Project description:Notch signaling is one of the central regulators of differentiation in a variety of organisms and tissue types. Within the hematopoietic system, Notch is essential for the emergence of definitive HSC during fetal life and controls adult HSC differentiation to the T-cell lineage. Notch activation is controlled by the gamma-secretase complex complex, composed of presenilin, nicastrin (Ncstn), anterior pharynx-1 (Aph1), and presenilin enhancer-2 To determine other role of Notch signaling in HSC we designed a conditional mouse model of Notch activation. WT and N1-IC+ HSC were analysed to determined genes controlled by Notch signaling. Bone marrow lineage negative, cKit+, Sca1+ cells were sorted from WT and N1-IC+ littermates for RNA extraction and hybridization on Affymetrix microarrays
Project description:Notch signaling is one of the central regulators of differentiation in a variety of organisms and tissue types. Within the hematopoietic system, Notch is essential for the emergence of definitive HSC during fetal life and controls adult HSC differentiation to the T-cell lineage. Notch activation is controlled by the gamma-secretase complex complex, composed of presenilin, nicastrin (Ncstn), anterior pharynx-1 (Aph1), and presenilin enhancer-2 To determine other role of Notch signaling in HSC we designed a conditional mouse model of Nicastrin deletion. WT and KO HSC were analysed to determined genes controlled by Notch signaling. Bone marrow lineage negative, cKit+, Sca1+ cells were sorted from WT and Ncstn KO littermates for RNA extraction and hybridization on Affymetrix microarrays
Project description:Notch signaling is one of the central regulators of differentiation in a variety of organisms and tissue types. Within the hematopoietic system, Notch is essential for the emergence of definitive HSC during fetal life and controls adult HSC differentiation to the T-cell lineage. Notch activation is controlled by the gamma-secretase complex complex, composed of presenilin, nicastrin (Ncstn), anterior pharynx-1 (Aph1), and presenilin enhancer-2 To determine other role of Notch signaling in HSC we designed a conditional mouse model of Nicastrin deletion. WT and KO HSC were analysed to determined genes controlled by Notch signaling. Bone marrow lineage negative, cKit+, Sca1+ and lineage negative, cKit+, Sca1- CD34+ FcgammaRII/III+ cells were sorted from WT and Ncstn KO littermates for RNA extraction and hybridization on Affymetrix microarrays
Project description:Notch signaling is one of the central regulators of differentiation in a variety of organisms and tissue types. Within the hematopoietic system, Notch is essential for the emergence of definitive HSC during fetal life and controls adult HSC differentiation to the T-cell lineage. Notch activation is controlled by the gamma-secretase complex complex, composed of presenilin, nicastrin (Ncstn), anterior pharynx-1 (Aph1), and presenilin enhancer-2 To determine other role of Notch signaling in HSC we designed a conditional mouse model of Notch activation. WT and N1-IC+ HSC were analysed to determined genes controlled by Notch signaling.
Project description:Notch signaling is one of the central regulators of differentiation in a variety of organisms and tissue types. Within the hematopoietic system, Notch is essential for the emergence of definitive HSC during fetal life and controls adult HSC differentiation to the T-cell lineage. Notch activation is controlled by the gamma-secretase complex complex, composed of presenilin, nicastrin (Ncstn), anterior pharynx-1 (Aph1), and presenilin enhancer-2 To determine other role of Notch signaling in HSC we designed a conditional mouse model of Nicastrin deletion. WT and KO HSC were analysed to determined genes controlled by Notch signaling.
Project description:Notch signaling is one of the central regulators of differentiation in a variety of organisms and tissue types. Within the hematopoietic system, Notch is essential for the emergence of definitive HSC during fetal life and controls adult HSC differentiation to the T-cell lineage. Notch activation is controlled by the gamma-secretase complex complex, composed of presenilin, nicastrin (Ncstn), anterior pharynx-1 (Aph1), and presenilin enhancer-2 To determine other role of Notch signaling in HSC we designed a conditional mouse model of Nicastrin deletion. WT and KO HSC were analysed to determined genes controlled by Notch signaling.
Project description:Hematopoietic stem cells (HSCs) have long been the focus of developmental and regenerative studies, yet our understanding of the signaling events regulating their specification remains incomplete. We demonstrate that supt16h, a component of the FAcilitates Chromatin Transcription (FACT) complex, is required for HSC formation. Zebrafish supt16h mutants express reduced levels of Notch signaling components, genes essential for HSC development, due to abrogated transcription. Classically, Supt16h regulates transcription and nucleosome reorganization. Whereas global chromatin accessibility in supt16h mutants is unaffected, we observe a specific increase in accessibility at the p53 locus, causing an accumulation of p53 mRNA and protein. We further demonstrate that P53 levels directly influence expression of the Polycomb Group protein, phc1, which functions as a transcriptional repressor of Notch genes. Suppression of phc1 or its upstream regulator, p53, rescues both loss of Notch and loss of HSC phenotypes in supt16h mutants. Taken together, our results highlight a previously uncharacterized relationship between supt16h, p53, and phc1 to specify HSCs via modulation of Notch signaling.
Project description:Chromatin organization and accessibility are fundamental to how genes are transcriptionally controlled. We identify the first vertebrate mutant for supt16h, a component of the FACT (FAcilitates Chromatin Transcription) complex along with Ssrp1 known to reorganize nucleosomes and assist in transcriptional elongation. We demonstrate its importance in hematopoietic stem cell (HSC) specification by regulating the elongation of Notch genes. Unexpectedly, Assay for Transposase Accessible Chromatin (ATAC) sequencing revealed that loss of supt16h does not affect histone accessibility on a Notch-specific or global level. Although the majority of genes are unaffected, loss of supt16h alters chromatin accessibility significantly at the p53 locus, leading to its overexpression in mutants. Upon downregulation of p53, both loss of Notch and loss of HSC phenotypes are rescued. Notably, ssrp1 mutants possessed normal elongation of Notch genes, levels of P53, and specification of HSCs. Our results highlight the discrete effects of Supt16h and Ssrp1 during HSC specification. Additionally, we demonstrate the relationship between supt16h and p53 during transcriptional elongation to specify HSC fate via modulation of Notch signaling.
Project description:Chromatin organization and accessibility are fundamental to how genes are transcriptionally controlled. We identify the first vertebrate mutant for supt16h, a component of the FACT (FAcilitates Chromatin Transcription) complex along with Ssrp1 known to reorganize nucleosomes and assist in transcriptional elongation. We demonstrate its importance in hematopoietic stem cell (HSC) specification by regulating the elongation of Notch genes. Unexpectedly, Assay for Transposase Accessible Chromatin (ATAC) sequencing revealed that loss of supt16h does not affect histone accessibility on a Notch-specific or global level. Although the majority of genes are unaffected, loss of supt16h alters chromatin accessibility significantly at the p53 locus, leading to its overexpression in mutants. Upon downregulation of p53, both loss of Notch and loss of HSC phenotypes are rescued. Notably, ssrp1 mutants possessed normal elongation of Notch genes, levels of P53, and specification of HSCs. Our results highlight the discrete effects of Supt16h and Ssrp1 during HSC specification. Additionally, we demonstrate the relationship between supt16h and p53 during transcriptional elongation to specify HSC fate via modulation of Notch signaling.
Project description:Hematopoietic stem cells (HSCs) develop from the hemogenic endothelium (HE) in the aorta- gonads-and mesonephros (AGM) region and reside within Intra-aortic hematopoietic clusters (IAHC) along with hematopoietic progenitors (HPC). The signalling mechanisms that distinguish HSCs from HPCs are unknown. Notch signaling is essential for arterial specification, IAHC formation and HSC activity, but current studies on how Notch segregates these different fates are inconsistent. We now demonstrate that Notch activity is highest in a subset of, GFI1+, HSC-primed HE cells, and is gradually lost with HSC maturation. We uncover that the HSC phenotype is maintained due to increasing levels of NOTCH1 and JAG1 interactions on the surface of the same cell (cis) that renders the NOTCH1 receptor from being activated. Forced activation of the NOTCH1 receptor in IAHC activates a hematopoietic differentiation program. Our results indicate that NOTCH1-JAG1 cis-inhibition preserves the HSC phenotype in the hematopoietic clusters of the embryonic aorta.