicted, putative hsa-miR-486-3p targets. Among them, we selected c-maf transcript as upregulated upon myb silencing. Worth of note, c-maf silencing in CD34+ progenitor cells was able to reverse the affects of myb silencing on erythroid versus megakaryocyte lineage choice. Integrative miRNA/mRNA analysis highlighted a set of miRNAs and anticorrelated putative target mRNAs modulated upon myb silencing, therefore potential players in myb-driven HPCs lineage choice. Among them, we demonstrated the hsa-miR-486-3p/c-maf pair as partially contributing to the effects of myb on HPCs commitment. Therefore, our data collectively identified myb-driven hsa-miR-486-3p upregulation and subsequent c-maf downregulation as a new molecular mechanism through which cMyb favours erythropoiesis while restraining megakaryopoiesis.
Project description:Scl/Tal1 confers hemogenic competence and prevents cardiomyogenesis in embryonic endothelium. Here we show that Scl both directly activates a broad gene regulatory network required for hematopoietic stem/progenitor cell (HS/PC) development, and represses transcriptional regulators required for cardiogenesis. Cardiac repression occurs during a short developmental window through Scl binding to distant cardiac enhancers that harbor H3K4me1 at this stage. Scl binding to hematopoietic regulators extends throughout HS/PC and erythroid development and spreads from distant enhancers to promoters. Surprisingly, Scl complex partners Gata 1 and 2 are dispensable for hematopoietic versus cardiac specification and Scl binding to the majority of its target genes. Nevertheless, Gata factors co-operate with Scl to activate selected transcription factors to facilitate HS/PC emergence from hemogenic endothelium. These results uncover a dual function for Scl in dictating hematopoietic versus cardiac fate choice and suggest a mechanism by which lineage-specific bHLH factors direct the divergence of competing fates. Examination of Scl and Gata 1 & 2 target genes in ES cell derived day4.75 EB (embryoid body) Tie2+CD31+CD41- endothelial cells
Project description:Scl/Tal1 confers hemogenic competence and prevents cardiomyogenesis in embryonic endothelium. Here we show that Scl both directly activates a broad gene regulatory network required for hematopoietic stem/progenitor cell (HS/PC) development, and represses transcriptional regulators required for cardiogenesis. Cardiac repression occurs during a short developmental window through Scl binding to distant cardiac enhancers that harbor H3K4me1 at this stage. Scl binding to hematopoietic regulators extends throughout HS/PC and erythroid development and spreads from distant enhancers to promoters. Surprisingly, Scl complex partners Gata 1 and 2 are dispensable for hematopoietic versus cardiac specification and Scl binding to the majority of its target genes. Nevertheless, Gata factors co-operate with Scl to activate selected transcription factors to facilitate HS/PC emergence from hemogenic endothelium. These results uncover a dual function for Scl in dictating hematopoietic versus cardiac fate choice and suggest a mechanism by which lineage-specific bHLH factors direct the divergence of competing fates. Examination of Scl target genes in ES cell derived day4 EB (embryoid body) Flk+ mesodermal cells