Study on the mechanism of TSC22D3 regulating the stability of P53 to promote the quiescence of hematopoietic stem cells
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ABSTRACT: In adults, human hematopoietic stem cells (HSCs) are mostly in a quiescent state (G0 stage) and show multilineage reconstruction. When the cell cycle is activated, HSCs gradually lose the hematopoietic reconstruction ability. It indicates that the maintenance of the quiescent state of HSPCs has very important physiological significance. However, the maintenance and regulation mechanism of the quiescent state of HSCs has not yet been clarified. We found that TSC22D3 was highly enriched in quiescent state HSCs but downregulated in culture with the activation of the cell cycle. We further confirmed that stabilizing TSC22D3 expression in HSCs could promote the maintenance of the quiescent state and provide balanced multilineage reconstitution in primary mouse recipients.We found that overexpression of TSC22D3 can promote the maintenance of the resting state of HSCs and the ability of hematopoietic reconstitution by inhibiting the expression of cell cycle-related kinases. Also we confirmed that TSC22D3 can promote the accumulation of p53 protein in cells and up-regulate the expression of p21, p27 and other proteins by qPCR and western blot. Therefore, we speculate that TSC22D3 can promote the resting state of HSCs by regulating the stability of p53. It remains elusive that how TSC22D3 plays a role in the regulation of the maintenance of HSCs in vitro, therefore, further investigations are required to depict its underlying mechanism. On this basis, We firstly plan to analyze the potential downstream targets of TSC22D3 in the maintenance of HSCs in vitro through RNA-seq based transcriptome comparison; then, we will verify the predicted targets of TSC22D3 through Co-IP, gene overexpression, gene knockdown, and signaling pathway activation/inhibition. Our project could contribute to an in-depth understanding of the quiescent maintenance mechanisms of HSPCs in vitro and provide ideas for the treatment of leukemia and other malignant hematological diseases.
Project description:Mitochondrial metabolism determines bone marrow hematopoietic stem cell (HSC) heterogeneity, and influences long-term blood repopulation potential.Self-renewal and multilineage engraftment capacity of hematopoietic stem cells (HSCs) are key properties leveraged for their clinical use in bone marrow transplantation. Variations in long-term blood reconstitution ability are partly attributed to the functional heterogeneity in HSCs, which is influenced by the dynamic mitochondrial metabolic state, in addition to differences in gene expression. However, when and how this mitochondrial regulation of definitive HSCs originates is unexplored. Whether metabolic variation is an outcome of the diverse HSC milieu, or an inherent property of the emergent HSCs, is not known. Here, Wwe show that dynamic changes in mitochondrial activity during endothelial to hematopoietic transition (EHT) drives the production of mature HSCs in the mouse embryo. Pharmacological and genetic manipulations show that hematopoietic emergence during the endothelial to hematopoietic transition (EHT) in the aorta-gonad-mesonephros (AGM) region involves mitochondrial remodelling. reduced mitochondrial activity activates Wnt signalling to promote expansion of mature HSCs in the AGM. Further, single cell transcriptomics and functional assays uncovered mitochondrial membrane potential (MMP) driven functional heterogeneity within the mature HSC pool. MMPlow HSCs are myeloid-biased and exhibit enhanced differentiation potential. Contrarily, MMPhigh HSCs are lymphoid-biased with diminished differentiation potential. Mechanistically, low mitochondrial activity upregulates PI3K signalling to fuel embryonic HSC differentiation. We provide insights into the metabolic regulation of HSC origin and function, that can be leveraged to direct HSC fate decisions for clinical interventions.
Project description:Estrogens are potential regulators of the hematopoietic stem cell (HSC) niche and have effects on mature hematopoietic cells; however, whether estrogen signaling directly regulates normal and malignant HSC remains unclear. We demonstrate differential expression and specific roles of estrogen receptors (ER) in hematopoietic progenitors. ERa activation in short-term HSC and multipotent progenitors induced apoptosis. In contrast, the selective ER modulator (SERM) tamoxifen induced proliferation of quiescent long-term HSC, altered their self-renewal signature and compromised hematopoietic reconstitution following myelotoxic stress. Treatment with tamoxifen alone abolished hematopoietic progenitor expansion induced by JAK2V617F by restoring normal levels of apoptosis, blocked JAK2V617F-induced myeloproliferative neoplasm in vivo, and sensitized MLL-AF9+ leukemias to chemotherapy. Tamoxifen showed selective effects on mutant cells compared to normal ones, and had only a minor impact on steady-state hematopoiesis in disease-free animals. These results uncover specific regulation of hematopoietic progenitors by estrogens and potential anti-leukemic properties of SERM LT-HSCs, ST-HSCs and MPPs sorted from the bone marrow of mice treated with tamoxifen or vehicle (3 biological replicates per group)
Project description:Hematopoietic stem cells (HSCs) are maintained in the quiescent state for protection from exhaustion by a number of self-renewal divisions. To understand the in vivo kinetics of quiescent HSCs, we analyzed the cell cycle of CD201+150+48-Lin-Kit+Sca-1+ cells after transplantation and during development and aging using fluorescent ubiquitination-based cell cycle indicator (Fucci) mice to distinguish HSCs at the G0, G1, and S/G2/M phases. The quiescent HSC population, representing a functional HSC pool, rapidly expanded by three weeks after transplantation and by three weeks of age in development and gradually accumulated in bone marrow with aging. Single-cell RNA-sequencing with flow cytometric index sorting suggested that high CD201 and Sca-1 expression levels and a low level of mitochondrial activity were associated with quiescent HSCs. A novel set of candidate quiescent genes in HSCs was also provided. This study implied that controlling quiescent HSCs is important for the in vivo expansion and maintenance of functional HSCs.
Project description:A hallmark of adult hematopoiesis is the continuous replacement of blood cells with limited lifespans. While active hematopoietic stem cell (HSC) contribution to multilineage hematopoiesis is the foundation of clinical HSC transplantation, recent reports have questioned the physiological contribution of HSCs to normal/steady-state adult hematopoiesis. Here, we use inducible lineage tracing from genetically marked adult HSCs and reveal robust HSC-derived multilineage hematopoiesis. This commences via defined progenitor cells, but varies substantially in between different hematopoietic lineages. By contrast, adult HSC contribution to hematopoietic cells with proposed fetal origins is neglible. Finally, we establish that the HSC contribution to multilineage hematopoiesis declines with increasing age. Therefore, while HSCs are active contributors to native adult hematopoiesis, it appears that the numerical increase of HSCs is a physiologically relevant compensatory mechanism to account for their reduced differentiation capacity with age
Project description:Transforming growth factor-β (TGF-β) is considered to play a role in the maintenance of quiescent hematopoietic stem cells (HSCs) in vivo. We asked a question of whether TGF-β could be used to control the cell cycle status of HSCs in vitro. To examine the effect of TGF-β on the HSC function, we used in vitro culture system in which HSCs divide with retention of short- and long-term reconstitution ability. Single-cell analyses showed that regardless of its concentrations, TGF-β slowed down cell cycle progression of HSCs, but consequently suppressed the self-renewal potential, particularly in cycling HSCs. This study highlighted a role of TGF-β in the negative regulation of HSC number and function.
Project description:Hematopoietic stem cells (HSCs) are a specialized group of cells with the ability to self-renew and differentiate into distinct lineages of the entire hematopoietic system throughout lifetime. The maintenance of a quiescent state is essential for sustaining the normal function of HSCs. Many regulatory factors involved in HSC quiescence maintenance have been found. However the role steroid receptor coactivator 3 (SRC-3) in the regulation of HSC maintenance remains unexplored. We used microarrays to detail the global programme of gene expression in lineage- Sca1+ c-Kit+ cells (LSKs) from wild-type (WT) and SRC-3 knockout (KO) mice and identified distinct classes of altered genes after SRC-3 knockout.
Project description:Blood flow promotes emergence of definitive hematopoietic stem cells (HSCs) in the developing embryo, yet the signals generated by hemodynamic forces that influence hematopoietic potential remain poorly defined. In transplantation assays of hematopoietic reconstitution, we find that fluid shear stress endows long-term multilineage engraftment potential upon early hematopoietic tissues at E9.5 not previously described to harbor HSCs. Effects on hematopoiesis appear to be mediated in part by prostaglandin E2 (PGE2) and the cyclic AMP-protein kinase A (cAMP-PKA) signaling axis. Studies of Ncx1 cardiac mutants corroborate that blood flow is required for sufficient COX2 levels and phosphorylation of CREB. Further implicating PGE2 in mediating the effects of shear stress, we find that E10.5 and E11.5 AGM treated transiently with the synthetic analog dmPGE2 engraft more robustly and contribute to greater lymphoid reconstitution. These data provide a mechanism by which biomechanical forces induced by blood flow modulate hematopoietic potential. -
Project description:Hematopoietic stem cells (HSCs) balance self-renewal and differentiation to maintain hematopoietic fitness throughout life. In steady-state conditions, HSC exhaustion is prevented by the maintenance of most HSCs in a quiescent state, with cells entering the cell cycle only occasionally. HSC quiescence is regulated by retinoid and fatty-acid ligands of transcriptional factors of the nuclear retinoid X receptor (RXR) family. Here, we show that dual deficiency for hematopoietic RXRa and RXRb induces HSC exhaustion, myeloid cell/megakaryocyte differentiation, and myeloproliferative-like disease. RXRa and RXRb maintain HSC quiescence, survival, and chromatin compaction; moreover, transcriptome changes in RXRa;RXRb-deficient HSCs include premature acquisition of an aging-like HSC signature, MYC pathway upregulation, and RNA intron retention. Fitness loss and associated RNA transcriptome and splicing alterations in RXRa;RXRb-deficient HSCs are prevented by Myc haploinsufficiency. Our study reveals the critical importance of RXRs for the maintenance of HSC fitness and their protection from premature aging.
Project description:Hematopoietic stem cells (HSCs) balance self-renewal and differentiation to maintain hematopoietic fitness throughout life. In steady-state conditions, HSC exhaustion is prevented by the maintenance of most HSCs in a quiescent state, with cells entering the cell cycle only occasionally. HSC quiescence is regulated by retinoid and fatty-acid ligands of transcriptional factors of the nuclear retinoid X receptor (RXR) family. Here, we show that dual deficiency for hematopoietic RXRa and RXRb induces HSC exhaustion, myeloid cell/megakaryocyte differentiation, and myeloproliferative-like disease. RXRa and RXRb maintain HSC quiescence, survival, and chromatin compaction; moreover, transcriptome changes in RXRa;RXRb-deficient HSCs include premature acquisition of an aging-like HSC signature, MYC pathway upregulation, and RNA intron retention. Fitness loss and associated RNA transcriptome and splicing alterations in RXRa;RXRb-deficient HSCs are prevented by Myc haploinsufficiency. Our study reveals the critical importance of RXRs for the maintenance of HSC fitness and their protection from premature aging.
Project description:The hematopoietic stem cell (HSC) compartment is heterogeneous, yet our understanding of the identities of different HSC subtypes is limited. Here we show that platelet integrin CD41 (M-NM-1IIb), currently thought to only transiently mark fetal HSCs, is expressed on an adult HSC subtype that accumulates with age. CD41+ HSCs were largely quiescent and exhibited myeloerythroid and megakaryocyte gene priming, governed by Gata1, whereas CD41- HSCs were more proliferative and exhibited lymphoid gene priming. When isolated without the use of blocking antibodies, CD41+ HSCs possessed long-term repopulation capacity upon serial transplantations and showed a marked myeloid-bias compared to CD41-HSCs, which yielded a more lymphoid-biased progeny. CD41-knockout mice displayed multilineage hematopoietic defects coupled with decreased quiescence and survival of HSCs, suggesting that CD41 is functionally relevant for HSC maintenance and hematopoietic homeostasis. Transplantation experiments indicated that CD41-KO associated defects are long-term transplantable and HSC-derived, and in part mediated through the loss of platelet mass leading to decreases in HSC exposure to important platelet released cytokines, such as TGFM-NM-21. In summary, our data provide a novel marker to identify a myeloid-biased HSC subtype that becomes prevalent with age, and highlights the dogma of HSC regulation by their progeny. For microarray analysis, 1000 HSCs were FACS sorted from pools of 4-5 mice directly into lysis buffer, RNA extracted and whole transcript amplification was performed as previously described (Gonzalez-Roca E, Garcia-Albeniz X, Rodriguez-Mulero S, Gomis RR, Kornacker K, Auer H. Accurate expression profiling of very small cell populations. PLoS One. 2010;5:e14418.)