Elevated Expression of Mir-130a in t(8,21) AML Reinforces the Aberrant Molecular Program of AML1-ETO

Background: Deregulation of self-renewal and differentiation programs are central to the pathogenesis of hematologic malignancies. MicroRNAs (miRNAs) represent a large class of post-transcriptional regulators that mediate repression of multiple target mRNAs and are frequently deregulated in acute myeloid leukemia (AML). From our previous in vivo miRNA enforced expression screen in human hematopoietic stem and progenitor cells (HSPC), we identified miR-130a as a regulator of self-renewal and lineage specification. Enforced expression of miR-130a in human cord blood (CB) derived HSPC caused an expansion of HSC, block in erythroid differentiation and abnormal myelopoiesis in xenografts. Thus, we examined miR-130a expression in AML and found miR-130a to be specifically upregulated in t(8,21) AML. The translocation t(8,21) is one of the most common karyotypic abnormalities in AML, accounting up to 10% of all AML cases. The consequence of this translocation is a fusion of AML1 and ETO genes, resulting in a formation of the AML1-ETO (AE) oncofusion protein, which acts as a dominant repressor of the wild type AML1/RUNX1. The ETO moiety mediates the recruitment of the nuclear corepressor (NCoR) and histone deacetylases (HDAC1-3) to block RUNX1 target gene expression. This prevents myeloid maturation, apoptosis and promotes leukemogenesis. Here we investigated the molecular mechanism of miR-130a in t(8,21) AML and how it contributes to the leukemogenesis of this AML subtype. Results: Using the TCGA dataset and our PMCC patient cohort, we identified miR-130a to be upregulated in t(8,21) AML and high miR-130a expression was associated with worse patient overall survival. To interrogate the functional significance of elevated miR-130a in t(8,21) AML, we performed knock-down (KD) experiments in the Kasumi-1 cell line, which represents a well characterized model system for t(8,21) AML. Notably, KD of miR-130a induced a significant reduction in the CD34+ cell population and an increase in differentiated CD11b+CD15+ and pro-apoptotic annexin V+ cells. We next examined the impact of miR-130a KD in CD34+ blasts from primary t(8,21) AML patient samples. In line with our findings in the Kasumi-1 cells, miR-130a KD decreased the proportion of CD34+ cells and increased the proportion of differentiated CD11b+CD15+ blasts. To investigate the effect of miR-130a KD on leukemic engraftment in vivo, we transduced CD34+ blasts from 2 patient samples and transplanted them into NSG-GF mice. miR-130a KD decreased leukemic engraftment and the proportion of transduced cells, corroborating the functional significance of high miR-130a expression in t(8,21) AML. To investigate the mechanistic action of miR-130a, we performed label-free semi-quantitative proteomics in human CB derived HSPC to uncover miR-130a targets. Surprisingly, we found the beta subunit of RUNX1, CBFb, and Transducin Beta Like 1 X-Linked Receptor 1, TBL1XR1, to be among the most repressed targets. TBL1XR1 is a component of the nuclear receptor corepressor (NCoR) complex and is involved in NCoR degradation. Thus, we performed western and immunoprecipitations (IP) assays in Flag-AE Kasumi-1 cells following miR-130a KD to examine changes in the expression of proteins associated with the AE complex. We observed increased expression of CBFβ, TBL1XR1 and CEBPA with miR-130a KD. Notably, miR-130a KD resulted in a dramatic decrease of NCoR protein levels. IP of Flag-AE showed decreased association of CBFβ and NCoR with AE, despite unaltered protein levels of AE. To investigate changes in binding occupancy of Flag-AE after miR-130a KD, we performed Cleavage Under the Targets and Release Using Nuclease (CUT&RUN) assay. Surprisingly, we observed 2-fold gain of AE sites in miR-130a KD sample compared to control. De novo motif enrichment analysis showed loss of motives for ETS and HOX transcription factors known to associate with AE following miR-130a KD. Genomic distribution of the peaks revealed a dramatic shift of AE peaks away from the promoter region to introns in miR-130a KD. Pathway enrichment analysis of the unique peaks gained in miR-130a KD showed stress responses and organelle disassembly, in line with the differentiation phenotype observed with miR-130a KD. Collectively, we uncovered a novel mechanism by which miR-130a reinforces the aberrant AE molecular program by controlling the composition and binding of the AE complex. Disclosures Dick: Bristol-Myers Squibb/Celgene: Research Funding.

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Interferon-Gamma Impairs Expansion and Hematopoietic Support of Bone Marrow Mesenchymal Stromal Cells

Blood ◽

10.1182/blood.v128.22.3884.3884 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3884-3884

Author(s):

Marieke Goedhart ◽

Anne Cornelissen ◽

Carlijn Kuijk ◽

Sulima Geerman ◽

Fernanda Pascutti ◽

...

Keyword(s):

Stromal Cells ◽

Stromal Compartment ◽

Self Renewal ◽

Hematopoietic Stem ◽

Ifn Γ ◽

Immunomodulatory Properties ◽

Pre Treatment ◽

The Impact

Abstract Maintenance of hematopoietic stem cells (HSCs) and regulation of their quiescence and self-renewal is critical for maintaining a lifelong supply of blood cells. The ability of HSCs to stay quiescent is thought to depend on their specific niche in the bone marrow (BM). Mesenchymal stromal cells (MSC) in the BM are multipotent stem cells that form part of the vascular HSC niche and provide micro-environmental support to HSCs both in vivo and upon expansion ex vivo. Culture-expanded MSCs also exhibit immunomodulatory properties that can be enhanced by pre-treatment with interferon-gamma (IFN-γ). BM MSC are thus attractive candidates for cellular therapy after hematopoietic stem cell transplantation, for promoting rapid hematopoietic recovery and reducing the incidence or severity of graft versus host disease. Although IFN-γ pre-treatment can improve the immunomodulatory properties of MSCs, elevated IFN-γ levels have also been associated with anemia and BM failure in multiple chronic inflammatory diseases. While the impact of IFN-γ on HSC has been elucidated in recent years, it remains largely unknown whether IFN-γ can also influence hematopoietic support by BM stromal cells. In this study, we aim to elucidate the impact of IFN-γ on hematopoietic support of BM MSC. We show that in vitro expansion of primary BM MSC cultures from healthy donors was significantly reduced in the presence of IFN-γ, and this effect could be reproduced in the BM stromal cell line MS-5. Concurrently, IFN-γ diminished the clonal capacity of BM MSC, as measured by CFU-F assays. In addition, BM MSC that were pre-stimulated with IFN-γ produced significantly lower levels of CXCL12, suggesting a loss of hematopoietic support potential. Indeed, support of CD34+ hematopoietic stem and progenitor cells (HSPC) in a co-culture assay was greatly reduced in when MSC were pre-treated with IFN-γ. To determine the impact of IFN-γ on BM MSC in vivo, we investigated the BM stromal compartment of IFN-γ AU-rich element deleted (ARE-Del) mice, which constitutively express IFN-γ in steady state conditions. FACS analysis revealed a remodeling of the BM stromal compartment in ARE-Del mice compared to littermate controls, with significantly fewer MSCs, identified as CD45-Ter119-CD31-CD51+PDGFRa+ cells. Numbers of other stromal cell subsets, such as osteoblasts and fibroblasts, were not altered. The reduction of BM MSC in ARE-Del mice coincided with a loss of quiescence in HSCs; only 35% of long term HSC (LT-HSC) in ARE-Del mice were quiescent, compared to 70% in WT mice, as determined by Ki-67 staining. Loss of quiescence in LT-HSC did not lead to increased self-renewal, but rather induced increased differentiation towards short-term HSC and multi-potent progenitors. We then sorted LT-HSC from WT and ARE-Del mice and performed in vitro HSC culture assays in the absence of IFN-γ. Absolute numbers of LT-HSC were rapidly decreased in ARE-Del compared to WT cultures after 3 and 7 days of HSC culture, while numbers of more differentiated progenitors were increased. These data indicate that an IFN-γ-mediated loss of BM MSC in ARE-Del mice leads to loss of quiescent LT-HSCs and induces a tendency towards HSC differentiation over self-renewal. In conclusion, we have shown that IFN-γ has a negative impact on expansion and hematopoietic support of BM MSC in vitro and in vivo across species. Although IFN-γ treatment enhances the immunomodulatory function of MSCs in a clinical setting, it is obvious from our data that IFN-γ impairs their HSC supporting function. These data also provide more insight in the underlying mechanism by which IFN-γ contributes to the pathogenesis of anemia and BM failure. Disclosures No relevant conflicts of interest to declare.

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Phf6-null hematopoietic stem cells have enhanced self-renewal capacity and oncogenic potentials

Blood Advances ◽

10.1182/bloodadvances.2019000391 ◽

2019 ◽

Vol 3 (15) ◽

pp. 2355-2367 ◽

Cited By ~ 7

Author(s):

Yueh-Chwen Hsu ◽

Tsung-Chih Chen ◽

Chien-Chin Lin ◽

Chang-Tsu Yuan ◽

Chia-Lang Hsu ◽

...

Keyword(s):

Stem Cells ◽

Hematopoietic Stem Cells ◽

Knockout Mice ◽

Neurodevelopmental Disorder ◽

Loss Of Function ◽

Self Renewal ◽

Hematopoietic Stem ◽

Knockout Mouse Model ◽

The Impact

Abstract Plant homeodomain finger gene 6 (PHF6) encodes a 365-amino-acid protein containing 2 plant homology domain fingers. Germline mutations of human PHF6 cause Börjeson-Forssman-Lehmann syndrome, a congenital neurodevelopmental disorder. Loss-of-function mutations of PHF6 are detected in patients with acute leukemia, mainly of T-cell lineage and in a small proportion of myeloid lineage. The functions of PHF6 in physiological hematopoiesis and leukemogenesis remain incompletely defined. To address this question, we generated a conditional Phf6 knockout mouse model and investigated the impact of Phf6 loss on the hematopoietic system. We found that Phf6 knockout mice at 8 weeks of age had reduced numbers of CD4+ and CD8+ T cells in the peripheral blood compared with the wild-type littermates. There were decreased granulocyte-monocytic progenitors but increased Lin–c-Kit+Sca-1+ cells in the marrow of young Phf6 knockout mice. Functional studies, including competitive repopulation unit and serial transplantation assays, revealed an enhanced reconstitution and self-renewal capacity in Phf6 knockout hematopoietic stem cells (HSCs). Aged Phf6 knockout mice had myelodysplasia-like presentations, including decreased platelet counts, megakaryocyte dysplasia, and enlarged spleen related to extramedullary hematopoiesis. Moreover, we found that Phf6 loss lowered the threshold of NOTCH1-induced leukemic transformation at least partially through increased leukemia-initiating cells. Transcriptome analysis on the restrictive rare HSC subpopulations revealed upregulated cell cycling and oncogenic functions, with alteration of key gene expression in those pathways. In summary, our studies show the in vivo crucial roles of Phf6 in physiological and malignant hematopoiesis.

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Interferon-Gamma Impairs the Self-Renewal of Hematopoietic Stem Cells

Blood ◽

10.1182/blood.v118.21.2351.2351 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2351-2351

Author(s):

Alexander M. de Bruin ◽

Berend Hooibrink ◽

Martijn A. Nolte

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Hematopoietic Stem Cells ◽

Interferon Gamma ◽

Chimeric Mice ◽

Self Renewal ◽

Hematopoietic Stem ◽

The Impact

Abstract Abstract 2351 Regulation of hematopoiesis during stress situations, such as bacterial or viral infections, is crucial for the maintenance of sufficient numbers of cells in the blood. It has become clear that activated immune cells provide such feedback signals to the bone marrow. An important mediator in this respect is the pro-inflammatory cytokine Interferon-gamma (IFNγ), which is produced in the bone marrow by activated T cells during the course of an infection. As such, we have previously shown that T cell-derived IFNγ can directly influence the output of myeloid and erythroid cells. To address whether IFNγ can also influence the function of hematopoietic stem cells (HSCs), we cultured highly purified HSCs from murine bone marrow with or without IFNγ and found that IFNγ strongly reduced the absolute number of HSCs in these cultures, both phenotypically and functionally. We confirmed that the functional impact of IFNγ was due to a direct effect on HSCs and not mediated by more differentiated progenitors. In addition, IFNγ does not directly influence the quiescent state of purified HSC, nor their cell cycle entry. By labeling HSCs with CFSE, we found that IFNγ reduces HSC expansion in vitro by decreasing their proliferative capacity, but not their ability to differentiate. To investigate the impact of IFNγ on HSCs in vivo, we infected WT and IFNγ−/− mice with lymphocytic choriomeningitis virus (LCMV) and found that IFNγ severely impaired HSC recovery upon infection. Finally, to exclude indirect effects of IFNγ on other cell types we generated chimeric mice with bone marrow from both WT and IFNγR−/− mice. Infection of these mixed-chimeric mice with LCMV resulted in decreased recovery of WT HSCs, but not of IFNγR−/− HSCs in the same mouse, which formally demonstrates that IFNγ directly impairs the proliferation of HSCs in vivo. Based on these experiments we conclude that IFNγ reduces HSC self renewal both in vitro and in vivo. Importantly, we thereby challenge the current concept in literature that IFNγ would induce the proliferation of HSCs (Baldridge et al, Nature 2010). Our findings thus provide challenging new insight regarding the impact of immune activation on hematopoiesis and will contribute significantly to the scientific discussion concerning this process. Moreover, our data also provide an explanation for the occurrence of anemia and bone marrow failure in several human diseases in which IFNγ is chronically produced. Disclosures: No relevant conflicts of interest to declare.

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Epigenetic Modification Can Regulate the Stem Cell State of Hematopoietic Cells.

Blood ◽

10.1182/blood.v108.11.1356.1356 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1356-1356

Author(s):

Il-Hoan Oh ◽

Hye-Jung Kim ◽

Yun Shin Chung

Keyword(s):

Dna Methylation ◽

Stem Cell ◽

De Novo ◽

Epigenetic Modification ◽

Hematopoietic Cells ◽

Self Renewal ◽

Hematopoietic Stem ◽

Cd34 Cells ◽

Marrow Cells

Abstract The maintenance of undifferentiated state and ability for self-renewal constitutes key properties of hematopoietic stem cell (HSC). To explore the possibility that epigenetic modification contributes to regulation of HSC functions, we have studied whether distinctive epigenetic modification can be correlated to different functions of hematopoietic cells. As a first approach, the global DNA methylations in non-coding repetitive elements were examined using mIAP, mEtn, and mc.satellite regions as marker loci. Sequencing of sodium bisulfite-modified CpG islands in these loci showed that most primitive Lin-c-kit+CD34− cells displayed highest level of DNA methylation as compared to the progenitor-enriched Lin-c-kit+CD34+ cells or differentiated counterpart (Lin+ cells) in mc satellite regions (85.7%, 60 %, 65%, respectively) and mEtn regions (73%, 58%, 74%, respectively), but not in mIAP region. Interestingly, whereas most primitive Lin-c-kit+CD34− cells expressed highest level of methyl cytosine binding protein (MeCp2) or DNA methyl transferase 3 (DNMT3a, 3b), the Lin+ cells expressed bare to minimal level of these gene products despite their high maintenance of DNA methylation, suggesting a differential de-novo methylations between these cells. Similarly, the most primitive Lin-c-kit+CD34− cells exhibited highest level of total acetylated histone (Ac-H4) but these cells expressed also high levels of histone deacetylase (HDAC) as well as histone acetyl transferase (HAT). Subsequent pulse-labeling with C14-acetate demonstrated that immature bone marrow cells (lin-), but not mature Lin+ cells, exhibited active acetylation of H4 with higher turn-overs, thus showing active remodeling of chromatin structures in immature hematopoietic cells. Next, to explore whether alterations in epigenetic modification could influence HSC function, the effect of epigenetic blockers (5-Azacytidine or TSA) were examined for their influence on in-vivo self-renewing activity of transplanted HSCs. Thus, recipients that had been lethally irradiated and transplanted with congeneic HSCs were treated with blockers during first two weeks of recovery, and transplanted into secondary recipients 18 weeks later to determine CRU numbers regenerated. The result of this CRU assay revealed that HSCs had underwent 32-folds higher self-renewal with inhibition of HDAC (22 vs. 738 CRUs), and 11-folds higher self-renewal with inhibition of DNA methylation (22 vs. 248 CRUs) showing that self-renewing potential of “stimulated” HSC is regulated by epigenetic modification. Next, to see if stem cell fate can be also influenced by epigenetic reprogramming, the effects of epigenetic blockers during “stationary” phase of hematopoiesis were examined by treating donor mice with epigenetic blockers for 3 weeks before sacrifice. Limiting dilution transplantation of these marrows revealed that the CRU frequencies in the treated (5-Azacytidine + TSA) donor marrows were 7-folds higher compared to the un-treated donor marrow cells (1/22,9000 vs. 1/3000) in the absence of increase in total marrow cell numbers, suggesting de-novo generation of CRUs with epigenetic manipulations. Taken together, these results show that the epigenetic modification should be an important regulatory mechanism for self-renewal and fate decisions for normal HSCs in-vivo.

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Differential impact of rhamnolipids and polysorbate80 on composition and functionality of the gut microbiota in the SHIME system.

10.1101/2021.12.15.472660 ◽

2021 ◽

Author(s):

Lisa Miclotte ◽

Ellen De Paepe ◽

Qiqiong Li ◽

Andreja Rajkovic ◽

John Van Camp ◽

...

Keyword(s):

Gut Microbiota ◽

Enrichment Analysis ◽

Human Colon ◽

Pathway Enrichment Analysis ◽

Analysis Tool ◽

Longitudinal Impact ◽

Cell Counts ◽

The Impact

Dietary emulsifiers have been shown to affect the composition and function of the gut microbial community, both in vivo and in vitro. Yet, several knowledge gaps remain to be addressed: the impact from a longer timeframe exposure on the gut microbiota, interindividual variability in microbiome response and the putative impact from novel clean label alternatives for current food emulsifiers. In the present study, the impact of one conventional dietary emulsifier, TWEEN80, and one potential novel alternative, rhamnolipids, on the human gut microbiota was investigated using the Mucosal Simulator of the Human Intestinal Microbial Ecosystem (M-SHIME). The faecal microbiota from two human donors, with high and low responsiveness to the emulsifiers, were exposed to 0,05 m% and 0,5 m% of the emulsifiers for 7 days. The results confirmed previous observations that the effects on the composition and functionality are both emulsifier- and donor dependent. The effects reached an equilibrium after about 3 days of exposure. Overall, TWEEN80 and rhamnolipids displayed opposite effects: TWEEN80 increased cell counts, reduced propionate concentration, increased butyrate levels, increased a.o. Faecalibacterium, Blautia and Hungatella abundance, while rhamnolipids did the opposite. Rhamnolipids also sharply increased the abundance of unclassified Lachnospiraceae. On the other hand, both emulsifiers increased the relative abundance of unclassified Enterobacteriaceae. Both emulsifiers also altered the microbial metabolome in different ways and a pathway enrichment analysis tool revealed that the metabolome alterations could be reminiscent of gut issues and obesity. Overall, the impact from the rhamnolipids was larger than that of TWEEN80 at similar concentrations, indicating that the former may not necessarily be a safer alternative for the latter. The response of the microbiota also depended on its original composition and the sensitivity status for which the faecal donors were selected, was preserved. Whether the same donor-diversity and longitudinal impact can be expected in the human colon as well and what impact this has on the host will have to be further investigated.

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Prolonged self-renewal activity unmasks telomerase control of telomere homeostasis and function of mouse hematopoietic stem cells

Blood ◽

10.1182/blood-2010-11-319632 ◽

2011 ◽

Vol 118 (7) ◽

pp. 1766-1773 ◽

Cited By ~ 11

Author(s):

Sanja Sekulovic ◽

Vala Gylfadottir ◽

Irma Vulto ◽

Maura Gasparetto ◽

Yasmine Even ◽

...

Keyword(s):

Stem Cells ◽

Hematopoietic Stem Cells ◽

Self Renewal ◽

Telomere Shortening ◽

Hematopoietic Stem ◽

Telomere Homeostasis ◽

And Function ◽

The Impact

Abstract Strategies for expanding hematopoietic stem cells (HSCs) could have significant utility for transplantation-based therapies. However, deleterious consequences of such manipulations remain unknown. Here we examined the impact of HSC self-renewal divisions in vitro and in vivo on their subsequent regenerative and continuing ability to sustain blood cell production in the absence of telomerase. HSC expansion in vitro was obtained using a NUP98-HOXA10hd transduction strategy and, in vivo, using a serial transplant protocol. We observed ∼ 10kb telomere loss in leukocytes produced in secondary mice transplanted with HSCs regenerated in primary recipients of NUP98-HOXA10hd-transduced and in vitro-expanded Tert−/− HSCs 6 months before. The second generation leukocytes also showed elevated expression of γH2AX (relative to control) indicative of greater accumulating DNA damage. In contrast, significant telomere shortening was not detected in leukocytes produced from freshly isolated, serially transplanted wild-type (WT) or Tert−/− HSCs, suggesting that HSC replication posttransplant is not limited by telomere shortening in the mouse. These findings document a role of telomerase in telomere homeostasis, and in preserving HSC functional integrity on prolonged self-renewal stimulation.

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EXTH-51. ANTI-INVASIVE EFFICACY AND SURVIVAL BENEFIT OF THE YAP-TEAD INHIBITOR VERTEPORFIN IN PRECLINICAL GLIOBLASTOMA MODELS

Neuro-Oncology ◽

10.1093/neuonc/noaa215.405 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii98-ii98

Author(s):

Anne Marie Barrette ◽

Alexandros Bouras ◽

German Nudelman ◽

Zarmeen Mussa ◽

Elena Zaslavsky ◽

...

Keyword(s):

Survival Benefit ◽

De Novo ◽

Epithelial Mesenchymal Transition ◽

Intraperitoneal Administration ◽

Standard Of Care ◽

Tumor Burden ◽

Mesenchymal Transition ◽

Protein Levels

Abstract Glioblastoma (GBM) remains an incurable disease, in large part due to its malignant infiltrative spread, and current clinical therapy fails to target the invasive nature of tumor cells in disease progression and recurrence. Here, we use the YAP-TEAD inhibitor Verteporfin to target a convergence point for regulating tumor invasion/metastasis and establish the robust anti-invasive therapeutic efficacy of this FDA-approved drug and its survival benefit across several preclinical glioma models. Using patient-derived GBM cells and orthotopic xenograft models (PDX), we show that Verteporfin treatment disrupts YAP/TAZ-TEAD activity and processes related to cell adhesion, migration and epithelial-mesenchymal transition. In-vitro, Verteporfin impairs tumor migration, invasion and motility dynamics. In-vivo, intraperitoneal administration of Verteporfin in mice with orthotopic PDX tumors shows consistent drug accumulation within the brain and decreased infiltrative tumor burden, across three independent experiments. Interestingly, PDX tumors with impaired invasion after Verteporfin treatment downregulate CDH2 and ITGB1 adhesion protein levels within the tumor microenvironment. Finally, Verteporfin treatment confers survival benefit in two independent PDX models: as monotherapy in de-novo GBM and in combination with standard-of-care chemoradiation in recurrent GBM. These findings indicate potential therapeutic value of this FDA-approved drug if repurposed for GBM patients.

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Effects of exogenous interleukin-7 on human thymus function

Blood ◽

10.1182/blood.v99.8.2851 ◽

2002 ◽

Vol 99 (8) ◽

pp. 2851-2858 ◽

Cited By ~ 97

Author(s):

Yukari Okamoto ◽

Daniel C. Douek ◽

Richard D. McFarland ◽

Richard A. Koup

Keyword(s):

T Cell ◽

T Cell Receptor ◽

De Novo ◽

Quantitative Polymerase Chain Reaction ◽

Cell Receptor ◽

Cellular Division ◽

Hematopoietic Stem ◽

Human Thymus ◽

Interleukin 7

Abstract Immune reconstitution is a critical component of recovery after treatment of human immunodeficiency virus (HIV) infection, cancer chemotherapy, and hematopoietic stem cell transplantation. The ability to enhance T-cell production would benefit such treatment. We examined the effects of exogenous interleukin-7 (IL-7) on apoptosis, proliferation, and the generation of T-cell receptor rearrangement excision circles (TRECs) in human thymus. Quantitative polymerase chain reaction demonstrated that the highest level of TRECs (14 692 copies/10 000 cells) was present in the CD1a+CD3−CD4+CD8+stage in native thymus, suggesting that TREC generation occurred following the cellular division in this subpopulation. In a thymic organ culture system, exogenous IL-7 increased the TREC frequency in fetal as well as infant thymus, indicating increased T-cell receptor (TCR) rearrangement. Although this increase could be due to the effect of IL-7 to increase thymocyte proliferation and decrease apoptosis of immature CD3− cells, the in vivo experiments using NOD/LtSz-scid mice given transplants of human fetal thymus and liver suggested that IL-7 can also directly enhance TREC generation. Our results provide compelling evidence that IL-7 has a direct effect on increasing TCR-αβ rearrangement and indicate the potential use of IL-7 for enhancing de novo naı̈ve T-cell generation in immunocompromised patients.

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Elevated Mcl-1 perturbs lymphopoiesis, promotes transformation of hematopoietic stem/progenitor cells, and enhances drug resistance

Blood ◽

10.1182/blood-2010-04-281071 ◽

2010 ◽

Vol 116 (17) ◽

pp. 3197-3207 ◽

Cited By ~ 80

Author(s):

Kirsteen J. Campbell ◽

Mary L. Bath ◽

Marian L. Turner ◽

Cassandra J. Vandenberg ◽

Philippe Bouillet ◽

...

Keyword(s):

Progenitor Cells ◽

Progenitor Cell ◽

Fetal Liver ◽

Cytotoxic Agents ◽

Hematopoietic Stem ◽

Stem And Progenitor Cells ◽

Fetal Liver Cells ◽

Follicular Lymphomas ◽

The Impact

Abstract Diverse human cancers with poor prognosis, including many lymphoid and myeloid malignancies, exhibit high levels of Mcl-1. To explore the impact of Mcl-1 overexpression on the hematopoietic compartment, we have generated vavP-Mcl-1 transgenic mice. Their lymphoid and myeloid cells displayed increased resistance to a variety of cytotoxic agents. Myelopoiesis was relatively normal, but lymphopoiesis was clearly perturbed, with excess mature B and T cells accumulating. Rather than the follicular lymphomas typical of vavP-BCL-2 mice, aging vavP-Mcl-1 mice were primarily susceptible to lymphomas having the phenotype of a stem/progenitor cell (11 of 30 tumors) or pre-B cell (12 of 30 tumors). Mcl-1 overexpression dramatically accelerated Myc-driven lymphomagenesis. Most vavP-Mcl-1/ Eμ-Myc mice died around birth, and transplantation of blood from bitransgenic E18 embryos into unirradiated mice resulted in stem/progenitor cell tumors. Furthermore, lethally irradiated mice transplanted with E13 fetal liver cells from Mcl-1/Myc bitransgenic mice uniformly died of stem/progenitor cell tumors. When treated in vivo with cyclophosphamide, tumors coexpressing Mcl-1 and Myc transgenes were significantly more resistant than conventional Eμ-Myc lymphomas. Collectively, these results demonstrate that Mcl-1 overexpression renders hematopoietic cells refractory to many cytotoxic insults, perturbs lymphopoiesis and promotes malignant transformation of hematopoietic stem and progenitor cells.

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The Act of Controlling Adult Stem Cell Dynamics: Insights from Animal Models

Biomolecules ◽

10.3390/biom11050667 ◽

2021 ◽

Vol 11 (5) ◽

pp. 667

Author(s):

Meera Krishnan ◽

Sahil Kumar ◽

Luis Johnson Kangale ◽

Eric Ghigo ◽

Prasad Abnave

Keyword(s):

Stem Cells ◽

Animal Models ◽

Adult Stem Cells ◽

The Body ◽

In Vivo Studies ◽

Self Renewal ◽

Hematopoietic Stem ◽

Organ Systems

Adult stem cells (ASCs) are the undifferentiated cells that possess self-renewal and differentiation abilities. They are present in all major organ systems of the body and are uniquely reserved there during development for tissue maintenance during homeostasis, injury, and infection. They do so by promptly modulating the dynamics of proliferation, differentiation, survival, and migration. Any imbalance in these processes may result in regeneration failure or developing cancer. Hence, the dynamics of these various behaviors of ASCs need to always be precisely controlled. Several genetic and epigenetic factors have been demonstrated to be involved in tightly regulating the proliferation, differentiation, and self-renewal of ASCs. Understanding these mechanisms is of great importance, given the role of stem cells in regenerative medicine. Investigations on various animal models have played a significant part in enriching our knowledge and giving In Vivo in-sight into such ASCs regulatory mechanisms. In this review, we have discussed the recent In Vivo studies demonstrating the role of various genetic factors in regulating dynamics of different ASCs viz. intestinal stem cells (ISCs), neural stem cells (NSCs), hematopoietic stem cells (HSCs), and epidermal stem cells (Ep-SCs).

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