scholarly journals SETD5 modulates homeostasis of hematopoietic stem cells by mediating RNA Polymerase II pausing in cooperation with HCF-1

Leukemia ◽  
2021 ◽  
Author(s):  
Mengke Li ◽  
Chen Qiu ◽  
Yujie Bian ◽  
Deyang Shi ◽  
Bichen Wang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Rna Polymerase ◽  
Hematopoietic Stem Cells ◽  
Rna Polymerase Ii ◽  
Critical Role ◽  
Whole Body ◽  
Hematopoietic Stem ◽  
Pol Ii

AbstractSETD5 mutations were identified as the genetic causes of neurodevelopmental disorders. While the whole-body knockout of Setd5 in mice leads to embryonic lethality, the role of SETD5 in adult stem cell remains unexplored. Here, a critical role of Setd5 in hematopoietic stem cells (HSCs) is identified. Specific deletion of Setd5 in hematopoietic system significantly increased the number of immunophenotypic HSCs by promoting HSC proliferation. Setd5-deficient HSCs exhibited impaired long-term self-renewal capacity and multiple-lineage differentiation potentials under transplantation pressure. Transcriptome analysis of Setd5-deficient HSCs revealed a disruption of quiescence state of long-term HSCs, a cause of the exhaustion of functional HSCs. Mechanistically, SETD5 was shown to regulate HSC quiescence by mediating the release of promoter-proximal paused RNA polymerase II (Pol II) on E2F targets in cooperation with HCF-1 and PAF1 complex. Taken together, these findings reveal an essential role of SETD5 in regulating Pol II pausing-mediated maintenance of adult stem cells.

Critical Role Of Jak2 In The Maintenance and Function Of Adult Hematopoietic Stem Cells

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1180-1180
Author(s):  
Hajime Akada ◽  
Saeko Akada ◽  
Golam Mohi
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Critical Role ◽  
Receptor Protein ◽  
Specific Gene ◽  
Hematopoietic Stem ◽  
And Function

Abstract Hematopoietic stem cells (HSCs) play an essential role in the long-term maintenance of hematopoiesis. Various intracellular signaling proteins, transcription factors and extracellular matrix proteins contribute to the maintenance and function of HSCs. Jak2, a member of the Janus family of non-receptor protein tyrosine kinases, is activated in response to a variety of cytokines. It has been shown that germ-line deletion of Jak2 results in embryonic lethality whereas post-natal or adult stage deletion of Jak2 results in anemia and thrombocytopenia in mice. However, the role of Jak2 in the maintenance and function of adult HSCs has remained elusive. Understanding the normal function of Jak2 in adult HSC/progenitors is of considerable significance since mutations in Jak2 have been associated with several myeloproliferative neoplasms (MPNs), and most patients treated with Jak2 inhibitors exhibit significant hematopoietic toxicities. To assess the role of Jak2 in adult HSCs, we have utilized a conditional Jak2 knock-out (Jak2 floxed) allele and an inducible MxCre line that can efficiently express Cre recombinase in adult HSC/progenitors after injections with polyinosine-polycytosine (pI-pC). We have found that deletion of Jak2 in adult mice results in pancytopenia, bone marrow aplasia and 100% lethality within 25 to 42 days after pI-pC induction. Analysis of the HSC/progenitor compartments revealed that Jak2-deficiency causes marked decrease in long-term HSCs, short-term HSCs, multipotent progenitors and early progenitors of all hematopoietic lineages, indicating a defect at the earliest stage of adult hematopoietic development. We have found that deletion of Jak2 leads to increased HSC cell cycle entry, suggesting that Jak2-deficiency results in loss of quiescence in HSCs. Jak2-deficiency also resulted in significant apoptosis in HSCs. Furthermore Jak2-deficient bone marrow cells were severely defective in reconstituting hematopoiesis in lethally-irradiated recipient animals. Competitive repopulations experiments also show that Jak2 is essential for HSC functional activity. We also have confirmed that the requirement for Jak2 in HSCs is cell-autonomous. To gain insight into the mechanism by which Jak2 controls HSC maintenance and function, we have performed phospho flow analysis on HSC-enriched LSK (lin-Sca-1+c-kit+) cells. TPO and SCF-evoked Akt and Erk activation was significantly reduced in Jak2-deficient LSK compared with control LSK. Stat5 phosphorylation in response to TPO was also completely inhibited in Jak2-deficient LSK cells. In addition, we observed significantly increased intracellular reactive oxygen species (ROS) levels and enhanced activation of p38 MAPK in Jak2-deficient LSK cells, consistent with the loss of quiescence observed in Jak2-deficient HSCs. Treatment with ROS scavenger N-acetyl cysteine partially rescued the defects in Jak2-deficient HSCs in reconstituting hematopoiesis in lethally irradiated recipient animals. Gene expression analysis revealed significant downregulation of HSC-specific gene sets in Jak2-deficient LSK cells. Taken together, our data strongly suggest that Jak2 plays a critical role in the maintenance of quiescence, survival and self-renewal of adult HSCs. Disclosures: No relevant conflicts of interest to declare.

Role of Cohesin-Resolving Protease, Separase, In Hematopoiesis.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1593-1593
Author(s):  
Lanelle V. Nakamura ◽  
Malini Mukherjee ◽  
Margaret A. Goodell ◽  
Debananda Pati
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Protein Complex ◽  
Conflicts Of Interest ◽  
Critical Role ◽  
Hematopoietic Stem ◽  
Sister Chromatids

Abstract Abstract 1593 Introduction: Cohesin is an evolutionarily conserved protein complex that forms during the replication of sister chromatids. It is a multi-protein complex that consists of four proteins, Smc1, Smc3, Rad21, and Scc3. Resolution of sister chromatid cohesion at the onset of anaphase depends on Separase, an endopeptidase that separates sister chromatids by cleaving cohesion Rad21. A recent study suggests a new role of Cohesin proteins in gene expression and development with implications in hematopoiesis. Our data indicates that cohesin-resolving protease Separase may play a critical role in hematopoiesis. HYPOTHESIS: We hypothesize that Separase plays a role in hematopoiesis by increasing the quantity of hematopoietic stem cells (HSC). METHODS: Our experimental approach was to isolate murine long-term HSC from WT mice and mice with one mutated copy of Separase (i.e. Separase heterozygotes). In addition, in vivo competitive long term repopulation assays were used assess the function of HSC in Separase heterozyotes. RESULTS: Separase heterozygote have increased HSC numbers (p<0.05) as compared to WT mice. In addition, an improved engraftment in a competitive repopulation assay (p < 0.001) was seen in the Separase heterozyotes. Analysis of the engrafted cells demonstrated no difference between the wild type and Separase heterozygote animals, indicating the increased engraftment may be due to unique features in the primitive hematopoietic stem cells. CONCLUSION: Investigation of the mechanism for improved HSC engraftment in Separase heterozygote mice will significantly contribute to our understanding of marrow engraftment and function. Elucidating the mechanisms of hematopoietic dysregulation will provide insights into the development of life-threatening disorders such as leukemia and, in the setting of bone marrow transplant, engraftment failure. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Rapid and sustained hematopoietic recovery in lethally irradiated mice transplanted with purified Thy-1.1lo Lin-Sca-1+ hematopoietic stem cells

Blood ◽  
1994 ◽  
Vol 83 (12) ◽  
pp. 3758-3779 ◽  
Author(s):  
N Uchida ◽  
HL Aguila ◽  
WH Fleming ◽  
L Jerabek ◽  
IL Weissman
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Blood Cells ◽  
Critical Role ◽  
White Blood Cells ◽  
Cell Types ◽  
Dose Dependence ◽  
Hematopoietic Stem ◽  
Hematopoietic Recovery

Abstract Hematopoietic stem cells (HSCs) are believed to play a critical role in the sustained repopulation of all blood cells after bone marrow transplantation (BMT). However, understanding the role of HSCs versus other hematopoietic cells in the quantitative reconstitution of various blood cell types has awaited methods to isolate HSCs. A candidate population of mouse HSCs, Thy-1.1lo Lin-Sca-1+ cells, was isolated several years ago and, recently, this population has been shown to be the only population of BM cells that contains HSCs in C57BL/Ka-Thy-1.1 mice. As few as 100 of these cells can radioprotect 95% to 100% of irradiated mice, resulting long-term multilineage reconstitution. In this study, we examined the reconstitution potential of irradiated mice transplanted with purified Thy-1.1lo Lin-Sca-1+ BM cells. Donor-derived peripheral blood (PB) white blood cells were detected as early as day 9 or 10 when 100 to 1,000 Thy-1.1lo Lin-Sca-1+ cells were used, with minor dose-dependent differences. The reappearance of platelets by day 14 and thereafter was also seen at all HSC doses (100 to 1,000 cells), with a slight dose-dependence. All studied HSC doses also allowed RBC levels to recover, although at the 100 cell dose a delay in hematocrit recovery was observed at day 14. When irradiated mice were transplanted with 500 Thy-1.1lo Lin-Sca-1+ cells compared with 1 x 10(6) BM cells (the equivalent amount of cells that contain 500 Thy-1.1lo Lin-Sca-1+ cells as well as progenitor and mature cells), very little difference in the kinetics of recovery of PB, white blood cells, platelets, and hematocrit was observed. Surprisingly, even when 200 Thy1.1lo Lin-Sca- 1+ cells were mixed with 4 x 10(5) Sca-1- BM cells in a competitive repopulation assay, most of the early (days 11 and 14) PB myeloid cells were derived from the HSC genotype, indicating the superiority of the Thy-1.1lo Lin-Sca-1+ cells over Sca-1- cells even in the early phases of myeloid reconstitution. Within the Thy-1.1lo Lin-Sca-1+ population, the Rhodamine 123 (Rh123)hi subset dominates in PB myeloid reconstitution at 10 to 14 days, only to be overtaken by the Rh123lo subset at 3 weeks and thereafter. These findings indicate that HSCs can account for the early phase of hematopoietic recovery, as well as sustained hematopoiesis, and raise questions about the role of non-HSC BM populations in the setting of BMT.

scholarly journals Critical Role of Thrombopoietin in Maintaining Adult Quiescent Hematopoietic Stem Cells

2007 ◽  
Vol 1 (6) ◽  
pp. 671-684 ◽  
Author(s):  
Hong Qian ◽  
Natalija Buza-Vidas ◽  
Craig D. Hyland ◽  
Christina T. Jensen ◽  
Jennifer Antonchuk ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Critical Role ◽  
Hematopoietic Stem

scholarly journals The critical role of agrin in the hematopoietic stem cell niche

Blood ◽  
2011 ◽  
Vol 118 (10) ◽  
pp. 2733-2742 ◽  
Author(s):  
Cristina Mazzon ◽  
Achille Anselmo ◽  
Javier Cibella ◽  
Cristiana Soldani ◽  
Annarita Destro ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Critical Role ◽  
Hematopoietic Stem ◽  
Hematopoietic Stem Cell Niche ◽  
Cell Niche ◽  
Deficient Mice

Abstract Hematopoiesis is the process leading to the sustained production of blood cells by hematopoietic stem cells (HSCs). Growth, survival, and differentiation of HSCs occur in specialized microenvironments called “hematopoietic niches,” through molecular cues that are only partially understood. Here we show that agrin, a proteoglycan involved in the neuromuscular junction, is a critical niche-derived signal that controls survival and proliferation of HSCs. Agrin is expressed by multipotent nonhematopoietic mesenchymal stem cells (MSCs) and by differentiated osteoblasts lining the endosteal bone surface, whereas Lin−Sca1+c-Kit+ (LSK) cells express the α-dystroglycan receptor for agrin. In vitro, agrin-deficient MSCs were less efficient in supporting proliferation of mouse Lin−c-Kit+ cells, suggesting that agrin plays a role in the hematopoietic cell development. These results were indeed confirmed in vivo through the analysis of agrin knockout mice (Musk-L;Agrn−/−). Agrin-deficient mice displayed in vivo apoptosis of CD34+CD135− LSK cells and impaired hematopoiesis, both of which were reverted by an agrin-sufficient stroma. These data unveil a crucial role of agrin in the hematopoietic niches and in the cross-talk between stromal and hematopoietic stem cells.

scholarly journals Hematopoietic stem cells fail to regenerate following inflammatory challenge

2020 ◽  
Author(s):  
Ruzhica Bogeska ◽  
Paul Kaschutnig ◽  
Malak Fawaz ◽  
Ana-Matea Mikecin ◽  
Marleen Büchler-Schäff ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Recovery Period ◽  
Cumulative Impact ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Inflammatory Stress ◽  
Kinetics Of

AbstractHematopoietic stem cells (HSCs) are canonically defined by their capacity to maintain the HSC pool via self-renewal divisions. However, accumulating evidence suggests that HSC function is instead preserved by sustaining long-term quiescence. Here, we study the kinetics of HSC recovery in mice, following an inflammatory challenge that induces HSCs to exit dormancy. Repeated inflammatory challenge resulted in a progressive depletion of functional HSCs, with no sign of later recovery. Underlying this observation, label retention experiments demonstrated that self-renewal divisions were absent or extremely rare during challenge, as well as during any subsequent recovery period. While depletion of functional HSCs held no immediate consequences, young mice exposed to inflammatory challenge developed blood and bone marrow hypocellularity in old age, similar to elderly humans. The progressive, irreversible attrition of HSC function demonstrates that discreet instances of inflammatory stress can have an irreversible and therefore cumulative impact on HSC function, even when separated by several months. These findings have important implications for our understanding of the role of inflammation as a mediator of dysfunctional tissue maintenance and regeneration during ageing.

Human FLT3/FLK2 Targets Hematopoietic Stem Cells and Granulocyte/Macrophage Progenitors.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1263-1263
Author(s):  
Yoshikane Kikushige ◽  
Goichi Yoshimoto ◽  
Toshihiro Miyamoto ◽  
Fumihiko Ishikawa ◽  
Hiromi Iwasaki ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Expression Pattern ◽  
Critical Role ◽  
Active Form ◽  
Myelogenous Leukemia ◽  
Hematopoietic Stem ◽  
Flt3 Expression ◽  
Myeloid Progenitors

Abstract FLT3/FLK2, a member of the receptor tyrosine kinase family, plays a critical role in maintenance of hematopoietic homeostasis, and the constitutively active form of the FLT3 mutation is one of the most common genetic abnormalities in acute myelogenous leukemia. In murine hematopoiesis, Flt3 is not expressed in self-renewing long-term hematopoietic stem cells (LT-HSCs), but its expression is restricted to the multipotent and the lymphoid progenitor stages at which cells are incapable of self-renewal. In order to test whether Flt3 expression can delineate such a developmental pathway also in human hematopoiesis, we have analyzed the expression of human Flt3 (hFlt3) in prospectively-purified human stem and progenitors (PNAS 2002) by utilizing 7-color FACS and a highly efficient xenograft systems. We have found that Flt3 expression in early hematopoiesis is completely different between human and mice: hCD34+hCD38-hCD90+Lin-LT-HSCs capable of long-term reconstitution in xenogeneic hosts uniformly express hFlt3, and its expression is upregulated through hCD34+hCD38+hCD45RA-hCD123+Lin-common myeloid progenitors (CMPs) to hCD34+hCD38+hCD45RA+hCD123+Lin-granulocyte/macrophage progenitors (GMPs), but hCD34+hCD38+hCD45RA-hCD123-Lin- megakaryocyte/erythrocyte progenitors (MEPs) shut off its expression in human. Furthermore, we have also demonstrated that hFlt3 signaling can prevent stem and progenitors from apoptotic cell death in vitro without any effects on lineage fate decision. Next, we tried to find key molecules for Flt3-Flt3 ligand (FL)-mediating anti-apoptotic effect. First, we tested expression pattern of anti-apoptotic Bcl-2 family genes in HSCs, CMPs, GMPs, MEPs and common lymphoid progenitors (CLPs) in human hematopoiesis. Mcl-1, an indispensable survival factor for murine hematopoiesis (Science, 2005), was also expressed at the highest level in human HSCs, whereas Bcl-2 and Bcl-xL was highly expressed in GMPs and MEPs, respectively. Next, we examined whether FL stimulation can upregulate the expression of Bcl-2 family genes in human purified HSCs and progenitors. FL significantly upregulated the expression of Mcl-1, but not of Bcl-2 or Bcl-xL in HSCs as well as CMPs and GMPs. In conclusion, our data show that the distribution of Flt3 is quite different in mouse and human hematopoeisis. Human Flt3 targets LT-HSCs and myeloid progenitors except for MEPs. Flt3 signaling might support cell survival in early hematopoiesis including the HSC and the myeloid progenitor stages through upregulation of Mcl-1. This is a striking example that the expression pattern of key molecules could be significantly different between human and mouse.

scholarly journals Critical Role of Jak2 in the Maintenance and Function of Adult Hematopoietic Stem Cells

Stem Cells ◽  
2014 ◽  
Vol 32 (7) ◽  
pp. 1878-1889 ◽  
Author(s):  
Hajime Akada ◽  
Saeko Akada ◽  
Robert E. Hutchison ◽  
Kazuhito Sakamoto ◽  
Kay-Uwe Wagner ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Critical Role ◽  
Hematopoietic Stem ◽  
And Function

Matching at the MHC class I K locus is essential for long-term engraftment of purified hematopoietic stem cells: a role for host NK cells in regulating HSC engraftment

Blood ◽  
2004 ◽  
Vol 104 (3) ◽  
pp. 873-880 ◽  
Author(s):  
Yiming Huang ◽  
Francine Rezzoug ◽  
Paula M. Chilton ◽  
H. Leighton Grimes ◽  
Daniel E. Cramer ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Nk Cells ◽  
Mhc Class I ◽  
Nk Cell ◽  
Critical Role ◽  
Allogeneic Transplantation ◽  
Class I ◽  
Hematopoietic Stem

AbstractThe events that regulate engraftment and long-term repopulating ability of hematopoietic stem cells (HSCs) after transplantation are not well defined. We report for the first time that major histocompatibility complex (MHC) class I K plays a critical role in HSC engraftment via interaction with recipient natural killer (NK) cells. Durable engraftment of purified HSCs requires MHC class I K matching between HSC donor and recipient. In the absence of MHC class I K matching, HSCs exhibit impaired long-term engraftment (P = .01). Dependence on MHC class I K matching is eliminated in B6 beige mice that lack NK cell function, as well as in wild-type mice depleted of NK cells, implicating a possible regulatory role of NK cells for HSC engraftment. The coadministration of CD8+/T-cell receptor–negative (TCR-) graft facilitating cells (FCs) matched at MHC class I K to the HSC donor overcomes the requirement for MHC class I K matching between HSCs and recipient. These data demonstrate that FCs inhibit NK cell effects on the HSCs. Notably, FCs do not suppress the cytotoxic activity of activated NK cells. Enhanced green fluorescent protein–positive (EGFP+) FCs persist for one month following allogeneic transplantation, making cold target inhibition an unlikely mechanism. Therefore, MHC class I may play a critical role in the initiating events that dictate HSC engraftment and/or NK-mediated rejection following allogeneic transplantation.

ETO2 Controls Hematopoietic Stem Cell Expansion.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 396-396
Author(s):  
Stephane Barakat ◽  
Julie Lambert ◽  
Guy Sauvageau ◽  
Trang Hoang
Keyword(s):  
Stem Cells ◽  
Transcription Factor ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Short Term ◽  
Self Renewal ◽  
Hematopoietic Stem

Abstract Abstract 396 Hematopoietic stem cells that provide short term reconstitution (ST-HSCs) as well as hematopoietic progenitors expand from a small population of long term hematopoietic stem cells (LT-HSCs) that are mostly dormant cells. The mechanisms underlying this expansion remain to be clarified. SCL (stem cell leukemia), is a bHLH transcription factor that controls HSC quiescence and long term competence. Using a proteomics approach to identify components of the SCL complex in erythroid cells, we and others recently showed that the ETO2 co-repressor limits the activity of the SCL complex via direct interaction with the E2A transcription factor. ETO2/CBF2T3 is highly homologous to ETO/CBFA2T1 and both are translocation partners for AML1. We took several approaches to identify ETO2 function in HSCs. We initially found by Q-PCR that ETO2 is highly expressed in populations of cells enriched in short-term HSC (CD34+Flt3-Kit+Sca+Lin-) and lympho-myeloid progenitors (CD34+Flt3+Kit+Sca+Lin-) and at lower levels in LT-HSCs (CD34-Kit+Sca+Lin- or CD150+CD48-Kit+Sca+Lin-). Next, the role of ETO2 was studied by overexpression or downregulation combined with transplantation in mice. Ectopic ETO2 expression induces a 100 fold expansion of LT-HSCs in vivo in transplanted mice associated with differentiation blockade in all lineages, suggesting that ETO2 overexpression overcomes the mechanisms that limit HSC expansion in vivo. We are currently testing the role of the NHR1 domain of ETO2 in this expansion. Conversely, shRNAs directed against ETO2 knock down ET02 levels in Kit+Sca+Lin- cells, causing a ten-fold decrease in this population after transplantation, associated with reduced short-term reconstitution in mice. Finally, proliferation assays using Hoechst and CFSE indicate that ETO2 downregulation affects cell division (CFSE) and leads to an accumulation of Kit+Sca+Lin-cells in G0/G1 state (Hoescht). In conclusion, we show that ETO2 is highly expressed in ST-HSCs and lymphoid progenitors, and controls their expansion by regulating cell cycle entry at the G1-S checkpoint. In addition, ETO2 overexpression converts the self-renewal of maintenance into self-renewal of expansion in LT-HSCs. Disclosures: No relevant conflicts of interest to declare.

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