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Marrow JP, Alshamali R, Edgett BA, Allwood MA, Cochrane KLS, Al-Sabbag S, Ayoub A, Ask K, Hare GMT, Brunt KR, Simpson JA. Cardiomyocyte crosstalk with endothelium modulates cardiac structure, function, and ischemia-reperfusion injury susceptibility through erythropoietin. Front Physiol 2024; 15:1397049. [PMID: 39011088 PMCID: PMC11246973 DOI: 10.3389/fphys.2024.1397049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 06/03/2024] [Indexed: 07/17/2024] Open
Abstract
Erythropoietin (EPO) exerts non-canonical roles beyond erythropoiesis that are developmentally, structurally, and physiologically relevant for the heart as a paracrine factor. The role for paracrine EPO signalling and cellular crosstalk in the adult is uncertain. Here, we provided novel evidence showing cardiomyocyte restricted loss of function in Epo in adult mice induced hyper-compensatory increases in Epo expression by adjacent cardiac endothelial cells via HIF-2α independent mechanisms. These hearts showed concentric cellular hypertrophy, elevated contractility and relaxation, and greater resistance to ischemia-reperfusion injury. Voluntary exercise capacity compared to control hearts was improved independent of any changes to whole-body metabolism or blood O2 content or delivery (i.e., hematocrit). Our findings suggest cardiac EPO had a localized effect within the normoxic heart, which was regulated by cell-specific EPO-reciprocity between cardiomyocytes and endothelium. Within the heart, hyper-compensated endothelial Epo expression was accompanied by elevated Vegfr1 and Vegfb RNA, that upon pharmacological pan-inhibition of VEGF-VEGFR signaling, resulted in a paradoxical upregulation in whole-heart Epo. Thus, we provide the first evidence that a novel EPO-EPOR/VEGF-VEGFR axis exists to carefully mediate cardiac homeostasis via cardiomyocyte-endothelial EPO crosstalk.
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Affiliation(s)
- Jade P Marrow
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
- IMPART Investigator Team Canada, Guelph, ON, Canada
| | - Razan Alshamali
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
- IMPART Investigator Team Canada, Guelph, ON, Canada
| | - Brittany A Edgett
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
- IMPART Investigator Team Canada, Guelph, ON, Canada
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Melissa A Allwood
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
- IMPART Investigator Team Canada, Guelph, ON, Canada
| | - Kyla L S Cochrane
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
- IMPART Investigator Team Canada, Guelph, ON, Canada
| | - Sara Al-Sabbag
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Anmar Ayoub
- Firestone Institute for Respiratory Health, McMaster University, Hamilton, ON, Canada
| | - Kjetil Ask
- Firestone Institute for Respiratory Health, McMaster University, Hamilton, ON, Canada
| | - Gregory M T Hare
- IMPART Investigator Team Canada, Guelph, ON, Canada
- Department of Anesthesiology and Pain Medicine, St Michael's Hospital, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
| | - Keith R Brunt
- IMPART Investigator Team Canada, Guelph, ON, Canada
- Department of Pharmacology, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
| | - Jeremy A Simpson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
- IMPART Investigator Team Canada, Guelph, ON, Canada
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2
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Lanzolla G, Merceron C, Khan MP, Sabini E, Giaccia A, Schipani E. Osteoblastic erythropoietin is not required for bone mass accrual. JBMR Plus 2024; 8:ziae052. [PMID: 38764792 PMCID: PMC11102573 DOI: 10.1093/jbmrpl/ziae052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 03/19/2024] [Accepted: 04/08/2024] [Indexed: 05/21/2024] Open
Abstract
Erythropoietin (EPO), primarily produced by interstitial fibroblasts in the kidney during adulthood, and its receptor are well-known for their crucial role in regulating erythropoiesis. Recent research has unveiled an additional function of circulating EPO in the control of bone mass accrual and homeostasis through its receptor, which is expressed in both osteoblasts and osteoclasts. Notably, cells of the osteoblast lineage can produce and secrete functional EPO upon activation of the hypoxia signaling pathway. However, the physiological relevance of osteoblastic EPO remains to be fully elucidated. This study aimed to investigate the potential role of osteoblastic EPO in regulating bone mass accrual and erythropoiesis in young adult mice. To accomplish this, we employed a mutant mouse model lacking EPO specifically in mesenchymal progenitors and their descendants. Our findings indicate that in vivo loss of EPO in the osteoblast lineage does not significantly affect either bone mass accrual or erythropoiesis in young adult mice. Further investigations are necessary to comprehensively understand the potential contribution of EPO produced and secreted by osteoblast cells during aging, repair, and under pathological conditions.
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Affiliation(s)
- Giulia Lanzolla
- Department of Orthopaedic Surgery, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, United States
| | - Christophe Merceron
- Department of Orthopaedic Surgery, School of Medicine, University of Michigan, Ann Arbor, MI 48109, United States
| | - Mohd Parvez Khan
- Department of Orthopaedic Surgery, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, United States
- Department of Orthopaedic Surgery, School of Medicine, University of Michigan, Ann Arbor, MI 48109, United States
| | - Elena Sabini
- Department of Orthopaedic Surgery, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, United States
| | - Amato Giaccia
- Department of Radiation Oncology, Stanford University Medical School, Stanford, CA 94304, United States
| | - Ernestina Schipani
- Department of Orthopaedic Surgery, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, United States
- Department of Orthopaedic Surgery, School of Medicine, University of Michigan, Ann Arbor, MI 48109, United States
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Ling Y, Wu J, Liu Y, Meng P, Sun Y, Zhao D, Lin Q. Establishment of a Diamond-Blackfan anemia like model in zebrafish. Dev Dyn 2024. [PMID: 38450920 DOI: 10.1002/dvdy.703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 02/03/2024] [Accepted: 02/19/2024] [Indexed: 03/08/2024] Open
Abstract
BACKGROUND Anemia is defined as a lack of erythrocytes, low hemoglobin levels, or abnormal erythrocyte morphology. Diamond-Blackfan anemia (DBA) is a rare and severe congenital hypoplastic anemia that occurs due to the dominant inheritance of a ribosomal protein gene mutation. Even rarer is a case described as Diamond-Blackfan anemia like (DBAL), which occurs due to a loss-of-function EPO mutation recessive inheritance. The effective cures for DBAL are bone marrow transfusion and treatment with erythropoiesis-stimulating agents (ESAs). To effectively manage the condition, construction of DBAL models to identify new medical methods or screen drugs are necessary. RESULTS Here, an epoa-deficient mutant zebrafish called epoaszy8 was generated to model DBAL. The epoa-deficiency in zebrafish caused developmental defects in erythroid cells, leading to severe congenital anemia. Using the DBAL model, we validated a loss-of-function EPO mutation using an in vivo functional analysis and explored the ability of ESAs to alleviate congenital anemia. CONCLUSIONS Together, our study demonstrated that epoa deficiency in zebrafish leads to a phenotype resembling DBAL. The DBAL zebrafish model was found to be beneficial for the in vivo assessment of patient-derived EPO variants with unclear implications and for devising potential therapeutic approaches for DBAL.
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Affiliation(s)
- Yiming Ling
- The Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou, China
| | - Jiaye Wu
- The Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou, China
| | - Yushi Liu
- The Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou, China
| | - Panpan Meng
- The Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou, China
| | - Ying Sun
- The Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou, China
| | - Dejian Zhao
- Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, China
| | - Qing Lin
- The Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou, China
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4
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Allwood MA, Edgett BA, Platt MJ, Marrow JP, Coyle-Asbil B, Holjak EJB, Nelson VL, Bangali S, Alshamali R, Jacyniak K, Klein JM, Farquharson L, Romanova N, Northrup V, Ogilvie LM, Ayoub A, Ask K, Vickaryous MK, Hare GMT, Brunt KR, Simpson JA. Novel roles of cardiac-derived erythropoietin in cardiac development and function. J Mol Cell Cardiol 2024; 188:90-104. [PMID: 38382296 DOI: 10.1016/j.yjmcc.2024.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 01/15/2024] [Accepted: 01/22/2024] [Indexed: 02/23/2024]
Abstract
The role of erythropoietin (EPO) has extended beyond hematopoiesis to include cytoprotection, inotropy, and neurogenesis. Extra-renal EPO has been reported for multiple tissue/cell types, but the physiological relevance remains unknown. Although the EPO receptor is expressed by multiple cardiac cell types and human recombinant EPO increases contractility and confers cytoprotection against injury, whether the heart produces physiologically meaningful amounts of EPO in vivo is unclear. We show a distinct circadian rhythm of cardiac EPO mRNA expression in adult mice and increased mRNA expression during embryogenesis, suggesting physiological relevance to cardiac EPO production throughout life. We then generated constitutive, cardiomyocyte-specific EPO knockout mice driven by the Mlc2v promoter (EPOfl/fl:Mlc2v-cre+/-; EPOΔ/Δ-CM). During cardiogenesis, cardiac EPO mRNA expression and cellular proliferation were reduced in EPOΔ/Δ-CM hearts. However, in adult EPOΔ/Δ- CM mice, total heart weight was preserved through increased cardiomyocyte cross-sectional area, indicating the reduced cellular proliferation was compensated for by cellular hypertrophy. Echocardiography revealed no changes in cardiac dimensions, with modest reductions in ejection fraction, stroke volume, and tachycardia, whereas invasive hemodynamics showed increased cardiac contractility and lusitropy. Paradoxically, EPO mRNA expression in the heart was elevated in adult EPOΔ/Δ-CM, along with increased serum EPO protein content and hematocrit. Using RNA fluorescent in situ hybridization, we found that Epo RNA colocalized with endothelial cells in the hearts of adult EPOΔ/Δ-CM mice, identifying the endothelial cells as a cell responsible for the EPO hyper-expression. Collectively, these data identify the first physiological roles for cardiomyocyte-derived EPO. We have established cardiac EPO mRNA expression is a complex interplay of multiple cell types, where loss of embryonic cardiomyocyte EPO production results in hyper-expression from other cells within the adult heart.
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Affiliation(s)
- Melissa A Allwood
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; IMPART investigator Team, Canada
| | - Brittany A Edgett
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; Department of Pharmacology, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada; IMPART investigator Team, Canada; Department of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Mathew J Platt
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; IMPART investigator Team, Canada
| | - Jade P Marrow
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; IMPART investigator Team, Canada
| | - Bridget Coyle-Asbil
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; IMPART investigator Team, Canada
| | - Emma J B Holjak
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; IMPART investigator Team, Canada
| | - Victoria L Nelson
- Department of Pharmacology, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada; IMPART investigator Team, Canada
| | - Swara Bangali
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Razan Alshamali
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; IMPART investigator Team, Canada
| | - Kathy Jacyniak
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Jorden M Klein
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Laura Farquharson
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Nadya Romanova
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Victoria Northrup
- Department of Pharmacology, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada; IMPART investigator Team, Canada
| | - Leslie M Ogilvie
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; IMPART investigator Team, Canada
| | - Anmar Ayoub
- Firestone Institute for Respiratory Health, McMaster University, Hamilton, Ontario, Canada
| | - Kjetil Ask
- Firestone Institute for Respiratory Health, McMaster University, Hamilton, Ontario, Canada
| | - Matthew K Vickaryous
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Gregory M T Hare
- Departments of Anesthesia & Physiology, St. Michel's Hospital, University of Toronto, Toronto, Ontario, Canada; IMPART investigator Team, Canada
| | - Keith R Brunt
- Department of Pharmacology, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada; IMPART investigator Team, Canada
| | - Jeremy A Simpson
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; IMPART investigator Team, Canada.
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5
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Yamazaki S, Hirano I, Kato K, Yamamoto M, Suzuki N. Defining the functionally sufficient regulatory region and liver-specific roles of the erythropoietin gene by transgene complementation. Life Sci 2021; 269:119075. [PMID: 33465391 DOI: 10.1016/j.lfs.2021.119075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/24/2020] [Accepted: 01/08/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND Erythropoietin (EPO) is an essential growth factor for erythroid cells and is mainly secreted from the kidneys and subsidiarily from the livers of adult mammals in an anemia/hypoxia-inducible manner. AIM AND METHOD To elucidate the regulatory mechanisms of stress-inducible and cell type-specific Epo gene transcription, the rate-limiting step of EPO production, we investigated the sufficiency of a 180-kb genomic fragment flanking the mouse Epo gene locus for recapitulating endogenous Epo gene function by a transgene complementation strategy. KEY FINDINGS While Epo gene-deficient mice exhibited lethal anemia in utero with defects in erythroblast proliferation and maturation, Epo-knockout mice integrated with the 180-kb Epo transgene showed normal erythropoiesis throughout life. In the transgene-rescued mice, liver-specific deletion of the transgene by the Cre-loxP recombination system caused neonatal anemia with erythropoietic defects in the liver but not in the spleen, indicating the essential function of hepatic EPO on normal erythropoiesis in the liver, which is the major erythropoietic site in late embryonic and neonatal stages. SIGNIFICANCE These results demonstrate that the 180 kb Epo gene flanking region contains the fully functional Epo gene unit and that EPO from the liver dominantly stimulates hepatic erythropoiesis but contributes less to erythropoiesis in other organs.
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Affiliation(s)
- Shun Yamazaki
- Division of Oxygen Biology, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan; Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Ikuo Hirano
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Koichiro Kato
- Division of Oxygen Biology, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Masayuki Yamamoto
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Norio Suzuki
- Division of Oxygen Biology, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
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6
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Perron-Deshaies G, St-Louis P, Romero H, Scorza T. Impact of Erythropoietin Production by Erythroblastic Island Macrophages on Homeostatic Murine Erythropoiesis. Int J Mol Sci 2020; 21:ijms21238930. [PMID: 33255601 PMCID: PMC7728051 DOI: 10.3390/ijms21238930] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 11/16/2022] Open
Abstract
Erythropoietin (EPO) is an essential hormone for erythropoiesis, protecting differentiating erythroblasts against apoptosis. EPO has been largely studied in stress or pathological conditions but its regulatory role in steady state erythropoiesis has been less documented. Herein, we report production of EPO by bone marrow-derived macrophages (BMDM) in vitro, and its further enhancement in BMDM conditioned with media from apoptotic cells. Confocal microscopy confirmed EPO production in erythroblastic island (EBI)-associated macrophages, and analysis of mice depleted of EBI macrophages by clodronate liposomes revealed drops in EPO levels in bone marrow (BM) cell lysates, and decreased percentages of EPO-responsive erythroblasts in the BM. We hypothesize that EBI macrophages are an in-situ source of EPO and sustain basal erythropoiesis in part through its secretion. To study this hypothesis, mice were injected with clodronate liposomes and were supplied with exogenous EPO (1-10 IU/mouse) to evaluate potential rescue of the deficiency in erythroid cells. Our results show that at doses of 5 and 10 IU, EPO significantly rescues BM steady state erythropoiesis in mice deficient of macrophages. We propose existence of a mechanism by which EBI macrophages secrete EPO in response to apoptotic erythroblasts, which is in turn controlled by the numbers of erythroid precursors generated.
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Affiliation(s)
- Genève Perron-Deshaies
- Département des Sciences Biologiques, Université du Québec à Montréal, Montreal, QC H3C 3P8, Canada; (G.P.-D.); (P.S.-L.); (H.R.)
| | - Philippe St-Louis
- Département des Sciences Biologiques, Université du Québec à Montréal, Montreal, QC H3C 3P8, Canada; (G.P.-D.); (P.S.-L.); (H.R.)
| | - Hugo Romero
- Département des Sciences Biologiques, Université du Québec à Montréal, Montreal, QC H3C 3P8, Canada; (G.P.-D.); (P.S.-L.); (H.R.)
- CHU Sainte-Justine Research Centre, Montreal, QC H3T 1C5, Canada
| | - Tatiana Scorza
- Département des Sciences Biologiques, Université du Québec à Montréal, Montreal, QC H3C 3P8, Canada; (G.P.-D.); (P.S.-L.); (H.R.)
- Correspondence: ; Tel.: +1-514-9873000 (ext. 1918)
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7
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Deregulated iron metabolism in bone marrow from adenine-induced mouse model of chronic kidney disease. Int J Hematol 2018; 109:59-69. [DOI: 10.1007/s12185-018-2531-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 09/04/2018] [Accepted: 09/05/2018] [Indexed: 12/11/2022]
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Abstract
Animal models of erythropoiesis have been, and will continue to be, important tools for understanding molecular mechanisms underlying the development of this cell lineage and the pathophysiology associated with various human erythropoietic diseases. In this regard, the mouse is probably the most valuable animal model available to investigators. The physiology and short gestational period of mice make them ideal for studying developmental processes and modeling human diseases. These attributes, coupled with cutting-edge genetic tools such as transgenesis, gene knockouts, conditional gene knockouts, and genome editing, provide a significant resource to the research community to test a plethora of hypotheses. This review summarizes the mouse models available for studying a wide variety of erythroid-related questions, as well as the properties inherent in each one.
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9
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She J, Yuan Z, Wu Y, Chen J, Kroll J. Targeting erythropoietin protects against proteinuria in type 2 diabetic patients and in zebrafish. Mol Metab 2017; 8:189-202. [PMID: 29203238 PMCID: PMC5985015 DOI: 10.1016/j.molmet.2017.11.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Revised: 11/08/2017] [Accepted: 11/09/2017] [Indexed: 12/17/2022] Open
Abstract
Objective Adult human kidneys produce erythropoietin (EPO), which regulates red blood cell formation; however, whether EPO also functions directly on kidney development and controls diabetic kidney disease remains unknown. Here we analyzed the role of EPO in kidney development and under hyperglycemic conditions in zebrafish and in humans. Methods Diabetic patients and respective controls were enrolled in two cohorts. Serum EPO level and urine protein change upon human EPO administration were then analyzed. Transient knockdown and permanent knockout of EPO and EPOR in renal TG(WT1B:EGFP) zebrafish were established using the morpholino technology and CRISPR/Cas9 technology. Zebrafish embryos were phenotypically analyzed using fluorescence microscopy, and functional assays were carried out with the help of TexasRed labeled 70 kDa Dextran. Apoptosis was determined using the TUNEL assay and Annexin V staining, and caspase inhibitor zVADfmk was used for rescue experiments. Results In type 2 diabetic patients, serum EPO level decreased with the duration of diabetes, which was linked to reduced kidney function. Human recombinant EPO supplementation ameliorated proteinuria in diabetic nephropathy patients. In zebrafish, loss-of-function studies for EPO and EPOR, showed morphological and functional alterations within the pronephros, adversely affecting pronephric structure, leading to slit diaphragm dysfunction by increasing apoptosis within the pronephros. Induction of hyperglycemia in zebrafish embryos induced pronephros alterations which were further worsened upon silencing of EPO expression. Conclusions EPO was identified as a direct renal protective factor, promoting renal embryonic development and protecting kidneys from hyperglycemia induced nephropathy. EPO exhibited renal protective and proteinuria ameliorating function in type 2 DM patients and in hyperglycemic zebrafish embryos. Enhanced co-expression of EPO and EPOR was identified in both glomeruli and tubuli of DN patients. EPO and its receptor directly regulate physiological kidney development via repressing apoptosis.
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Affiliation(s)
- Jianqing She
- Department of Cardiology, First Affiliated Hospital of Xi'an Jiaotong University, 710048 Xi'an, People's Republic of China; Department of Vascular Biology and Tumor Angiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Zuyi Yuan
- Department of Cardiology, First Affiliated Hospital of Xi'an Jiaotong University, 710048 Xi'an, People's Republic of China
| | - Yue Wu
- Department of Cardiology, First Affiliated Hospital of Xi'an Jiaotong University, 710048 Xi'an, People's Republic of China
| | - Junfang Chen
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Jens Kroll
- Department of Vascular Biology and Tumor Angiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany.
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10
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Ajibade TO, Oyagbemi AA, Durotoye LA, Omóbòwálé TO, Asenuga ER, Olayemi FO. Modulatory effects of melatonin and vitamin C on oxidative stress-mediated haemolytic anaemia and associated cardiovascular dysfunctions in rats. JOURNAL OF COMPLEMENTARY & INTEGRATIVE MEDICINE 2017; 14:/j/jcim.ahead-of-print/jcim-2015-0082/jcim-2015-0082.xml. [PMID: 28237973 DOI: 10.1515/jcim-2015-0082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 08/15/2016] [Indexed: 01/31/2023]
Abstract
Background Phenylhydrazine (PHE) in experimental animal models has been widely reported to cause haemolytic anaemia, via the induction of oxidative stress and thus causing deleterious cardiovascular complications. Hence, this study was designed to evaluate the possible modulatory role of melatonin (MLT) or vitamin C when co-administered with PHE. Methods Anaemia was established with PHE administration. MLT or vitamin C was co-administered with PHE. Haematological parameters, markers of oxidative stress, enzymic and non-enzymic antioxidants, blood pressure and electrocardiograms were assessed. Results PHE administration led to a significant (p<0.05) increase in malondialdehyde (MDA), and hydrogen peroxide (H2O2) generated in cardiac, renal and red blood cell (RBC) lysates. PHE also significantly reduced the activity of glutathione peroxidase (GPx), superoxide dismutase (SOD) and reduced glutathione (GSH) contents, respectively. The RBC counts, haemoglobin (Hb) concentration and packed cell volume (PCV) were also significantly reduced following the administration of PHE. Furthermore, the systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MABP) increased significantly in rats administered PHE alone. Similarly, PHE administration led to a significant drop in heart rate but prolonged QRS, QT and QTc interval. Pathology of the heart and kidney was also observed in PHE treated group. However, treatment with MLT and vitamin C improved enzymic and non-enzymic antioxidant system together with the restoration of SBP, DBP and MABP to near normal. The architectural anarchy observed in the heart and kidney of PHE administered rats was reversed to some extent. Conclusions Hence, MLT and vitamin C could be employed as therapeutic targets in various cardiovascular diseases and its complications.
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11
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Brown FC, Collett M, Tremblay CS, Rank G, De Camilli P, Booth CJ, Bitoun M, Robinson PJ, Kile BT, Jane SM, Curtis DJ. Loss of Dynamin 2 GTPase function results in microcytic anaemia. Br J Haematol 2017; 178:616-628. [PMID: 28466468 DOI: 10.1111/bjh.14709] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 01/27/2017] [Indexed: 12/24/2022]
Abstract
In a dominant mouse ethylnitrosurea mutagenesis screen for genes regulating erythropoiesis, we identified a pedigree with a novel microcytic hypochromia caused by a V235G missense mutation in Dynamin 2 (Dnm2). Mutations in Dnm2, a GTPase, are highly disease-specific and have been implicated in four forms of human diseases: centronuclear myopathy, Charcot-Marie Tooth neuropathy and, more recently, T-cell leukaemia and Hereditary Spastic Paraplegia, but red cell abnormalities have not been reported to date. The V235G mutation lies within a crucial GTP nucleotide-binding pocket of Dnm2, and resulted in defective GTPase activity and incompatibility with life in the homozygous state. Dnm2 is an essential mediator of clathrin-mediated endocytosis, which is required for the uptake of transferrin (Tf) into red cells for incorporation of haem. Accordingly, we observed significantly reduced Tf uptake by Dnm2+/V235G cells, which led to impaired endosome formation. Despite these deficiencies, surprisingly all iron studies were unchanged, suggesting an unexplained alternative mechanism underlies microcytic anaemia in Dnm2+/V235G mice. This study provides the first in vivo evidence for the requirements of Dnm2 in normal erythropoiesis.
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Affiliation(s)
- Fiona C Brown
- Australian Centre for Blood Diseases, Central Clinical School, Monash University and Alfred Health, Melbourne, Vic., Australia
| | - Michael Collett
- Cell Signalling Unit, Children's Medical Research Institute, The University of Sydney, Sydney, NSW, Australia
| | - Cedric S Tremblay
- Australian Centre for Blood Diseases, Central Clinical School, Monash University and Alfred Health, Melbourne, Vic., Australia
| | - Gerhard Rank
- Rotary Bone Marrow Research Laboratory, Royal Melbourne Hospital, Melbourne, Vic., Australia
| | - Pietro De Camilli
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Carmen J Booth
- Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Marc Bitoun
- Research Centre for Myology, UPMC Univ Paris 06 and INSERM UMRS 974, CNRS FRE 3617, Institute of Myology, Paris, France
| | - Phillip J Robinson
- Cell Signalling Unit, Children's Medical Research Institute, The University of Sydney, Sydney, NSW, Australia
| | - Benjamin T Kile
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Vic., Australia
| | - Stephen M Jane
- Australian Centre for Blood Diseases, Central Clinical School, Monash University and Alfred Health, Melbourne, Vic., Australia
| | - David J Curtis
- Australian Centre for Blood Diseases, Central Clinical School, Monash University and Alfred Health, Melbourne, Vic., Australia
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12
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Nishimura Y, Hsu HH, Wang PC. Detection of initial angiogenesis from dorsal aorta into metanephroi and elucidation of its role in kidney development. Regen Ther 2016; 4:27-35. [PMID: 31245485 PMCID: PMC6581801 DOI: 10.1016/j.reth.2016.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 12/13/2015] [Accepted: 01/06/2016] [Indexed: 12/13/2022] Open
Abstract
Reconstruction of blood vessels is considered the most difficult part for the complicated organs, therefore, blood vessel construction is regarded as a key point for kidney regeneration in vitro. Vasculogenesis and angiogenesis are the two mechanisms to form blood vessels in embryonic organs, and most studies resided in vaculogenesis. Angiogenesis resided mostly in adult diseases such as wound healing, growth of tumors, and psoriasis diseases. However, renal angiogenesis is simply attributed to the sprouting of pre-existing blood vessel from dorsal aorta into metanephroi, and its occurrence is considered to be at a late stage of metanephric development. Since no techniques are available for delicate detection, the initial angiogenesis from dorsal aorta into metanephroi as well as its role in kidney development still remained unclear. In this study, we developed a method to detect the initial angiogenesis of dorsal aorta into metanephroi, and firstly clarified that dorsal aorta angiogenesis occurred at an early stage of metanephric development. We also elucidated the role of dorsal aorta angiogenesis in promoting the early blood vessel formation, tubule formation and glomeruli maturation. It is suggested that blood flow and dynamic circulation of various factors at the early developing stage may be prerequisite to a successful construction of blood vessels in the complicated organs either in vitro or in vivo. These findings contribute to a better understanding of dorsal aorta angiogenesis during kidney development and shed light on its significant value for the application of tissue engineering to complicated organs.
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Affiliation(s)
| | | | - Pi-Chao Wang
- Division of Bioindustrial Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba City, Ibaraki 305-8572, Japan
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13
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Kobayashi H, Liu Q, Binns TC, Urrutia AA, Davidoff O, Kapitsinou PP, Pfaff AS, Olauson H, Wernerson A, Fogo AB, Fong GH, Gross KW, Haase VH. Distinct subpopulations of FOXD1 stroma-derived cells regulate renal erythropoietin. J Clin Invest 2016; 126:1926-38. [PMID: 27088801 DOI: 10.1172/jci83551] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 03/01/2016] [Indexed: 12/11/2022] Open
Abstract
Renal peritubular interstitial fibroblast-like cells are critical for adult erythropoiesis, as they are the main source of erythropoietin (EPO). Hypoxia-inducible factor 2 (HIF-2) controls EPO synthesis in the kidney and liver and is regulated by prolyl-4-hydroxylase domain (PHD) dioxygenases PHD1, PHD2, and PHD3, which function as cellular oxygen sensors. Renal interstitial cells with EPO-producing capacity are poorly characterized, and the role of the PHD/HIF-2 axis in renal EPO-producing cell (REPC) plasticity is unclear. Here we targeted the PHD/HIF-2/EPO axis in FOXD1 stroma-derived renal interstitial cells and examined the role of individual PHDs in REPC pool size regulation and renal EPO output. Renal interstitial cells with EPO-producing capacity were entirely derived from FOXD1-expressing stroma, and Phd2 inactivation alone induced renal Epo in a limited number of renal interstitial cells. EPO induction was submaximal, as hypoxia or pharmacologic PHD inhibition further increased the REPC fraction among Phd2-/- renal interstitial cells. Moreover, Phd1 and Phd3 were differentially expressed in renal interstitium, and heterozygous deficiency for Phd1 and Phd3 increased REPC numbers in Phd2-/- mice. We propose that FOXD1 lineage renal interstitial cells consist of distinct subpopulations that differ in their responsiveness to Phd2 inactivation and thus regulation of HIF-2 activity and EPO production under hypoxia or conditions of pharmacologic or genetic PHD inactivation.
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14
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Farsijani NM, Liu Q, Kobayashi H, Davidoff O, Sha F, Fandrey J, Ikizler TA, O'Connor PM, Haase VH. Renal epithelium regulates erythropoiesis via HIF-dependent suppression of erythropoietin. J Clin Invest 2016; 126:1425-37. [PMID: 26927670 DOI: 10.1172/jci74997] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 01/14/2016] [Indexed: 12/21/2022] Open
Abstract
The adult kidney plays a central role in erythropoiesis and is the main source of erythropoietin (EPO), an oxygen-sensitive glycoprotein that is essential for red blood cell production. Decreases of renal pO2 promote hypoxia-inducible factor 2-mediated (HIF-2-mediated) induction of EPO in peritubular interstitial fibroblast-like cells, which serve as the cellular site of EPO synthesis in the kidney. It is not clear whether HIF signaling in other renal cell types also contributes to the regulation of EPO production. Here, we used a genetic approach in mice to investigate the role of renal epithelial HIF in erythropoiesis. Specifically, we found that HIF activation in the proximal nephron via induced inactivation of the von Hippel-Lindau tumor suppressor, which targets the HIF-α subunit for proteasomal degradation, led to rapid development of hypoproliferative anemia that was associated with a reduction in the number of EPO-producing renal interstitial cells. Moreover, suppression of renal EPO production was associated with increased glucose uptake, enhanced glycolysis, reduced mitochondrial mass, diminished O2 consumption, and elevated renal tissue pO2. Our genetic analysis suggests that tubulointerstitial cellular crosstalk modulates renal EPO production under conditions of epithelial HIF activation in the kidney.
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15
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Phillips JK, Boyd R, Krockenberger MB, Burgio G. Progression of anemia and its relationship with renal function, blood pressure, and erythropoietin in rats with chronic kidney disease. Vet Clin Pathol 2015; 44:342-54. [DOI: 10.1111/vcp.12276] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jacqueline K. Phillips
- Australian School of Advanced Medicine; Macquarie University; Sydney NSW Australia
- School of Veterinary and Life Sciences; Murdoch University; Perth WA Australia
| | - Rochelle Boyd
- Australian School of Advanced Medicine; Macquarie University; Sydney NSW Australia
| | | | - Gaetan Burgio
- Australian School of Advanced Medicine; Macquarie University; Sydney NSW Australia
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16
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Kuzmac S, Grcevic D, Sucur A, Ivcevic S, Katavic V. Acute hematopoietic stress in mice is followed by enhanced osteoclast maturation in the bone marrow microenvironment. Exp Hematol 2014; 42:966-75. [DOI: 10.1016/j.exphem.2014.07.262] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 07/07/2014] [Accepted: 07/09/2014] [Indexed: 12/31/2022]
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17
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Coe LM, Madathil SV, Casu C, Lanske B, Rivella S, Sitara D. FGF-23 is a negative regulator of prenatal and postnatal erythropoiesis. J Biol Chem 2014; 289:9795-810. [PMID: 24509850 DOI: 10.1074/jbc.m113.527150] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Abnormal blood cell production is associated with chronic kidney disease (CKD) and cardiovascular disease (CVD). Bone-derived FGF-23 (fibroblast growth factor-23) regulates phosphate homeostasis and bone mineralization. Genetic deletion of Fgf-23 in mice (Fgf-23(-/-)) results in hypervitaminosis D, abnormal mineral metabolism, and reduced lymphatic organ size. Elevated FGF-23 levels are linked to CKD and greater risk of CVD, left ventricular hypertrophy, and mortality in dialysis patients. However, whether FGF-23 is involved in the regulation of erythropoiesis is unknown. Here we report that loss of FGF-23 results in increased hematopoietic stem cell frequency associated with increased erythropoiesis in peripheral blood and bone marrow in young adult mice. In particular, these hematopoietic changes are also detected in fetal livers, suggesting that they are not the result of altered bone marrow niche alone. Most importantly, administration of FGF-23 in wild-type mice results in a rapid decrease in erythropoiesis. Finally, we show that the effect of FGF-23 on erythropoiesis is independent of the high vitamin D levels in these mice. Our studies suggest a novel role for FGF-23 in erythrocyte production and differentiation and suggest that elevated FGF-23 levels contribute to the pathogenesis of anemia in patients with CKD and CVD.
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Affiliation(s)
- Lindsay M Coe
- From the Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York 10010
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18
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A mouse model of adult-onset anaemia due to erythropoietin deficiency. Nat Commun 2013; 4:1950. [PMID: 23727690 DOI: 10.1038/ncomms2950] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 04/30/2013] [Indexed: 12/14/2022] Open
Abstract
Erythropoietin regulates erythropoiesis in a hypoxia-inducible manner. Here we generate inherited super-anaemic mice (ISAM) as a mouse model of adult-onset anaemia caused by erythropoietin deficiency. ISAM express erythropoietin in the liver but lack erythropoietin production in the kidney. Around weaning age, when the major erythropoietin-producing organ switches from the liver to the kidney, ISAM develop anaemia due to erythropoietin deficiency, which is curable by administration of recombinant erythropoietin. In ISAM severe chronic anaemia enhances transgenic green fluorescent protein and Cre expression driven by the complete erythropoietin-gene regulatory regions, which facilitates efficient labelling of renal erythropoietin-producing cells. We show that the majority of cortical and outer medullary fibroblasts have the innate potential to produce erythropoietin, and also reveal a new set of erythropoietin target genes. ISAM are a useful tool for the evaluation of erythropoiesis-stimulating agents and to trace the dynamics of erythropoietin-producing cells.
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19
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Progress in detecting cell-surface protein receptors: the erythropoietin receptor example. Ann Hematol 2013; 93:181-92. [PMID: 24337485 PMCID: PMC3890056 DOI: 10.1007/s00277-013-1947-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 11/02/2013] [Indexed: 12/18/2022]
Abstract
Testing for the presence of specific cell-surface receptors (such as EGFR or HER2) on tumor cells is an integral part of cancer care in terms of treatment decisions and prognosis. Understanding the strengths and limitations of these tests is important because inaccurate results may occur if procedures designed to prevent false-negative or false-positive outcomes are not employed. This review discusses tests commonly used to identify and characterize cell-surface receptors, such as the erythropoietin receptor (EpoR). First, a summary is provided on the biology of the Epo/EpoR system, describing how EpoR is expressed on erythrocytic progenitors and precursors in the bone marrow where it mediates red blood cell production in response to Epo. Second, studies are described that investigated whether erythropoiesis-stimulating agents could stimulate tumor progression in cancer patients and whether EpoR is expressed and functional on tumor cells or on endothelial cells. The methods used in these studies included immunohistochemistry, Northern blotting, Western blotting, and binding assays. This review summarizes the strengths and limitations of these methods. Critically analyzing data from tests for cell-surface receptors such as EpoR requires understanding the techniques utilized and demonstrating that results are consistent with current knowledge about receptor biology.
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Liu Q, Davidoff O, Niss K, Haase VH. Hypoxia-inducible factor regulates hepcidin via erythropoietin-induced erythropoiesis. J Clin Invest 2012; 122:4635-44. [PMID: 23114598 DOI: 10.1172/jci63924] [Citation(s) in RCA: 229] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 09/06/2012] [Indexed: 02/06/2023] Open
Abstract
Iron demand in bone marrow increases when erythropoiesis is stimulated by hypoxia via increased erythropoietin (EPO) synthesis in kidney and liver. Hepcidin, a small polypeptide produced by hepatocytes, plays a central role in regulating iron uptake by promoting internalization and degradation of ferroportin, the only known cellular iron exporter. Hypoxia suppresses hepcidin, thereby enhancing intestinal iron uptake and release from internal stores. While HIF, a central mediator of cellular adaptation to hypoxia, directly regulates renal and hepatic EPO synthesis under hypoxia, the molecular basis of hypoxia/HIF-mediated hepcidin suppression in the liver remains unclear. Here, we used a genetic approach to disengage HIF activation from EPO synthesis and found that HIF-mediated suppression of the hepcidin gene (Hamp1) required EPO induction. EPO induction was associated with increased erythropoietic activity and elevated serum levels of growth differentiation factor 15. When erythropoiesis was inhibited pharmacologically, Hamp1 was no longer suppressed despite profound elevations in serum EPO, indicating that EPO by itself is not directly involved in Hamp1 regulation. Taken together, we provide in vivo evidence that Hamp1 suppression by the HIF pathway occurs indirectly through stimulation of EPO-induced erythropoiesis.
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Affiliation(s)
- Qingdu Liu
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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21
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Mille-Hamard L, Billat VL, Henry E, Bonnamy B, Joly F, Benech P, Barrey E. Skeletal muscle alterations and exercise performance decrease in erythropoietin-deficient mice: a comparative study. BMC Med Genomics 2012; 5:29. [PMID: 22748015 PMCID: PMC3473259 DOI: 10.1186/1755-8794-5-29] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 06/21/2012] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Erythropoietin (EPO) is known to improve exercise performance by increasing oxygen blood transport and thus inducing a higher maximum oxygen uptake (VO2max). Furthermore, treatment with (or overexpression of) EPO induces protective effects in several tissues, including the myocardium. However, it is not known whether EPO exerts this protective effect when present at physiological levels. Given that EPO receptors have been identified in skeletal muscle, we hypothesized that EPO may have a direct, protective effect on this tissue. Thus, the objectives of the present study were to confirm a decrease in exercise performance and highlight muscle transcriptome alterations in a murine EPO functional knock-out model (the EPO-d mouse). METHODS We determined VO2max peak velocity and critical speed in exhaustive runs in 17 mice (9 EPO-d animals and 8 inbred controls), using treadmill enclosed in a metabolic chamber. Mice were sacrificed 24h after a last exhaustive treadmill exercise at critical speed. The tibialis anterior and soleus muscles were removed and total RNA was extracted for microarray gene expression analysis. RESULTS The EPO-d mice's hematocrit was about 50% lower than that of controls (p<0.05) and their performance level was about 25% lower (p<0.001). A total of 1583 genes exhibited significant changes in their expression levels. However, 68 genes were strongly up-regulated (normalized ratio>1.4) and 115 were strongly down-regulated (normalized ratio<0.80). The transcriptome data mining analysis showed that the exercise in the EPO-d mice induced muscle hypoxia, oxidative stress and proteolysis associated with energy pathway disruptions in glycolysis and mitochondrial oxidative phosphorylation. CONCLUSIONS Our results showed that the lack of functional EPO induced a decrease in the aerobic exercise capacity. This decrease was correlated with the hematocrit and reflecting poor oxygen supply to the muscles. The observed alterations in the muscle transcriptome suggest that physiological concentrations of EPO exert both direct and indirect muscle-protecting effects during exercise. However, the signaling pathway involved in these protective effects remains to be described in detail.
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Affiliation(s)
- Laurence Mille-Hamard
- Unité de Biologie Intégrative des Adaptations à l'Exercice - INSERM 902, Genopole, F-91058, Evry, France.
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Abstract
PURPOSE OF REVIEW Acute anemic stress induces a physiological response that includes the rapid development of new erythrocytes. This process is referred to as stress erythropoiesis, which is distinct from steady state erythropoiesis. Much of what we know about stress erythropoiesis comes from the analysis of murine models. In this review, we will discuss our current understanding of the mechanisms that regulate stress erythropoiesis in mice and discuss outstanding questions in the field. RECENT FINDINGS Stress erythropoiesis occurs in the murine spleen, fetal liver and adult liver. The signals that regulate this process are Hedgehog, bone morphogenetic protein 4 (BMP4), stem cell factor and hypoxia. Recent findings show that stress erythropoiesis utilizes a population of erythroid-restricted self-renewing stress progenitors. Although the BMP4-dependent stress erythropoiesis pathway was first characterized during the recovery from acute anemia, analysis of a mouse model of chronic anemia demonstrated that activation of the BMP4-dependent stress erythropoiesis pathway provides compensatory erythropoiesis in response to chronic anemia as well. SUMMARY The BMP4-dependent stress erythropoiesis pathway plays a key role in the recovery from acute anemia and new data show that this pathway compensates for ineffective steady state erythropoiesis in a murine model of chronic anemia. The identification of a self-renewing population of stress erythroid progenitors in mice suggests that therapeutic manipulation of this pathway may be useful for the treatment of human anemia. However, the development of new therapies will await the characterization of an analogous pathway in humans.
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