Epo receptor signaling in macrophages alters the splenic niche to promote erythroid differentiation.
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ABSTRACT:
SUBMITTER: Chen Y
PROVIDER: S-EPMC7357191 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Erythropoiesis is a tightly regulated process. Development of red blood cells occurs through differentiation of hematopoietic stem cells (HSCs) into more committed progenitors and finally into erythrocytes. Binding of erythropoietin (Epo) to its receptor (EpoR) is required for erythropoiesis as it promotes survival and late maturation of erythroid progenitors. In vivo and in vitro studies have highlighted the requirement of EpoR signaling through Janus kinase 2 (Jak2) tyrosine kinase and Stat5a/b as a central pathway. Here, we demonstrate that phospholipase C gamma 1 (Plcγ1) is activated downstream of EpoR-Jak2 independently of Stat5. Plcγ1-deficient pro-erythroblasts and erythroid progenitors exhibited strong impairment in differentiation and colony-forming potential. In vivo, suppression of Plcγ1 in immunophenotypically defined HSCs (Lin(-)Sca1(+)KIT(+)CD48(-)CD150(+)) severely reduced erythroid development. To identify Plcγ1 effector molecules involved in regulation of erythroid differentiation, we assessed changes occurring at the global transcriptional and DNA methylation level after inactivation of Plcγ1. The top common downstream effector was H2afy2, which encodes for the histone variant macroH2A2 (mH2A2). Inactivation of mH2A2 expression recapitulated the effects of Plcγ1 depletion on erythroid maturation. Taken together, our findings identify Plcγ1 and its downstream target mH2A2, as a 'non-canonical' Epo signaling pathway essential for erythroid differentiation.
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Project description:The splenic microenvironment regulates hematopoietic stem and progenitor cell (HSPC) function, particularly during demand-adapted hematopoiesis; however, practical strategies to enhance splenic support of transplanted HSPCs have proved elusive. We have previously demonstrated that inhibiting 15-hydroxyprostaglandin dehydrogenase (15-PGDH), using the small molecule (+)SW033291 (PGDHi), increases BM prostaglandin E2 (PGE2) levels, expands HSPC numbers, and accelerates hematologic reconstitution after BM transplantation (BMT) in mice. Here we demonstrate that the splenic microenvironment, specifically 15-PGDH high-expressing macrophages, megakaryocytes (MKs), and mast cells (MCs), regulates steady-state hematopoiesis and potentiates recovery after BMT. Notably, PGDHi-induced neutrophil, platelet, and HSPC recovery were highly attenuated in splenectomized mice. PGDHi induced nonpathologic splenic extramedullary hematopoiesis at steady state, and pretransplant PGDHi enhanced the homing of transplanted cells to the spleen. 15-PGDH enzymatic activity localized specifically to macrophages, MK lineage cells, and MCs, identifying these cell types as likely coordinating the impact of PGDHi on splenic HSPCs. These findings suggest that 15-PGDH expression marks HSC niche cell types that regulate hematopoietic regeneration. Therefore, PGDHi provides a well-tolerated strategy to therapeutically target multiple HSC niches, promote hematopoietic regeneration, and improve clinical outcomes of BMT.
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Project description:The hormone erythropoietin (Epo) is required for erythropoiesis, yet its molecular mechanism of action remains poorly understood, particularly with respect to chromatin dynamics. To investigate how Epo modulates the erythroid epigenome, we performed epigenetic profiling using an ex vivo murine cell system that undergoes synchronous erythroid maturation in response to Epo stimulation. Our findings define the repertoire of Epo-modulated enhancers, illuminating a new facet of Epo signaling. First, a large number of enhancers rapidly responded to Epo stimulation, revealing a cis-regulatory network of Epo-responsive enhancers. In contrast, most of the other identified enhancers remained in an active acetylated state during Epo signaling, suggesting that most erythroid enhancers are established at an earlier precursor stage. Second, we identified several hundred super-enhancers that were linked to key erythroid genes, such as Tal1, Bcl11a, and Mir144/451. Third, experimental and computational validation revealed that many predicted enhancer regions were occupied by TAL1 and enriched with DNA-binding motifs for GATA1, KLF1, TAL1/E-box, and STAT5. Additionally, many of these cis-regulatory regions were conserved evolutionarily and displayed correlated enhancer:promoter acetylation. Together, these findings define a cis-regulatory enhancer network for Epo signaling during erythropoiesis, and provide the framework for future studies involving the interplay of epigenetics and Epo signaling.
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Project description:We provide an overview of the evidence for an erythropoietin-fibroblast growth factor 23 (FGF23) signaling pathway directly influencing erythroid cells in the bone marrow. We outline its importance for red blood cell production, which might add, among others, to the understanding of bone marrow responses to endogenous erythropoietin in rare hereditary anemias. FGF23 is a hormone that is mainly known as the core regulator of phosphate and vitamin D metabolism and it has been recognized as an important regulator of bone mineralization. Osseous tissue has been regarded as the major source of FGF23. Interestingly, erythroid progenitor cells highly express FGF23 protein and carry the FGF receptor. This implies that erythroid progenitor cells could be a prime target in FGF23 biology. FGF23 is formed as an intact, biologically active protein (iFGF23) and proteolytic cleavage results in the formation of the presumed inactive C-terminal tail of FGF23 (cFGF23). FGF23-knockout or injection of an iFGF23 blocking peptide in mice results in increased erythropoiesis, reduced erythroid cell apoptosis and elevated renal and bone marrow erythropoietin mRNA expression with increased levels of circulating erythropoietin. By competitive inhibition, a relative increase in cFGF23 compared to iFGF23 results in reduced FGF23 receptor signaling and mimics the positive effects of FGF23-knockout or iFGF23 blocking peptide. Injection of recombinant erythropoietin increases FGF23 mRNA expression in the bone marrow with a concomitant increase in circulating FGF23 protein. However, erythropoietin also augments iFGF23 cleavage, thereby decreasing the iFGF23 to cFGF23 ratio. Therefore, the net result of erythropoietin is a reduction of iFGF23 to cFGF23 ratio, which inhibits the effects of iFGF23 on erythropoiesis and erythropoietin production. Elucidation of the EPO-FGF23 signaling pathway and its downstream signaling in hereditary anemias with chronic hemolysis or ineffective erythropoiesis adds to the understanding of the pathophysiology of these diseases and its complications; in addition, it provides promising new targets for treatment downstream of erythropoietin in the signaling cascade.
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Project description:Erythropoiesis is a tightly regulated process. Development of red blood cells occurs through differentiation of hematopoietic stem cells into more committed progenitors and finally into erythrocytes. Binding of erythropoietin to its receptor (EpoR) is strictly required for erythropoiesis as it promotes survival and late maturation of erythroid progenitors. In vivo and in vitro studies have highlighted the requirement of EpoR signaling through Jak2 tyrosine-kinase and Stat5a/b as a central pathway. Here, we demonstrate that phospholipase C gamma 1 (Plcγ1) is activated downstream of EpoR/Jak2 independently of Stat5. Plcγ1-deficient proerythroblasts and erythroid progenitors exhibited strong impairment in differentiation and colony-forming potential. In vivo, suppression of Plcγ1 in immunophenotypically defined hematopoietic stem cells (Lin-Sca1+KIT+CD48-CD150+) severely reduced erythroid development. To identify Plcγ1 effector molecules involved in regulation of erythroid differentiation we assessed for changes on the level of transcription and DNA methylation after inactivation of Plcγ1. The single common downstream effector was H2AFY2, which encodes for the histone variant macroH2A2 (mH2A2). Suppression of macroH2A2 expression recapitulated the effects of Plcγ1 knockdown on erythroid maturation. Taken together, our findings identify Plcγ1 and its downstream target macroH2A2, as a “non-canonical” signaling pathway essential for erythroid differentiation.
2015-12-31 | GSE60087 | GEO
Project description:Although chemotherapy is designed to eradicate tumor cells, it also has significant effects on normal tissues. The platinum-induced fatty acid 16:4(n-3) (hexadeca-4,7,10,13-tetraenoic acid) induces systemic resistance to a broad range of DNA-damaging chemotherapeutics. We show that 16:4(n-3) exerts its effect by activating splenic F4/80+/CD11blow macrophages, which results in production of chemoprotective lysophosphatidylcholines (LPCs). Pharmacologic studies, together with analysis of expression patterns, identified GPR120 on F4/80+/CD11blow macrophages as the relevant receptor for 16:4(n-3). Studies that used splenocytes from GPR120-deficient mice have confirmed this conclusion. Activation of the 16:4(n-3)-GPR120 axis led to enhanced cPLA2 activity in these splenic macrophages and secretion of the resistance-inducing lipid mediator, lysophosphatidylcholine(24:1). These studies identify a novel and unexpected function for GPR120 and suggest that antagonists of this receptor might be effective agents to limit development of chemotherapy resistance.-Houthuijzen, J. M., Oosterom, I., Hudson, B. D., Hirasawa, A., Daenen, L. G. M., McLean, C. M., Hansen, S. V. F., van Jaarsveld, M. T. M., Peeper, D. S., Jafari Sadatmand, S., Roodhart, J. M. L., van de Lest, C. H. A., Ulven, T., Ishihara, K., Milligan, G., Voest, E. E. Fatty acid 16:4(n-3) stimulates a GPR120-induced signaling cascade in splenic macrophages to promote chemotherapy resistance.
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Project description:Erythropoiesis is a tightly regulated process. Development of red blood cells occurs through differentiation of hematopoietic stem cells into more committed progenitors and finally into erythrocytes. Binding of erythropoietin to its receptor (EpoR) is strictly required for erythropoiesis as it promotes survival and late maturation of erythroid progenitors. In vivo and in vitro studies have highlighted the requirement of EpoR signaling through Jak2 tyrosine-kinase and Stat5a/b as a central pathway. Here, we demonstrate that phospholipase C gamma 1 (Plcγ1) is activated downstream of EpoR/Jak2 independently of Stat5. Plcγ1-deficient proerythroblasts and erythroid progenitors exhibited strong impairment in differentiation and colony-forming potential. In vivo, suppression of Plcγ1 in immunophenotypically defined hematopoietic stem cells (Lin-Sca1+KIT+CD48-CD150+) severely reduced erythroid development. To identify Plcγ1 effector molecules involved in regulation of erythroid differentiation we assessed for changes on the level of transcription and DNA methylation after inactivation of Plcγ1. The single common downstream effector was H2AFY2, which encodes for the histone variant macroH2A2 (mH2A2). Suppression of macroH2A2 expression recapitulated the effects of Plcγ1 knockdown on erythroid maturation. Taken together, our findings identify Plcγ1 and its downstream target macroH2A2, as a ânon-canonicalâ signaling pathway essential for erythroid differentiation. MCIP-seq was used to interrogate methylation changes during Epo-induced differentiation of murine I/11 erythroblastic cell line upon knock-down of Plcy1 as compared to a mock control. Two different shRNA constructs that target Plcg1 were investigated at two different time points.
2015-12-31 | E-GEOD-60087 | biostudies-arrayexpress
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Project description:Disease progression and relapse of chronic myeloid leukemia (CML) are caused by therapy resistant leukemia stem cells (LSCs), and cure relies on their eradication. The microenvironment in the bone marrow (BM) is known to contribute to LSC maintenance and resistance. Although leukemic infiltration of the spleen is a hallmark of CML, it is unknown whether spleen cells form a niche that maintains LSCs. Here, we demonstrate that LSCs preferentially accumulate in the spleen and contribute to disease progression. Spleen LSCs were located in the red pulp close to red pulp macrophages (RPM) in CML patients and in a murine CML model. Pharmacologic and genetic depletion of RPM reduced LSCs and decreased their cell cycling activity in the spleen. Gene expression analysis revealed enriched stemness and decreased myeloid lineage differentiation in spleen leukemic stem and progenitor cells (LSPCs). These results demonstrate that splenic RPM form a niche that maintains CML LSCs in a quiescent state, resulting in disease progression and resistance to therapy.
| S-EPMC7613762 | biostudies-literature
Project description:CD34+ progenitors were isolated from the bone marrow of three healthy volunteers. CD34+CD71+CD45RA- were FACS sorted to enrich for erythroid progenitors. The cells were cultured for four hours with or without EPO in combination with LY294002, and harvested for RNA extraction, amplification and expression analysis. A compound treatment design type is where the response to administration of a compound or chemical (including biological compounds such as hormones) is assayed. Compound Based Treatment: EPO Keywords: compound_treatment_design
2006-11-10 | GSE6260 | GEO