scholarly journals Aldh2 dependent formaldehyde metabolism fuels purine demands in melanocyte stem cells

2021 ◽  
Author(s):  
Hannah Brunsdon ◽  
Alessandro Brombin ◽  
Samuel Peterson ◽  
John H. Postlethwait ◽  
E. Elizabeth Patton
Keyword(s):  
Stem Cells ◽  
De Novo ◽  
Purine Biosynthesis ◽  
Sequencing Analysis ◽  
Reaction Products ◽  
Nucleotide Biosynthesis ◽  
Hematopoietic Stem ◽  
Processing Enzymes ◽  
Melanocyte Stem Cells ◽  
Formaldehyde Metabolism

ABSTRACTAldehyde-processing enzymes are viewed as essential clearing agents that rapidly deactivate harmful aldehydes. In the bone marrow, two specific enzymes, aldehyde dehydrogenase (ALDH) 2 and alcohol dehydrogenase (ADH) 5, were previously reported to protect hematopoietic stem cells from endogenous formaldehyde accumulation. Unexpectedly, we found that melanocyte stem cells (McSCs) in zebrafish depend on formate, an Aldh2-generated reaction product, to drive regeneration. Activated McSCs require Aldh2 (but not Adh5) to generate differentiated progeny, and by using scRNA-sequencing analysis, we identified a de novo purine biosynthesis program that is uniquely present in activated McSCs. Consistent with formate serving as one-carbon units for nucleotide biosynthesis, we found that purine supplementation (but not pyrimidine supplementation) was able to restore melanocyte regeneration in the absence of Aldh2. This work shows that Aldh2 enzymes generate reaction products that are needed to meet metabolic demands in regeneration.

scholarly journals Evidence for malignant transformation in acute myeloid leukemia at the level of early hematopoietic stem cells by cytogenetic analysis of CD34+ subpopulations

Blood ◽  
1995 ◽  
Vol 86 (8) ◽  
pp. 2906-2912 ◽  
Author(s):  
D Haase ◽  
M Feuring-Buske ◽  
S Konemann ◽  
C Fonatsch ◽  
C Troff ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Malignant Transformation ◽  
Cell Sorting ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Leukemic Cells ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Acute myeloid leukemia (AML) is a heterogenous disease according to morphology, immunophenotype, and genetics. The retained capacity of differentiation is the basis for the phenotypic classification of the bulk population of leukemic blasts and the identification of distinct subpopulations. Within the hierarchy of hematopoietic development and differentiation it is still unknown at which stage the malignant transformation occurs. It was our aim to analyze the potential involvement of cells with the immunophenotype of pluripotent stem cells in the leukemic process by the use of cytogenetic and cell sorting techniques. Cytogenetic analyses of bone marrow aspirates were performed in 13 patients with AML (11 de novo and 2 secondary) and showed karyotype abnormalities in 10 cases [2q+, +4, 6p, t(6:9), 7, +8 in 1 patient each and inv(16) in 4 patients each]. Aliquots of the samples were fractionated by fluorescence-activated cell sorting of CD34+ cells. Two subpopulations, CD34+/CD38-(early hematopoietic stem cells) and CD34+/CD38+ (more mature progenitor cells), were screened for karyotype aberations as a marker for leukemic cells. Clonal abnormalities and evaluable metaphases were found in 8 highly purified CD34+/CD38-populations and in 9 of the CD34+/CD38-specimens, respectively. In the majority of cases (CD34+/CD38-, 6 of 8 informative samples; CD34+/CD38+, 5 of 9 informative samples), the highly purified CD34+ specimens also contained cytogenetically normal cells. Secondary, progression-associated chromosomal changes (+8, 12) were identified in the CD34+/CD38-cells of 2 patients. We conclude that clonal karyotypic abnormalities are frequently found in the stem cell-like (CD34+/CD38-) and more mature (CD34+/CD38+) populations of patients with AML, irrespective of the phenotype of the bulk population of leukemic blasts and of the primary or secondary character of the leukemia. Our data suggest that, in AML, malignant transformation as well as disease progression may occur at the level of CD34+/CD38-cells with multilineage potential.

scholarly journals Definitive Hematopoietic Stem Cells Minimally Contribute to Embryonic Hematopoiesis

2021 ◽  
Author(s):  
Bianca A Ulloa ◽  
Samima S Habbsa ◽  
Kathryn S Potts ◽  
Alana Lewis ◽  
Mia McKinstry ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
De Novo ◽  
Marker Gene ◽  
Lineage Tracing ◽  
Hematopoietic Stem ◽  
Functional Potential ◽  
Injury Model ◽  
Rare Cells

Hematopoietic stem cells (HSCs) are rare cells that arise in the embryo and sustain adult hematopoiesis. Although the functional potential of nascent HSCs is detectable by transplantation, their native contribution during development is unknown, in part due to the overlapping genesis and marker gene expression with other embryonic blood progenitors. Using single cell transcriptomics, we defined gene signatures that distinguish nascent HSCs from embryonic blood progenitors. Applying a new lineage tracing approach, we selectively tracked HSC output in situ and discovered significantly delayed lymphomyeloid contribution. Using a novel inducible HSC injury model, we demonstrated a negligible impact on larval lymphomyelopoiesis following HSC depletion. HSCs are not merely dormant at this developmental stage as they showed robust regeneration after injury. Combined, our findings illuminate that nascent HSCs self-renew but display differentiation latency, while HSC-independent embryonic progenitors sustain developmental hematopoiesis. Understanding the differences among embryonic HSC and progenitor populations will guide improved de novo generation and expansion of functional HSCs.

scholarly journals Disruption of de novo purine biosynthesis in Pseudomonas fluorescens Pf0-1 leads to reduced biofilm formation and a reduction in cell size of surface-attached but not planktonic cells

2015 ◽  
Author(s):  
Shiro Yoshioka ◽  
Peter D Newell
Keyword(s):  
Pseudomonas Fluorescens ◽  
Cell Size ◽  
Biofilm Formation ◽  
De Novo ◽  
Purine Biosynthesis ◽  
Model Organisms ◽  
Purine Nucleotides ◽  
Surface Attachment ◽  
Nucleotide Biosynthesis ◽  
Mutant Cells

Pseudomonas fluorescens Pf0-1 is one of the model organisms for biofilm research. Our previous transposon mutagenesis study suggested a requirement for the de novo purine nucleotide biosynthesis pathway for biofilm formation by this organism. This study was performed to verify that observation and investigate the basis for the defects in biofilm formation shown by purine biosynthesis mutants. Constructing deletion mutations in 8 genes in this pathway, we found that they all showed reductions in biofilm formation that could be partly or completely restored by nucleotide supplementation or genetic complementation. We demonstrated that, despite a reduction in biofilm formation, more viable mutant cells were recovered from the surface-attached population than from the planktonic phase under conditions of purine deprivation. Analyses using scanning electron microscopy revealed that the surface-attached mutant cells were 25~30% shorter in length than WT, which partly explains the reduced biomass in the mutant biofilms. The laser diffraction particle analyses confirmed this finding, and further indicated that the WT biofilm cells were smaller than their planktonic counterparts. The defects in biofilm formation and reductions in cell size shown by the mutants were fully recovered upon adenine or hypoxanthine supplementation, indicating that the purine shortages caused reductions in cell size. Our results are consistent with surface attachment serving as a survival strategy during nutrient deprivation, and indicate that changes in the cell size may be a natural response of P. fluorescens to growth on a surface. Finally, cell sizes in WT biofilms became slightly smaller in the presence of exogenous adenine than in its absence. Our findings suggest that purine nucleotides or related metabolites may influence the regulation of cell size in this bacterium.

scholarly journals Hematopoietic specification from human pluripotent stem cells: current advances and challenges toward de novo generation of hematopoietic stem cells

Blood ◽  
2013 ◽  
Vol 122 (25) ◽  
pp. 4035-4046 ◽  
Author(s):  
Igor I. Slukvin
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Pluripotent Stem Cells ◽  
De Novo ◽  
Human Pluripotent Stem Cells ◽  
Cellular Reprogramming ◽  
Hematopoietic Stem ◽  
Hematopoietic Development ◽  
Cellular Pathways

Abstract Significant advances in cellular reprogramming technologies and hematopoietic differentiation from human pluripotent stem cells (hPSCs) have already enabled the routine production of multiple lineages of blood cells in vitro and opened novel opportunities to study hematopoietic development, model genetic blood diseases, and manufacture immunologically matched cells for transfusion and cancer immunotherapy. However, the generation of hematopoietic cells with robust and sustained multilineage engraftment has not been achieved. Here, we highlight the recent advances in understanding the molecular and cellular pathways leading to blood development from hPSCs and discuss potential approaches that can be taken to facilitate the development of technologies for de novo production of hematopoietic stem cells.

scholarly journals Gene-edited stem cells enable CD33-directed immune therapy for myeloid malignancies

2019 ◽  
pp. 201819992 ◽  
Author(s):  
Florence Borot ◽  
Hui Wang ◽  
Yan Ma ◽  
Toghrul Jafarov ◽  
Azra Raza ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
Residual Disease ◽  
Immune Therapy ◽  
Leukemic Cells ◽  
Sequencing Analysis ◽  
Hematopoietic Stem ◽  
Genetic Ablation ◽  
Targeted Immunotherapy

Antigen-directed immunotherapies for acute myeloid leukemia (AML), such as chimeric antigen receptor T cells (CAR-Ts) or antibody-drug conjugates (ADCs), are associated with severe toxicities due to the lack of unique targetable antigens that can distinguish leukemic cells from normal myeloid cells or myeloid progenitors. Here, we present an approach to treat AML by targeting the lineage-specific myeloid antigen CD33. Our approach combines CD33-targeted CAR-T cells, or the ADC Gemtuzumab Ozogamicin with the transplantation of hematopoietic stem cells that have been engineered to ablate CD33 expression using genomic engineering methods. We show highly efficient genetic ablation of CD33 antigen using CRISPR/Cas9 technology in human stem/progenitor cells (HSPC) and provide evidence that the deletion of CD33 in HSPC doesn’t impair their ability to engraft and to repopulate a functional multilineage hematopoietic system in vivo. Whole-genome sequencing and RNA sequencing analysis revealed no detectable off-target mutagenesis and no loss of functional p53 pathways. Using a human AML cell line (HL-60), we modeled a postremission marrow with minimal residual disease and showed that the transplantation of CD33-ablated HSPCs with CD33-targeted immunotherapy leads to leukemia clearance, without myelosuppression, as demonstrated by the engraftment and recovery of multilineage descendants of CD33-ablated HSPCs. Our study thus contributes to the advancement of targeted immunotherapy and could be replicated in other malignancies.

The Role of Nucleophosmin In Hematopoietic Stem Cells and the Pathogenesis of Myelodysplastic Syndrome

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 95-95 ◽  
Author(s):  
Keisuke Ito ◽  
Paolo Sportoletti ◽  
John G Clohessy ◽  
Grisendi Silvia ◽  
Pier Paolo Pandolfi
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Myelodysplastic Syndrome ◽  
Cell Biology ◽  
De Novo ◽  
Stem Cell Biology ◽  
Hematopoietic Stem

Abstract Abstract 95 Myelodysplastic syndrome (MDS) is an incurable stem cell disorder characterized by ineffective hematopoiesis and an increased risk of leukemia transformation. Nucleophosmin (NPM) is directly implicated in primitive hematopoiesis, the pathogenesis of hematopoietic malignancies and more recently of MDS. However, little is known regarding the molecular role and function of NPM in MDS pathogenesis and in stem cell biology. Here we present data demonstrating that NPM plays a critical role in the maintenance of hematopoietic stem cells (HSCs) and the transformation of MDS into leukemia. NPM is located on chromosome 5q and is frequently lost in therapy-related and de novo MDS. We have previously shown that Npm1 acts as a haploinsufficient tumor suppressor in the hematopoietic compartment and Npm1+/− mice develop a hematologic syndrome with features of human MDS, including increased susceptibility to leukemogenesis. As HSCs have been demonstrated to be the target of the primary neoplastic event in MDS, a functional analysis of the HSC compartment is essential to understand the molecular mechanisms in MDS pathogenesis. However, the role of NPM in adult hematopoiesis remains largely unknown as Npm1-deficiency leads to embryonic lethality. To investigate NPM function in adult hematopoiesis, we have generated conditional knockout mice of Npm1, using the Cre-loxP system. Analysis of Npm1 conditional mutants crossed with Mx1-Cre transgenic mice reveals that Npm1 plays a crucial role in adult hematopoiesis and ablation of Npm1 in adult HSCs leads to aberrant cycling and followed by apoptosis. Analysis of cell cycle status revealed that HSCs are impaired in their ability to maintain quiescence after Npm1-deletion and are rapidly depleted in vivo as well as in vitro. Competitive reconstitution assay revealed that Npm1 acts cell-autonomously to maintain HSCs. Conditional inactivation of Npm1 leads to an MDS phenotype including a profoundly impaired ability to differentiate into cells of the erythroid lineage, megakaryocyte dyspoiesis and centrosome amplification. Furthermore, Npm1 loss evokes a p53-dependent response and Npm1-deleted HSCs undergo apoptosis in vivo and in vitro. Strikingly, transfer of the Npm1 mutation into a p53-null background rescued the apoptosis of Npm1-ablated HSCs and resulted in accelerated transformation to an aggressive and lethal form of acute myeloid leukemia. Our findings highlight the crucial role of NPM in stem cell biology and identify a new mechanism by which MDS can progress to leukemia. This has important therapeutic implications for de novo MDS as well as therapy-related MDS, which is known to rapidly evolve to leukemia with frequent loss or mutation of TRP53. Disclosures: No relevant conflicts of interest to declare.

scholarly journals A New Entity of Acute Myeloid Leukemia Driven By Epigenetic and Somatic Dis-Regulation of Uncx, a Novel Homeobox Transcription Factor Gene

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1356-1356
Author(s):  
Giulia Daniele ◽  
Clelia Tiziana Storlazzi ◽  
Cristina Papayannidis ◽  
Ilaria Iacobucci ◽  
Angelo Lonoce ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Transcription Factor ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Ectopic Expression ◽  
Response To Therapy ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Abstract We describe a new AML entity, occurring in 30% of de novo acute myeloid leukemia, due to structural and epigenetic deregulation of the UNCX homeobox (HB) gene. By molecular approaches, we identified a M5 AML patient with a t(7;10)(p22;p14) translocation as the sole cytogenetic anomaly and showing ectopic expression of UNCX (7p22.3), which encode for a transcription factor involved in somitogenesis and neurogenesis. Since UNCX was never reported in association with cancer but only with common myeloid cell proliferation and regulation of cell differentiation, we decided to investigate its contribution to leukemogenesis. We observed UNCX ectopic expression in 32.3% (20/62) and in 8% (6/75) of acute myeloid leukemia (AML) patients and cell lines, respectively. Notably, retroviral-mediated UNCX transfer in CD34+ HSCs induced a slow-down in their proliferation and differentiation and transduced cells showed a lower growth rate but a higher percentage of CD34+ stem cells in liquid culture than controls. Additionally, UNCX infected cells displayed a decrease of MAP2K1 proliferation marker but increase of KLF4, HOXA10, and CCNA1, associated with impaired differentiation and pluripotency. Similarly, UNCX-positive patients revealed alteration of gene pathways involved in proliferation, cell cycle control and hematopoiesis. Since HB genes encode for transcription factors showing a crucial role in normal hematopoiesis and in leukemogenesis, we focused our attention on the role of altered UNCX expression level. Of note, its murine ortholog, (Uncx) was previously described as embedded within a low-methylated regions (≤ 10%) called "canyon" and dysregulated in murine hematopoietic stem cells (HSCs) as a consequence of altered methylation at canyons edges (borders) due to Dnmt3a inactivation. In our hands, UNCX activation was accompanied by methylation changes at both its canyon borders, clearly indicating an epigenetic regulation of this gene, although not induced by DNMT3A mutations. Clinical parameters and correlation with response to therapy will be presented. Taken together, our results indicate that more than 30% of de novo AML have a novel entity with a putative leukemogenic role of UNCX, whose activation may be ascribed to epigenetic regulators. Acknowledgments: MG, CP, GS, and AP(2) and this work was supported by ELN, AIL, AIRC, progetto Regione-Università 2010-12 (L. Bolondi), Fondazione del Monte di Bologna e Ravenna, FP7 NGS-PTL project. CTS, GD and AL are supported by Associazione Italiana Ricerca sul Cancro (AIRC) funding. Disclosures Nadarajah: MLL Munich Leukemia Laboratory: Employment. Martinelli:MSD: Consultancy; Novartis: Consultancy, Speakers Bureau; Ariad: Consultancy; BMS: Consultancy, Speakers Bureau; Pfizer: Consultancy; AMGEN: Consultancy; ROCHE: Consultancy.

scholarly journals Generation of Retinoic Acid-Dependent Definitive Hematopoietic Progenitors from Human Pluripotent Stem Cells

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 35-35
Author(s):  
Stephanie A Luff ◽  
J Philip Creamer ◽  
Carissa Dege ◽  
Rebecca Scarfò ◽  
Samantha Morris ◽  
...  
Keyword(s):  
Stem Cells ◽  
Retinoic Acid ◽  
Pluripotent Stem Cells ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Human Pluripotent Stem Cells ◽  
Human Embryos ◽  
Dependent Manner ◽  
Hematopoietic Stem

The generation of the hematopoietic stem cells (HSCs) from human pluripotent stem cells (hPSCs) is a major goal for regenerative medicine. In the embryo, HSCs derive from a HOXA+ population known as hemogenic endothelium (HE) in a retinoic acid (RA)-dependent manner. Using hPSCs, we have previously identified a KDR+CD235a− mesodermal population that gives rise to a clonally multipotent HOXA+ definitive HE. However, this HE lacks HSC-like capacity in the absence of exogenous transgenes and is functionally unresponsive to RA treatment. Thus, the specification of an RA-dependent hematopoietic program from hPSCs has remained elusive. Through single cell RNA-seq (scRNA-seq) analyses, we identified that 2 distinct KDR+CD235a− populations exist prior to HE specification, distinguishable by CXCR4 expression. Interestingly, KDR+CD235a−CXCR4− mesoderm expressed CYP26A1, an RA degrading enzyme, and harbored definitive hematopoietic potential within hPSC differentiation cultures in the absence of RA signaling, indicating the HE specified from CXCR4− mesoderm as RA-independent (RAi). In sharp contrast, KDR+CD235a−CXCR4+ mesoderm exclusively expressed ALDH1A2, the key enzyme in the synthesis of RA, but lacked hematopoietic potential under the same culture conditions. However, the stage-specific application of RA signaling to CXCR4+ mesoderm resulted in the robust specification of CD34+HOXA+ HE with definitive erythroid, myeloid, and lymphoid hematopoietic potential, establishing this HE as RA-dependent (RAd). Furthermore, while RAi HE entirely failed to persist following murine hematopoietic xenografts, RAd HE transiently persisted within the peripheral blood and bone marrow of murine hosts. To assess whether these functionally distinct hPSC mesodermal progenitors are physiologically relevant to human embryonic development, we integrated scRNA-seq datasets from the hPSC mesodermal cultures and a gastrulating human embryo. These analyses revealed that in vivo, distinct KDR+CXCR4−CYP26A1+ and KDR+CXCR4+ALDH1A2+ populations can be found at the stage of emergent mesoderm, following patterning of nascent mesoderm. Additional comparison to later stage human embryos demonstrated that RAd HE has a more fetal-like HOXA expression pattern than RAi HE. Scoring of single fetal HE cells against hPSC-derived HE revealed that while some early fetal HE cells were similar to RAi HE, the late fetal HE cells, which are hypothesized to give rise to HSCs, were more similar to RAd HE. Lastly, as HSC-competent HE is expected to express arterial genes, we found a subset of late fetal HE with this phenotype that were exclusively similar to RAd HE. Collectively, these data represent the first ever characterization of RA-dependent hPSC-derived definitive hematopoiesis and its mesodermal progenitor. Additionally, we provide evidence for in vivo mesodermal and HE correlates for both RAi and RAd hematopoietic programs within human embryos. This novel insight into human hematopoietic development will serve as an important tool for modeling development and ultimately provide the basis for de novo specification of HSCs. Disclosures No relevant conflicts of interest to declare.

Human Lymphoid and Myeloid Cell Development in NOD/LtSz-scid IL2rγnull Mice Engrafted with Mobilized Human Hematopoietic Stem Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 248-248 ◽  
Author(s):  
Leonard Shultz ◽  
Bonnie L. Lyons ◽  
Lisa M. Burzenski ◽  
Bruce Gott ◽  
X. Chen ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Nk Cells ◽  
De Novo ◽  
Cell Development ◽  
In Vivo Model ◽  
Hematopoietic Stem ◽  
Human T Cell

Abstract We have developed, characterized, and validated a new genetic stock of IL-2r common γ (gamma) chain deficient NOD/LtSz-scid (NOD-scid IL2rγnull) mice that support high levels of human hematopoietic stem cell (HSC) engraftment and multilineage differentiation. Histology, flow cytometry, and functional assays document a severe depletion of lymphocytes and NK cells in NOD-scid IL2rγnull mice. These mice survive beyond 16 months of age and untreated as well as sub-lethally irradiated NOD-scid IL2rγnull mice are resistant to the development of lymphomas and are “non-leaky” throughout life. Intravenous injection of sub-lethally irradiated NOD-scid IL2rγnull mice with 7 x 105 human mobilized CD34+ stem cells leads to high levels of multilineage engraftment. At 10 weeks after engraftment, percentages of human hematopoietic CD45+ cells are six-fold higher in the bone marrow of NOD-scid IL2rγnull mice as compared to NOD-scid controls. Human CD45+ cells include immature and mature B cells, NK cells, myeloid cells, plasmacytoid dendritic cells and HSCs. Spleens from engrafted NOD-scid IL2rγnull mice contain high percentages of immature and mature B cells but low percentages of T cells. Treatment with human Fc-IL7 fusion protein leads to a high percentage of human CD4+CD8+ immature thymocytes and high percentages of CD4+CD8− and CD4−CD8+ mature human T cells in the spleen and blood. Validation of de novo human T cell development was carried out by quantifying T cell receptor excision circles in thymocytes and by analyses of TCRβ repertoire diversity. Human T cell function was evidenced by proliferative responses to PHA and streptococcal superantigen. NOD-scid IL2rγnull mice engrafted with human HSC generate differentiated functional human T and B cells and provide an in vivo model of multilineage human hematopoietic cell engraftment.

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