Jagged2 acts as a Delta-like Notch ligand during early hematopoietic cell fate decisions

Abstract Notch signaling critically mediates various hematopoietic lineage decisions and is induced in mammals by Notch ligands that are classified into 2 families, Delta-like (Delta-like-1, -3 and -4) and Jagged (Jagged1 and Jagged2), based on structural homology with both Drosophila ligands Delta and Serrate, respectively. Because the functional differences between mammalian Notch ligands were still unclear, we have investigated their influence on early human hematopoiesis and show that Jagged2 affects hematopoietic lineage decisions very similarly as Delta-like-1 and -4, but very different from Jagged1. OP9 coculture experiments revealed that Jagged2, like Delta-like ligands, induces T-lineage differentiation and inhibits B-cell and myeloid development. However, dose-dependent Notch activation studies, gene expression analysis, and promoter activation assays indicated that Jagged2 is a weaker Notch1-activator compared with the Delta-like ligands, revealing a Notch1 specific signal strength hierarchy for mammalian Notch ligands. Strikingly, Lunatic-Fringe– mediated glycosylation of Notch1 potentiated Notch signaling through Delta-like ligands and also Jagged2, in contrast to Jagged1. Thus, our results reveal a unique role for Jagged1 in preventing the induction of T-lineage differentiation in hematopoietic stem cells and show an unexpected functional similarity between Jagged2 and the Delta-like ligands.

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Runx1 Is Required for Notch-Induced Specification of Megakaryocyte Development from Early Hematopoietic Stem and Progenitor Cells

Blood ◽

10.1182/blood.v112.11.1370.1370 ◽

2008 ◽

Vol 112 (11) ◽

pp. 1370-1370

Author(s):

Melanie G Cornejo ◽

Thomas Mercher ◽

Joseph D. Growney ◽

Jonathan Jesneck ◽

Ivan Maillard ◽

...

Keyword(s):

Notch Signaling ◽

Cell Fate ◽

Stromal Cells ◽

Gfp Expression ◽

Hematopoietic Stem ◽

Cell Fate Decisions ◽

Insight Into ◽

Megakaryocyte Differentiation

Abstract The Notch signaling pathway is involved in a broad spectrum of cell fate decisions during development, and in the hematopoietic system, it is known to favor T cell- vs B cell lineage commitment. However, its role in myeloid lineage development is less well understood. We have shown, using heterotypic co-cultures of murine primary hematopoietic stem cells (Lin-Sca-1+ckit+ HSCs) and OP9 stromal cells expressing the Notch ligand Delta1 (OP9-DL1), that Notch signaling derived from cell non-autonomous cues acts as a positive regulator of megakaryocyte fate from LSK cells. Bone marrow transplantation experiments with a constitutively active Notch mutant resulted in enhanced megakaryopoiesis in vivo, with increased MEP numbers and megakaryocyte colony formation. In contrast, expression of dnMAML using a conditional ROSA26 knock-in mouse model significantly impaired megakaryopoiesis in vivo, with a marked decrease in megakaryocyte progenitors. In order to understand the cellular differentiation pathways controlled by Notch, we first examined the ability of various purified progenitor populations to differentiate toward megakaryocytes upon Notch stimulation in vitro. We observed that CMP and MEP, but not GMP, can engage megakaryopoiesis upon Notch stimulation. Our results were consistent with expression analysis of Notch signaling genes in these purified progenitors and were supported by the observation that transgenic Notch reporter mice display higher levels of reporter (i.e. GFP) expression in HSC and MEP, vs. CMP and GMP in vivo. Furthermore, purified progenitors with high GFP expression gave rise to increased numbers of megakarocyte-containing colonies when plated in vitro compared to GFP-negative progenitors. In addition, further purification of the HSC population into long-term (LT), short-term (ST), and lymphoid-primed myeloid progenitors (LMPP) before plating on OP9-DL1 stroma showed that LMPP have a reduced ability to give rise to megakaryocytes compared to the other two populations. These data support the hypothesis that there is an early commitment to erythro/megakaryocytic fate from HSC prior to lymphoid commitment. To gain insight into the molecular mechanism underlying Notch-induced megakaryopoiesis, we performed global gene expression analysis that demonstrated the engagement of a megakaryopoietic transcriptional program when HSC were co-cultured with OP9-DL1 vs. OP9 stroma or OP9-DL1 treated with gamma-secretase inhibitor. Of interest, Runx1 was among the most upregulated genes in HSC co-cultured on OP9-DL1 stroma. To assess whether Notch signaling engages megakaryocytic fate through induction of Runx1, we plated HSC from Runx1 −/− mice on OP9-DL1 stroma. Compared to WT cells, Runx1 −/− HSC had a severely reduced ability to develop into CD41+ cells. In contrast, overexpression of Runx1 in WT HSC was sufficient to induce megakaryocyte fate on OP9 stroma without Notch stimulation. Together, our results indicate that Notch pathway activation induced by stromal cells is an important regulator of cell fate decisions in early progenitors. We show that Notch signaling is upstream of Runx1 during Notch-induced megakaryocyte differentiation and that Runx1 is an essential target of Notch signaling. We believe that these results provide important insight into the pathways controlling megakaryocyte differentiation, and may have important therapeutic potential for megakaryocyte lineage-related disorders.

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Notch Signaling Induces Megakaryocytic Cell Fate.

Blood ◽

10.1182/blood.v110.11.200.200 ◽

2007 ◽

Vol 110 (11) ◽

pp. 200-200

Author(s):

Thomas Mercher ◽

Melanie Cornejo ◽

Christopher Sears ◽

Thomas Kindler ◽

Sandra Moore ◽

...

Keyword(s):

Bone Marrow ◽

Bone Marrow Transplantation ◽

Notch Signaling ◽

Cell Fate ◽

Marrow Transplantation ◽

Notch Pathway ◽

Severe Thrombocytopenia ◽

Hematopoietic Stem ◽

Cell Fate Decisions

Abstract The Notch pathway regulates a broad range of biological mechanisms including proliferation, border formation and cell fate decisions. In the hematopoietic system, Notch signaling is generally thought to specify T cell lineage fate at the expense of the B cell whereas its role in the myeloid lineage development is unclear. When using heterotypic co-cultures of murine primary hematopoietic stem cells (HSC: Lin-Sca1+Kit+) with OP9 stromal cells, or OP9 cells expressing the Notch ligand Delta1 (OP9-DL1), we unexpectedly observed the development of large cells with cytoplasmic protrusions reminiscent of proplatelet production by megakaryocytes on OP9-DL1 stroma. These cells stained positive for acetylcholinesterase, specific for megakaryocyte, and displayed large polylobated nuclei. Flow cytometric analysis indicated a 10-fold increase in the number of CD41+ cells in OP9-DL1 co-cultures compared to parental OP9 co-cultures. Expression of a constitutively active intra-cellular Notch (ICN) mutant allowed differentiation of HSC into CD41+ cells in parental OP9 co-cultures without DL1 stimulation, whereas expression of a dominant-negative MAML1 (dnMAML1) mutant abrogated this effect in OP9-DL1 co-cultures. In addition, megakaryocyte differentiation in OP9-DL1 co-cultures was blocked by γ-secretase inhibitors treatment and rescued by ectopic expression of ICN. Global gene expression analysis demonstrated engagement of a megakaryopoietic transcriptional program when HSC were co-cultured with OP9-DL1 vs. OP9 stroma or OP9-DL1 stroma treated with γ-secretase inhibitor. Bone marrow transplantation experiments with ICN, resulted in enhanced megakaryopoiesis in vivo with increased MEP numbers and megakaryocyte colony formation. Furthermore, transplantation of bone marrow cells transduced with dnMAML1 significantly impaired megakaryopoiesis in vivo with a 4- to 7-fold decrease in maturing megakaryocytes. These findings demonstrate a positive regulatory role for Notch signaling in specification of megakaryocyte development, and indicate that Notch plays a complex role in cell fate decisions among myeloid progenitors. They suggest the possibility that inhibition of Notch signaling may have therapeutic potential in malignancies of the megakaryocytic lineage. Furthermore, Notch pathway stimulation could be of value in enhancing megakaryocyte growth in clinical contexts associated with severe thrombocytopenia, such as hematopoietic reconstitution following bone marrow transplantation or chemotherapy.

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LncRNA Spehd regulates hematopoietic stem cells and progenitors and is required for multilineage differentiation

10.1101/340034 ◽

2018 ◽

Author(s):

M Joaquina Delás ◽

Benjamin T Jackson ◽

Tatjana Kovacevic ◽

Silvia Vangelisti ◽

Ester Munera Maravilla ◽

...

Keyword(s):

Cell Fate ◽

Expression Patterns ◽

Specific Expression ◽

Protein Coding ◽

Hematopoietic Stem ◽

Cell Fate Decisions ◽

Lineage Differentiation ◽

Oxidative Phosphorylation Pathway ◽

Cell Type Specific Expression

SummaryLong non-coding RNAs (lncRNAs) show patterns of tissue- and cell-type-specific expression that are very similar to those of protein coding genes and consequently have the potential to control stem and progenitor cell fate decisions along a differentiation trajectory. To understand the roles that lncRNAs might play in hematopoiesis, we selected a subset of mouse lncRNAs with potentially relevant expression patterns and refined our candidate list using evidence of conserved expression in human blood lineages. For each candidate, we assessed its possible role in hematopoietic differentiation in vivo using competitive transplantation. Our studies identified two lncRNAs that were required for hematopoiesis. One of these, Spehd, showed defective multi-lineage differentiation, and its silencing yielded common myeloid progenitors deficient in their oxidative phosphorylation pathway. This effort not only suggests that lncRNAs can contribute to differentiation decisions during hematopoiesis but also provides a path toward the identification of functional lncRNAs in other differentiation hierarchies.

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Notch Signaling in B Cell Immune Responses

Frontiers in Immunology ◽

10.3389/fimmu.2020.609324 ◽

2021 ◽

Vol 11 ◽

Cited By ~ 1

Author(s):

Matthew Garis ◽

Lee Ann Garrett-Sinha

Keyword(s):

B Cells ◽

Immune Responses ◽

B Cell ◽

Notch Signaling ◽

Cell Fate ◽

B Lymphocyte ◽

Notch Signaling Pathway ◽

Hematopoietic Stem ◽

Cell Fate Decisions ◽

Stem Cell Maintenance

The Notch signaling pathway is highly evolutionarily conserved, dictating cell fate decisions and influencing the survival and growth of progenitor cells that give rise to the cells of the immune system. The roles of Notch signaling in hematopoietic stem cell maintenance and in specification of T lineage cells have been well-described. Notch signaling also plays important roles in B cells. In particular, it is required for specification of marginal zone type B cells, but Notch signaling is also important in other stages of B cell development and activation. This review will focus on established and new roles of Notch signaling during B lymphocyte lineage commitment and describe the function of Notch within mature B cells involved in immune responses.

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Density-Dependent Regulation of Hematopoietic Stem Cell Fate by the Notch Ligand, Delta1.

Blood ◽

10.1182/blood.v104.11.1700.1700 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1700-1700

Author(s):

Mari H. Dallas ◽

Colleen Delaney ◽

Barbara Varnum-Finney ◽

Irwin D. Bernstein

Keyword(s):

T Cell ◽

Notch Signaling ◽

Cell Fate ◽

Myeloid Differentiation ◽

Hematopoietic Stem ◽

Notch Ligand ◽

Cell Fate Decisions ◽

Human Igg1 ◽

Cell Commitment ◽

Number Of Cells

Notch signaling regulates multiple cell fate decisions by hematopoietic precursors. Previously, we found that endogenous Notch signaling in cultures of murine hematopoietic precursors (Lin-Sca-1+ c-Kit+) leads to a multi-log increase in the number of Sca-1+ c-Kit+ cells, inhibition of myeloid differentiation, and promotion of T/NK differentiation. To activate Notch signaling in those studies, a single dose (10μg/ml) of engineered Notch ligand consisting of the extracellular domain of Delta1 fused to the Fc domain of human IgG1 (Delta1ext-IgG) was immobilized to the plastic tissue culture surface. To investigate quantitative effects of Notch signaling, bone marrow Lin-Sca-1+ c-Kit+ (LSK) cells were cultured with plates coated with increasing concentrations of Delta1ext-IgG in media supplemented with 20% FBS, SCF (100 ng/mL), Flt3L (100 ng/mL), IL6 (100ng/mL) and IL11 (10ng/mL). LSK cells cultured for 14 days with control human IgG1 underwent terminal myeloid differentiation (determined by expression of GR1 and F4/80) with no further increase in cell number, whereas at all densities of Delta1ext-IgG there was approximately a 3 log greater number of cells than in control cultures. Furthermore, the portion of cells that maintained Sca-1 and c-Kit expression increased at greater densities of Delta1ext-IgG (10%, 32%, 77%, 71%, 71% and 71% for plates coated with ligand at 0.6, 1.25, 2.5, 5, 10 and 20 μg/ml, respectively, and 5% for human IgG1 control at 10μg/ml), whereas the portion of cells undergoing myeloid differentiation decreased at greater ligand densities (48%, 33%, 5%, 3%, 3% and 3% respectively, and 40% for control). In contrast, a substantial increase in the portion of cells expressing B220+ was observed at relatively low densities of Delta1ext-IgG (30% at 0.6 μg/ml and 19% at 1.25 μg/ml) compared to control (4%), but was no longer evident with further increases in ligand density (1.8%, 2%, 1.2%, m1.6% at 2.5, 5, 10 and 20 μg/ml respectively). Furthermore, promotion of early T cell differentiation was observed in ligand containing cultures with the generation of increased number of cells co-expressing Thy1.2 and CD25 (14%, 24%, 22% and 24% at 2.5, 5, 10 and 20 μg/ml respectively). Further evidence for T cell commitment was established by quantitative RT-PCR in which increased expression of CD3ε and pre-Tα was observed by 28 days of culture. Thus these studies demonstrate that culture with different densities of the Notch ligand, Delta1ext-IgG results in differential cell fate outcome with inhibition of myeloid differentiation and promotion of early T cell induction that is maximal at high ligand densities and of B220+ cells at relatively lower densities.

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Jagged1-induced Notch signaling drives proliferation of multiple myeloma cells

Blood ◽

10.1182/blood-2003-07-2254 ◽

2004 ◽

Vol 103 (9) ◽

pp. 3511-3515 ◽

Cited By ~ 150

Author(s):

Franziska Jundt ◽

Kristina Schulze Pröbsting ◽

Ioannis Anagnostopoulos ◽

Gwendolin Muehlinghaus ◽

Manik Chatterjee ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Notch Signaling ◽

Cell Fate ◽

Plasma Cells ◽

Control Cell ◽

Hematopoietic Stem ◽

Cell Fate Decisions ◽

Notch Receptors

Abstract Notch receptors expressed on hematopoietic stem cells interact with their ligands on bone marrow stromal cells and thereby control cell fate decisions and survival. We recently demonstrated that Notch signaling is involved in proliferation and survival of B cell-derived tumor cells of classic Hodgkin disease and described a novel mechanism for the oncogenic capacity of Notch. In this study we investigated whether Notch signaling is involved in the tight interactions between neoplastic plasma cells and their bone marrow microenvironment, which are essential for tumor cell growth in multiple myeloma (MM). Here we demonstrate that Notch receptors and their ligand Jagged1 are highly expressed in cultured and primary MM cells, whereas nonneoplastic counterparts show low to undetectable levels of Notch. Functional data indicate that ligand-induced Notch signaling is a growth factor for MM cells and suggest that these interactions contribute to myelomagenesis in vivo. (Blood. 2004;103:3511-3515)

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Immobilization of Notch ligand, Delta-1, is required for induction of notch signaling

Journal of Cell Science ◽

10.1242/jcs.113.23.4313 ◽

2000 ◽

Vol 113 (23) ◽

pp. 4313-4318 ◽

Cited By ~ 11

Author(s):

B. Varnum-Finney ◽

L. Wu ◽

M. Yu ◽

C. Brashem-Stein ◽

S. Staats ◽

...

Keyword(s):

Cell Fate ◽

Extracellular Domain ◽

Notch Ligand ◽

Cell Fate Decisions ◽

Plastic Surface ◽

Ligand Stabilization ◽

Potential Activity ◽

Inhibition Of Differentiation ◽

Notch Ligands ◽

Notch Activation

Cell-cell interactions mediated by Notch and its ligands are known to effect many cell fate decisions in both invertebrates and vertebrates. However, the mechanisms involved in ligand induced Notch activation are unknown. Recently it was shown that, in at least some cases, endocytosis of the extracellular domain of Notch and ligand by the signaling cell is required for signal induction in the receptive cell. These results imply that soluble ligands (ligand extracellular domains) although capable of binding Notch would be unlikely to activate it. To test the potential activity of soluble Notch ligands, we generated monomeric and dimeric forms of the Notch ligand Delta-1 by fusing the extracellular domain to either a series of myc epitopes (Delta-1(ext-myc)) or to the Fc portion of human IgG-1 (Delta-1(ext-IgG)), respectively. Notch activation, assayed by inhibition of differentiation in C2 myoblasts and by HES1 transactivation in U20S cells, occurred when either Delta-1(ext-myc) or Delta-1(ext-IgG) were first immobilized on the plastic surface. However, Notch was not activated by either monomeric or dimeric ligand in solution (non-immobilized). Furthermore, both non-immobilized Delta-1(ext-myc) and Delta-1(ext-IgG) blocked the effect of immobilized Delta. These results indicate that Delta-1 extracellular domain must be immobilized to induce Notch activation in C2 or U20S cells and that non-immobilized Delta-1 extracellular domain is inhibitory to Notch function. These results imply that ligand stabilization may be essential for Notch activation.

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Abstract 3380: Acetylation-dependent Regulation Of Notch1 Signaling In Endothelial Cells

Circulation ◽

10.1161/circ.118.suppl_18.s_415-c ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Virginia Guarani ◽

Franck Dequiedt ◽

Andreas M Zeiher ◽

Stefanie Dimmeler ◽

Michael Potente

Keyword(s):

Endothelial Cells ◽

Notch Signaling ◽

Cell Fate ◽

Molecular Mechanisms ◽

Trichostatin A ◽

Notch Pathway ◽

Dependent Manner ◽

Class Iii ◽

Cell Fate Decisions ◽

Knock Down

The Notch signaling pathway is a versatile regulator of cell fate decisions and plays an essential role for embryonic and postnatal vascular development. As only modest differences in Notch pathway activity suffice to determine dramatic differences in blood vessel development, this pathway is tightly regulated by a variety of molecular mechanisms. Reversible acetylation has emerged as an important post-translational modification of several non-histone proteins, which are targeted by histone deacetylases (HDACs). Here, we report that specifically the Notch1 intracellular domain (NICD) is itself an acetylated protein and that its acetylation level is tightly regulated by the SIRT1 deacetylase, which we have previously identified as a key regulator of endothelial angiogenic functions during vascular growth. Coexpression of NICD with histone acetyltransferases such as p300 or PCAF induced a dose- and time-dependent acetylation of NICD. Blocking HDAC activity using the class III HDAC inhibitor nicotinamid (NAM), but not the class I/II HDAC inhibior trichostatin A, resulted in a significant increase of NICD acetylation suggesting that NICD is targetd by class III HDACs for deacetylation. Among the class III HDACs with deacetylase activity (SIRT1, 2, 3, 5), knock down of specifically SIRT1 resulted in enhanced acetylation of NICD. Moreover, wild type SIRT1, but not a catalytically inactive mutant catalyzed the deacetylation of NICD in a nicotinamid-dependent manner. SIRT1, but SIRT2, SIRT3 or SIRT5, associated with NICD through its catalytic domain demonstrating that SIRT1 is a direct NICD deacetylase. Enhancing NICD acetylation by either overexpression of p300 or inhibition of SIRT1 activity using NAM or RNAi-mediated knock down resulted in enhanced NICD protein stability by blocking its ubiquitin-mediated degradation. Consistent with these results, loss of SIRT1 amplified Notch target gene expression in endothelial cells in response to NICD overexpression or treatment with the Notch ligand Dll4. In summary, our results identify reversible acetylation of NICD as a novel molecular mechanism to control Notch signaling and suggest that deacetylation of NICD by SIRT1 plays a key role in the dynamic regulation of Notch signaling in endothelial cells.

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Depletion of L3MBTL1 promotes the erythroid differentiation of human hematopoietic progenitor cells: possible role in 20q− polycythemia vera

Blood ◽

10.1182/blood-2010-02-270611 ◽

2010 ◽

Vol 116 (15) ◽

pp. 2812-2821 ◽

Cited By ~ 39

Author(s):

Fabiana Perna ◽

Nadia Gurvich ◽

Ruben Hoya-Arias ◽

Omar Abdel-Wahab ◽

Ross L. Levine ◽

...

Keyword(s):

Polycythemia Vera ◽

Progenitor Cells ◽

Cell Fate ◽

Myeloproliferative Neoplasms ◽

Erythroid Differentiation ◽

Polycomb Group ◽

Human Cord Blood ◽

Hematopoietic Stem ◽

Cell Fate Decisions ◽

Cd34 Cells

Abstract L3MBTL1, the human homolog of the Drosophila L(3)MBT polycomb group tumor suppressor gene, is located on chromosome 20q12, within the common deleted region identified in patients with 20q deletion-associated polycythemia vera, myelodysplastic syndrome, and acute myeloid leukemia. L3MBTL1 is expressed within hematopoietic CD34+ cells; thus, it may contribute to the pathogenesis of these disorders. To define its role in hematopoiesis, we knocked down L3MBTL1 expression in primary hematopoietic stem/progenitor (ie, CD34+) cells isolated from human cord blood (using short hairpin RNAs) and observed an enhanced commitment to and acceleration of erythroid differentiation. Consistent with this effect, overexpression of L3MBTL1 in primary hematopoietic CD34+ cells as well as in 20q− cell lines restricted erythroid differentiation. Furthermore, L3MBTL1 levels decrease during hemin-induced erythroid differentiation or erythropoietin exposure, suggesting a specific role for L3MBTL1 down-regulation in enforcing cell fate decisions toward the erythroid lineage. Indeed, L3MBTL1 knockdown enhanced the sensitivity of hematopoietic stem/progenitor cells to erythropoietin (Epo), with increased Epo-induced phosphorylation of STAT5, AKT, and MAPK as well as detectable phosphorylation in the absence of Epo. Our data suggest that haploinsufficiency of L3MBTL1 contributes to some (20q−) myeloproliferative neoplasms, especially polycythemia vera, by promoting erythroid differentiation.

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Post-transcriptional regulation in hematopoiesis: RNA binding proteins take control

Biochemistry and Cell Biology ◽

10.1139/bcb-2017-0310 ◽

2019 ◽

Vol 97 (1) ◽

pp. 10-20 ◽

Cited By ~ 7

Author(s):

Laura P.M.H. de Rooij ◽

Derek C.H. Chan ◽

Ava Keyvani Chahi ◽

Kristin J. Hope

Keyword(s):

Transcriptional Regulation ◽

Stem Cell ◽

Cell Fate ◽

Binding Proteins ◽

Rna Binding ◽

Rna Binding Proteins ◽

Control Of Gene Expression ◽

Hematopoietic Stem ◽

Cell Fate Decisions ◽

Post Transcriptional Regulation

Normal hematopoiesis is sustained through a carefully orchestrated balance between hematopoietic stem cell (HSC) self-renewal and differentiation. The functional importance of this axis is underscored by the severity of disease phenotypes initiated by abnormal HSC function, including myelodysplastic syndromes and hematopoietic malignancies. Major advances in the understanding of transcriptional regulation of primitive hematopoietic cells have been achieved; however, the post-transcriptional regulatory layer that may impinge on their behavior remains underexplored by comparison. Key players at this level include RNA-binding proteins (RBPs), which execute precise and highly coordinated control of gene expression through modulation of RNA properties that include its splicing, polyadenylation, localization, degradation, or translation. With the recent identification of RBPs having essential roles in regulating proliferation and cell fate decisions in other systems, there has been an increasing appreciation of the importance of post-transcriptional control at the stem cell level. Here we discuss our current understanding of RBP-driven post-transcriptional regulation in HSCs, its implications for normal, perturbed, and malignant hematopoiesis, and the most recent technological innovations aimed at RBP–RNA network characterization at the systems level. Emerging evidence highlights RBP-driven control as an underappreciated feature of primitive hematopoiesis, the greater understanding of which has important clinical implications.

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