Project description:Long-term hematopoietic stem cells (LT-HSCs) reside in bone marrow (BM) niches with low levels of oxygen and reactive oxygen species (ROS). ROS enhancement results in differentiation of LT-HSCs. Redox disturbances are involved in BM failure and leukemia. Paraoxonase-2 (PON2) has been shown to be important for ROS control. However, the role of PON2 in the hematopoietic system has not been addressed. Analysis of young mice with inactivated Pon2 gene (Pon2-/- mice; 3 months) revealed changes in quantity of hematopoietic stem and progenitor cells (HSPCs), which indicate changes in cell differentiation. Experiments with aged PON2-/- mice (>9 months) showed alterations of the HSPC compartment indicating changed self-renewal ability of HSCs and myeloid skewing. Reciprocal BM transplantation reveals cell intrinsic as well as extrinsic phenotypes. We observed markedly enhanced superoxide levels in BM as well as slightly enhanced total ROS level in short term (ST)-HSCs and multipotent progenitor cells (MPPs) of young mice. In aged mice, total ROS level was slightly increased in all 3 fractions of the Lin-, Sca1+, ckit+ (LSK) population. No changes in the amount of DNA double-strand breaks in LSK cells and decreased apoptosis rates in LT-HSCs of young as well as LT- and ST-HSCs of aged PON2-/- mice were seen, indicating a strong compensation mechanism. Changes of gene expression in PON2-/- LT-HSCs identified by RNA sequencing strengthened our conclusions. Additionally, competitive and serial bone marrow transplantation experiments exposed advantages of PON2-/- BMCs in multi-lineage reconstitution. Collectively, these analyses propose PON2 as crucial redox control enzyme in HSCs.
Project description:Thiol-dependent redox regulation is essential for the rapid adaptation of chloroplast metabolism to unpredictable changes of light intensity. The disulfide reductase activity of thioredoxins (Trxs), which relies on photo-reduced ferredoxin (Fdx) and a Fdx-dependent Trx reductase (FTR), constitutes the Fdx-FTR-Trxs system, which links chloroplast redox regulation to light. In addition, chloroplasts harbor an NADPH-dependent Trx reductase (NTR) with a joint Trx domain, NTRC. The activity of these two redox systems is integrated by the balance of the hydrogen peroxide scavenging enzyme 2-Cys peroxiredoxin (2-Cys Prx), which thus plays a key role in maintaining the reducing capacity of chloroplast Trxs in response to light intensity. Based on the severe phenotype of mutant lines lacking NTRC, it is clear that this enzyme plays an essential role in chloroplast redox homeostasis. However, whether the function of NTRC depends on its capacity of reduce 2-Cys Prxs or has additional targets remains unknown. Here, we have addressed this issue by a comparative analysis of the triple mutant of Arabidopsis thaliana, ntrc-2cpab, simultaneously lacking 2-Cys Prxs and NTRC, and the double mutant 2cpab lacking 2-Cys Prxs. The phenotype of the ntrc-2cpab mutant is indistinguishable of the 2cpab mutant, as shown by growth rate, photosynthesis performance, light-dependent redox regulation of enzyme activity and comparative transcriptomics based RNA-Seq. Based on these results, we propose that the function of NTRC in chloroplast redox homeostasis is exerted by the regulation of the redox balance of 2-Cys Prxs rather than by the direct reduction of additional targets.
Project description:Fetal and adult hematopoietic stem and progenitor cells (HSPCs) are characterized by distinct redox homeostasis that may influence their differential cellular behaviour in normal and malignant haematopoiesis. In this work, we have applied a quantitative mass spectrometry-based redox proteomic approach to comprehensively describe reversible cysteine modifications in primary mouse fetal and adult HSPCs. We defined the redox state of 4455 cysteines in fetal and adult HSPCs and demonstrated a higher susceptibility to oxidation of protein thiols in fetal HSPCs. Our data identified ontogenically active redox switches in proteins with a pronounced role in metabolism and protein homeostasis. Additional redox proteomic analysis identified redox switches acting in mitochondrial respiration as well as protein homeostasis to be triggered during onset of MLL-ENL leukemogenesis in fetal HSPCs. Our data has demonstrated that redox signalling contributes to the regulation of fundamental processes of developmental hematopoiesis and has pinpointed potential targetable redox-sensitive proteins in in utero-initiated MLL-rearranged leukaemia. An H9 human embryonic stem cells cell line was applied to validate data from the primary cells.
Project description:The platelet-derived growth factor (PDGF) signaling system contributes to tumor angiogenesis and vascular remodeling. Here, we show PDGF-BB markedly induces erythropoietin (EPO) mRNA and protein expression by targeting the PDGFR-beta+ stromal and perivascular compartments. In mouse tumor models, PDGF-BB-induced EPO promotes tumor growth via two mechanisms: 1) paracrine stimulation of tumor angiogenesis by directly inducing endothelial cell proliferation, migration, sprouting and tube formation; and 2) endocrine stimulation of extramedullary hematopoiesis leading to increased oxygen perfusion and protection against tumor-associated anemia. Similarly, delivery of an adenovirus-PDGF-BB to tumor-free mice markedly increases EPO production and hematopoietic parameters. An EPO blockade specifically attenuates PDGF-BB-induced tumor growth, angiogenesis and hematopoiesis. At the molecular level, we show that the PDGF-BB-PDGFR-beta signaling system activates EPO promoter via in part transcriptional regulation of ATF3 by possible association with c-Jun and SP1. These findings uncover a novel mechanism of PDGF-BB-induced tumor growth, angiogenesis and hematopoiesis. Comparison of S17 stromal cells treated with PDGF-BB for 72h to control
Project description:Self-renewal and differentiation of hematopoietic stem and progenitor cells (HSPCs) is carefully controlled by extrinsic and intrinsic factors, to ensure the lifelong process of hematopoiesis. Apurinic/apyrimidinic endonuclease 1 (APEX1) is a multifunctional protein implicated in DNA repair and transcriptional regulation. Although previous studies have emphasized the necessity of studying APEX1 in lineage-specific context and its role in some progenitor cells, no studies have assessed the role of APEX1, nor its two enzymatic domains, in supporting adult HSPC function. In this study, we demonstrated that complete loss of APEX1 from murine bone marrow HSPCs (induced by CRSIPR/Cas9) caused severe hematopoietic failure following transplantation, as well as an ex vivo HSPC expansion defect. Using specific inhibitors against either the nuclease or redox domains of APEX1 in combination with single cell transcriptomics (CITE-seq), we found that both APEX1 nuclease and redox domains are regulating mouse ex vivo HSPC proliferation, differentiation and survival, but through distinct mechanisms. Inhibition of the APEX1 nuclease function resulted in loss of HSPCs accompanied by early activation of differentiation programs and enhanced lineage commitment. By contrast, inhibition of the APEX1 redox function significantly downregulated interferon signaling in expanding HSPCs and their progeny, resulting in dysfunctional megakaryocyte-biased HSPCs, loss of monocytes and lymphoid progenitor cells. In conclusion, we demonstrate that APEX1 is a key regulator for adult regenerative hematopoiesis, and that the APEX1 nuclease and redox domains differentially impact lineage specification and stemness of functional ex vivo cultured HSPCs.
Project description:Transcriptional profiling was done following APE1/Ref1 silencing using conditional gene expression knockdown by RNA interference (RNAi) technology in HeLa cell lines. APE1 is a DNA-repair enzyme and transcriptional co-activator. Knockdown leads to cell-growth arrest, apoptosis and impairment in the intracellular redox state and cytoskeletal perturbation.
Project description:JS-K, a NO donor which capable to induce cancer apopotosis, it's killing mechanism was investigated in this study. We found out that JS-K induce apopotosis via deregulating the GSH/GSSG redox couple. Leukemia cells were treated with JS-K and then assayed for metabolic changes by LC/MS and gene expression alterations by microarray.
Project description:We proposed that besides TET family dioxygenase oxidizing 5mC to 5hmC, there is a non-enzyme pathway which is due to hydroxyl radica l(OH) or OH-like species also involvement in demethylation of 5mC forming 5hmC. This pathway includes classical fenton reagents such as H2O2 and Fe2+, and more important redox-activity quinoid compounds, especially, tetrachloro-1,4-benzoquinone (TCBQ), which was reported producing hydroxyl radicals independent of transition metal Examination of 5hmC and transcriptome levels with TCBQ and DMSO in human MRC-5 cell lines