Slc20a1b is essential for hematopoietic stem/progenitor cell expansion in zebrafish
Ontology highlight
ABSTRACT: Hematopoietic stem and progenitor cells (HSPCs) are able to self-renew and can give rise to all blood lineages throughout their lifetime, yet the mechanisms regulating HSPC development have yet to be discovered. In this study, we characterized a hematopoiesis defective zebrafish mutant line named smu07, which was obtained from our previous forward genetic screening, and found the HSPC expansion deficiency in the mutant. Positional cloning identified that slc20a1b, which encodes a sodium phosphate cotransporter, contributed to the smu07 blood phenotype. Further analysis demonstrated that mutation of slc20a1b affects HSPC expansion through cell cycle arrest at G2/M phases in a cell-autonomous manner. Our study shows that slc20a1b is a vital regulator for HSPC proliferation in zebrafish early hematopoiesis and provides valuable insights into HSPC development.
Project description:Hematopoietic stem cells (HSCs) possess the potential for self-renew and the capacity, throughout life, to differentiate into all blood cell lineages. Yet, the mechanistic basis for HSC development remains largely unknown. In this study, we characterized a zebrafish smu471 mutant with hematopoietic stem/progenitor cell (HSPC) defects and found that sart3 was the causative gene. RNA expression profiling of the sart3smu471 mutant revealed spliceosome and p53 signaling pathway to be the most significantly enriched pathways in the sart3smu471 mutant. Knock down of p53 rescued HSPC development in the sart3smu471 mutant. Interestingly, the p53 inhibitor, mdm4, had undergone an alternative splicing event in the mutant. Restoration of mdm4 partially rescued HSPC deficiency. Thus, our data suggest that HSPC proliferation and maintenance require sart3 to ensure the correct splicing and expression of mdm4, so that the p53 pathway is properly inhibited to prevent definitive hematopoiesis failure. This study expands our knowledge of the regulatory mechanisms that impact HSPC development and sheds light on the mechanistic basis and potential therapeutic use of sart3 in spliceosome-mdm4-p53 related disorders.
Project description:Osteolineage cell-derived extracellular vesicles (EVs) play a regulatory role in hematopoiesis and have been shown to promote the ex vivo expansion of human hematopoietic stem and progenitor cells (HSPCs). Here, we demonstrate that EVs from different human osteolineage sources do not have the same HSPC expansion promoting potential. Comparison of stimulatory and non-stimulatory osteolineage EVs by next-generation sequencing and mass spectrometry analyses revealed distinct microRNA and protein signatures identifying EV-derived candidate regulators of ex vivo HSPC expansion. Accordingly, the treatment of umbilical cord blood-derived CD34+ HSPCs with stimulatory EVs altered HSPC transcriptome, including genes with known roles in cell proliferation. An integrative bioinformatics approach, which connects the HSPC gene expression data with the candidate cargo in stimulatory EVs, delineated the potentially targeted biological functions and pathways during hematopoietic cell expansion and development. In conclusion, our study gives novel insights into the complex biological role of EVs in osteolineage cell-HSPC crosstalk and promotes the utility of EVs and their cargo as therapeutic agents in regenerative medicine.
Project description:Pre-mRNA splicing is a precise regulated process, and is crucial for system development and homeostasis maintenance. Mutations in spliceosomal components have been found in various hematopoietic malignancies (HMs), and have been considered as oncogenic derivers of HMs. However, the role of spliceosomal components in normal and malignant hematopoiesis remain largely unknown. Pre-mRNA processing factor 31 (PRPF31) is a constitutive spliceosomal component, which mutations are associated with autosomal dominant retinitis pigmentosa. PRPF31 was found to be mutated in several HMs, but the function of PRPF31 in normal hematopoiesis has not been explored. In this study, we generated a prpf31 knockout zebrafish line, and discovered that prpf31 mutants exhibited severe defects in hematopoietic stem and progenitor cell (HSPC) expansion and its sequentially differentiated lineages. Immunofluorescence results showed that Prpf31 deficient HSPCs underwent malformed mitosis and M phase arrest during HSPC expansion. Transcriptome analysis and experimental validations revealed that Prpf31 deficiency extensively perturbed the alternative splicing of mitosis-related genes. Collectively, our findings elucidate a previously undescribed role for Prpf31 in HSPC expansion, through regulating the alternative splicing of mitosis-related genes.
Project description:Hypercholesterolemia, the driving force of atherosclerosis, accelerates the expansion and mobilization of hematopoietic stem and progenitor cells (HSPCs). The molecular determinants connecting hypercholesterolemia with hematopoiesis are underexplored. Here we report that a novel somite-derived pro-hematopoietic cue, AIBP, orchestrates HSPC emergence from the hemogenic endothelium, a type of specialized endothelium manifesting hematopoietic potential. Mechanistically, AIBP-mediated cholesterol efflux activates endothelial Srebp2, the master transcription factor for cholesterol biosynthesis, which transactivates Notch and promotes HSPC emergence. Srebp2 inhibition impairs hypercholesterolemia-induced HSPC expansion. Srebp2 activation and Notch upregulation are associated with HSPC expansion in hypercholesterolemic human subjects. Genome-wide ChIP-seq, RNA-seq, and ATAC-seq indicate that Srebp2 trans-regulates Notch pathway genes required for hematopoiesis. Our studies outline a novel AIBP-regulated Srebp2-dependent paradigm for HSPC emergence in development and HPSC expansion in atherosclerotic cardiovascular disease.
Project description:Osteolineage cell-derived extracellular vesicles (EVs) play a regulatory role in hematopoiesis and have been shown to promote the ex vivo expansion of human hematopoietic stem and progenitor cells (HSPCs). Here, we demonstrate that EVs from different human osteolineage sources do not have the same HSPC expansion promoting potential. Comparison of stimulatory and non-stimulatory osteolineage EVs by next-generation sequencing and mass spectrometry analyses revealed distinct microRNA (miRNA) and protein signatures identifying EV-derived candidate regulators of ex vivo HSPC expansion. Accordingly, the treatment of umbilical cord blood-derived CD34+ HSPCs with stimulatory EVs altered HSPC transcriptome, including genes with known roles in cell proliferation. An integrative bioinformatics approach, which connects the HSPC gene expression data with the candidate cargo in stimulatory EVs, delineated the potentially targeted biological functions and pathways during hematopoietic cell expansion and development. In conclusion, our study gives novel insights into the complex biological role of EVs in osteolineage cell-HSPC crosstalk and promotes the utility of EVs and their cargo as therapeutic agents in regenerative medicine.
Project description:Osteolineage cell-derived extracellular vesicles (EVs) play a regulatory role in hematopoiesis and have been shown to promote the ex vivo expansion of human hematopoietic stem and progenitor cells (HSPCs). Here, we demonstrate that EVs from different human osteolineage sources do not have the same HSPC expansion promoting potential. Comparison of stimulatory and non-stimulatory osteolineage EVs by next-generation sequencing and mass spectrometry analyses revealed distinct microRNA (miRNA) and protein signatures identifying EV-derived candidate regulators of ex vivo HSPC expansion. Accordingly, the treatment of umbilical cord blood-derived CD34+ HSPCs with stimulatory EVs altered HSPC transcriptome, including genes with known roles in cell proliferation. An integrative bioinformatics approach, which connects the HSPC gene expression data with the candidate cargo in stimulatory EVs, delineated the potentially targeted biological functions and pathways during hematopoietic cell expansion and development. In conclusion, our study gives novel insights into the complex biological role of EVs in osteolineage cell-HSPC crosstalk and promotes the utility of EVs and their cargo as therapeutic agents in regenerative medicine.
Project description:GATA2 is a pivotal hematopoietic transcription factor required for generation and maintenance of hematopoietic stem cells (HSCs). Due to early embryonic lethality of Gata2 deficiency in mice, its role during adult hematopoiesis is incompletely understood. In zebrafish, mammalian functions of Gata2 are split between two orthologues: Gata2a and Gata2b. Previous studies have shown that Gata2b is prominently expressed in hematopoietic stem and progenitor cells (HSPCs), whereas Gata2a is mainly expressed in the vasculature. We found that Gata2b deficient zebrafish have a reduction in embryonic definitive HSPC numbers and have impaired myeloid lineage differentiation, but are viable. This allowed us to study the role of Gata2b in adult hematopoiesis. To assess the impact of Gata2b deficiency on the transcriptional profile of HSPCs and differentiated cells, we sorted the entire progenitor and HSPC population including the lymphoid population from kidney marrow (KM) of WT and germline Gata2b deficient zebrafish based on scatter profiles and processed for single-cell RNA sequencing. To enrich the scarce HSC population, we used pooled KM from two WT and Gata2b deficient Tg(CD41:GFP) zebrafish per sample and included all CD41:GFPlow expressing cells present in the kidney marrow pool as these cells were shown to contain transplantable HSCs.
Project description:To characterize the mechanism by which AML derived extracellular vesicles(EV) impaired the vascular architecture and function, EV or PBS injected flk:GFP zebrafish larvae were used for sorting endothelial cells and performing RNA-Seq. Vascular niches sustain hematopoietic stem and progenitor cells (HSPC) and are drastically remodeled in myeloid leukemia to support pathological progression. By utilizing the leukemia-xenografted zebrafish model, we identified that myeloid leukemia secreted extracellular vesicles (EVs) to impair HSPC proliferation, survival and differentiation towards lymphoid/erythroid lineages. The leukemia EVs delivered arginase-1 into venous vasculature to deplete L-arginine and cause NOS uncoupling, which catalyzes production of ROS instead of NO. The oxidative stress caused endothelial cell loss, vascular constriction and failure of secreting niche factors and supporting hematopoiesis. Our findings indicate that myeloid leukemia impaired the vascular function of supporting hematopoiesis by delivering arginase in EVs and arginase inhibition has the potential to improve normal hematopoiesis in myeloid leukemia.
Project description:U2AF1 is involved in the recognition of the 3’ splice site during pre-mRNA splicing. Mutations in U2AF1 are frequently observed in myelodysplastic syndromes. However, the role of wild-type U2AF1 in normal hematopoiesis has remained elusive. Using a novel conditional U2af1 knockout allele, we have found that deletion of U2af1 results in profound defects in hematopoiesis characterized by pancytopenia, ablation of hematopoietic stem/progenitor cells (HSPC) leading to bone marrow failure and early lethality in mice. U2af1 deletion impairs HSPC function and repopulation capacity. U2af1 deletion also causes increased DNA damage and reduced survival in hematopoietic progenitors. RNA sequencing analysis reveals significant alterations in the expression of genes related to HSC maintenance, cell proliferation and DNA damage response-related pathways in U2af1-deficient HSPC. U2af1 deficiency also induces splicing alterations in genes important for HSPC function. Collectively, these results suggest an important role for U2af1 in the maintenance and function of HSPC in normal hematopoiesis. A better understanding of the normal function of U2AF1 in hematopoiesis is important for development of appropriate therapeutic approaches for U2AF1 mutant induced hematologic malignancies.
Project description:Hematopoietic stem cells (HSC) has unique characteristic to self-renew and replenish the entire blood system. During development, HSCs originate in the aorta-gonads-mesonephros (AGM), from where they migrate into the fetal liver at E11. Once resided in fetal liver HSC proliferate extensively to make sufficient stem pool for adult life. Around birth, HSC from FL migrate to bone marrow (BM) which is major site of hematopoiesis for whole adult life. In contrast to FL HSC, BM HSC remain quiescence state and give rise to different blood cell type under normal homeostatic condition. It has shown that FL HSCs display significantly faster expansion kinetics when transplanted into lethally irradiate mice, compared with HSCs from adult BM. However, detail molecular mechanism behind the difference in self-renewal potential is not fully understood. Here, we present the genome-wide transcriptome analysis of more proliferative FL HSC compared to quiescent BM HSC using RNA-Seq platform.