BMP4 and Madh5 regulate the erythroid response to acute anemia

Blood ◽  
2005 ◽  
Vol 105 (7) ◽  
pp. 2741-2748 ◽  
Author(s):  
Laurie E. Lenox ◽  
John M. Perry ◽  
Robert F. Paulson
Keyword(s):  
Steady State ◽  
Mutant Mice ◽  
Systemic Response ◽  
Erythroid Progenitors ◽  
New Model ◽  
Acute Anemia ◽  
Erythroid Response ◽  
Flexed Tail

Abstract Acute anemia initiates a systemic response that results in the rapid mobilization and differentiation of erythroid progenitors in the adult spleen. The flexed-tail (f) mutant mice exhibit normal steady-state erythropoiesis but are unable to rapidly respond to acute erythropoietic stress. Here, we show that f/f mutant mice have a mutation in Madh5. Our analysis shows that BMP4/Madh5-dependent signaling, regulated by hypoxia, initiates the differentiation and expansion of erythroid progenitors in the spleen. These findings suggest a new model where stress erythroid progenitors, resident in the spleen, are poised to respond to changes in the microenvironment induced by acute anemia.

BMP4/Madh5 Dependent Signaling Is Required for the Expansion of a Population of Stress Erythroid Progenitors in the Fetal Liver.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4195-4195
Author(s):  
Robert F. Paulson ◽  
Prashanth Porayette
Keyword(s):  
Bone Marrow ◽  
Steady State ◽  
Fetal Liver ◽  
Erythroid Progenitors ◽  
Acute Anemia ◽  
Erythroid Response ◽  
Stress Erythropoiesis ◽  
And Control ◽  
Flexed Tail

Abstract Fetal liver hematopoiesis is primarily erythropoiesis, which robustly produces erythrocytes to meet the growing need of the developing embryo. In many ways fetal liver erythropoiesis resembles stress erythropoiesis in the adult, where in response to acute anemia, a unique population of stress erythroid progenitors is rapidly expanded in the spleen. The development of these stress progenitors requires BMP4/Madh5 dependent signals. Spleen stress progenitors exhibit properties that are distinct from bone marrow steady state progenitors in that they are able to rapidly form large BFU-E colonies, which require only Epo stimulation for their generation. Mice mutant at the flexed-tail locus exhibit a defective stress erythroid response because of a mutation in Madh5. In addition to this defect, flexed-tail mice also exhibit a severe fetal-neonatal anemia. We have analyzed fetal liver erythropoiesis in flexed-tail and control embryos. We show that BMP4 is expressed in the fetal liver and its expression correlates with the time of maximum erythropoiesis. In flexed-tail mutant embryos the expression is delayed and this correlates with both a delay and a defect in the expansion of erythroid progenitors. Our analysis also shows that the fetal liver contains two types of erythroid progenitors. One type exhibits the properties of stress BFU-E found in the adult spleen, which are compromised in flexed-tail embryos and a second type that is similar to bone marrow steady state BFU-E. These data demonstrate that BMP4 dependent signaling drives the expansion of erythroid progenitors in the fetal liver in a manner similar to stress erythropoiesis in the adult spleen.

scholarly journals BMP4, SCF, and hypoxia cooperatively regulate the expansion of murine stress erythroid progenitors

Blood ◽  
2007 ◽  
Vol 109 (10) ◽  
pp. 4494-4502 ◽  
Author(s):  
John M. Perry ◽  
Omid F. Harandi ◽  
Robert F. Paulson
Keyword(s):  
Rapid Expansion ◽  
Low Oxygen ◽  
Spleen Cells ◽  
Erythroid Progenitors ◽  
Acute Anemia ◽  
Erythroid Response ◽  
Hypoxic Conditions ◽  
Vitro Analysis

Abstract The erythroid response to acute anemia relies on the rapid expansion in the spleen of a specialized population of erythroid progenitors termed stress BFU-E. This expansion requires BMP4/Madh5-dependent signaling in vivo; however, in vitro, BMP4 alone cannot recapitulate the expansion of stress BFU-E observed in vivo, which suggests that other signals are required. In this report we show that mutation of the Kit receptor results in a severe defect in the expansion of stress BFU-E, indicating a role for the Kit/SCF signaling pathway in stress erythropoiesis. In vitro analysis showed that BMP4 and SCF are necessary for the expansion of stress BFU-E, but only when spleen cells were cultured in BMP4 + SCF at low-oxygen concentrations did we recapitulate the expansion of stress BFU-E observed in vivo. Culturing spleen cells in BMP4, SCF under hypoxic conditions resulted in the preferential expansion of erythroid progenitors characterized by the expression of Kit, CD71, and TER119. This expression pattern is also seen in stress erythroid progenitors isolated from patients with sickle cell anemia and patients with β-thalassemia. Taken together these data demonstrate that SCF and hypoxia synergize with BMP4 to promote the expansion and differentiation of stress BFU-E during the recovery from acute anemia.

scholarly journals Nrf2 Null Mice Are Deficient in CD169+ Macrophages, Associated with Impaired Erythroid Response and Delayed Recovery from Acute Blood Loss

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1038-1038
Author(s):  
Oluwabukola Gbotosho ◽  
Maria G Kapetanaki ◽  
Mark A Ross ◽  
Samit Ghosh ◽  
Frances Weidert ◽  
...  
Keyword(s):  
Steady State ◽  
Blood Loss ◽  
Peripheral Blood ◽  
Research Funding ◽  
Heme Oxygenase 1 ◽  
Acute Blood Loss ◽  
Erythroid Progenitors ◽  
Erythroid Response ◽  
Stress Erythropoiesis ◽  
Deficient Mice

Erythropoiesis occurs in specialized niches in the bone marrow consisting of a central macrophage, surrounded by differentiating erythroblasts. This central macrophage has been identified by several markers including, CD169 (Sialoadhesin or Siglec-1), F4/80, CD11b, VCAM-1, ER-HR3 and Ly-6G. These CD169+ macrophages support erythropoiesis both at steady state and during stress. Nuclear factor erythroid 2-related factor 2 (Nrf2) is the master regulator of the cellular oxidative defense system. It modulates hematopoietic stem cells but its loss produces no visible phenotype in steady state hematological parameters. However, the importance of Nrf2 and macrophage subsets has not been fully characterized during recovery from stress erythropoiesis. We examined specific subsets of CD169+ macrophage populations in Nrf2 knockout (Nrf2−/−) mice as well as the role of Nrf2 in recovery from stress erythropoiesis in vivo. We quantified the expression of CD169, F4/80 and CD11b, markers of central macrophages, in the BM and spleen of Nrf2+/+ and Nrf2-/- mice at steady state. Surprisingly, Nrf2-/- mice showed a phenotype characterized by lower percentages of cells expressing known macrophage markers. We observed a significant decrease of 47% (p≤0.01), 24% (p≤0.01) and 50% (p≤0.01) in BM macrophage subpopulations expressing F4/80hiCD169hi, F4/80hiCD11bhi and CD169hiCD11bhi respectively, in age-matched Nrf2-/- mice compared to Nrf2+/+ control mice (Fig. 1a). In the spleen, we also observed a similar significant deficiency in BM macrophages (p≤0.01). Further validating this phenotype, immunofluorescence staining of isolated spleen tissue showed that expression of CD169+ macrophages was dramatically lower in spleen sections of Nrf2-/- mice than in Nrf2+/+ control mice. We hypothesized that our macrophage-deficient mice would display a defect in recovery from blood loss. Five to seven days after acute blood loss, immature erythroid progenitors (CD71hiTer119hi) increased in marrow by about 5-fold in Nrf2+/+ mice (p≤0.001, Fig. 1b), and mature erythroid progenitors (CD71loTer119hi) increased in marrow by 12-fold (p≤0.05) but the erythroid marrow response was impaired significantly in the macrophage deficient Nrf2-/- mice. To extend our observations regarding macrophage deficiency and impaired erythroid response, we chose a more functional outcome of recovery from anemia after high-grade blood loss produced by daily phlebotomies over 3 consecutive days to induce stress erythropoiesis in Nrf2+/+ and Nrf2-/- mice. We found significantly lower packed cell volume values specifically on Days 2, 4 and 10, implying delayed erythroid recovery (p≤0.05, two-way ANOVA). The Nrf2-/- mice also showed a significant decline in total hemoglobin than the Nrf2+/+ mice (p≤0.05). Additionally, peripheral blood reticulocyte response to blood loss is delayed in Nrf2 deficient mice compared to age-matched controls (11.0 ± 0.6% vs. 14.8 ± 0.6%, p≤0.001). We analyzed expression of heme-oxygenase 1 (HO-1), a well-known Nrf2-regulated gene. HO-1 mRNA expression increased 3-fold and 23-fold in Nrf2+/+ mice animals subjected to phlebotomy and hemin treatment compared to 2-fold and 12-fold expression in Nrf2-deficient mice (p≤0.05). We demonstrate for the first time that Nrf2-deficient mice have a deficiency of macrophages that includes subsets considered erythroblastic island (EI) macrophages, and that this deficiency is associated with impaired erythroid response to induced stress. Secondly, our multiple phlebotomies data in aggregate demonstrate that Nrf2-/- mice deficient in BM macrophages have significant delay in functional erythroid response and recovery from experimentally-induced anemia. Thirdly, impaired inducibility of HO-1 is a known feature of Nrf2-/- mice, which we confirmed in our results, could be contributing to the impairment in erythroid response. However, it is not likely that restricted iron trafficking to erythroid progenitors occurs in Nrf2-/- mice, since there is no characteristic alteration of mean corpuscular volume and mean corpuscular hemoglobin in peripheral blood. This is an area worthy of additional investigation. We conclude that the Nrf2 gene plays a previously unappreciated role in erythroid biology that appears to be mediated through macrophage function. Disclosures Ofori-Acquah: Shire Human Genetic Therapies Inc: Other: Financial Relationship. Kato:Bayer: Research Funding; Novartis, Global Blood Therapeutics: Consultancy, Research Funding.

90 Bcs1L A232G mutant mice: A new model of complex III deficiency and hepatic cirrhosis

Mitochondrion ◽  
2010 ◽  
Vol 10 (2) ◽  
pp. 225
Author(s):  
Per Levéen ◽  
Heike Kotarsky ◽  
Eva Hanson ◽  
Eskil Elmér ◽  
Vineta Fellman
Keyword(s):  
Hepatic Cirrhosis ◽  
Mutant Mice ◽  
Complex Iii ◽  
New Model

scholarly journals Laminin α2 chain-null mutant mice by targeted disruption of the Lama2 gene: a new model of merosin (laminin 2)-deficient congenital muscular dystrophy

FEBS Letters ◽  
1997 ◽  
Vol 415 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Yuko Miyagoe ◽  
Kazunori Hanaoka ◽  
Ikuya Nonaka ◽  
Michiko Hayasaka ◽  
Yoko Nabeshima ◽  
...  
Keyword(s):  
Muscular Dystrophy ◽  
Congenital Muscular Dystrophy ◽  
Mutant Mice ◽  
Null Mutant ◽  
Targeted Disruption ◽  
New Model ◽  
Null Mutant Mice ◽  
Laminin Α2

EPO-Dependent Recovery of Late-Stage Erythroid Progenitors in the Marrow Precedes Splenic Expansion: Insights From a Sublethal Radiation Model

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 180-180
Author(s):  
Scott A Peslak ◽  
Jesse Wenger ◽  
Amali P Epa ◽  
Jeffrey C Bemis ◽  
Paul D Kingsley ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Steady State ◽  
Late Stage ◽  
Erythroid Cell ◽  
Functional Evaluation ◽  
Erythroid Progenitors ◽  
Erythroid Progenitor ◽  
Irradiation Injury ◽  
Radiation Induced ◽  
Sublethal Irradiation

Abstract Abstract 180 Erythropoiesis is a robust process of cellular expansion and maturation that occurs in the bone marrow and spleen of mice. Following clastogenic injury such as total body irradiation (TBI), erythroblasts are severely depleted in these organs, resulting in loss of reticulocyte output and the development of a mild anemia (Peslak et al., Exp. Hematol. 2011). However, the mechanistic and microenvironmental factors underlying erythroid recovery following sublethal TBI are poorly understood. To this end, we utilized colony assays to quantify erythroid progenitors, which consist of immature d7 erythroid burst-forming units (BFU-E) and more mature d3 BFU-E and erythroid colony forming units (CFU-E). Imaging flow cytometry was used to quantify erythroblast precursors. We found that d7 BFU-E undergo a slow, incomplete recovery during the first 10 days post-4 Gy TBI of C57Bl/6 mice. In contrast, d3 BFU-E exhibit a robust recovery beginning at 4 days post-TBI that is immediately followed by a rapid increase in CFU-E numbers to over 200 percent of steady-state levels. This initial erythroid progenitor recovery is followed by a wave of erythroid precursor maturation and red cell formation that occurs in close association with macrophages in the bone marrow. These erythroblast islands undergo a rapid synchronous expansion that peaks at 6 days post-TBI, suggesting that the bone marrow microenvironment plays a role in the recovery of the erythron from sublethal TBI. We hypothesized that erythropoietin (EPO), the primary regulator of erythroid survival and proliferation, mediates the rapid, specific expansion of late-stage erythroid progenitors following radiation injury. We found that plasma EPO levels increase 13-fold 4 days after 4 Gy TBI, temporally correlated with expansion of d3 BFU-E. Furthermore, maintenance of steady-state hematocrit levels following TBI prevented EPO induction and blocked expansion of late-stage erythroid progenitors, while exogenous EPO administered at 1 hour post-radiation specifically advanced recovery of late-stage progenitors. These data indicate that EPO is required for expansion of d3 BFU-E and CFU-E following radiation-induced marrow depletion. During times of acute hypoxia, such as the severe anemia induced by bleeding or phenylhydrazine exposure, EPO production is rapidly upregulated and splenic stress erythropoiesis is induced. Surprisingly, splenic erythropoiesis is absent during the rapid initial recovery of erythropoiesis in the bone marrow at 4–6 days post-TBI. However, a massive expansion of CFU-E begins at 7–8 days post-4 Gy TBI in spleen. EPO administration at 4 days following 4 Gy TBI significantly enhances late-stage progenitor recovery exclusively in the marrow, indicating that erythroid progenitors are not present in spleen at the time of rapid bone marrow expansion and that late-stage erythroid progenitor recovery initiates in the marrow and subsequently proceeds to the spleen. Furthermore, we found that erythroid progenitors transiently emerge in the bloodstream at 6–8 days post-TBI, following marrow recovery and prior to initiation of splenic erythropoiesis. These data are consistent with endogenous migration of the erythron from the bone marrow to the spleen during recovery from radiation-induced erythroid injury. Taken together, our data indicate that recovery from sublethal irradiation injury is regulated primarily by the EPO-induced expansion of late-stage erythroid progenitors in the bone marrow. This form of clastogenic injury is critically different from bleeding or hemolysis, which preserve bone marrow and splenic erythroblasts and induce expansion of splenic erythroid stress progenitors. Sublethal irradiation injury thus provides a unique model for the in vivo study of endogenous erythroid recovery. This model may be clinically useful for the functional evaluation of therapeutic factors that regulate or modulate erythroid cell maturation. Disclosures: Bemis: Litron Laboratories: Employment, Patents & Royalties.

scholarly journals Early mammalian erythropoiesis requires the Dot1L methyltransferase

Blood ◽  
2010 ◽  
Vol 116 (22) ◽  
pp. 4483-4491 ◽  
Author(s):  
Yi Feng ◽  
Yanping Yang ◽  
Manoela M. Ortega ◽  
Jessica N. Copeland ◽  
Mingcai Zhang ◽  
...  
Keyword(s):  
Histone Methylation ◽  
Histone H3 ◽  
Mutant Mice ◽  
Myeloid Differentiation ◽  
Wild Type ◽  
Erythroid Progenitors ◽  
Small Vessels ◽  
Histone H3 Methylation ◽  
Important Regulator ◽  
Steady State Levels

Histone methylation is an important regulator of gene expression; its coordinated activity is critical in complex developmental processes such as hematopoiesis. Disruptor of telomere silencing 1-like (DOT1L) is a unique histone methyltransferase that specifically methylates histone H3 at lysine 79. We analyzed Dot1L-mutant mice to determine influence of this enzyme on embryonic hematopoiesis. Mutant mice developed more slowly than wild-type embryos and died between embryonic days 10.5 and 13.5, displaying a striking anemia, especially apparent in small vessels of the yolk sac. Further, a severe, selective defect in erythroid, but not myeloid, differentiation was observed. Erythroid progenitors failed to develop normally, showing retarded progression through the cell cycle, accumulation during G0/G1 stage, and marked increase in apoptosis in response to erythroid growth factors. GATA2, a factor essential for early erythropoiesis, was significantly reduced in Dot1L-deficient cells, whereas expression of PU.1, a transcription factor that inhibits erythropoiesis and promotes myelopoiesis, was increased. These data suggest a model whereby DOT1L-dependent lysine 79 of histone H3 methylation serves as a critical regulator of a differentiation switch during early hematopoiesis, regulating steady-state levels of GATA2 and PU.1 transcription, thus controlling numbers of circulating erythroid and myeloid cells.

scholarly journals Transgene Insertion in Proximity to thec-myb Gene Disrupts Erythroid-Megakaryocytic Lineage Bifurcation

2006 ◽  
Vol 26 (21) ◽  
pp. 7953-7965 ◽  
Author(s):  
Harumi Y. Mukai ◽  
Hozumi Motohashi ◽  
Osamu Ohneda ◽  
Norio Suzuki ◽  
Masumi Nagano ◽  
...  
Keyword(s):  
Bone Marrow Cells ◽  
Regulatory Region ◽  
Erythropoietin Receptor ◽  
Mutant Mice ◽  
Mouse Bone Marrow ◽  
Erythroid Progenitors ◽  
Myb Gene ◽  
Transgene Insertion

ABSTRACT The nuclear proto-oncogene c-myb plays crucial roles in the growth, survival, and differentiation of hematopoietic cells. We established three lines of erythropoietin receptor-transgenic mice and found that one of them exhibited anemia, thrombocythemia, and splenomegaly. These abnormalities were independent of the function of the transgenic erythropoietin receptor and were observed exclusively in mice harboring the transgene homozygously, suggesting transgenic disruption of a certain gene. The transgene was inserted 77 kb upstream of the c-myb gene, and c-Myb expression was markedly decreased in megakaryocyte/erythrocyte lineage-restricted progenitors (MEPs) of the homozygous mutant mice. In the bone marrows and spleens of the mutant mice, numbers of megakaryocytes were increased and numbers of erythroid progenitors were decreased. These abnormalities were reproducible in vitro in a coculture assay of MEPs with OP9 cells but eliminated by the retroviral expression of c-Myb in MEPs. The erythroid/megakaryocytic abnormalities were reconstituted in mice in vivo by transplantation of mutant mouse bone marrow cells. These results demonstrate that the transgene insertion into the c-myb gene far upstream regulatory region affects the gene expression at the stage of MEPs, leading to an imbalance between erythroid and megakaryocytic cells, and suggest that c-Myb is an essential regulator of the erythroid-megakaryocytic lineage bifurcation.

A new model to predict the behaviour of cavitated squeeze-film bearings

1987 ◽  
Vol 411 (1841) ◽  
pp. 445-466
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Lift Force ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Successful Operation ◽  
New Model ◽  
Damping Coefficients ◽  
Stiffness Coefficients ◽  
Linear Damping

Squeeze-film bearings are used extensively to control vibration in rotor-bearing systems. No closed-form mathematical model exists to represent the stiffness and dam ping characteristics of a cavitated squeeze-film bearing when it is describing a non-circular, non-concentric orbit. In this paper nonlinear expressions are developed for the oil-film forces from which are derived two direct linear stiffness and two direct linear damping coefficients with all the cross stiffness and dam ping coefficients zero. The linearized stiffness coefficients and the damping coefficients are functions of the amplitude of the journal orbit. The dynamic lift-force which is fundamental to the successful operation of a cavitated squeeze-film bearing when designed without centralizing springs has not previously been predicted analytically. An expression is derived for this lift force. Its magnitude is shown to be dependent upon the amplitude of the steady-state orbit, that is, it is dependent upon the dynamic load. A numerical experiment is performed to assess the validity of the new model over a range of operating conditions.

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