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Bouten J, Declercq L, Boone J, Brocherie F, Bourgois JG. Apnoea as a novel method to improve exercise performance: A current state of the literature. Exp Physiol 2024. [PMID: 39031986 DOI: 10.1113/ep091905] [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: 04/18/2024] [Accepted: 06/25/2024] [Indexed: 07/22/2024]
Abstract
Acute breath-holding (apnoea) induces a spleen contraction leading to a transient increase in haemoglobin concentration. Additionally, the apnoea-induced hypoxia has been shown to lead to an increase in erythropoietin concentration up to 5 h after acute breath-holding, suggesting long-term haemoglobin enhancement. Given its potential to improve haemoglobin content, an important determinant for oxygen transport, apnoea has been suggested as a novel training method to improve aerobic performance. This review aims to provide an update on the current state of the literature on this topic. Although the apnoea-induced spleen contraction appears to be effective in improving oxygen uptake kinetics, this does not seem to transfer into immediately improved aerobic performance when apnoea is integrated into a warm-up. Furthermore, only long and intense apnoea protocols in individuals who are experienced in breath-holding show increased erythropoietin and reticulocytes. So far, studies on inexperienced individuals have failed to induce acute changes in erythropoietin concentration following apnoea. As such, apnoea training protocols fail to demonstrate longitudinal changes in haemoglobin mass and aerobic performance. The low hypoxic dose, as evidenced by minor oxygen desaturation, is likely insufficient to elicit a strong erythropoietic response. Apnoea therefore does not seem to be useful for improving aerobic performance. However, variations in apnoea, such as hypoventilation training at low lung volume and repeated-sprint training in hypoxia through short end-expiratory breath-holds, have been shown to induce metabolic adaptations and improve several physical qualities. This shows promise for application of dynamic apnoea in order to improve exercise performance. HIGHLIGHTS: What is the topic of this review? Apnoea is considered as an innovative method to improve performance. This review discusses the effectiveness of apnoea (training) on performance. What advances does it highlight? Although the apnoea-induced spleen contraction and the increase in EPO observed in freedivers seem promising to improve haematological variables both acutely and on the long term, they do not improve exercise performance in an athletic population. However, performing repeated sprints on end-expiratory breath-holds seems promising to improve repeated-sprint capacity.
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Affiliation(s)
- Janne Bouten
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
- Laboratory of Sport, Expertise and Performance (EA 7370), French Institute of Sport (INSEP), Paris, France
| | - Louise Declercq
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Jan Boone
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Franck Brocherie
- Laboratory of Sport, Expertise and Performance (EA 7370), French Institute of Sport (INSEP), Paris, France
| | - Jan G Bourgois
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
- Centre of Sports Medicine, Ghent University Hospital, Ghent, Belgium
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Lanser L, Plaikner M, Fauser J, Petzer V, Denicolò S, Haschka D, Neuwirt H, Stefanow K, Rudnicki M, Kremser C, Henninger B, Weiss G. Tissue Iron Distribution in Anemic Patients with End-Stage Kidney Disease: Results of a Pilot Study. J Clin Med 2024; 13:3487. [PMID: 38930016 PMCID: PMC11204586 DOI: 10.3390/jcm13123487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 06/07/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
Background/Objectives: Anemia is a frequent multifactorial co-morbidity in end-stage kidney disease (ESKD) associated with morbidity and poor QoL. Apart from insufficient erythropoietin formation, iron deficiency (ID) contributes to anemia development. Identifying patients in need of iron supplementation with current ID definitions is difficult since no good biomarker is available to detect actual iron needs. Therefore, new diagnostic tools to guide therapy are needed. Methods: We performed a prospective cohort study analyzing tissue iron content with MRI-based R2*-relaxometry in 20 anemic ESKD patients and linked it with iron biomarkers in comparison to 20 otherwise healthy individuals. Results: ESKD patients had significantly higher liver (90.1 s-1 vs. 36.1 s-1, p < 0.001) and spleen R2* values (119.8 s-1 vs. 19.3 s-1, p < 0.001) compared to otherwise healthy individuals, while their pancreas and heart R2* values did not significantly differ. Out of the 20 ESKD patients, 17 had elevated spleen and 12 had elevated liver R2* values. KDIGO guidelines (focusing on serum iron parameters) would recommend iron supplementation in seven patients with elevated spleen and four patients with elevated liver R2* values. Conclusions: These findings highlight that liver and especially spleen iron concentrations are significantly higher in ESKD patients compared to controls. Tissue iron overload diverged from classical iron parameters suggesting need of iron supplementation. Measurement of MRI-guided tissue iron distribution might help guide treatment of anemic ESKD patients.
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Affiliation(s)
- Lukas Lanser
- Department of Internal Medicine II, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Michaela Plaikner
- Department of Radiology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Josia Fauser
- Department of Internal Medicine V, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Verena Petzer
- Department of Internal Medicine V, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Sara Denicolò
- Department of Internal Medicine IV, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - David Haschka
- Department of Internal Medicine II, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Hannes Neuwirt
- Department of Internal Medicine IV, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Kiril Stefanow
- Department of Internal Medicine IV, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Michael Rudnicki
- Department of Internal Medicine IV, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Christian Kremser
- Department of Radiology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Benjamin Henninger
- Department of Radiology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Guenter Weiss
- Department of Internal Medicine II, Medical University of Innsbruck, 6020 Innsbruck, Austria
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Dou X, Chen Z, Liu Y, Li Y, Ye J, Lu L. Zebrafish mutants in egln1 display a hypoxic response and develop polycythemia. Life Sci 2024; 344:122564. [PMID: 38492922 DOI: 10.1016/j.lfs.2024.122564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/10/2024] [Accepted: 03/13/2024] [Indexed: 03/18/2024]
Abstract
AIMS Prolyl hydroxylase domain 2 (PHD2), encoded by the Egln1 gene, serves as a pivotal regulator of the hypoxia-inducible factor (HIF) pathway and acts as a cellular oxygen sensor. Somatic inactivation of Phd2 in mice results in polycythemia and congestive heart failure. However, due to the embryonic lethality of Phd2 deficiency, its role in development remains elusive. Here, we investigated the function of two egln1 paralogous genes, egln1a and egln1b, in zebrafish. MAIN METHODS The egln1 null zebrafish were generated using the CRISPR/Cas9 system. Quantitative real-time PCR assays and Western blot analysis were employed to detect the effect of egln1 deficiency on the hypoxia signaling pathway. The hypoxia response of egln1 mutant zebrafish were assessed by analyzing heart rate, gill agitation frequency, and blood flow velocity. Subsequently, o-dianisidine staining and in situ hybridization were used to investigate the role of egln1 in zebrafish hematopoietic function. KEY FINDINGS Our data show that the loss of egln1a or egln1b individually has no visible effects on growth rate. However, the egln1a; egln1b double mutant displayed significant growth retardation and elevated mortality at around 2.5 months old. Both egln1a-null and egln1b-null zebrafish embryo exhibited enhanced tolerance to hypoxia, systemic hypoxic response that include hif pathway activation, increased cardiac activity, and polycythemia. SIGNIFICANCE Our research introduces zebrafish egln1 mutants as the first congenital embryonic viable systemic vertebrate animal model for PHD2, providing novel insights into hypoxic signaling and the progression of PHD2- associated disease.
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Affiliation(s)
- Xuehan Dou
- Laboratory for Marine Drugs and Bioproducts of Laoshan Laboratory, Qingdao, China; Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China
| | - Zhongyuan Chen
- Laboratory for Marine Drugs and Bioproducts of Laoshan Laboratory, Qingdao, China; Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China
| | - Yunzhang Liu
- Laboratory for Marine Drugs and Bioproducts of Laoshan Laboratory, Qingdao, China; Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China
| | - Yun Li
- Laboratory for Marine Drugs and Bioproducts of Laoshan Laboratory, Qingdao, China; Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China
| | - Junli Ye
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Ling Lu
- Laboratory for Marine Drugs and Bioproducts of Laoshan Laboratory, Qingdao, China; Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China.
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Şoroğlu CV, Uslu-Bıçak İ, Toprak SF, Yavuz AS, Sözer S. Effect of hypoxia on HIF-1α and NOS3 expressions in CD34 + cells of JAK2V617F-positive myeloproliferative neoplasms. Adv Med Sci 2023; 68:169-175. [PMID: 37075583 DOI: 10.1016/j.advms.2023.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 02/20/2023] [Accepted: 03/25/2023] [Indexed: 04/21/2023]
Abstract
PURPOSE Myeloproliferative neoplasms (MPN) are a heterogeneous group of hematopoietic stem-cell diseases with excessive proliferation of one or more blood cell lines. In this study, we evaluated the effect of different oxygen concentrations on HIF-1α and NOS3 gene expression to determine the effect of the bone marrow microenvironment on JAK2V617F positive Philadelphia chromosome negative (Ph-) MPNs. PATIENTS AND METHODS Peripheral blood mononuclear cells (MNC) of 12 patients with Ph- MPN were collected. The presence of JAK2V617F allele status was determined with allele-specific nested PCR analysis. MPN CD34+ and CD34depleted populations were isolated from MNC by magnetic beads. Separate cell cultures of CD34+/depleted populations were managed at different oxygen concentrations including anoxia (∼0%), hypoxia (∼3%), and normoxia (∼20%) conditions for 24 h. HIF-1α and NOS3 gene expression changes were examined in each population related to JAK2V617F status with real time RT-PCR. RESULT It was revealed that relative HIF-1α and NOS3 expressions were significantly increased in response to decreased oxygen concentration in all samples. Relative HIF-1α and NOS3 expressions were found to be higher especially in CD34+ and CD34depleted populations carrying JAK2V617F mutations compared to MPN patients carrying wild-type JAK2. CONCLUSION JAK2V617F might have specific role in HIF-1α and NOS3 regulations with respect to low oxygen concentrations in Ph- MPN. Further evaluations might reveal the effect of JAK2V617F on Ph- MPN pathogenesis in bone marrow microenvironment.
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Affiliation(s)
- Can Veysel Şoroğlu
- Department of Genetics, Aziz Sancar Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey; Institute of Health Sciences, Istanbul University, Istanbul, Turkey
| | - İldeniz Uslu-Bıçak
- Department of Genetics, Aziz Sancar Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey; Institute of Health Sciences, Istanbul University, Istanbul, Turkey
| | - Selin Fulya Toprak
- Department of Genetics, Aziz Sancar Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey; Institute of Health Sciences, Istanbul University, Istanbul, Turkey
| | - Akif Selim Yavuz
- Division of Hematology, Department of Internal Medicine, Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Selçuk Sözer
- Department of Genetics, Aziz Sancar Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey.
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Gangat N, Szuber N, Tefferi A. JAK2 unmutated erythrocytosis: 2023 Update on diagnosis and management. Am J Hematol 2023; 98:965-981. [PMID: 36966432 DOI: 10.1002/ajh.26920] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/18/2023] [Accepted: 03/22/2023] [Indexed: 03/27/2023]
Abstract
DISEASE OVERVIEW JAK2 unmutated or non-polycythemia vera (PV) erythrocytosis encompasses a heterogenous spectrum of hereditary and acquired entities. DIAGNOSIS Foremost in the evaluation of erythrocytosis is the exclusion of PV through JAK2 (inclusive of exons 12-15) mutation screening. Initial assessment should also include gathering of previous records on hematocrit (Hct) and hemoglobin (Hgb) levels, in order to streamline the diagnostic process by first distinguishing longstanding from acquired erythrocytosis; subsequent subcategorization is facilitated by serum erythropoietin (Epo) measurement, germline mutation screening, and review of historical data, including comorbid conditions and medication list. Hereditary erythrocytosis constitutes the main culprit in the context of longstanding erythrocytosis, especially when associated with a positive family history. In this regard, a subnormal serum Epo level suggests EPO receptor mutation. Otherwise, considerations include those associated with decreased (high oxygen affinity Hgb variants, 2,3-bisphosphoglycerate deficiency, PIEZO1 mutations, methemoglobinemia) or normal oxygen tension at 50% Hgb saturation (P50). The latter include germline oxygen sensing pathway (HIF2A-PHD2-VHL) and other rare mutations. Acquired erythrocytosis commonly results from central (e.g., cardiopulmonary disease, high-altitude habitat) or peripheral (e.g., renal artery stenosis) hypoxia. Other noteworthy conditions associated with acquired erythrocytosis include Epo-producing tumors (e.g., renal cell carcinoma, cerebral hemangioblastoma) and drugs (e.g., testosterone, erythropoiesis stimulating agents, sodium-glucose cotransporter-2 inhibitors). Idiopathic erythrocytosis is an ill-defined terminology that presumes the existence of an increased Hgb/Hct level without an identifiable etiology. Such classification often lacks accounting for normal outliers and is marred by truncated diagnostic evaluation. MANAGEMENT Current consensus treatment guidelines are not supported by hard evidence and their value is further undermined by limited phenotypic characterization and unfounded concerns for thrombosis. We are of the opinion that cytoreductive therapy and indiscriminate use of phlebotomy should be avoided in the treatment of non-clonal erythrocytosis. However, it is reasonable to consider therapeutic phlebotomy if one were to demonstrate value in symptom control, with frequency determined by symptoms rather than Hct level. In addition, cardiovascular risk optimization and low dose aspirin is often advised. FUTURE DIRECTIONS Advances in molecular hematology might result in better characterization of "idiopathic erythrocytosis" and expansion of the repertoire for germline mutations in hereditary erythrocytosis. Prospective controlled studies are needed to clarify potential pathology from JAK2 unmutated erythrocytosis, as well as to document the therapeutic value of phlebotomy.
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Affiliation(s)
- Naseema Gangat
- Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Natasha Szuber
- Department of Hematology, Université de Montréal, Montréal, Quebec, Canada
| | - Ayalew Tefferi
- Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
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Rahbar Saadat Y, Hosseiniyan Khatibi SM, Sani A, Zununi Vahed S, Ardalan M. Ischemic tubular injury: Oxygen-sensitive signals and metabolic reprogramming. Inflammopharmacology 2023:10.1007/s10787-023-01232-x. [PMID: 37131045 DOI: 10.1007/s10787-023-01232-x] [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: 07/23/2022] [Accepted: 03/21/2023] [Indexed: 05/04/2023]
Abstract
The kidneys are the most vulnerable organs to severe ischemic insult that results in cellular hypoxia under pathophysiological conditions. Large amounts of oxygen are consumed by the kidneys, mainly to produce energy for tubular reabsorption. Beyond high oxygen demand and the low oxygen supply, different other factors make kidneys vulnerable to ischemia which is deemed to be a major cause of acute kidney injury (AKI). On the other hand, kidneys are capable of sensing and responding to oxygen alternations to evade harms resulting from inadequate oxygen. The hypoxia-inducible factor (HIF) is the main conserved oxygen-sensing mechanism that maintains homeostasis under hypoxia through direct/indirect regulation of several genes that contribute to metabolic adaptation, angiogenesis, energy conservation, erythropoiesis, and so on. In response to oxygen availability, prolyl-hydroxylases (PHDs) control the HIF stability. This review focuses on the oxygen-sensing mechanisms in kidneys, particularly in proximal tubular cells (PTCs) and discusses the molecules involved in ischemic response and metabolic reprogramming. Moreover, the possible roles of non-coding RNAs (microRNAs and long non-coding RNAs) in the development of ischemic AKI are put forward.
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Affiliation(s)
| | | | - Anis Sani
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
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Zhang P, Bai L, Tong Y, Guo S, Lu W, Yuan Y, Wang W, Jin Y, Gao P, Liu J. CIRP attenuates acute kidney injury after hypothermic cardiovascular surgery by inhibiting PHD3/HIF-1α-mediated ROS-TGF-β1/p38 MAPK activation and mitochondrial apoptotic pathways. Mol Med 2023; 29:61. [PMID: 37127576 PMCID: PMC10152741 DOI: 10.1186/s10020-023-00655-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 04/18/2023] [Indexed: 05/03/2023] Open
Abstract
BACKGROUND The ischemia-reperfusion (IR) environment during deep hypothermic circulatory arrest (DHCA) cardiovascular surgery is a major cause of acute kidney injury (AKI), which lacks preventive measure and treatment. It was reported that cold inducible RNA-binding protein (CIRP) can be induced under hypoxic and hypothermic stress and may have a protective effect on multiple organs. The purpose of this study was to investigate whether CIRP could exert renoprotective effect during hypothermic IR and the potential mechanisms. METHODS Utilizing RNA-sequencing, we compared the differences in gene expression between Cirp knockout rats and wild-type rats after DHCA and screened the possible mechanisms. Then, we established the hypothermic oxygen-glucose deprivation (OGD) model using HK-2 cells transfected with siRNA to verify the downstream pathways and explore potential pharmacological approach. The effects of CIRP and enarodustat (JTZ-951) on renal IR injury (IRI) were investigated in vivo and in vitro using multiple levels of pathological and molecular biological experiments. RESULTS We discovered that Cirp knockout significantly upregulated rat Phd3 expression, which is the key regulator of HIF-1α, thereby inhibiting HIF-1α after DHCA. In addition, deletion of Cirp in rat model promoted apoptosis and aggravated renal injury by reactive oxygen species (ROS) accumulation and significant activation of the TGF-β1/p38 MAPK inflammatory pathway. Then, based on the HK-2 cell model of hypothermic OGD, we found that CIRP silencing significantly stimulated the expression of the TGF-β1/p38 MAPK inflammatory pathway by activating the PHD3/HIF-1α axis, and induced more severe apoptosis through the mitochondrial cytochrome c-Apaf-1-caspase 9 and FADD-caspase 8 death receptor pathways compared with untransfected cells. However, silencing PHD3 remarkably activated the expression of HIF-1α and alleviated the apoptosis of HK-2 cells in hypothermic OGD. On this basis, by pretreating HK-2 and rats with enarodustat, a novel HIF-1α stabilizer, we found that enarodustat significantly mitigated renal cellular apoptosis under hypothermic IR and reversed the aggravated IRI induced by CIRP defect, both in vitro and in vivo. CONCLUSION Our findings indicated that CIRP may confer renoprotection against hypothermic IRI by suppressing PHD3/HIF-1α-mediated apoptosis. PHD3 inhibitors and HIF-1α stabilizers may have clinical value in renal IRI.
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Affiliation(s)
- Peiyao Zhang
- State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 102308, China
- Department of Cardiopulmonary Bypass, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No.167, North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Liting Bai
- Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China
| | - Yuanyuan Tong
- Department of Anesthesiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
| | - Shengwen Guo
- Department of Anesthesiology, Xiamen Cardiovascular Hospital, Xiamen University, Xiamen, Fujian, 361000, China
| | - Wenlong Lu
- State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 102308, China
| | - Yue Yuan
- Department of Endocrinology, Drum Tower Hospital affiliated to Nanjing University Medical School, Branch of National Clinical Research Centre for Metabolic Diseases, Nanjing, Jiangsu, 210008, China
| | - Wenting Wang
- Department of Cardiopulmonary Bypass, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No.167, North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Yu Jin
- Department of Cardiopulmonary Bypass, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No.167, North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Peng Gao
- Department of Cardiopulmonary Bypass, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No.167, North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Jinping Liu
- Department of Cardiopulmonary Bypass, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No.167, North Lishi Road, Xicheng District, Beijing, 100037, China.
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Elliott J. Therapeutics of managing reduced red cell mass associated with chronic kidney disease - Is there a case for earlier intervention? J Vet Pharmacol Ther 2023; 46:145-157. [PMID: 37036059 DOI: 10.1111/jvp.13127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/27/2023] [Accepted: 03/28/2023] [Indexed: 04/11/2023]
Abstract
Reduced red cell mass is a poor prognostic indicator in chronic kidney disease (CKD) patients. Whilst overt anaemia impacts on the quality of life of patients with CKD, lowered red cell mass may also compromise oxygen delivery to proximal tubular cells and contribute to progressive kidney injury. Epidemiological data from cats with CKD support this hypothesis although controlled interventional studies involving drugs that raise red cell mass in trials designed to test this hypothesis are lacking in both human and veterinary medicine. Recombinant analogues of erythropoietin (EPO) are currently standard of care for human CKD patients where low red cell mass impacts on their quality of life. Resistance to EPO is encountered in 20% to 40% of patients treated, probably due to functional iron deficiency, reflecting the difficulties of managing iron deficiency associated with the chronic inflammation of CKD. Similar issues are likely faced in managing anaemia in feline CKD although published data on the use of human EPO analogues are limited as such treatment in cats risks antibody formation resulting in red cell aplasia and transfusion dependency and so is reserved for late stage cases only. This article reviews the recent alternative therapeutic approach to increase red cell mass using HIF-prolyl hydroxylase inhibitors and explains their mode of action and theoretical advantages over EPO analogues in the context of iron metabolism. The results of human clinical trials and the potential benefit of adopting this approach in feline CKD patients are discussed.
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Affiliation(s)
- Jonathan Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, NW1 0TU, UK
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Ren Z, Potenza DM, Ma Y, Ajalbert G, Hoogewijs D, Ming XF, Yang Z. Role of Arginase-II in Podocyte Injury under Hypoxic Conditions. Biomolecules 2022; 12:biom12091213. [PMID: 36139052 PMCID: PMC9496188 DOI: 10.3390/biom12091213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/25/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022] Open
Abstract
Hypoxia plays a crucial role in acute and chronic renal injury, which is attributable to renal tubular and glomerular cell damage. Some studies provide evidence that hypoxia-dependent upregulation of the mitochondrial enzyme arginase type-II (Arg-II) in tubular cells promotes renal tubular injury. It is, however, not known whether Arg-II is also expressed in glomerular cells, particularly podocytes under hypoxic conditions, contributing to hypoxia-induced podocyte injury. The effects of hypoxia on human podocyte cells (AB8/13) in cultures and on isolated kidneys from wild-type (wt) and arg-ii gene-deficient (arg-ii−/−) mice ex vivo, as well as on mice of the two genotypes in vivo, were investigated, respectively. We found that the Arg-II levels were enhanced in cultured podocytes in a time-dependent manner over 48 h, which was dependent on the stabilization of hypoxia-inducible factor 1α (HIF1α). Moreover, a hypoxia-induced derangement of cellular actin cytoskeletal fibers, a decrease in podocin, and an increase in mitochondrial ROS (mtROS) generation—as measured by MitoSOX—were inhibited by adenoviral-mediated arg-ii gene silencing. These effects of hypoxia on podocyte injury were mimicked by the HIFα stabilizing drug DMOG, which inhibits prolyl hydroxylases (PHD), the enzymes involved in HIFα degradation. The silencing of arg-ii prevented the detrimental effects of DMOG on podocytes. Furthermore, the inhibition of mtROS generation by rotenone—the inhibitor of respiration chain complex-I—recapitulated the protective effects of arg-ii silencing on podocytes under hypoxic conditions. Moreover, the ex vivo experiments with isolated kidney tissues and the in vivo experiments with mice exposed to hypoxic conditions showed increased Arg-II levels in podocytes and decreased podocyte markers regarding synaptopodin in wt mice but not in arg-ii−/− mice. While age-associated albuminuria was reduced in the arg-ii−/− mice, the hypoxia-induced increase in albuminuria was, however, not significantly affected in the arg-ii−/−. Our study demonstrates that Arg-II in podocytes promotes cell injury. Arg-ii ablation seems insufficient to protect mice in vivo against a hypoxia-induced increase in albuminuria, but it does reduce albuminuria in aging.
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Affiliation(s)
- Zhilong Ren
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
- Department of Nephrology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Duilio Michele Potenza
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Yiqiong Ma
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
- Department of Nephrology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Guillaume Ajalbert
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - David Hoogewijs
- Integrative Oxygen Physiology, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Xiu-Fen Ming
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
- Correspondence: (X.-F.M.); (Z.Y.); Tel.: +41-26-300-85-93 (Z.Y.)
| | - Zhihong Yang
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
- Correspondence: (X.-F.M.); (Z.Y.); Tel.: +41-26-300-85-93 (Z.Y.)
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Dahl SL, Bapst AM, Khodo SN, Scholz CC, Wenger RH. Fount, fate, features, and function of renal erythropoietin-producing cells. Pflugers Arch 2022; 474:783-797. [PMID: 35750861 PMCID: PMC9338912 DOI: 10.1007/s00424-022-02714-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 05/18/2022] [Accepted: 05/27/2022] [Indexed: 12/19/2022]
Abstract
Renal erythropoietin (Epo)-producing (REP) cells represent a rare and incompletely understood cell type. REP cells are fibroblast-like cells located in close proximity to blood vessels and tubules of the corticomedullary border region. Epo mRNA in REP cells is produced in a pronounced "on-off" mode, showing transient transcriptional bursts upon exposure to hypoxia. In contrast to "ordinary" fibroblasts, REP cells do not proliferate ex vivo, cease to produce Epo, and lose their identity following immortalization and prolonged in vitro culture, consistent with the loss of Epo production following REP cell proliferation during tissue remodelling in chronic kidney disease. Because Epo protein is usually not detectable in kidney tissue, and Epo mRNA is only transiently induced under hypoxic conditions, transgenic mouse models have been developed to permanently label REP cell precursors, active Epo producers, and inactive descendants. Future single-cell analyses of the renal stromal compartment will identify novel characteristic markers of tagged REP cells, which will provide novel insights into the regulation of Epo expression in this unique cell type.
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Affiliation(s)
- Sophie L Dahl
- Institute of Physiology and National Centre of Competence in Research "Kidney.CH", University of Zürich, CH-8057, Zurich, Switzerland
| | - Andreas M Bapst
- Institute of Physiology and National Centre of Competence in Research "Kidney.CH", University of Zürich, CH-8057, Zurich, Switzerland
| | - Stellor Nlandu Khodo
- Institute of Physiology and National Centre of Competence in Research "Kidney.CH", University of Zürich, CH-8057, Zurich, Switzerland
| | - Carsten C Scholz
- Institute of Physiology and National Centre of Competence in Research "Kidney.CH", University of Zürich, CH-8057, Zurich, Switzerland
- Institute of Physiology, University Medicine Greifswald, D-17475, Greifswald, Germany
| | - Roland H Wenger
- Institute of Physiology and National Centre of Competence in Research "Kidney.CH", University of Zürich, CH-8057, Zurich, Switzerland.
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11
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Keppner A, Maric D, Orlando IMC, Falquet L, Hummler E, Hoogewijs D. Analysis of the Hypoxic Response in a Mouse Cortical Collecting Duct-Derived Cell Line Suggests That Esrra Is Partially Involved in Hif1α-Mediated Hypoxia-Inducible Gene Expression in mCCD cl1 Cells. Int J Mol Sci 2022; 23:7262. [PMID: 35806266 PMCID: PMC9267015 DOI: 10.3390/ijms23137262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/22/2022] [Accepted: 06/27/2022] [Indexed: 11/16/2022] Open
Abstract
The kidney is strongly dependent on a continuous oxygen supply, and is conversely highly sensitive to hypoxia. Controlled oxygen gradients are essential for renal control of solutes and urine-concentrating mechanisms, which also depend on various hormones including aldosterone. The cortical collecting duct (CCD) is part of the aldosterone-sensitive distal nephron and possesses a key function in fine-tuned distal salt handling. It is well known that aldosterone is consistently decreased upon hypoxia. Furthermore, a recent study reported a hypoxia-dependent down-regulation of sodium currents within CCD cells. We thus investigated the possibility that cells from the cortical collecting duct are responsive to hypoxia, using the mouse cortical collecting duct cell line mCCDcl1 as a model. By analyzing the hypoxia-dependent transcriptome of mCCDcl1 cells, we found a large number of differentially-expressed genes (3086 in total logFC< −1 or >1) following 24 h of hypoxic conditions (0.2% O2). A gene ontology analysis of the differentially-regulated pathways revealed a strong decrease in oxygen-linked processes such as ATP metabolic functions, oxidative phosphorylation, and cellular and aerobic respiration, while pathways associated with hypoxic responses were robustly increased. The most pronounced regulated genes were confirmed by RT-qPCR. The low expression levels of Epas1 under both normoxic and hypoxic conditions suggest that Hif-1α, rather than Hif-2α, mediates the hypoxic response in mCCDcl1 cells. Accordingly, we generated shRNA-mediated Hif-1α knockdown cells and found Hif-1α to be responsible for the hypoxic induction of established hypoxically-induced genes. Interestingly, we could show that following shRNA-mediated knockdown of Esrra, Hif-1α protein levels were unaffected, but the gene expression levels of Egln3 and Serpine1 were significantly reduced, indicating that Esrra might contribute to the hypoxia-mediated expression of these and possibly other genes. Collectively, mCCDcl1 cells display a broad response to hypoxia and represent an adequate cellular model to study additional factors regulating the response to hypoxia.
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Affiliation(s)
- Anna Keppner
- Section of Medicine, Department of Endocrinology, Metabolism and Cardiovascular System (EMC), Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland; (A.K.); (D.M.); (I.M.C.O.)
- National Center of Competence in Research Kidney Control of Homeostasis (NCCR Kidney.CH), University of Zurich, CH-8006 Zürich, Switzerland
| | - Darko Maric
- Section of Medicine, Department of Endocrinology, Metabolism and Cardiovascular System (EMC), Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland; (A.K.); (D.M.); (I.M.C.O.)
- National Center of Competence in Research Kidney Control of Homeostasis (NCCR Kidney.CH), University of Zurich, CH-8006 Zürich, Switzerland
| | - Ilaria Maria Christina Orlando
- Section of Medicine, Department of Endocrinology, Metabolism and Cardiovascular System (EMC), Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland; (A.K.); (D.M.); (I.M.C.O.)
| | - Laurent Falquet
- Section of Science, Department of Biology, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland;
| | - Edith Hummler
- Department of Biomedical Sciences, University of Lausanne, CH-1011 Lausanne, Switzerland;
| | - David Hoogewijs
- Section of Medicine, Department of Endocrinology, Metabolism and Cardiovascular System (EMC), Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland; (A.K.); (D.M.); (I.M.C.O.)
- National Center of Competence in Research Kidney Control of Homeostasis (NCCR Kidney.CH), University of Zurich, CH-8006 Zürich, Switzerland
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12
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Abstract
Cellular hypoxia occurs when the demand for sufficient molecular oxygen needed to produce the levels of ATP required to perform physiological functions exceeds the vascular supply, thereby leading to a state of oxygen depletion with the associated risk of bioenergetic crisis. To protect against the threat of hypoxia, eukaryotic cells have evolved the capacity to elicit oxygen-sensitive adaptive transcriptional responses driven primarily (although not exclusively) by the hypoxia-inducible factor (HIF) pathway. In addition to the canonical regulation of HIF by oxygen-dependent hydroxylases, multiple other input signals, including gasotransmitters, non-coding RNAs, histone modifiers and post-translational modifications, modulate the nature of the HIF response in discreet cell types and contexts. Activation of HIF induces various effector pathways that mitigate the effects of hypoxia, including metabolic reprogramming and the production of erythropoietin. Drugs that target the HIF pathway to induce erythropoietin production are now approved for the treatment of chronic kidney disease-related anaemia. However, HIF-dependent changes in cell metabolism also have profound implications for functional responses in innate and adaptive immune cells, and thereby heavily influence immunity and the inflammatory response. Preclinical studies indicate a potential use of HIF therapeutics to treat inflammatory diseases, such as inflammatory bowel disease. Understanding the links between HIF, cellular metabolism and immunity is key to unlocking the full therapeutic potential of drugs that target the HIF pathway. Hypoxia-dependent changes in cellular metabolism have important implications for the effective functioning of multiple immune cell subtypes. This Review describes the inputs that shape the hypoxic response in individual cell types and contexts, and the implications of this response for cellular metabolism and associated alterations in immune cell function. Hypoxia is a common feature of particular microenvironments and at sites of immunity and inflammation, resulting in increased activity of the hypoxia-inducible factor (HIF). In addition to hypoxia, multiple inputs modulate the activity of the HIF pathway, allowing nuanced downstream responses in discreet cell types and contexts. HIF-dependent changes in cellular metabolism mitigate the effects of hypoxia and ensure that energy needs are met under conditions in which oxidative phosphorylation is reduced. HIF-dependent changes in metabolism also profoundly affect the phenotype and function of immune cells. The immunometabolic effects of HIF have important implications for targeting the HIF pathway in inflammatory disease.
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Affiliation(s)
- Cormac T Taylor
- School of Medicine, The Conway Institute & Systems Biology Ireland, University College Dublin, Belfield, Dublin, Ireland.
| | - Carsten C Scholz
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,Institute of Physiology, University Medicine Greifswald, Greifswald, Germany
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13
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Dahl SL, Pfundstein S, Hunkeler R, Dong X, Knöpfel T, Spielmann P, Scholz CC, Nolan KA, Wenger RH. Fate-mapping of erythropoietin-producing cells in mouse models of hypoxaemia and renal tissue remodelling reveals repeated recruitment and persistent functionality. Acta Physiol (Oxf) 2022; 234:e13768. [PMID: 34982511 PMCID: PMC9286872 DOI: 10.1111/apha.13768] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 09/08/2021] [Accepted: 01/01/2022] [Indexed: 12/17/2022]
Abstract
Aim Fibroblast‐like renal erythropoietin (Epo) producing (REP) cells of the corticomedullary border region “sense” a decrease in blood oxygen content following anaemia or hypoxaemia. Burst‐like transcription of Epo during tissue hypoxia is transient and is lost during fibrotic tissue remodelling, as observed in chronic kidney disease. The reason for this loss of Epo expression is under debate. Therefore, we tested the hypothesis that REP cell migration, loss and/or differentiation may cause Epo inhibition. Methods Using a reporter mouse that allows permanent labelling of active REP cells at any given time point, we analysed the spatiotemporal fate of REP cells following their initial hypoxic recruitment in models of hypoxaemia and renal tissue remodelling. Results In long‐term tracing experiments, tagged REP reporter cells neither died, proliferated, migrated nor transdifferentiated into myofibroblasts. Approximately 60% of tagged cells re‐expressed Epo upon a second hypoxic stimulus. In an unilateral model of tissue remodelling, tagged cells proliferated and ceased to produce Epo before a detectable increase in myofibroblast markers. Treatment with a hypoxia‐inducible factor (HIF) stabilizing agent (FG‐4592/roxadustat) re‐induced Epo expression in the previously active REP cells of the damaged kidney to a similar extent as in the contralateral healthy kidney. Conclusions Rather than cell death or differentiation, these results suggest cell‐intrinsic transient inhibition of Epo transcription: following long‐term dormancy, REP cells can repeatedly be recruited by tissue hypoxia, and during myofibrotic tissue remodelling, dormant REP cells are efficiently rescued by a pharmaceutic HIF stabilizer, demonstrating persistent REP cell functionality even during phases of Epo suppression.
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Affiliation(s)
- Sophie L. Dahl
- Institute of Physiology University of Zurich Zurich Switzerland
- National Center of Competence in Research “Kidney.CH” Zurich Switzerland
| | - Svende Pfundstein
- Institute of Physiology University of Zurich Zurich Switzerland
- National Center of Competence in Research “Kidney.CH” Zurich Switzerland
| | - Rico Hunkeler
- Institute of Physiology University of Zurich Zurich Switzerland
- National Center of Competence in Research “Kidney.CH” Zurich Switzerland
| | - Xingtong Dong
- Institute of Physiology University of Zurich Zurich Switzerland
| | - Thomas Knöpfel
- Institute of Physiology University of Zurich Zurich Switzerland
| | | | - Carsten C. Scholz
- Institute of Physiology University of Zurich Zurich Switzerland
- National Center of Competence in Research “Kidney.CH” Zurich Switzerland
| | - Karen A. Nolan
- Institute of Physiology University of Zurich Zurich Switzerland
- National Center of Competence in Research “Kidney.CH” Zurich Switzerland
| | - Roland H. Wenger
- Institute of Physiology University of Zurich Zurich Switzerland
- National Center of Competence in Research “Kidney.CH” Zurich Switzerland
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14
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Jatho A, Zieseniss A, Brechtel-Curth K, Guo J, Böker KO, Salinas G, Wenger RH, Katschinski DM. The HIFα-Stabilizing Drug Roxadustat Increases the Number of Renal Epo-Producing Sca-1 + Cells. Cells 2022; 11:cells11040753. [PMID: 35203399 PMCID: PMC8869801 DOI: 10.3390/cells11040753] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 02/01/2023] Open
Abstract
Inhibition of the prolyl-4-hydroxylase domain (PHD) enzymes, leading to the stabilization of hypoxia-inducible factor (HIF) α as well as to the stimulation of erythropoietin (Epo) synthesis, is the functional mechanism of the new anti-anemia drug roxadustat. Little is known about the effects of roxadustat on the Epo-producing cell pool. To gain further insights into the function of PHD inhibitors, we characterized the abundance of mesenchymal stem cell (MSC)-like cells after roxadustat treatment of mice. The number of Sca-1+ mesenchymal cells following roxadustat treatment increased exclusively in the kidneys. Isolated Sca-1+ cells demonstrated typical features of MSC-like cells, including adherence to tissue culture plates, trilineage differentiation potential, and expression of MSC markers. Kidney-derived Sca-1+ MSC-like cells were cultured for up to 21 days. Within the first few days in culture, cells stabilized HIF-1α and HIF-2α and temporarily increased Epo production upon incubation in hypoxia. In summary, we have identified a Sca-1+ MSC-like cell population that is involved in renal Epo production and might contribute to the strong anti-anemic effect of the PHD inhibitor roxadustat.
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Affiliation(s)
- Aline Jatho
- Institute of Cardiovascular Physiology, University Medical Center Göttingen, Georg-August-University Göttingen, 37073 Goettingen, Germany; (A.Z.); (K.B.-C.); (J.G.)
- Correspondence: (A.J.); (D.M.K.)
| | - Anke Zieseniss
- Institute of Cardiovascular Physiology, University Medical Center Göttingen, Georg-August-University Göttingen, 37073 Goettingen, Germany; (A.Z.); (K.B.-C.); (J.G.)
| | - Katja Brechtel-Curth
- Institute of Cardiovascular Physiology, University Medical Center Göttingen, Georg-August-University Göttingen, 37073 Goettingen, Germany; (A.Z.); (K.B.-C.); (J.G.)
| | - Jia Guo
- Institute of Cardiovascular Physiology, University Medical Center Göttingen, Georg-August-University Göttingen, 37073 Goettingen, Germany; (A.Z.); (K.B.-C.); (J.G.)
| | - Kai Oliver Böker
- Department of Trauma Surgery, Orthopaedics and Plastic Surgery, University Medical Center Göttingen, Georg-August-University Göttingen, 37075 Goettingen, Germany;
| | - Gabriela Salinas
- NGS-Integrative Genomics Core Unit (NIG), Institute of Human Genetics, University Medical Center Göttingen, Georg-August-University Göttingen, 37073 Goettingen, Germany;
| | - Roland H. Wenger
- National Centre of Competence in Research “Kidney.CH”, 8057 Zurich, Switzerland;
- Institute of Physiology, University of Zürich, 8057 Zurich, Switzerland
| | - Dörthe M. Katschinski
- Institute of Cardiovascular Physiology, University Medical Center Göttingen, Georg-August-University Göttingen, 37073 Goettingen, Germany; (A.Z.); (K.B.-C.); (J.G.)
- Correspondence: (A.J.); (D.M.K.)
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15
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Cui Y, Li H, Yu SJ, Afedo SY, Bai XF. Effects of PHD and HSP90 on erythropoietin production in yak (Bos grunniens) renal interstitial fibroblast-like cells under hypoxia. J Mol Histol 2022; 53:395-411. [PMID: 35084636 DOI: 10.1007/s10735-021-10054-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 12/23/2021] [Indexed: 11/24/2022]
Abstract
Erythropoietin (EPO), a central protein of erythropoiesis, plays an important role during hypoxia adaptation and is regulated by hypoxia-inducible factor (HIF). However, there is no report on EPO-producing cells and their regulatory mechanisms in yak (Bos grunniens). To understand EPO production and regulation of yak, kidneys from different age of yak were collected and expression of EPO, hypoxia-inducible factor 1 alpha (HIF-1α), and hypoxia-inducible factor 2 alpha (HIF-2α) were detected. Then renal tubule epithelial cells (RTECs) and peritubular interstitial fibroblast-like (RIFs) cells were isolated and cultured to determine their EPO production abilities. Subsequently, the cells were treated with dimethyloxalylglycine (DMOG) and Geldanamycin (GA), which are inhibitors of prolyl-4-hydroxylase domain (PHD) and heat shock protein 90 (HSP90) respectively, and siRNAs of HIF-1α and HIF-2α to explore their effect on EPO production and regulation. The results showed that expressions of EPO, HIF-1α, and HIF-2α were different in the different age groups of yak. High DMOG concentration caused a corresponding increase in the levels of HIF-1α and HIF-2α in RIFs and RTECs, however, EPO levels increased in RIFs only and was not detected at any concentration in RTECs; suggesting that EPO was produced in RIFs. Upon treating RIFs with siRNAs of HIF-1α and HIF-2α, we found that EPO was regulated by PHD through HIF-2α. In addition, increasing GA concentration caused a decrease in expression of HSP90, HIF-1α, HIF-2α, and EPO in RIFs. In conclusion, these findings support our proposition that PHD regulates EPO via HIF-2α in yak RIFs, while HSP90 impelled EPO expression.
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Affiliation(s)
- Yan Cui
- College of Veterinary Medicine, Gansu Agricultural University, No. 1 Yingmen village, Anning District, Lanzhou, 730070, Gansu, People's Republic of China. .,Gansu Province Livestock Embryo Engineering Research Center, Gansu Agricultural University, Lanzhou, 730070, China.
| | - Hui Li
- College of Veterinary Medicine, Gansu Agricultural University, No. 1 Yingmen village, Anning District, Lanzhou, 730070, Gansu, People's Republic of China
| | - Si-Jiu Yu
- College of Veterinary Medicine, Gansu Agricultural University, No. 1 Yingmen village, Anning District, Lanzhou, 730070, Gansu, People's Republic of China.,Gansu Province Livestock Embryo Engineering Research Center, Gansu Agricultural University, Lanzhou, 730070, China
| | - Seth Yaw Afedo
- College of Veterinary Medicine, Gansu Agricultural University, No. 1 Yingmen village, Anning District, Lanzhou, 730070, Gansu, People's Republic of China
| | - Xue-Feng Bai
- College of Veterinary Medicine, Gansu Agricultural University, No. 1 Yingmen village, Anning District, Lanzhou, 730070, Gansu, People's Republic of China
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16
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Bouten J, Debusschere J, Lootens L, Declercq L, Van Eenoo P, Boone J, Bourgois JG. Six weeks of static apnea training does not affect Hbmass and exercise performance. J Appl Physiol (1985) 2022; 132:673-681. [PMID: 35050796 DOI: 10.1152/japplphysiol.00770.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
PURPOSE Acute apnea is known to induce decreases in oxyhemoglobin desaturation (SpO2) and increases in erythropoietin concentration ([EPO]). This study examined the potential of an apnea training program to induce erythropoiesis and increase hematological parameters and exercise performance. METHODS Twenty-two male subjects were randomly divided into an apnea and control group. The apnea group performed a 6-week apnea training program consisting of a daily series of 5 maximal static apneas. Before and after training, subjects visited the lab on three test days to perform 1) a ramp incremental test measuring V̇O2peak, 2) CO-rebreathing for Hb mass determination and a 3-km time trial and 3) an apnea test protocol with continuous finger SpO2 registration. Venous blood samples were drawn before and 180 minutes after the apnea test for analysis of [EPO]. RESULTS Minimal SpO2 reached during the apnea test protocol was 91 ±7% pre and 82 ±7% post apnea training. The apnea test protocol did not elicit an acute increase in [EPO] (p=0.685) before nor after the training program. Consequently, resting [EPO] (p=0.170), Hbmass (p=0.134), V̇O2peak (p=0.796) and 3-km cycling time trial performance (p=0.509) were not affected either. CONCLUSION The apnea test and training protocol, consisting of 5 maximal static apneas, did not induce a sufficiently strong hypoxic stimulus to cause erythropoiesis and therefore did not result in an increase in resting [EPO], Hbmass, V̇O2peak or time trial performance. Longer and/or more intense training sessions inducing a stronger hypoxic stimulus are probably needed to obtain changes in hematological and exercise parameters.
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Affiliation(s)
- Janne Bouten
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Jonas Debusschere
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Leen Lootens
- Doping Control Laboratory, Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
| | - Louise Declercq
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Peter Van Eenoo
- Doping Control Laboratory, Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
| | - Jan Boone
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Jan Gustaaf Bourgois
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.,Centre of Sports Medicine, Ghent University, Ghent, Belgium
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17
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Bapst AM, Knöpfel T, Nolan KA, Imeri F, Schuh CD, Hall AM, Guo J, Katschinski DM, Wenger RH. Neurogenic and pericytic plasticity of conditionally immortalized cells derived from renal erythropoietin-producing cells. J Cell Physiol 2022; 237:2420-2433. [PMID: 35014036 PMCID: PMC9303970 DOI: 10.1002/jcp.30677] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 12/17/2021] [Accepted: 12/22/2021] [Indexed: 12/19/2022]
Abstract
In adult mammals, the kidney is the main source of circulating erythropoietin (Epo), the master regulator of erythropoiesis. In vivo data in mice demonstrated multiple subtypes of interstitial renal Epo‐producing (REP) cells. To analyze the differentiation plasticity of fibroblastoid REP cells, we used a transgenic REP cell reporter mouse model to generate conditionally immortalized REP‐derived (REPD) cell lines. Under nonpermissive conditions, REPD cells ceased from proliferation and acquired a stem cell‐like state, with strongly enhanced hypoxia‐inducible factor 2 (HIF‐2α), stem cell antigen 1 (SCA‐1), and CD133 expression, but also enhanced alpha‐smooth muscle actin (αSMA) expression, indicating myofibroblastic signaling. These cells maintained the “on‐off” nature of Epo expression observed in REP cells in vivo, whereas other HIF target genes showed a more permanent regulation. Like REP cells in vivo, REPD cells cultured in vitro generated long tunneling nanotubes (TNTs) that aligned with endothelial vascular structures, were densely packed with mitochondria and became more numerous under hypoxic conditions. Although inhibition of mitochondrial oxygen consumption blunted HIF signaling, removal of the TNTs did not affect or even enhance the expression of HIF target genes. Apart from pericytes, REPD cells readily differentiated into neuroglia but not adipogenic, chondrogenic, or osteogenic lineages, consistent with a neuronal origin of at least a subpopulation of REP cells. In summary, these results suggest an unprecedented combination of differentiation features of this unique cell type.
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Affiliation(s)
- Andreas M Bapst
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Thomas Knöpfel
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Karen A Nolan
- Institute of Physiology, University of Zürich, Zürich, Switzerland.,National Centre of Competence in Research "Kidney.CH", University of Zürich, Zürich, Switzerland
| | - Faik Imeri
- Institute of Physiology, University of Zürich, Zürich, Switzerland.,National Centre of Competence in Research "Kidney.CH", University of Zürich, Zürich, Switzerland
| | - Claus D Schuh
- National Centre of Competence in Research "Kidney.CH", University of Zürich, Zürich, Switzerland.,Institute of Anatomy, University of Zürich, Zürich, Switzerland
| | - Andrew M Hall
- National Centre of Competence in Research "Kidney.CH", University of Zürich, Zürich, Switzerland.,Institute of Anatomy, University of Zürich, Zürich, Switzerland
| | - Jia Guo
- Institute for Cardiovascular Physiology, University Medical Center Göttingen, Georg-August-University, Göttingen, Germany
| | - Dörthe M Katschinski
- Institute for Cardiovascular Physiology, University Medical Center Göttingen, Georg-August-University, Göttingen, Germany
| | - Roland H Wenger
- Institute of Physiology, University of Zürich, Zürich, Switzerland.,National Centre of Competence in Research "Kidney.CH", University of Zürich, Zürich, Switzerland
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18
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Yamamoto H, Nobori K, Matsuda Y, Hayashi Y, Hayasaki T, Akizawa T. Molidustat for Renal Anemia in Nondialysis Patients Previously Treated with Erythropoiesis-Stimulating Agents: A Randomized, Open-Label, Phase 3 Study. Am J Nephrol 2021; 52:884-893. [PMID: 34569482 DOI: 10.1159/000518072] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 06/10/2021] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Erythropoiesis-stimulating agents (ESAs) are the current standard of care for anemia due to chronic kidney disease (CKD) in patients not undergoing dialysis. Molidustat, an oral hypoxia-inducible factor prolyl hydroxylase inhibitor, is being investigated as an alternative treatment for renal anemia. Molidustat was evaluated in five phase 3 studies, the molidustat once daily improves renal anemia by inducing erythropoietin (MIYABI) program. The present study investigated the safety and efficacy of molidustat in Japanese patients with renal anemia not undergoing dialysis and previously treated with ESAs. METHODS This was a 52-week, active-controlled, randomized (1:1), open-label, parallel-group, multicenter, phase 3 study in Japanese patients with anemia due to CKD (stages 3-5). Molidustat was initiated at 25 mg or 50 mg once daily according to previous ESA dose. The ESA darbepoetin alfa (darbepoetin) was initiated at a starting dose in accordance with the previous ESA dose and injected subcutaneously once every 2 or 4 weeks. Doses were regularly titrated to maintain hemoglobin (Hb) levels in the target range of 11.0-13.0 g/dL. The primary efficacy outcome was the mean Hb level and its change from baseline during the evaluation period (weeks 30-36). The safety outcomes included evaluation of all adverse events. RESULTS In total, 164 patients were randomized to receive molidustat (n = 82) or darbepoetin (n = 82). Baseline characteristics were well balanced. Mean (standard deviation) Hb levels at baseline were 11.31 (0.68) g/dL for molidustat and 11.27 (0.64) g/dL for darbepoetin. The mean (95% confidence interval [CI]) for mean Hb levels during the evaluation period for molidustat (11.67 [11.48-11.85] g/dL) and darbepoetin (11.53 [11.31-11.74] g/dL) was within the target range. Based on a noninferiority margin of 1.0 g/dL, molidustat was noninferior to darbepoetin regarding the change in mean Hb level during the evaluation period from baseline, with a least squares mean (95% CI) difference (molidustat-darbepoetin) of 0.13 (-0.15, 0.40) g/dL. The proportion of patients who reported at least 1 treatment-emergent adverse event (TEAE) was 92.7% for molidustat and 96.3% for darbepoetin. TEAEs leading to death were reported in 2 patients (2.4%) in the molidustat group and none in the darbepoetin group; serious TEAEs were reported in 32.9% and 26.8% of patients, respectively. DISCUSSION/CONCLUSION Molidustat was noninferior to darbepoetin and maintained Hb levels in the prespecified target range in patients with renal anemia not undergoing dialysis and previously treated with ESA. Molidustat was well tolerated, and no new safety signal was observed.
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Affiliation(s)
- Hiroyasu Yamamoto
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
| | - Kiyoshi Nobori
- Research and Development Japan, Bayer Yakuhin, Ltd., Osaka, Japan
| | - Yoshimi Matsuda
- Research and Development Japan, Bayer Yakuhin, Ltd., Osaka, Japan
| | - Yasuhiro Hayashi
- Medical Affairs and Pharmacovigilance, Bayer Yakuhin, Ltd., Osaka, Japan
| | - Takanori Hayasaki
- Medical Affairs and Pharmacovigilance, Bayer Yakuhin, Ltd., Osaka, Japan
| | - Tadao Akizawa
- Division of Nephrology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
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Akizawa T, Nobori K, Matsuda Y, Taki K, Hayashi Y, Hayasaki T, Yamamoto H. Molidustat for the treatment of anemia in Japanese patients undergoing peritoneal dialysis: a single-arm, open-label, phase 3 study. Ther Apher Dial 2021; 26:368-377. [PMID: 34310049 PMCID: PMC9290504 DOI: 10.1111/1744-9987.13713] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 07/21/2021] [Indexed: 02/06/2023]
Abstract
This 36‐week, open‐label, single‐arm, phase 3 study investigated the safety and efficacy of molidustat in Japanese patients with renal anemia undergoing peritoneal dialysis. Molidustat was titrated every 4 weeks to maintain Hb levels within the target range (≥11.0 and <13.0 g/dL). The primary efficacy outcome was the responder rate, defined as the proportion of patients who met all of the following criteria: (1) mean Hb levels in the target range during the evaluation period (Weeks 30–36); (2) ≥50% of Hb values within the target range during the evaluation period; and (3) no rescue treatment before the end of the evaluation period. Overall, 51 patients received molidustat. The responder rate (95% CI) during the evaluation period was 54.9% (40.3, 68.9). Overall, 98.0% of patients experienced at least 1 adverse event during the study. No deaths were reported. Molidustat maintained Hb levels in the prespecified range in more than half of the patients and was well tolerated.
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Affiliation(s)
- Tadao Akizawa
- Division of Nephrology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
| | - Kiyoshi Nobori
- Bayer Yakuhin Ltd, Research & Development Japan, Osaka, Japan
| | - Yoshimi Matsuda
- Bayer Yakuhin Ltd, Research & Development Japan, Osaka, Japan
| | - Kentaro Taki
- Bayer Yakuhin Ltd, Medical Affairs and Pharmacovigilance, Osaka, Japan
| | - Yasuhiro Hayashi
- Bayer Yakuhin Ltd, Medical Affairs and Pharmacovigilance, Osaka, Japan
| | - Takanori Hayasaki
- Bayer Yakuhin Ltd, Medical Affairs and Pharmacovigilance, Osaka, Japan
| | - Hiroyasu Yamamoto
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
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A reliable set of reference genes to normalize oxygen-dependent cytoglobin gene expression levels in melanoma. Sci Rep 2021; 11:10879. [PMID: 34035373 PMCID: PMC8149659 DOI: 10.1038/s41598-021-90284-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 05/10/2021] [Indexed: 12/17/2022] Open
Abstract
Cytoglobin (CYGB) is a ubiquitously expressed protein with a protective role against oxidative stress, fibrosis and tumor growth, shown to be transcriptionally regulated under hypoxic conditions. Hypoxia-inducible CYGB expression is observed in several cancer cell lines and particularly in various melanoma-derived cell lines. However, reliable detection of hypoxia-inducible mRNA levels by qPCR depends on the critical choice of suitable reference genes for accurate normalization. Limited evidence exists to support selection of the commonly used reference genes in hypoxic models of melanoma. This study aimed to select the optimal reference genes to study CYGB expression levels in melanoma cell lines exposed to hypoxic conditions (0.2% O2) and to the HIF prolyl hydroxylase inhibitor roxadustat (FG-4592). The expression levels of candidate genes were assessed by qPCR and the stability of genes was evaluated using the geNorm and NormFinder algorithms. Our results display that B2M and YWHAZ represent the most optimal reference genes to reliably quantify hypoxia-inducible CYGB expression in melanoma cell lines. We further validate hypoxia-inducible CYGB expression on protein level and by using CYGB promoter-driven luciferase reporter assays in melanoma cell lines.
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21
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Portolés J, Martín L, Broseta JJ, Cases A. Anemia in Chronic Kidney Disease: From Pathophysiology and Current Treatments, to Future Agents. Front Med (Lausanne) 2021; 8:642296. [PMID: 33842503 PMCID: PMC8032930 DOI: 10.3389/fmed.2021.642296] [Citation(s) in RCA: 100] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/01/2021] [Indexed: 12/19/2022] Open
Abstract
Anemia is a common complication in chronic kidney disease (CKD), and is associated with a reduced quality of life, and an increased morbidity and mortality. The mechanisms involved in anemia associated to CKD are diverse and complex. They include a decrease in endogenous erythropoietin (EPO) production, absolute and/or functional iron deficiency, and inflammation with increased hepcidin levels, among others. Patients are most commonly managed with oral or intravenous iron supplements and with erythropoiesis stimulating agents (ESA). However, these treatments have associated risks, and sometimes are insufficiently effective. Nonetheless, in the last years, there have been some remarkable advances in the treatment of CKD-related anemia, which have raised great expectations. On the one hand, a novel family of drugs has been developed: the hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs). These agents induce, among other effects, an increase in the production of endogenous EPO, improve iron availability and reduce hepcidin levels. Some of them have already received marketing authorization. On the other hand, recent clinical trials have elucidated important aspects of iron supplementation, which may change the treatment targets in the future. This article reviews the current knowledge of the pathophysiology CKD-related anemia, current and future therapies, the trends in patient management and the unmet goals.
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Affiliation(s)
- Jose Portolés
- Department of Nephrology, Puerta de Hierro Majadahonda University Hospital, Madrid, Spain
- Anemia Working Group Spanish Society of Nephrology, Madrid, Spain
| | - Leyre Martín
- Department of Nephrology, Puerta de Hierro Majadahonda University Hospital, Madrid, Spain
- Anemia Working Group Spanish Society of Nephrology, Madrid, Spain
| | - José Jesús Broseta
- Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain
| | - Aleix Cases
- Anemia Working Group Spanish Society of Nephrology, Madrid, Spain
- Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain
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22
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HIF2A gain-of-function mutation modulates the stiffness of smooth muscle cells and compromises vascular mechanics. iScience 2021; 24:102246. [PMID: 33796838 PMCID: PMC7995528 DOI: 10.1016/j.isci.2021.102246] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/26/2020] [Accepted: 02/25/2021] [Indexed: 02/08/2023] Open
Abstract
Heterozygous gain-of-function (GOF) mutations of hypoxia-inducible factor 2α (HIF2A), a key hypoxia-sensing regulator, are associated with erythrocytosis, thrombosis, and vascular complications that account for morbidity and mortality of patients. We demonstrated that the vascular pathology of HIF2A GOF mutations is independent of erythrocytosis. We generated HIF2A GOF-induced pluripotent stem cells (iPSCs) and differentiated them into endothelial cells (ECs) and smooth muscle cells (SMCs). Unexpectedly, HIF2A-SMCs, but not HIF2A-ECs, were phenotypically aberrant, more contractile, stiffer, and overexpressed endothelin 1 (EDN1), myosin heavy chain, elastin, and fibrillin. EDN1 inhibition and knockdown of EDN1-receptors both reduced HIF2-SMC stiffness. Hif2A GOF heterozygous mice displayed pulmonary hypertension, had SMCs with more disorganized stress fibers and higher stiffness in their pulmonary arterial smooth muscle cells, and had more deformable pulmonary arteries compared with wild-type mice. Our findings suggest that targeting these vascular aberrations could benefit patients with HIF2A GOF and conditions of augmented hypoxia signaling. HIF2-SMCs are stiffer than WT-SMCs and differ in contractile SMC marker expression HIF2-SMCs and WT-SMCs differ in EDN1 production and ECM composition HIF- 2α induces EDN1; EDNI subsequently induces SMC stiffening Hif2A GOF mouse arterial SMCs have more disorganized stress fibers and are stiffer
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23
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High-altitude deer mouse hypoxia-inducible factor-2α shows defective interaction with CREB-binding protein. J Biol Chem 2021; 296:100461. [PMID: 33639161 PMCID: PMC8024697 DOI: 10.1016/j.jbc.2021.100461] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 02/16/2021] [Accepted: 02/23/2021] [Indexed: 12/26/2022] Open
Abstract
Numerous mammalian species have adapted to the chronic hypoxia of high altitude. Recent genomic studies have identified evidence for natural selection of genes and associated genetic changes in these species. A major gap in our knowledge is an understanding of the functional significance, if any, of these changes. Deer mice (Peromyscus maniculatus) live at both low and high altitudes in North America, providing an opportunity to identify functionally important genetic changes. High-altitude deer mice show evidence of natural selection on the Epas1 gene, which encodes for hypoxia-inducible factor-2α (Hif-2α), a central transcription factor of the hypoxia-inducible factor pathway. An SNP encoding for a T755M change in the Hif-2α protein is highly enriched in high-altitude deer mice, but its functional significance is unknown. Here, using coimmunoprecipitation and transcriptional activity assays, we show that the T755M mutation produces a defect in the interaction of Hif-2α with the transcriptional coactivator CREB-binding protein. This results in a loss of function because of decreased transcriptional activity. Intriguingly, the effect of this mutation depends on the amino acid context. Interchanges between methionine and threonine at the corresponding position in house mouse (Mus musculus) Hif-2α are without effects on CREB-binding protein binding. Furthermore, transfer of a set of deer mouse–specific Hif-2α amino acids to house mouse Hif-2α is sufficient to confer sensitivity of house mouse Hif-2α to the T755M substitution. These findings provide insight into high-altitude adaptation in deer mice and evolution at the Epas1 locus.
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24
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Gangat N, Szuber N, Pardanani A, Tefferi A. JAK2 unmutated erythrocytosis: current diagnostic approach and therapeutic views. Leukemia 2021; 35:2166-2181. [PMID: 34021251 PMCID: PMC8324477 DOI: 10.1038/s41375-021-01290-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/28/2021] [Accepted: 05/06/2021] [Indexed: 02/08/2023]
Abstract
JAK2 unmutated or non-polycythemia vera (PV) erythrocytosis encompasses both hereditary and acquired conditions. A systematic diagnostic approach begins with documentation of historical hematocrit (Hct)/hemoglobin (Hgb) measurements and classification of the process as life-long/unknown duration or acquired. Further investigation in both categories is facilitated by determination of serum erythropoietin level (EPO). Workup for hereditary/congenital erythrocytosis requires documentation of family history and laboratory screening for high-oxygen affinity hemoglobin variants, 2, 3 biphosphoglycerate deficiency, and germline mutations that are known to alter cellular oxygen sensing (e.g., PHD2, HIF2A, VHL) or EPO signaling (e.g., EPOR mutations); the latter is uniquely associated with subnormal EPO. Acquired erythrocytosis is often elicited by central or peripheral hypoxia resulting from cardiopulmonary disease/high-altitude dwelling or renal artery stenosis, respectively; EPO in the former instance is often normal (compensated by negative feed-back). Other conditions associated with acquired erythrocytosis include EPO-producing tumors and the use of drugs that promote erythropoiesis (e.g., testosterone, erythropoiesis stimulating agents). "Idiopathic erythrocytosis" loosely refers to an otherwise not explained situation. Historically, management of non-PV erythrocytosis has been conflicted by unfounded concerns regarding thrombosis risk, stemming from limited phenotypic characterization, save for Chuvash polycythemia, well-known for its thrombotic tendency. In general, cytoreductive therapy should be avoided and phlebotomy is seldom warranted where frequency is determined by symptom control rather than Hct threshold. Although not supported by hard evidence, cardiovascular risk optimization and low-dose aspirin use are often advised. Application of modern genetic tests and development of controlled therapeutic intervention trials are needed to advance current clinical practice.
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Affiliation(s)
- Naseema Gangat
- grid.66875.3a0000 0004 0459 167XDivision of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN USA
| | - Natasha Szuber
- grid.14848.310000 0001 2292 3357Department of Hematology, Université de Montréal, Montréal, QC Canada
| | - Animesh Pardanani
- grid.66875.3a0000 0004 0459 167XDivision of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN USA
| | - Ayalew Tefferi
- grid.66875.3a0000 0004 0459 167XDivision of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN USA
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25
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Maxwell KD, Chuang J, Chaudhry M, Nie Y, Bai F, Sodhi K, Liu J, Shapiro JI. The potential role of Na-K-ATPase and its signaling in the development of anemia in chronic kidney disease. Am J Physiol Renal Physiol 2020; 320:F234-F242. [PMID: 33356956 DOI: 10.1152/ajprenal.00244.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Chronic kidney disease (CKD) is one of the most prominent diseases affecting our population today. According to the Factsheet published by Centers for Disease Control and Prevention (CDC), it effects approximately 15% of the total population in the United States in some way, shape, or form. Within the myriad of symptomatology associated with CKD, one of the most prevalent factors in terms of affecting quality of life is anemia. Anemia of CKD cannot be completely attributed to one mechanism or cause, but rather has a multifactorial origin in the pathophysiology of CKD. While briefly summarizing well-documented risk factors, this review, as a hypothesis, aims to explore the possible role of Na-K-ATPase and its signaling function [especially recent identified reactive oxygen species (ROS) amplification function] in the interwoven mechanisms of development of the anemia of CKD.
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Affiliation(s)
- Kyle D Maxwell
- Department of Biomsedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
| | - Justin Chuang
- Department of Biomsedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
| | - Muhammad Chaudhry
- Department of Biomsedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
| | - Ying Nie
- Department of Biomsedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
| | - Fang Bai
- Department of Biomsedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
| | - Komal Sodhi
- Department of Biomsedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia.,Department of Medicine, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
| | - Jiang Liu
- Department of Biomsedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
| | - Joseph I Shapiro
- Department of Medicine, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
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26
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Orlando IMC, Lafleur VN, Storti F, Spielmann P, Crowther L, Santambrogio S, Schödel J, Hoogewijs D, Mole DR, Wenger RH. Distal and proximal hypoxia response elements cooperate to regulate organ-specific erythropoietin gene expression. Haematologica 2020; 105:2774-2784. [PMID: 33256376 PMCID: PMC7716368 DOI: 10.3324/haematol.2019.236406] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 12/18/2019] [Indexed: 11/09/2022] Open
Abstract
While it is well-established that distal hypoxia response elements (HREs) regulate hypoxia-inducible factor (HIF) target genes such as erythropoietin (Epo), an interplay between multiple distal and proximal (promoter) HREs has not been described so far. Hepatic Epo expression is regulated by a HRE located downstream of the EPO gene, but this 3' HRE is dispensable for renal EPO gene expression. We previously identified a 5' HRE and could show that both HREs direct exogenous reporter gene expression. Here, we show that whereas in hepatic cells the 3' but not the 5' HRE is required, in neuronal cells both the 5' and 3' HREs contribute to endogenous Epo induction. Moreover, two novel putative HREs were identified in the EPO promoter. In hepatoma cells HIF interacted mainly with the distal 3' HRE, but in neuronal cells HIF most strongly bound the promoter, to a lesser extent the 3' HRE, and not at all the 5' HRE. Interestingly, mutation of either of the two distal HREs abrogated HIF binding to the 3' and promoter HREs. These results suggest that a canonical functional HRE can recruit multiple, not necessarily HIF, transcription factors to mediate HIF binding to different distant HREs in an organ-specific manner.
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Affiliation(s)
- Ilaria M. C. Orlando
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- National Center of Competence in Research “Kidney.CH”, Zurich, Switzerland
| | | | - Federica Storti
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- National Center of Competence in Research “Kidney.CH”, Zurich, Switzerland
| | - Patrick Spielmann
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- National Center of Competence in Research “Kidney.CH”, Zurich, Switzerland
| | - Lisa Crowther
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- National Center of Competence in Research “Kidney.CH”, Zurich, Switzerland
| | - Sara Santambrogio
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- National Center of Competence in Research “Kidney.CH”, Zurich, Switzerland
| | - Johannes Schödel
- Department of Nephrology and Hypertension, Universitatsklinikum Erlangen, Friedrich-Alexander-Universitat Erlangen-Nurnberg, Erlangen, Germany
| | - David Hoogewijs
- National Center of Competence in Research “Kidney.CH”, Zurich, Switzerland
- Department of Medicine/Physiology, University of Fribourg, Fribourg, Switzerland
| | - David R. Mole
- NDM Research Building, University of Oxford, Oxford, UK
| | - Roland H. Wenger
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- National Center of Competence in Research “Kidney.CH”, Zurich, Switzerland
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27
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Chin K, Cazorla-Bak MP, Liu E, Nghiem L, Zhang Y, Yu J, Wilson DF, Vinogradov SA, Gilbert RE, Connelly KA, Evans RG, Baker AJ, David Mazer C, Hare GMT. Renal microvascular oxygen tension during hyperoxia and acute hemodilution assessed by phosphorescence quenching and excitation with blue and red light. Can J Anaesth 2020; 68:214-225. [PMID: 33174162 DOI: 10.1007/s12630-020-01848-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 08/05/2020] [Accepted: 08/14/2020] [Indexed: 12/13/2022] Open
Abstract
PURPOSE The kidney plays a central physiologic role as an oxygen sensor. Nevertheless, the direct mechanism by which this occurs is incompletely understood. We measured renal microvascular partial pressure of oxygen (PkO2) to determine the impact of clinically relevant conditions that acutely change PkO2 including hyperoxia and hemodilution. METHODS We utilized two-wavelength excitation (red and blue spectrum) of the intravascular phosphorescent oxygen sensitive probe Oxyphor PdG4 to measure renal tissue PO2 in anesthetized rats (2% isoflurane, n = 6) under two conditions of altered arterial blood oxygen content (CaO2): 1) hyperoxia (fractional inspired oxygen 21%, 30%, and 50%) and 2) acute hemodilutional anemia (baseline, 25% and 50% acute hemodilution). The mean arterial blood pressure (MAP), rectal temperature, arterial blood gases (ABGs), and chemistry (radiometer) were measured under each condition. Blue and red light enabled measurement of PkO2 in the superficial renal cortex and deeper cortical and medullary tissue, respectively. RESULTS PkO2 was higher in the superficial renal cortex (~ 60 mmHg, blue light) relative to the deeper renal cortex and outer medulla (~ 45 mmHg, red light). Hyperoxia resulted in a proportional increase in PkO2 values while hemodilution decreased microvascular PkO2 in a linear manner in both superficial and deeper regions of the kidney. In both cases (blue and red light), PkO2 correlated with CaO2 but not with MAP. CONCLUSION The observed linear relationship between CaO2 and PkO2 shows the biological function of the kidney as a quantitative sensor of anemic hypoxia and hyperoxia. A better understanding of the impact of changes in PkO2 may inform clinical practices to improve renal oxygen delivery and prevent acute kidney injury.
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Affiliation(s)
- Kyle Chin
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada
| | - Melina P Cazorla-Bak
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Elaine Liu
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada
| | - Linda Nghiem
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
| | - Yanling Zhang
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
| | - Julie Yu
- Deaprtment of Anesthesia and Perioperative Medicine, Western University, London, ON, Canada
| | - David F Wilson
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Richard E Gilbert
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.,Division of Endocrinology, Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Kim A Connelly
- 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.,Division of Cardiology, Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Andrew J Baker
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.,Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - C David Mazer
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Gregory M T Hare
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, 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.
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28
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Wrobeln A, Jägers J, Quinting T, Schreiber T, Kirsch M, Fandrey J, Ferenz KB. Albumin-derived perfluorocarbon-based artificial oxygen carriers can avoid hypoxic tissue damage in massive hemodilution. Sci Rep 2020; 10:11950. [PMID: 32686717 PMCID: PMC7371727 DOI: 10.1038/s41598-020-68701-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 06/26/2020] [Indexed: 12/29/2022] Open
Abstract
Artificial blood for clinical use is not yet available therefore, we previously developed artificial oxygen carriers (capsules) and showed their functionality in vitro and biocompatibility in vivo. Herein, we assessed the functionality of the capsules in vivo in a normovolemic hemodilution rat-model. We stepwise exchanged the blood of male Wistar-rats with medium either in the presence of capsules (treatment) or in their absence (control). We investigated tissue hypoxia thoroughly through online biomonitoring, determination of enzyme activity and pancreatic hormones in plasma, histochemical and immunohistochemical staining of small intestine, heart, liver and spleen as well as in situ hybridization of kidneys. After hemodilution, treated animals show higher arterial blood pressure and have a stable body temperature. Additionally, they show a more stable pH, a higher oxygen partial pressure (pO2), and a lower carbon dioxide partial pressure (pCO2). Interestingly, blood-glucose-levels drop severely in treated animals, presumably due to glucose consumption. Creatine kinase values in these animals are increased and isoenzyme analysis indicates the spleen as origin. Moreover, the small intestine of treated animals show reduced hypoxic injury compared to controls and the kidneys have reduced expression of the hypoxia-inducible erythropoietin mRNA. In conclusion, our capsules can prevent hypoxic tissue damage. The results provide a proof of concept for capsules as adequate erythrocyte substitute.
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Affiliation(s)
- Anna Wrobeln
- Institute of Physiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45122, Essen, Germany
| | - Johannes Jägers
- Institute of Physiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45122, Essen, Germany
| | - Theresa Quinting
- Institute of Physiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45122, Essen, Germany
| | - Timm Schreiber
- Institute of Physiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45122, Essen, Germany
| | - Michael Kirsch
- Institute of Physiological Chemistry, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45122, Essen, Germany
| | - Joachim Fandrey
- Institute of Physiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45122, Essen, Germany
| | - Katja B Ferenz
- Institute of Physiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45122, Essen, Germany. .,CeNIDE (Center for Nanointegration Duisburg-Essen) University of Duisburg-Essen, Carl-Benz-Strasse 199, 47057, Duisburg, Germany.
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Faivre A, Scholz CC, de Seigneux S. Hypoxia in chronic kidney disease: towards a paradigm shift? Nephrol Dial Transplant 2020; 36:1782-1790. [PMID: 33895835 DOI: 10.1093/ndt/gfaa091] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Indexed: 11/15/2022] Open
Abstract
Chronic kidney disease (CKD) is defined as an alteration of kidney structure and/or function lasting for >3 months [1]. CKD affects 10% of the general adult population and is responsible for large healthcare costs [2]. Since the end of the last century, the role of hypoxia in CKD progression has controversially been discussed. To date, there is evidence of the presence of hypoxia in late-stage renal disease, but we lack time-course evidence, stage correlation and also spatial co-localization with fibrotic lesions to ensure its causative role. The classical view of hypoxia in CKD progression is that it is caused by peritubular capillary alterations, renal anaemia and increased oxygen consumption regardless of the primary injury. In this classical view, hypoxia is assumed to further induce pro-fibrotic and pro-inflammatory responses, as well as oxidative stress, leading to CKD worsening as part of a vicious circle. However, recent investigations tend to question this paradigm, and both the presence of hypoxia and its role in CKD progression are still not clearly demonstrated. Hypoxia-inducible factor (HIF) is the main transcriptional regulator of the hypoxia response. Genetic HIF modulation leads to variable effects on CKD progression in different murine models. In contrast, pharmacological modulation of the HIF pathway [i.e. by HIF hydroxylase inhibitors (HIs)] appears to be generally protective against fibrosis progression experimentally. We here review the existing literature on the role of hypoxia, the HIF pathway and HIF HIs in CKD progression and summarize the evidence that supports or rejects the hypoxia hypothesis, respectively.
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Affiliation(s)
- Anna Faivre
- Department of Cell physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Carsten C Scholz
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Centre of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Sophie de Seigneux
- Department of Cell physiology and Metabolism, University of Geneva, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.CH", Zurich, Switzerland.,Department of Medicine, Service of Nephrology, Geneva University Hospitals, Geneva, Switzerland
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SCHMIDT WALTERFJ, HOFFMEISTER TORBEN, HAUPT SANDRA, SCHWENKE DIRK, WACHSMUTH NADINEB, BYRNES WILLIAMC. Chronic Exposure to Low-Dose Carbon Monoxide Alters Hemoglobin Mass and V˙O2max. Med Sci Sports Exerc 2020; 52:1879-1887. [DOI: 10.1249/mss.0000000000002330] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Shibuya S, Toda T, Ozawa Y, Yata MJV, Shimizu T. Acai Extract Transiently Upregulates Erythropoietin by Inducing a Renal Hypoxic Condition in Mice. Nutrients 2020; 12:nu12020533. [PMID: 32092924 PMCID: PMC7071527 DOI: 10.3390/nu12020533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 02/06/2023] Open
Abstract
Acai (Euterpe oleracea Mart. Palmae, Arecaceae) is a palm plant native to the Brazilian Amazon. It contains many nutrients, such as polyphenols, iron, vitamin E, and unsaturated fatty acids, so in recent years, many of the antioxidant and anti-inflammatory effects of acai have been reported. However, the effects of acai on hematopoiesis have not been investigated yet. In the present study, we administered acai extract to mice and evaluated its hematopoietic effects. Acai treatment significantly increased the erythrocytes, hemoglobin, and hematocrit contents compared to controls for four days. Then, we examined the hematopoietic-related markers following a single injection. Acai administration significantly increased the levels of the hematopoietic-related hormone erythropoietin in blood compared to controls and also transiently upregulated the gene expression of Epo in the kidney. Furthermore, in the mice treated with acai extract, the kidneys were positively stained with the hypoxic probe pimonidazole in comparison to the controls. These results demonstrated that acai increases the erythropoietin expression via hypoxic action in the kidney. Acai can be expected to improve motility through hematopoiesis.
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Affiliation(s)
- Shuichi Shibuya
- Aging Stress Response Research Project Team, National Center for Geriatrics and Gerontology, 7-430 Morioka-cho, Obu, Aichi 474-8511, Japan;
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan; (T.T.); (Y.O.)
| | - Toshihiko Toda
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan; (T.T.); (Y.O.)
| | - Yusuke Ozawa
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan; (T.T.); (Y.O.)
| | | | - Takahiko Shimizu
- Aging Stress Response Research Project Team, National Center for Geriatrics and Gerontology, 7-430 Morioka-cho, Obu, Aichi 474-8511, Japan;
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan; (T.T.); (Y.O.)
- Correspondence: ; Tel.: +81-562-44-5651; Fax: +81-562-48-2373
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Song D, Guan W, Coon LM, Al-Kali A, Oliveira JL, Lee FS. An Erythrocytosis-Associated Mutation in the Zinc Finger of PHD2 Provides Insights into Its Binding of p23. HYPOXIA 2019; 7:81-86. [PMID: 31853455 PMCID: PMC6916684 DOI: 10.2147/hp.s230502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 10/16/2019] [Indexed: 12/30/2022]
Abstract
Background Loss of function mutations in the EGLN1 gene are a cause of erythrocytosis. EGLN1 encodes for prolyl hydroxylase domain protein 2 (PHD2). PHD2 hydroxylates and downregulates hypoxia-inducible factor-2α (HIF-2α), a transcription factor that regulates erythropoiesis. While the large majority of erythrocytosis-associated EGLN1 mutations occur within its catalytic domain, rare mutations reside in its zinc finger. This zinc finger binds a Pro-Xaa-Leu-Glu motif in p23, an HSP90 cochaperone that facilitates hydroxylation of HIF-α, an HSP90 client. Essentially nothing is known about the specific interactions between the PHD2 zinc finger and p23. Results Here, we characterize an erythrocytosis-associated mutation in the zinc finger, K55N, that abolishes interaction with p23. We provide evidence that the affected residue, Lys-55, interacts with Asp-152 of p23. We also present results that indicate that PHD2 Arg-32 interacts with p23 Glu-160. Conclusion These studies not only reinforce the importance of the PHD2 zinc finger in the control of erythropoiesis, but also lead to a model in which a peptide motif in p23 binds in a specific orientation to a predicted groove in the zinc finger of PHD2.
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Affiliation(s)
- Daisheng Song
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wei Guan
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, People's Republic of China.,Hubei Province Key Laboratory of Molecular Imaging, Wuhan 430022, People's Republic of China
| | - Lea M Coon
- Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Aref Al-Kali
- Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Jennifer L Oliveira
- Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Frank S Lee
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Lappin TR, Lee FS. Update on mutations in the HIF: EPO pathway and their role in erythrocytosis. Blood Rev 2019; 37:100590. [PMID: 31350093 DOI: 10.1016/j.blre.2019.100590] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 07/02/2019] [Accepted: 07/15/2019] [Indexed: 12/20/2022]
Abstract
Identification of the underlying defects in congenital erythrocytosis has provided mechanistic insights into the regulation of erythropoiesis and oxygen homeostasis. The Hypoxia Inducible Factor (HIF) pathway plays a key role in this regard. In this pathway, an enzyme, Prolyl Hydroxylase Domain protein 2 (PHD2), constitutively prolyl hydroxylates HIF-2α, thereby targeting HIF-2α for degradation by the von Hippel Lindau (VHL) tumor suppressor protein. Under hypoxia, this modification is attenuated, resulting in the stabilization of HIF-2α and transcriptional activation of the erythropoietin (EPO) gene. Circulating EPO then binds to the EPO receptor (EPOR) on red cell progenitors in the bone marrow, leading to expansion of red cell mass. Loss of function mutations in PHD2 and VHL, as well as gain of function mutations in HIF-2α and EPOR, are well established causes of erythrocytosis. Here, we highlight recent developments that show that the study of this condition is still evolving. Specifically, novel mutations have been identified that either change amino acids in the zinc finger domain of PHD2 or alter splicing of the VHL gene. In addition, continued study of HIF-2α mutations has revealed a distinctive genotype-phenotype correlation. Finally, novel mutations have recently been identified in the EPO gene itself. Thus, the cascade of genes that at a molecular level leads to EPO action, namely PHD2 - > HIF2A - > VHL - > EPO - > EPOR, are all mutational targets in congenital erythrocytosis.
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Affiliation(s)
- Terence R Lappin
- Centre for Cancer Research and Cell Biology, Queen's University, Belfast, UK.
| | - Frank S Lee
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Histone H3K9 demethylase JMJD1A is a co-activator of erythropoietin expression under hypoxia. Int J Biochem Cell Biol 2019; 109:33-39. [PMID: 30716474 DOI: 10.1016/j.biocel.2019.01.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/27/2019] [Accepted: 01/31/2019] [Indexed: 01/04/2023]
Abstract
Erythropoietin (EPO) is a secreted hormone that stimulates the production of red blood cells, and the level of EPO is increased under hypoxia. The expression of EPO is regulated not only by the hypoxia-inducible factor (HIF) but also partly through epigenetic modifications, including histone acetylation and methylation. In this study, we report that histone H3K9 demethylase JMJD1 A is regulated by HIF-2α in HepG2 cells under hypoxia. Knockdown or over-expression of JMJD1 A can decrease or increase EPO expression, respectively. JMJD1 A can interact with HIF-2α to form a co-activator complex, which binds to the hypoxia response elements of EPO and increases EPO expression by catalyzing demethylation of H3K9me2, a transcription suppression marker. The results demonstrate that JMJD1 A is a co-activator of EPO expression.
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35
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Abstract
SIGNIFICANCE Hydroxyproline is a structurally and physiologically important imino acid in animals. It is provided from diets and endogenous synthesis, and its conversion into glycine enhances the production of glutathione, DNA, heme, and protein. Furthermore, oxidation of hydroxyproline by hydroxyproline oxidase (OH-POX) plays an important role in cell antioxidative reactions, survival, and homeostasis. Understanding the mechanisms whereby hydroxyproline participates in metabolism and cell signaling can improve the nutrition and health of animals and humans. Recent Advances: Hydroxyproline is highly abundant in milk and is utilized for renal synthesis of glycine to support neonatal growth, development, and survival. The oxidation of hydroxyproline by mitochondrial OH-POX generates reactive oxygen species (ROS). Enhanced ROS production contributes to the regulation of oxidative defense, apoptosis, angiogenesis, tumorigenesis, hypoxic responses, and cell survival in animals. CRITICAL ISSUES Although dietary hydroxyproline enters the portal circulation, its utilization by the portal-drained viscera is unknown. Pathways for hydroxyproline metabolism and their regulation at the molecular, cellular, and whole-body levels remain to be defined. Furthermore, the mechanisms responsible for hydroxyproline-derived ROS and related metabolites to induce cell survival or apoptosis are unknown. FUTURE DIRECTIONS Interorgan metabolism of hydroxyproline (including synthesis, catabolism, and flux) in animals must be quantified using isotope technologies. Efforts should also be directed toward studying dietary, hormonal, and epigenetic regulation of OH-POX expression at transcriptional and translational levels. Another emerging research need is to understand the roles of cellular redox and signaling networks involving both ROS and Δ1-pyrroline-3-hydroxy-5-carboxylate in nutrition, health, and disease.
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Affiliation(s)
- Zhenlong Wu
- 1 State Key Laboratory of Animal Nutrition, China Agricultural University , Beijing, China
| | - Yongqing Hou
- 2 Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University , Wuhan, China
| | - Zhaolai Dai
- 1 State Key Laboratory of Animal Nutrition, China Agricultural University , Beijing, China
| | - Chien-An A Hu
- 2 Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University , Wuhan, China .,3 Department of Biochemistry and Molecular Biology, University of New Mexico , Health Sciences Center, Albuquerque, New Mexico
| | - Guoyao Wu
- 1 State Key Laboratory of Animal Nutrition, China Agricultural University , Beijing, China .,2 Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University , Wuhan, China .,4 Department of Animal Science, Texas A&M University , College Station, Texas
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Abstract
PURPOSE OF REVIEW Historically, the identity of O2-sensing renal erythropoietin (Epo)-producing (REP) cells was a matter of debate. This review summarizes how recent breakthroughs in transgenic mouse and in-situ hybridization techniques have facilitated sensitive and specific detection of REP cells and accelerated advancements in the understanding of the regulation of renal Epo production in health and disease. RECENT FINDINGS REP cells are a dynamically regulated unique subpopulation of tubulointerstitial cells with features of fibroblasts, pericytes and neurons. Under normal conditions, REP cells are located in the corticomedullary border region within a steep decrement in O2 availability. During the progression of chronic kidney disease (CKD), REP cells cease Epo production, dedifferentiate and contribute to the progression of renal fibrosis. However, CKD patients with renal anaemia still respond with elevated Epo production following treatment with hypoxia-mimicking agents. SUMMARY We hypothesize that REP cells are neuron-like setpoint providers and controllers, which integrate information about blood O2 concentration and local O2 consumption via tissue pO2, and combine these inputs with intrinsic negative feedback loops and perhaps tubular cross-talk, converging in Epo regulation.
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Macdougall IC, Akizawa T, Berns JS, Bernhardt T, Krueger T. Effects of Molidustat in the Treatment of Anemia in CKD. Clin J Am Soc Nephrol 2018; 14:28-39. [PMID: 30559105 PMCID: PMC6364546 DOI: 10.2215/cjn.02510218] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 10/12/2018] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND OBJECTIVES The efficacy and safety of molidustat, a hypoxia-inducible factor-prolyl hydroxylase inhibitor, have been evaluated in three 16-week, phase 2b studies in patients with CKD and anemia who are not on dialysis (DaIly orAL treatment increasing endOGenoUs Erythropoietin [DIALOGUE] 1 and 2) and in those who are on dialysis (DIALOGUE 4). DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS DIALOGUE 1 was a placebo-controlled, fixed-dose trial (25, 50, and 75 mg once daily; 25 and 50 mg twice daily). DIALOGUE 2 and 4 were open-label, variable-dose trials, in which treatment was switched from darbepoetin (DIAGLOGUE 2) or epoetin (DIALOGUE 4) to molidustat or continued with the original agents. Starting molidustat ranged between 25-75 and 25-150 mg daily in DIAGLOGUE 2 and 4, respectively, and could be titrated to maintain hemoglobin levels within predefined target ranges. The primary end point was the change in hemoglobin level between baseline and the mean value from the last 4 weeks of the treatment period. RESULTS In DIAGLOGUE 1 (n=121), molidustat treatment was associated with estimated increases in mean hemoglobin levels of 1.4-2.0 g/dl. In DIAGLOGUE 2 (n=124), hemoglobin levels were maintained within the target range after switching to molidustat, with an estimated difference in mean change in hemoglobin levels between molidustat and darbepoetin treatments of up to 0.6 g/dl. In DIAGLOGUE 4 (n=199), hemoglobin levels were maintained within the target range after switching to molidustat 75 and 150 mg, with estimated differences in mean change between molidustat and epoetin treatment of -0.1 and 0.4 g/dl. Molidustat was generally well tolerated, and most adverse events were mild or moderate in severity. CONCLUSIONS The overall phase 2 efficacy and safety profile of molidustat in patients with CKD and anemia enables the progression of its development into phase 3.
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Affiliation(s)
| | - Tadao Akizawa
- Division of Nephrology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
| | - Jeffrey S Berns
- Perelman School of Medicine at the University of Pennsylvania, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Thomas Bernhardt
- Departments of Pharmaceutials Development, and TA Cardiology and Nephrology, Bayer AG, Berlin, Germany; and
| | - Thilo Krueger
- Departments of Research and Development, and Pharmaceuticals, Bayer AG, Wuppertal, Germany
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Generation of renal Epo-producing cell lines by conditional gene tagging reveals rapid HIF-2 driven Epo kinetics, cell autonomous feedback regulation, and a telocyte phenotype. Kidney Int 2018; 95:375-387. [PMID: 30502050 DOI: 10.1016/j.kint.2018.08.043] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 08/18/2018] [Accepted: 08/23/2018] [Indexed: 12/14/2022]
Abstract
Erythropoietin (Epo) is essential for erythropoiesis and is mainly produced by the fetal liver and the adult kidney following hypoxic stimulation. Epo regulation is commonly studied in hepatoma cell lines, but differences in Epo regulation between kidney and liver limit the understanding of Epo dysregulation in polycythaemia and anaemia. To overcome this limitation, we have generated a novel transgenic mouse model expressing Cre recombinase specifically in the active fraction of renal Epo-producing (REP) cells. Crossing with reporter mice confirmed the inducible and highly specific tagging of REP cells, located in the corticomedullary border region where there is a steep drop in oxygen bioavailability. A novel method was developed to selectively grow primary REP cells in culture and to generate immortalized clonal cell lines, called fibroblastoid atypical interstitial kidney (FAIK) cells. FAIK cells show very early hypoxia-inducible factor (HIF)-2α induction, which precedes Epo transcription. Epo induction in FAIK cells reverses rapidly despite ongoing hypoxia, suggesting a cell autonomous feedback mechanism. In contrast, HIF stabilizing drugs resulted in chronic Epo induction in FAIK cells. RNA sequencing of three FAIK cell lines derived from independent kidneys revealed a high degree of overlap and suggests that REP cells represent a unique cell type with properties of pericytes, fibroblasts, and neurons, known as telocytes. These novel cell lines may be helpful to investigate myofibroblast differentiation in chronic kidney disease and to elucidate the molecular mechanisms of HIF stabilizing drugs currently in phase III studies to treat anemia in end-stage kidney disease.
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Bissinger R, Bhuyan AAM, Qadri SM, Lang F. Oxidative stress, eryptosis and anemia: a pivotal mechanistic nexus in systemic diseases. FEBS J 2018; 286:826-854. [PMID: 30028073 DOI: 10.1111/febs.14606] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 06/15/2018] [Accepted: 07/18/2018] [Indexed: 12/21/2022]
Abstract
The average lifespan of circulating erythrocytes usually exceeds hundred days. Prior to that, however, erythrocytes may be exposed to oxidative stress in the circulation which could cause injury and trigger their suicidal death or eryptosis. Oxidative stress activates Ca2+ -permeable nonselective cation channels in the cell membrane, thus, stimulating Ca2+ entry and subsequent cell membrane scrambling resulting in phosphatidylserine exposure and activation of Ca2+ -sensitive K+ channels leading to K+ exit, hyperpolarization, Cl- exit, and ultimately cell shrinkage due to loss of KCl and osmotically driven water. While the mechanistic link between oxidative stress and anemia remains ill-defined, several diseases such as diabetes, hepatic failure, malignancy, chronic kidney disease and inflammation have been identified to display both increased oxidative stress as well as eryptosis. Recent compelling evidence suggests that oxidative stress is an important perpetrator in accelerating erythrocyte loss in different systemic conditions and an underlying mechanism for anemia associated with these pathological states. In the present review, we discuss the role of oxidative stress in reducing erythrocyte survival and provide novel insights into the possible use of antioxidants as putative antieryptotic and antianemic agents in a variety of systemic diseases.
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Affiliation(s)
- Rosi Bissinger
- Department of Internal Medicine III, Eberhard-Karls-University Tübingen, Germany
| | - Abdulla Al Mamun Bhuyan
- Department of Vegetative & Clinical Physiology, Institute of Physiology, Eberhard-Karls-University Tübingen, Germany
| | - Syed M Qadri
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.,Centre for Innovation, Canadian Blood Services, Hamilton, ON, Canada
| | - Florian Lang
- Department of Vegetative & Clinical Physiology, Institute of Physiology, Eberhard-Karls-University Tübingen, Germany.,Department of Molecular Medicine II, Heinrich Heine University, Düsseldorf, Germany
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Beck H, Jeske M, Thede K, Stoll F, Flamme I, Akbaba M, Ergüden J, Karig G, Keldenich J, Oehme F, Militzer H, Hartung IV, Thuss U. Discovery of Molidustat (BAY 85-3934): A Small-Molecule Oral HIF-Prolyl Hydroxylase (HIF-PH) Inhibitor for the Treatment of Renal Anemia. ChemMedChem 2018; 13:988-1003. [PMID: 29485740 PMCID: PMC6001664 DOI: 10.1002/cmdc.201700783] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/20/2018] [Indexed: 12/17/2022]
Abstract
Small-molecule inhibitors of hypoxia-inducible factor prolyl hydroxylases (HIF-PHs) are currently under clinical development as novel treatment options for chronic kidney disease (CKD) associated anemia. Inhibition of HIF-PH mimics hypoxia and leads to increased erythropoietin (EPO) expression and subsequently increased erythropoiesis. Herein we describe the discovery, synthesis, structure-activity relationship (SAR), and proposed binding mode of novel 2,4-diheteroaryl-1,2-dihydro-3H-pyrazol-3-ones as orally bioavailable HIF-PH inhibitors for the treatment of anemia. High-throughput screening of our corporate compound library identified BAY-908 as a promising hit. The lead optimization program then resulted in the identification of molidustat (BAY 85-3934), a novel small-molecule oral HIF-PH inhibitor. Molidustat is currently being investigated in clinical phase III trials as molidustat sodium for the treatment of anemia in patients with CKD.
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Affiliation(s)
- Hartmut Beck
- Medicinal Chemistry WuppertalBayer AG42096WuppertalGermany
| | - Mario Jeske
- Medicinal Chemistry WuppertalBayer AG42096WuppertalGermany
| | - Kai Thede
- Medicinal Chemistry BerlinBayer AG13342BerlinGermany
| | | | - Ingo Flamme
- Cardiology Research WuppertalBayer AG42096WuppertalGermany
| | - Metin Akbaba
- Medicinal Chemistry WuppertalBayer AG42096WuppertalGermany
| | | | - Gunter Karig
- Medicinal Chemistry WuppertalBayer AG42096WuppertalGermany
| | | | - Felix Oehme
- Cardiology Research WuppertalBayer AG42096WuppertalGermany
| | | | | | - Uwe Thuss
- DMPK WuppertalBayer AG42096WuppertalGermany
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Fuady JH, Gutsche K, Santambrogio S, Varga Z, Hoogewijs D, Wenger RH. Estrogen-dependent downregulation of hypoxia-inducible factor (HIF)-2α in invasive breast cancer cells. Oncotarget 2018; 7:31153-65. [PMID: 27105516 PMCID: PMC5058746 DOI: 10.18632/oncotarget.8866] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 03/31/2016] [Indexed: 12/17/2022] Open
Abstract
The involvement of estrogen (E2) and hypoxia in tumor progression is well established. Hypoxia has been reported to activate and degrade estrogen receptor alpha (ERα) in breast cancer cells. Furthermore, E2 has been shown to regulate hypoxia-inducible factor (HIF)-1α protein, but its role in HIF-2α regulation remains largely unexplored. In this study, we found that both HIF-2α mRNA and protein were down-regulated in ER positive but not ER negative breast cancer cells upon treatment with E2. The analysis of 690 samples derived from 608 mixed and 82 triple-negative breast cancer patients revealed that high nuclear HIF-2α tumor levels are associated with a worse prognosis specifically in human epidermal growth factor receptor 2 (HER2) and hormone receptor positive patients. Consistently, ERα/HER2 positive breast cancer cells displayed less pronounced downregulation of HIF-2α by E2. Experiments using a histone deacetylase inhibitor indicate that the E2 mediated decrease in HIF-2α mRNA is due to transcriptional repression. A functional estrogen response element (ERE) was identified in the first intron of the gene encoding HIF-2α (EPAS1), suggesting transcriptional co-repressor recruitment by ERα. Our results demonstrate a novel modulation of HIF-2α in breast cancer cells, explaining the opposing regulation between HIF-1α and HIF-2α in hormone-responsive breast cancer.
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Affiliation(s)
- Jerry H Fuady
- Institute of Physiology and Zurich Centre for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Katrin Gutsche
- Institute of Physiology and Zurich Centre for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Sara Santambrogio
- Institute of Physiology and Zurich Centre for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Zsuzsanna Varga
- Institute of Surgical Pathology, University Hospital Zurich, Zurich, Switzerland
| | - David Hoogewijs
- Institute of Physiology, University of Duisburg-Essen, Essen, Germany
| | - Roland H Wenger
- Institute of Physiology and Zurich Centre for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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Chen N, Qian J, Chen J, Yu X, Mei C, Hao C, Jiang G, Lin H, Zhang X, Zuo L, He Q, Fu P, Li X, Ni D, Hemmerich S, Liu C, Szczech L, Besarab A, Neff TB, Peony Yu KH, Valone FH. Phase 2 studies of oral hypoxia-inducible factor prolyl hydroxylase inhibitor FG-4592 for treatment of anemia in China. Nephrol Dial Transplant 2017; 32:1373-1386. [PMID: 28371815 PMCID: PMC5837707 DOI: 10.1093/ndt/gfx011] [Citation(s) in RCA: 146] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/29/2016] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND FG-4592 (roxadustat) is an oral hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor (HIF-PHI) promoting coordinated erythropoiesis through the transcription factor HIF. Two Phase 2 studies were conducted in China to explore the safety and efficacy of FG-4592 (USAN name: roxadustat, CDAN name: ), a HIF-PHI, in patients with anemia of chronic kidney disease (CKD), both patients who were dialysis-dependent (DD) and patients who were not dialysis-dependent (NDD). METHODS In the NDD study, 91 participants were randomized to low (1.1-1.75 mg/kg) or high (1.50-2.25 mg/kg) FG-4592 starting doses or to placebo. In the DD study, 87 were enrolled to low (1.1-1.8 mg/kg), medium (1.5-2.3 mg/kg) and high (1.7-2.3 mg/kg) starting FG-4592 doses or to continuation of epoetin alfa. In both studies, only oral iron supplementation was allowed. RESULTS In the NDD study, hemoglobin (Hb) increase ≥1 g/dL from baseline was achieved in 80.0% of subjects in the low-dose cohort and 87.1% in the high-dose cohort, versus 23.3% in the placebo arm (P < 0.0001, both). In the DD study, 59.1%, 88.9% (P = 0.008) and 100% (P = 0.0003) of the low-, medium- and high-dose subjects maintained their Hb levels after 5- and 6-weeks versus 50% of the epoetin alfa-treated subjects. In both studies, significant reductions in cholesterol were noted in FG-4592-treated subjects, with stability or increases in serum iron, total iron-binding capacity (TIBC) and transferrin (without intravenous iron administration). In the NDD study, hepcidin levels were significantly reduced across all FG-4592-treated arms as compared with no change in the placebo arm. In the DD study, hepcidin levels were also reduced in a statistically significant dose-dependent manner in the highest dose group as compared with the epoetin alfa-treated group. Adverse events were similar for FG-4592-treated and control subjects. CONCLUSIONS FG-4592 may prove an effective alternative for managing anemia of CKD. It is currently being investigated in a pivotal global Phase 3 program.
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Affiliation(s)
- Nan Chen
- Institute of Nephrology, Department of Nephrology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | | | | | - Xueqing Yu
- Sun Yat-Sen University, Guangzhou, China
| | | | | | - Gengru Jiang
- Xinhua Hospital, Jiaotong University, Shanghai, China
| | - Hongli Lin
- Dalian Medical University, Dalian, China
| | | | - Li Zuo
- Beijing University First Hospital, Beijing, China
| | - Qiang He
- Sichuan Province Hospital, Chengdu, China
| | - Ping Fu
- West China Hospital, Chengdu, China
| | - Xuemei Li
- Union Medical College Hospital, Beijing, China
| | - Dalvin Ni
- FibroGen, Inc., San Francisco, CA, USA
| | | | | | - Lynda Szczech
- FibroGen, Inc., San Francisco, CA, USA
- Correspondence and offprint requests to: Lynda Szczech; E-mail:
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De Smet S, van Herpt P, D'Hulst G, Van Thienen R, Van Leemputte M, Hespel P. Physiological Adaptations to Hypoxic vs. Normoxic Training during Intermittent Living High. Front Physiol 2017; 8:347. [PMID: 28620311 PMCID: PMC5449743 DOI: 10.3389/fphys.2017.00347] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/11/2017] [Indexed: 12/16/2022] Open
Abstract
In the setting of “living high,” it is unclear whether high-intensity interval training (HIIT) should be performed “low” or “high” to stimulate muscular and performance adaptations. Therefore, 10 physically active males participated in a 5-week “live high-train low or high” program (TR), whilst eight subjects were not engaged in any altitude or training intervention (CON). Five days per week (~15.5 h per day), TR was exposed to normobaric hypoxia simulating progressively increasing altitude of ~2,000–3,250 m. Three times per week, TR performed HIIT, administered as unilateral knee-extension training, with one leg in normobaric hypoxia (~4,300 m; TRHYP) and with the other leg in normoxia (TRNOR). “Living high” elicited a consistent elevation in serum erythropoietin concentrations which adequately predicted the increase in hemoglobin mass (r = 0.78, P < 0.05; TR: +2.6%, P < 0.05; CON: −0.7%, P > 0.05). Muscle oxygenation during training was lower in TRHYP vs. TRNOR (P < 0.05). Muscle homogenate buffering capacity and pH-regulating protein abundance were similar between pretest and posttest. Oscillations in muscle blood volume during repeated sprints, as estimated by oscillations in NIRS-derived tHb, increased from pretest to posttest in TRHYP (~80%, P < 0.01) but not in TRNOR (~50%, P = 0.08). Muscle capillarity (~15%) as well as repeated-sprint ability (~8%) and 3-min maximal performance (~10–15%) increased similarly in both legs (P < 0.05). Maximal isometric strength increased in TRHYP (~8%, P < 0.05) but not in TRNOR (~4%, P > 0.05). In conclusion, muscular and performance adaptations were largely similar following normoxic vs. hypoxic HIIT. However, hypoxic HIIT stimulated adaptations in isometric strength and muscle perfusion during intermittent sprinting.
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Affiliation(s)
- Stefan De Smet
- Department of Kinesiology, Exercise Physiology Research Group, KU LeuvenLeuven, Belgium
| | - Paul van Herpt
- Department of Kinesiology, Exercise Physiology Research Group, KU LeuvenLeuven, Belgium
| | - Gommaar D'Hulst
- Department of Kinesiology, Exercise Physiology Research Group, KU LeuvenLeuven, Belgium
| | - Ruud Van Thienen
- Department of Kinesiology, Exercise Physiology Research Group, KU LeuvenLeuven, Belgium
| | - Marc Van Leemputte
- Department of Kinesiology, Exercise Physiology Research Group, KU LeuvenLeuven, Belgium
| | - Peter Hespel
- Department of Kinesiology, Exercise Physiology Research Group, KU LeuvenLeuven, Belgium.,Athletic Performance Center, Bakala Academy, KU LeuvenLeuven, Belgium
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The functional interplay between the HIF pathway and the ubiquitin system - more than a one-way road. Exp Cell Res 2017; 356:152-159. [PMID: 28315321 DOI: 10.1016/j.yexcr.2017.03.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 03/13/2017] [Indexed: 12/30/2022]
Abstract
The hypoxia inducible factor (HIF) pathway and the ubiquitin system represent major cellular processes that are involved in the regulation of a plethora of cellular signaling pathways and tissue functions. The ubiquitin system controls the ubiquitination of proteins, which is the covalent linkage of one or several ubiquitin molecules to specific targets. This ubiquitination is catalyzed by approximately 1000 different E3 ubiquitin ligases and can lead to different effects, depending on the type of internal ubiquitin chain linkage. The best-studied function is the targeting of proteins for proteasomal degradation. The activity of E3 ligases is antagonized by proteins called deubiquitinases (or deubiquitinating enzymes), which negatively regulate ubiquitin chains. This is performed in most cases by the catalytic removal of these chains from the targeted protein. The HIF pathway is regulated in an oxygen-dependent manner by oxygen-sensing hydroxylases. Covalent modification of HIFα subunits leads to the recruitment of an E3 ligase complex via the von Hippel-Lindau (VHL) protein and the subsequent polyubiquitination and proteasomal degradation of HIFα subunits, demonstrating the regulation of the HIF pathway by the ubiquitin system. This unidirectional effect of an E3 ligase on the HIF pathway is the best-studied example for the interplay between these two important cellular processes. However, additional regulatory mechanisms of the HIF pathway through the ubiquitin system are emerging and, more recently, also the reciprocal regulation of the ubiquitin system through components of the HIF pathway. Understanding these mechanisms and their relevance for the activity of each other is of major importance for the comprehensive elucidation of the oxygen-dependent regulation of cellular processes. This review describes the current knowledge of the functional bidirectional interplay between the HIF pathway and the ubiquitin system on the protein level.
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Abstract
The human brain requires uninterrupted delivery of blood-borne oxygen and nutrients to sustain its function. Focal ischemia, particularly, ischemic stroke, and global ischemia imposed by cardiac arrest disrupt the brain's fuel supply. The resultant ATP depletion initiates a complex injury cascade encompassing intracellular Ca2+ overload, glutamate excitotoxicity, oxido-nitrosative stress, extracellular matrix degradation, and inflammation, culminating in neuronal and astroglial necrosis and apoptosis, neurocognitive deficits, and even death. Unfortunately, brain ischemia has proven refractory to pharmacological intervention. Many promising treatments afforded brain protection in animal models of focal and global ischemia, but failed to improve survival and neurocognitive recovery of stroke and cardiac arrest patients in randomized clinical trials. The culprits are the blood-brain barrier (BBB) that limits transferral of medications to the brain parenchyma, and the sheer complexity of the injury cascade, which presents a daunting array of targets unlikely to respond to monotherapies. Erythropoietin is a powerful neuroprotectant capable of interrupting multiple aspects of the brain injury cascade. Preclinical research demonstrates erythropoietin's ability to suppress glutamate excitotoxicity and intracellular Ca2+ overload, dampen oxidative stress and inflammation, interrupt the apoptotic cascade, and preserve BBB integrity. However, the erythropoietin dosages required to traverse the BBB and achieve therapeutically effective concentrations in the brain parenchyma impose untoward side effects. Recent discoveries that hypoxia induces erythropoietin production within the brain and that neurons, astroglia, and cerebrovascular endothelium harbor membrane erythropoietin receptors, raise the exciting prospect of harnessing endogenous erythropoietin to protect the brain from the ravages of ischemia-reperfusion.
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Affiliation(s)
- Robert T Mallet
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, TX, United States.
| | - Myoung-Gwi Ryou
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, TX, United States; Tarleton State University, Fort Worth, TX, United States
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46
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Locatelli F, Fishbane S, Block GA, Macdougall IC. Targeting Hypoxia-Inducible Factors for the Treatment of Anemia in Chronic Kidney Disease Patients. Am J Nephrol 2017; 45:187-199. [PMID: 28118622 DOI: 10.1159/000455166] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Anemia, a common complication of chronic kidney disease (CKD), has previously been attributed primarily to decreased production of erythropoietin. More recently, it has become apparent that the etiology of anemia involves several other factors, most notably dysfunctional iron metabolism, mediated via increased hepcidin activity and reduced clearance. Current management of anemia in patients with advanced CKD is based on erythropoiesis-stimulating agents and iron supplementation, along with red blood cell transfusions when necessary; however, safety considerations associated with these therapies highlight the need to pursue alternative treatment options targeting other mechanisms such as hypoxia-inducible factors (HIFs) that act as central regulators of erythropoiesis by coordinating a series of graded hypoxic responses. SUMMARY This review discusses the discovery of the HIF pathway and its regulation via HIF prolyl hydroxylase enzymes in the context of erythropoiesis and iron metabolism. The rationale for targeting this pathway and the clinical development of HIF prolyl hydroxylase inhibitors are reviewed, with a commentary on the potential implications of this class of agents in CKD anemia management. Key Messages: Pharmacologic activation of the HIF pathway results in a transient pseudo-hypoxic state that stimulates erythropoiesis in CKD patients with anemia. Results from clinical studies of a number of HIF prolyl hydroxylase inhibitors are increasingly available and provide support for the continued evaluation of the risk-benefit ratio of this novel therapeutic approach to the treatment of anemia in CKD.
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47
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Nolan KA, Scholz CC. Hypoxia: from basic mechanisms to therapeutics - a meeting report on the Keystone and HypoxiaNet Symposium. HYPOXIA 2016; 3:67-72. [PMID: 27774483 PMCID: PMC5045090 DOI: 10.2147/hp.s83240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In May 2015, the hypoxia research community came together at the largest meeting in this field to date, to present and discuss their most recent and mainly unpublished findings. This meeting report aims to summarize the data presented at this conference, which were broadly separated into the areas of the cellular hypoxic response, the relevance of the hypoxic response in health and disease, and the development of new therapeutics targeting the hypoxic response.
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Affiliation(s)
- Karen A Nolan
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Carsten C Scholz
- Institute of Physiology, University of Zürich, Zürich, Switzerland
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Frise MC, Cheng HY, Nickol AH, Curtis MK, Pollard KA, Roberts DJ, Ratcliffe PJ, Dorrington KL, Robbins PA. Clinical iron deficiency disturbs normal human responses to hypoxia. J Clin Invest 2016; 126:2139-50. [PMID: 27140401 PMCID: PMC4887172 DOI: 10.1172/jci85715] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/10/2016] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Iron bioavailability has been identified as a factor that influences cellular hypoxia sensing, putatively via an action on the hypoxia-inducible factor (HIF) pathway. We therefore hypothesized that clinical iron deficiency would disturb integrated human responses to hypoxia. METHODS We performed a prospective, controlled, observational study of the effects of iron status on hypoxic pulmonary hypertension. Individuals with absolute iron deficiency (ID) and an iron-replete (IR) control group were exposed to two 6-hour periods of isocapnic hypoxia. The second hypoxic exposure was preceded by i.v. infusion of iron. Pulmonary artery systolic pressure (PASP) was serially assessed with Doppler echocardiography. RESULTS Thirteen ID individuals completed the study and were age- and sex-matched with controls. PASP did not differ by group or study day before each hypoxic exposure. During the first 6-hour hypoxic exposure, the rise in PASP was 6.2 mmHg greater in the ID group (absolute rises 16.1 and 10.7 mmHg, respectively; 95% CI for difference, 2.7-9.7 mmHg, P = 0.001). Intravenous iron attenuated the PASP rise in both groups; however, the effect was greater in ID participants than in controls (absolute reductions 11.1 and 6.8 mmHg, respectively; 95% CI for difference in change, -8.3 to -0.3 mmHg, P = 0.035). Serum erythropoietin responses to hypoxia also differed between groups. CONCLUSION Clinical iron deficiency disturbs normal responses to hypoxia, as evidenced by exaggerated hypoxic pulmonary hypertension that is reversed by subsequent iron administration. Disturbed hypoxia sensing and signaling provides a mechanism through which iron deficiency may be detrimental to human health. TRIAL REGISTRATION ClinicalTrials.gov (NCT01847352). FUNDING M.C. Frise is the recipient of a British Heart Foundation Clinical Research Training Fellowship (FS/14/48/30828). K.L. Dorrington is supported by the Dunhill Medical Trust (R178/1110). D.J. Roberts was supported by R&D funding from National Health Service (NHS) Blood and Transplant and a National Institute for Health Research (NIHR) Programme grant (RP-PG-0310-1004). This research was funded by the NIHR Oxford Biomedical Research Centre Programme.
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Affiliation(s)
- Matthew C. Frise
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - Hung-Yuan Cheng
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - Annabel H. Nickol
- Oxford University Hospitals NHS Foundation Trust, Oxford Centre for Respiratory Medicine, Churchill Hospital, Oxford, United Kingdom
| | - M. Kate Curtis
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - Karen A. Pollard
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - David J. Roberts
- University of Oxford, Nuffield Department of Clinical Laboratory Sciences, and National Health Service Blood and Transplant Oxford Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - Peter J. Ratcliffe
- University of Oxford, Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, Old Road Campus, Headington, Oxford, United Kingdom
| | - Keith L. Dorrington
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - Peter A. Robbins
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
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Barba T, Boileau JC, Pasquet F, Hot A, Pavic M. [Inherited primitive and secondary polycythemia]. Rev Med Interne 2016; 37:460-5. [PMID: 26827274 DOI: 10.1016/j.revmed.2015.12.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 10/21/2015] [Accepted: 12/28/2015] [Indexed: 12/12/2022]
Abstract
Myeloproliferative disorders and secondary polycythemia cover most of the polycythemia cases encountered in daily practice. Inherited polycythemias are rare entities that have to be suspected when the classical causes of acquired polycythemia have been ruled out. Recent advances were made in the understanding of these pathologies, which are still little known to the physicians. This review reports the state of knowledge and proposes an algorithm to follow when confronted to a possible case of inherited polycythemia.
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Affiliation(s)
- T Barba
- Service de médecine interne, hôpital Édouard-Herriot, 5, place d'Arsonval, 69003 Lyon, France.
| | - J-C Boileau
- Service d'hématologie-oncologie, faculté de médecine et des sciences de la santé, CHU de Sherbrooke, 2500, boulevard de l'Université, Sherbrooke, Canada
| | - F Pasquet
- Service de médecine interne, hôpital d'instruction des armées Desgenettes, 108, boulevard Pinel, 69003 Lyon, France
| | - A Hot
- Service de médecine interne, hôpital Édouard-Herriot, 5, place d'Arsonval, 69003 Lyon, France
| | - M Pavic
- Service d'hématologie-oncologie, faculté de médecine et des sciences de la santé, CHU de Sherbrooke, 2500, boulevard de l'Université, Sherbrooke, Canada
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50
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Lelli A, Nolan KA, Santambrogio S, Gonçalves AF, Schönenberger MJ, Guinot A, Frew IJ, Marti HH, Hoogewijs D, Wenger RH. Induction of long noncoding RNA MALAT1 in hypoxic mice. HYPOXIA 2015; 3:45-52. [PMID: 27774481 PMCID: PMC5045088 DOI: 10.2147/hp.s90555] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Long thought to be “junk DNA”, in recent years it has become clear that a substantial fraction of intergenic genomic DNA is actually transcribed, forming long noncoding RNA (lncRNA). Like mRNA, lncRNA can also be spliced, capped, and polyadenylated, affecting a multitude of biological processes. While the molecular mechanisms underlying the function of lncRNAs have just begun to be elucidated, the conditional regulation of lncRNAs remains largely unexplored. In genome-wide studies our group and others recently found hypoxic transcriptional induction of a subset of lncRNAs, whereof nuclear-enriched abundant/autosomal transcript 1 (NEAT1) and metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) appear to be the lncRNAs most ubiquitously and most strongly induced by hypoxia in cultured cells. Hypoxia-inducible factor (HIF)-2 rather than HIF-1 seems to be the preferred transcriptional activator of these lncRNAs. For the first time, we also found strong induction primarily of MALAT1 in organs of mice exposed to inspiratory hypoxia. Most abundant hypoxic levels of MALAT1 lncRNA were found in kidney and testis. In situ hybridization revealed that the hypoxic induction in the kidney was confined to proximal rather than distal tubular epithelial cells. Direct oxygen-dependent regulation of MALAT1 lncRNA was confirmed using isolated primary kidney epithelial cells. In summary, high expression levels and acute, profound hypoxic induction of MALAT1 suggest a hitherto unrecognized role of this lncRNA in renal proximal tubular function.
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Affiliation(s)
- Aurelia Lelli
- Institute of Physiology and Zurich Center for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Karen A Nolan
- Institute of Physiology and Zurich Center for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Sara Santambrogio
- Institute of Physiology and Zurich Center for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Ana Filipa Gonçalves
- Institute of Physiology and Zurich Center for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Miriam J Schönenberger
- Institute of Physiology and Zurich Center for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Anna Guinot
- Institute of Physiology and Zurich Center for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Ian J Frew
- Institute of Physiology and Zurich Center for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Hugo H Marti
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - David Hoogewijs
- Institute of Physiology and Zurich Center for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Zurich, Switzerland; Institute of Physiology, University of Duisburg-Essen, Essen, Germany
| | - Roland H Wenger
- Institute of Physiology and Zurich Center for Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
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