1
|
Li Y, Xu A, Liu S, Zhang W, Zhou D, OuYang Q, Zi H, Zhang B, Zhang N, Geng W, Zhou Y, Duan W, Wang X, Zhao X, Ou X, Fan C, Jia J, Huang J. SUGP2 p.(Arg639Gln) variant is involved in the pathogenesis of hemochromatosis via the CIRBP/BMPER signaling pathway. Am J Hematol 2024; 99:1691-1703. [PMID: 38800953 DOI: 10.1002/ajh.27377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 05/07/2024] [Accepted: 05/12/2024] [Indexed: 05/29/2024]
Abstract
Pathogenic variants in HFE and non-HFE genes have been identified in hemochromatosis in different patient populations, but there are still a certain number of patients with unexplained primary iron overload. We recently identified in Chinese patients a recurrent p.(Arg639Gln) variant in SURP and G-patch domain containing 2 (SUGP2), a potential mRNA splicing-related factor. However, the target gene of SUGP2 and affected iron-regulating pathway remains unknown. We aimed to investigate the pathogenicity and underlying mechanism of this variant in hemochromatosis. RNA-seq analysis revealed that SUGP2 knockdown caused abnormal alternative splicing of CIRBP pre-mRNA, resulting in an increased normal splicing form of CIRBP V1, which in turn increased the expression of BMPER by enhancing its mRNA stability and translation. Furthermore, RNA-protein pull-down and RNA immunoprecipitation assays revealed that SUGP2 inhibited splicing of CIRBP pre-mRNA by a splice site variant at CIRBP c.492 and was more susceptible to CIRBP c.492 C/C genotype. Cells transfected with SUGP2 p.(Arg639Gln) vector showed up-regulation of CIRBP V1 and BMPER expression and down-regulation of pSMAD1/5 and HAMP expression. CRISPR-Cas9 mediated SUGP2 p.(Arg622Gln) knock-in mice showed increased iron accumulation in the liver, higher total serum iron, and decreased serum hepcidin level. A total of 10 of 54 patients with hemochromatosis (18.5%) harbored the SUGP2 p.(Arg639Gln) variant and carried CIRBP c.492 C/C genotype, and had increased BMPER expression in the liver. Altogether, the SUGP2 p.(Arg639Gln) variant down-regulates hepcidin expression through the SUGP2/CIRBP/BMPER axis, which may represent a novel pathogenic factor for hemochromatosis.
Collapse
Affiliation(s)
- Yanmeng Li
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine on Liver Cirrhosis, National Clinical Research Center for Digestive Diseases, Beijing, China
- Beijing Institute of Clinical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Anjian Xu
- Beijing Institute of Clinical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Susu Liu
- Division of Animal Model Research, Institute for Laboratory Animal Resources, National Institutes for Food and Drug Control (NIFDC), Beijing, China
| | - Wei Zhang
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine on Liver Cirrhosis, National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Donghu Zhou
- Beijing Institute of Clinical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Qin OuYang
- Beijing Institute of Clinical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Huaduan Zi
- Beijing Institute of Clinical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Bei Zhang
- Beijing Institute of Clinical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Ning Zhang
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine on Liver Cirrhosis, National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Wei Geng
- Department of Gastroenterology, Beijing United Family Hospital, Beijing, China
| | - Yiming Zhou
- Department of Liver Disease, The Seventh Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Weijia Duan
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine on Liver Cirrhosis, National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Xiaoming Wang
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine on Liver Cirrhosis, National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Xinyan Zhao
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine on Liver Cirrhosis, National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Xiaojuan Ou
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine on Liver Cirrhosis, National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Changfa Fan
- Division of Animal Model Research, Institute for Laboratory Animal Resources, National Institutes for Food and Drug Control (NIFDC), Beijing, China
| | - Jidong Jia
- Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine on Liver Cirrhosis, National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Jian Huang
- Beijing Institute of Clinical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| |
Collapse
|
2
|
Ogawa C, Tsuchiya K, Maeda K. Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors and Iron Metabolism. Int J Mol Sci 2023; 24:ijms24033037. [PMID: 36769359 PMCID: PMC9917929 DOI: 10.3390/ijms24033037] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 01/24/2023] [Accepted: 01/31/2023] [Indexed: 02/08/2023] Open
Abstract
The production of erythropoietin (EPO), the main regulator of erythroid differentiation, is regulated by hypoxia-inducible factor (HIF). HIF2α seems to be the principal regulator of EPO transcription, but HIF1α and 3α also may have additional influences on erythroid maturation. HIF is also involved in the regulation of iron, an essential component in erythropoiesis. Iron is essential for the organism but is also highly toxic, so its absorption and retention are strictly controlled. HIF also induces the synthesis of proteins involved in iron regulation, thereby ensuring the availability of iron necessary for hematopoiesis. Iron is a major component of hemoglobin and is also involved in erythrocyte differentiation and proliferation and in the regulation of HIF. Renal anemia is a condition in which there is a lack of stimulation of EPO synthesis due to decreased HIF expression. HIF prolyl hydroxylase inhibitors (HIF-PHIs) stabilize HIF and thereby allow it to be potent under normoxic conditions. Therefore, unlike erythropoiesis-stimulating agents, HIF-PHI may enhance iron absorption from the intestinal tract and iron supply from reticuloendothelial macrophages and hepatocytes into the plasma, thus facilitating the availability of iron for hematopoiesis. The only HIF-PHI currently on the market worldwide is roxadustat, but in Japan, five products are available. Clinical studies to date in Japan have also shown that HIF-PHIs not only promote hematopoiesis, but also decrease hepcidin, the main regulator of iron metabolism, and increase the total iron-binding capacity (TIBC), which indicates the iron transport capacity. However, concerns about the systemic effects of HIF-PHIs have not been completely dispelled, warranting further careful monitoring.
Collapse
Affiliation(s)
- Chie Ogawa
- Maeda Institute of Renal Research, Kawasaki 211-0063, Japan
- Biomarker Society, INC, Kawasaki 211-0063, Japan
- Correspondence: ; Tel.: +81-44-711-3221
| | - Ken Tsuchiya
- Biomarker Society, INC, Kawasaki 211-0063, Japan
- Department of Blood Purification, Tokyo Women’s Medical University, Tokyo 162-8666, Japan
| | - Kunimi Maeda
- Maeda Institute of Renal Research, Kawasaki 211-0063, Japan
- Biomarker Society, INC, Kawasaki 211-0063, Japan
| |
Collapse
|
3
|
Abstract
The liver is the major target organ of continued alcohol consumption at risk and resulting alcoholic liver disease (ALD) is the most common liver disease worldwide. The underlying molecular mechanisms are still poorly understood despite decades of scientific effort limiting our abilities to identify those individuals who are at risk to develop the disease, to develop appropriate screening strategies and, in addition, to develop targeted therapeutic approaches. ALD is predestined for the newly evolving translational medicine, as conventional clinical and health care structures seem to be constrained to fully appreciate this disease. This concept paper aims at summarizing the 15 years translational experience at the Center of Alcohol Research in Heidelberg, namely based on the long-term prospective and detailed characterization of heavy drinkers with mortality data. In addition, novel experimental findings will be presented. A special focus will be the long-known hepatic iron accumulation, the somewhat overlooked role of the hematopoietic system and novel insights into iron sensing and the role of hepcidin. Our preliminary work indicates that enhanced red blood cell (RBC) turnover is critical for survival in ALD patients. RBC turnover is not primarily due to vitamin deficiency but rather to ethanol toxicity directly targeted to erythrocytes but also to the bone marrow stem cell compartment. These novel insights also help to explain long-known aspects of ALD such as mean corpuscular volume of erythrocytes (MCV) and elevated aspartate transaminase (GOT/AST) levels. This work also aims at identifying future projects, naming unresolved observations, and presenting novel hypothetical concepts still requiring future validation.
Collapse
|
4
|
Wang S, Chen C, Yu L, Mueller J, Rausch V, Mueller S. Bone morphogenetic protein 6-mediated crosstalk between endothelial cells and hepatocytes recapitulates the iron-sensing pathway in vitro. J Biol Chem 2021; 297:101378. [PMID: 34740612 PMCID: PMC8637636 DOI: 10.1016/j.jbc.2021.101378] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/26/2021] [Accepted: 10/27/2021] [Indexed: 12/21/2022] Open
Abstract
Liver sinusoidal endothelial cell–derived bone morphogenetic protein 6 (BMP6) and the BMP6–small mothers against decapentaplegic homolog (SMAD) signaling pathway are essential for the expression of hepcidin, the secretion of which is considered the systemic master switch of iron homeostasis. However, there are continued controversies related to the strong and direct suppressive effect of iron on hepatocellular hepcidin in vitro in contrast to in vivo conditions. Here, we directly studied the crosstalk between endothelial cells (ECs) and hepatocytes using in vitro coculture models that mimic hepcidin signaling in vivo. Huh7 cells were directly cocultured with ECs, and EC conditioned media (CM) were also used to culture Huh7 cells and primary mouse hepatocytes. To explore the reactions of ECs to surrounding iron, they were grown in the presence of ferric ammonium citrate and heme, two iron-containing molecules. We found that both direct coculture with ECs and EC-CM significantly increased hepcidin expression in Huh7 cells. The upstream SMAD pathway, including phosphorylated SMAD1/5/8, SMAD1, and inhibitor of DNA binding 1, was induced by EC-CM, promoting hepcidin expression. Efficient blockage of this EC-mediated hepcidin upregulation by an inhibitor of the BMP6 receptor ALK receptor tyrosine kinase 2/3 or BMP6 siRNA identified BMP6 as a major hepcidin regulator in this coculture system, which highly fits the model of hepcidin regulation by iron in vivo. In addition, EC-derived BMP6 and hepcidin were highly sensitive to levels of not only ferric iron but also heme as low as 500 nM. We here establish a hepatocyte–endothelial coculture system to fully recapitulate iron regulation by hepcidin using EC-derived BMP6.
Collapse
Affiliation(s)
- Shijin Wang
- Center for Alcohol Research and Salem Medical Center, University of Heidelberg, Heidelberg, Germany
| | - Cheng Chen
- Center for Alcohol Research and Salem Medical Center, University of Heidelberg, Heidelberg, Germany
| | - Linna Yu
- Center for Alcohol Research and Salem Medical Center, University of Heidelberg, Heidelberg, Germany
| | - Johannes Mueller
- Center for Alcohol Research and Salem Medical Center, University of Heidelberg, Heidelberg, Germany
| | - Vanessa Rausch
- Center for Alcohol Research and Salem Medical Center, University of Heidelberg, Heidelberg, Germany
| | - Sebastian Mueller
- Center for Alcohol Research and Salem Medical Center, University of Heidelberg, Heidelberg, Germany.
| |
Collapse
|
5
|
Petrillo S, Manco M, Altruda F, Fagoonee S, Tolosano E. Liver Sinusoidal Endothelial Cells at the Crossroad of Iron Overload and Liver Fibrosis. Antioxid Redox Signal 2021; 35:474-486. [PMID: 32689808 DOI: 10.1089/ars.2020.8168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Significance: Liver fibrosis results from different etiologies and represents one of the most serious health issues worldwide. Fibrosis is the outcome of chronic insults on the liver and is associated with several factors, including abnormal iron metabolism. Recent Advances: Multiple mechanisms underlying the profibrogenic role of iron have been proposed. The pivotal role of liver sinusoidal endothelial cells (LSECs) in iron-level regulation, as well as their morphological and molecular dedifferentiation occurring in liver fibrosis, has encouraged research on LSECs as prime regulators of very early fibrotic events. Importantly, normal differentiated LSECs may act as gatekeepers of fibrogenesis by maintaining the quiescence of hepatic stellate cells, while LSECs capillarization precedes the onset of liver fibrosis. Critical Issues: In the present review, the morphological and molecular alterations occurring in LSECs after liver injury are addressed in an attempt to highlight how vascular dysfunction promotes fibrogenesis. In particular, we discuss in depth how a vicious loop can be established in which iron dysregulation and LSEC dedifferentiation synergize to exacerbate and promote the progression of liver fibrosis. Future Directions: LSECs, due to their pivotal role in early liver fibrosis and iron homeostasis, show great promises as a therapeutic target. In particular, new strategies can be devised for restoring LSECs differentiation and thus their role as regulators of iron homeostasis, hence preventing the progression of liver fibrosis or, even better, promoting its regression. Antioxid. Redox Signal. 35, 474-486.
Collapse
Affiliation(s)
- Sara Petrillo
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Torino, Torino, Italy
| | - Marta Manco
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Torino, Torino, Italy
| | - Fiorella Altruda
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Torino, Torino, Italy
| | - Sharmila Fagoonee
- Institute of Biostructure and Bioimaging, CNR c/o Molecular Biotechnology Center, Torino, Italy
| | - Emanuela Tolosano
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Torino, Torino, Italy
| |
Collapse
|
6
|
Colucci S, Marques O, Altamura S. 20 years of Hepcidin: How far we have come. Semin Hematol 2021; 58:132-144. [PMID: 34389105 DOI: 10.1053/j.seminhematol.2021.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/12/2021] [Accepted: 05/31/2021] [Indexed: 12/20/2022]
Abstract
Twenty years ago the discovery of hepcidin deeply changed our understanding of the regulation of systemic iron homeostasis. It is now clear that hepcidin orchestrates systemic iron levels by controlling the amount of iron exported into the bloodstream through ferroportin. Hepcidin expression is increased in situations where systemic iron levels should be reduced, such as in iron overload and infection. Conversely, hepcidin is repressed during iron deficiency, hypoxia or expanded erythropoiesis, to increase systemic iron availability and sustain erythropoiesis. In this review, we will focus on molecular mechanisms of hepcidin regulation and on the pathological consequences of their disruption.
Collapse
Affiliation(s)
- Silvia Colucci
- Department of Pediatric Hematology, Oncology and Immunology - University of Heidelberg, Heidelberg, Germany.; Molecular Medicine Partnership Unit, EMBL and University of Heidelberg, Heidelberg, Germany
| | - Oriana Marques
- Department of Pediatric Hematology, Oncology and Immunology - University of Heidelberg, Heidelberg, Germany.; Molecular Medicine Partnership Unit, EMBL and University of Heidelberg, Heidelberg, Germany
| | - Sandro Altamura
- Department of Pediatric Hematology, Oncology and Immunology - University of Heidelberg, Heidelberg, Germany.; Molecular Medicine Partnership Unit, EMBL and University of Heidelberg, Heidelberg, Germany..
| |
Collapse
|
7
|
Huang W, Xu X, Liu M, Cui W, Peng G. Downregulation of Hsa_circ_0000735 Inhibits the Proliferation, Migration, Invasion, and Glycolysis in Non-small-cell Lung Cancer by Targeting miR-940/BMPER Axis. Onco Targets Ther 2020; 13:8427-8439. [PMID: 32922033 PMCID: PMC7457839 DOI: 10.2147/ott.s253474] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/18/2020] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Lung cancer is the most commonly diagnosed cancer and the major cause of cancer-related deaths worldwide. The increasing studies have demonstrated that circular RNA (circRNA) was involved in the progression of various cancers, including non-small-cell lung cancer (NSCLC). This study was designed to assess the expression, roles and functional mechanisms of circ_0000735 in NSCLC. MATERIALS AND METHODS The expression levels of circ_0000735, miR-940 and bone morphogenetic protein binding endothelial cell precursor-derived regulator (BMPER) were estimated by the real-time quantitative polymerase chain reaction (RT-qPCR). The biological behaviors of NSCLC cells such as proliferation, migration and invasion were analyzed by cell counting kit-8 (CCK-8), colony-forming assays and transwell assay, respectively. Furthermore, extracellular acid ratio and lactate production were tested to assess glycolysis levels of NSCLC cells. The interaction relationship among circ_0000735, BMPER and miR-940 was analyzed by bioinformatics database and dual-luciferase reporter assay. The protein expression level of BMPER was assessed by Western blot assay. Tumorigenesis assay was established to clarify the functional roles of circ_0000735 in vivo. RESULTS Circ_0000735 was upregulated and significantly correlated with overall survival in patients with NSCLC. In addition, the loss-of-functional experiments revealed that knockdown of circ_0000735 repressed proliferation, migration, invasion and glycolysis of NSCLC cells and tumor growth in vivo, which was overturned by overexpression of BMPER. Similarly, overexpression of circ_0000735 enhanced proliferation, migration, invasion, and glycolysis of NSCLC cells. In addition, we also confirmed that overexpression of miR-940 impeded proliferation, migration, invasion, and glycolysis of NSCLC cells. Furthermore, overexpression of BMPER abolished si-circ_0000735 induced effects on NSCLC cells. CONCLUSION Circ_0000735 regulated proliferation, migration, invasion, and glycolysis in NSCLC cells by targeting miR-940/BMPER axis.
Collapse
Affiliation(s)
- Weizhe Huang
- Department of Thoracic Surgery, The First Affiliated Hospital of Shantou University Medical College, Shantou515041, Guangdong, People’s Republic of China
| | - Xin Xu
- Department of Thoracic Surgery, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou510120, Guangdong, People’s Republic of China
- State Key Laboratory of Respiratory Disease, Guangzhou510120, Guangdong, People’s Republic of China
- National Clinical Research Center for Respiratory Disease, Guangzhou510120, Guangdong, People’s Republic of China
- Guangzhou Institute of Respiratory Health, Guangzhou510120, Guangdong, People’s Republic of China
| | - Mengyang Liu
- Department of Thoracic Surgery, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou510120, Guangdong, People’s Republic of China
- State Key Laboratory of Respiratory Disease, Guangzhou510120, Guangdong, People’s Republic of China
- National Clinical Research Center for Respiratory Disease, Guangzhou510120, Guangdong, People’s Republic of China
- Guangzhou Institute of Respiratory Health, Guangzhou510120, Guangdong, People’s Republic of China
| | - Weixue Cui
- Department of Thoracic Surgery, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou510120, Guangdong, People’s Republic of China
- State Key Laboratory of Respiratory Disease, Guangzhou510120, Guangdong, People’s Republic of China
- National Clinical Research Center for Respiratory Disease, Guangzhou510120, Guangdong, People’s Republic of China
- Guangzhou Institute of Respiratory Health, Guangzhou510120, Guangdong, People’s Republic of China
| | - Guilin Peng
- Department of Thoracic Surgery, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou510120, Guangdong, People’s Republic of China
- State Key Laboratory of Respiratory Disease, Guangzhou510120, Guangdong, People’s Republic of China
- National Clinical Research Center for Respiratory Disease, Guangzhou510120, Guangdong, People’s Republic of China
- Guangzhou Institute of Respiratory Health, Guangzhou510120, Guangdong, People’s Republic of China
- Correspondence: Guilin Peng Tel +86-20-83062114 Email
| |
Collapse
|
8
|
Asperti M, Denardo A, Gryzik M, Arosio P, Poli M. The role of heparin, heparanase and heparan sulfates in hepcidin regulation. VITAMINS AND HORMONES 2019; 110:157-188. [PMID: 30798810 DOI: 10.1016/bs.vh.2019.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hepcidin is considered the major regulator of systemic iron homeostasis in human and mice, and its expression in the liver is mainly regulated at a transcriptional level. Central to its regulation are the bone morphogenetic proteins, particularly BMP6, that are heparin binding proteins. Heparin was found to inhibit hepcidin expression and BMP6 activity in hepatic cell lines and in mice, suggesting that endogenous heparan sulfates are involved in the pathway of hepcidin expression. This was confirmed by the study of cells and mice overexpressing heparanase, the enzyme that hydrolyzes heparan sulfates, and by cellular models with altered heparan sulfates. The evidences supporting the role of heparan sulfate in hepcidin expression are summarized in this chapter and open the way for new understanding in hepcidin expression and its control in pathological condition.
Collapse
Affiliation(s)
- Michela Asperti
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Andrea Denardo
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Magdalena Gryzik
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Paolo Arosio
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
| | - Maura Poli
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| |
Collapse
|
9
|
Padmanabhan N, Menelaou K, Gao J, Anderson A, Blake GET, Li T, Daw BN, Watson ED. Abnormal folate metabolism causes age-, sex- and parent-of-origin-specific haematological defects in mice. J Physiol 2018; 596:4341-4360. [PMID: 30024025 PMCID: PMC6138292 DOI: 10.1113/jp276419] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 06/27/2018] [Indexed: 12/27/2022] Open
Abstract
KEY POINTS Folate (folic acid) deficiency and mutations in folate-related genes in humans result in megaloblastic anaemia. Folate metabolism, which requires the enzyme methionine synthase reductase (MTRR), is necessary for DNA synthesis and the transmission of one-carbon methyl groups for cellular methylation. In this study, we show that the hypomorphic Mtrrgt/gt mutation in mice results in late-onset and sex-specific blood defects, including macrocytic anaemia, extramedullary haematopoiesis and lymphopenia. Notably, when either parent carries an Mtrrgt allele, blood phenotypes result in their genetically wildtype adult daughters, the effects of which are parent specific. Our data establish a new model for studying the mechanism of folate metabolism in macrocytic anaemia aetiology and suggest that assessing parental folate status might be important when diagnosing adult patients with unexplained anaemia. ABSTRACT The importance of the vitamin folate (also known as folic acid) in erythrocyte formation, maturation and/or longevity is apparent since folate deficiency in humans causes megaloblastic anaemia. Megaloblastic anaemia is a type of macrocytic anaemia whereby erythrocytes are enlarged and fewer in number. Folate metabolism is required for thymidine synthesis and one-carbon metabolism, though its specific role in erythropoiesis is not well understood. Methionine synthase reductase (MTRR) is a key enzyme necessary for the progression of folate metabolism since knocking down the Mtrr gene in mice results in hyperhomocysteinaemia and global DNA hypomethylation. We demonstrate here that abnormal folate metabolism in mice caused by Mtrrgt/gt homozygosity leads to haematopoietic phenotypes that are sex and age dependent. Specifically, Mtrrgt/gt female mice displayed macrocytic anaemia, which might be due to defective erythroid differentiation at the exclusion of haemolysis. This was associated with increased renal Epo mRNA expression, hypercellular bone marrow, and splenic extramedullary haematopoiesis. In contrast, the male response differed since Mtrrgt/gt male mice were not anaemic but did display erythrocytic macrocytosis and lymphopenia. Regardless of sex, these phenotypes were late onset. Remarkably, we also show that when either parent carries an Mtrrgt allele, a haematological defect results in their adult wildtype daughters. However, the specific phenotype was dependent upon the sex of the parent. For instance, wildtype daughters of Mtrr+/gt females displayed normocytic anaemia. In contrast, wildtype daughters of Mtrr+/gt males exhibited erythrocytic microcytosis not associated with anaemia. Therefore, abnormal folate metabolism affects adult haematopoiesis in an age-, sex- and parent-specific manner.
Collapse
Affiliation(s)
- Nisha Padmanabhan
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
- Centre for Trophoblast ResearchUniversity of CambridgeCambridgeUK
| | - Katerina Menelaou
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
- Centre for Trophoblast ResearchUniversity of CambridgeCambridgeUK
| | - Jiali Gao
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
| | - Alexander Anderson
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
- Centre for Trophoblast ResearchUniversity of CambridgeCambridgeUK
| | - Georgina E. T. Blake
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
- Centre for Trophoblast ResearchUniversity of CambridgeCambridgeUK
| | - Tanya Li
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
| | - B. Nuala Daw
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
- Centre for Trophoblast ResearchUniversity of CambridgeCambridgeUK
| | - Erica D. Watson
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
- Centre for Trophoblast ResearchUniversity of CambridgeCambridgeUK
| |
Collapse
|
10
|
Green tea activity and iron overload induced molecular fibrogenesis of rat liver. Saudi J Biol Sci 2017; 26:531-540. [PMID: 30899168 PMCID: PMC6408694 DOI: 10.1016/j.sjbs.2017.08.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 05/24/2017] [Accepted: 08/17/2017] [Indexed: 12/21/2022] Open
Abstract
Iron overload toxicity was shown to associate with chronic liver diseases which lead to hepatic fibrosis and subsequently the progression to cancer through oxidative stress and apoptotic pathways. Green tea potential activity as chelating, anti-oxidative, or anti-apoptotic mechanisms against metal toxicity was poorly clarified. Here, we are trying to evaluate the anti-oxidant and anti-apoptotic properties of green tea in the regulation of serum hepcidin levels, reduction in iron overloads, and improve of liver fibrosis in iron overloaded experimental rats. Three groups of male adult rats were randomly classified into three groups and treated as follows: control rats, iron treated rats for two months in drinking water followed by either vehicle or green tea extract (AGTE; 100 mg/kg) treatment for 2 more months. Thereafter, we studied the effects of AGTE on iron overload-induced lipid peroxidation, anti-oxidant depletion, liver cell injury and apoptosis. Treatment of iron-overloaded rats with AGTE resulted in marked decreases in iron accumulation within liver, depletion in serum ferritin, and hepcidin levels. Iron-overloaded rats had significant increase in malonyldialdehyde (MDA), a marker of lipid peroxidation and nitric oxide (NO) in liver when compared to control group. Also, significant change in cytochrome c and DNA content as apoptotic markers were reported in iron treated rats. The effects of iron overload on lipid peroxidation, NO levels, cytochrome c and DNA content were significantly reduced by the intervention treatment with AGTE (P < 0.001). Furthermore, the endogenous anti-oxidant capacities/levels (TAC) in liver were also significantly decreased in chronic iron overload and administration of AGTE restored the decrease in the hepatic antioxidant activities/levels. Also, hepatic hepcidin was shown to be significantly correlated with oxidative and apoptotic relating biomarkers as well as an improvement in liver fibrosis of iron treated rats following AGTE treatment. In-vitro analysis showed that, the improvement in iron toxicity of the liver depend mainly on antioxidant and protective ability of green tea polyphenolic compounds especiallyepigallocatechin-3-gallate (EGCG). Our study showed that green tea extract (GTE) ameliorates iron overload induced hepatotoxicity, apoptosis and oxidative stress in rat liver via inhibition of hepatic iron accumulation; improve of liver antioxidant capacity, and down regulation of serum hepcidin as well as reduction in the release of apoptotic relating proteins.
Collapse
|
11
|
Upanan S, McKie AT, Latunde-Dada GO, Roytrakul S, Uthaipibull C, Pothacharoen P, Kongtawelert P, Fucharoen S, Srichairatanakool S. Hepcidin suppression in β-thalassemia is associated with the down-regulation of atonal homolog 8. Int J Hematol 2017; 106:196-205. [PMID: 28405918 DOI: 10.1007/s12185-017-2231-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 03/25/2017] [Accepted: 04/03/2017] [Indexed: 01/19/2023]
Abstract
Atonal homolog 8 (ATOH8) is defined as a positive regulator of hepcidin transcription, which links erythropoietic activity with iron-sensing molecules. In the present study, we investigated the association between hepcidin and ATOH8 expression in β-thalassemia. We found that inhibition of hepcidin expression in β-thalassemia is correlated with reduced ATOH8 expression. Hepatic hepcidin 1 (Hamp1) and Atoh8 mRNA expression were down-regulated in β-thalassemic mice. Hepcidin (HAMP) and ATOH8 mRNA expression were consistently suppressed in Huh7 cells cultured in medium supplemented with β-thalassemia patient serum. The Huh7 cells, which were transfected with ATOH8-FLAG expression plasmid and cultured in the supplemented medium, exhibited increased levels of ATOH8 mRNA, ATOH8-FLAG protein, pSMAD1,5,8, and HAMP mRNA. Interestingly, over-expression of ATOH8 reversed the effects of hepcidin suppression induced by the β-thalassemia patient sera. In conclusion, hepcidin suppression in β-thalassemia is associated with the down-regulation of ATOH8 in response to anemia. We, therefore, suggest that ATOH8 is an important transcriptional regulator of hepcidin in β-thalassemia.
Collapse
Affiliation(s)
- Supranee Upanan
- Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Andrew T McKie
- Division of Diabetes and Nutritional Sciences, School of Medicine, King's College London, London, SE1 9NH, UK
| | - Gladys O Latunde-Dada
- Division of Diabetes and Nutritional Sciences, School of Medicine, King's College London, London, SE1 9NH, UK
| | - Sittiruk Roytrakul
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani, 12120, Thailand
| | - Chairat Uthaipibull
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani, 12120, Thailand
| | - Peraphan Pothacharoen
- Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Prachya Kongtawelert
- Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Suthat Fucharoen
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom, 73170, Thailand
| | - Somdet Srichairatanakool
- Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
| |
Collapse
|
12
|
Bone morphogenetic protein-binding endothelial regulator of liver sinusoidal endothelial cells induces iron overload in a fatty liver mouse model. J Gastroenterol 2017; 52:341-351. [PMID: 27364348 PMCID: PMC5323480 DOI: 10.1007/s00535-016-1237-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 06/19/2016] [Indexed: 02/06/2023]
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is frequently accompanied by iron overload. However, because of the complex hepcidin-regulating molecules, the molecular mechanism underlying iron overload remains unknown. To identify the key molecule involved in NAFLD-associated iron dysregulation, we performed whole-RNA sequencing on the livers of obese mice. METHODS Male C57BL/6 mice were fed a regular or high-fat diet for 16 or 48 weeks. Internal iron was evaluated by plasma iron, ferritin or hepatic iron content. Whole-RNA sequencing was performed by transcriptome analysis using semiconductor high-throughput sequencer. Mouse liver tissues or isolated hepatocytes and sinusoidal endothelial cells were used to assess the expression of iron-regulating molecules. RESULTS Mice fed a high-fat diet for 16 weeks showed excess iron accumulation. Longer exposure to a high-fat diet increased hepatic fibrosis and intrahepatic iron accumulation. A pathway analysis of the sequencing data showed that several inflammatory pathways, including bone morphogenetic protein (BMP)-SMAD signaling, were significantly affected. Sequencing analysis showed 2314 altered genes, including decreased mRNA expression of the hepcidin-coding gene Hamp. Hepcidin protein expression and SMAD phosphorylation, which induces Hamp, were found to be reduced. The expression of BMP-binding endothelial regulator (BMPER), which inhibits BMP-SMAD signaling by binding BMP extracellularly, was up-regulated in fatty livers. In addition, immunohistochemical and cell isolation analyses showed that BMPER was primarily expressed in the liver sinusoidal endothelial cells (LSECs) rather than hepatocytes. CONCLUSIONS BMPER secretion by LSECs inhibits BMP-SMAD signaling in hepatocytes and further reduces hepcidin protein expression. These intrahepatic molecular interactions suggest a novel molecular basis of iron overload in NAFLD.
Collapse
|
13
|
Abstract
Iron is required for many biological processes but is also toxic in excess; thus, body iron balance is maintained through sophisticated regulatory mechanisms. The lack of a regulated iron excretory mechanism means that body iron balance is controlled at the level of absorption from the diet. Iron absorption is regulated by the hepatic peptide hormone hepcidin. Hepcidin also controls iron release from cells that recycle or store iron, thus regulating plasma iron concentrations. Hepcidin exerts its effects through its receptor, the cellular iron exporter ferroportin. Important regulators of hepcidin, and therefore of systemic iron homeostasis, include plasma iron concentrations, body iron stores, infection and inflammation, and erythropoiesis. Disturbances in the regulation of hepcidin contribute to the pathogenesis of many iron disorders: hepcidin deficiency causes iron overload in hereditary hemochromatosis and nontransfused β-thalassemia, whereas overproduction of hepcidin is associated with iron-restricted anemias seen in patients with chronic kidney disease, chronic inflammatory diseases, some cancers, and inherited iron-refractory iron deficiency anemia. This review summarizes our current understanding of the molecular mechanisms and signaling pathways involved in the control of hepcidin synthesis in the liver, a principal determinant of plasma hepcidin concentrations.
Collapse
Affiliation(s)
- Veena Sangkhae
- Center for Iron Disorders, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA
| | - Elizabeta Nemeth
- Center for Iron Disorders, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA
| |
Collapse
|
14
|
Wallace DF. The Regulation of Iron Absorption and Homeostasis. Clin Biochem Rev 2016; 37:51-62. [PMID: 28303071 PMCID: PMC5198508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Iron is an essential element in biology, required for numerous cellular processes. Either too much or too little iron can be detrimental, and organisms have developed mechanisms for balancing iron within safe limits. In mammals there are no controlled mechanisms for the excretion of excess iron, hence body iron homeostasis is regulated at the sites of absorption, utilisation and recycling. This review will discuss the discoveries that have been made in the past 20 years into advancing our understanding of iron homeostasis and its regulation. The study of iron-associated disorders, such as the iron overload condition hereditary haemochromatosis and various forms of anaemia have been instrumental in increasing our knowledge in this area, as have cellular and animal model studies. The liver has emerged as the major site of systemic iron regulation, being the location where the iron regulatory hormone hepcidin is produced. Hepcidin is a negative regulator of iron absorption and recycling, achieving this by binding to the only known cellular iron exporter ferroportin and causing its internalisation and degradation, thereby reducing iron efflux from target cells and reducing serum iron levels. Much of the research in the iron metabolism field has focussed on the regulation of hepcidin and its interaction with ferroportin. The advances in this area have greatly increased our knowledge of iron metabolism and its regulation and have led to the development of novel diagnostics and therapeutics for iron-associated disorders.
Collapse
|
15
|
Chen H, Choesang T, Li H, Sun S, Pham P, Bao W, Feola M, Westerman M, Li G, Follenzi A, Blanc L, Rivella S, Fleming RE, Ginzburg YZ. Increased hepcidin in transferrin-treated thalassemic mice correlates with increased liver BMP2 expression and decreased hepatocyte ERK activation. Haematologica 2015; 101:297-308. [PMID: 26635037 DOI: 10.3324/haematol.2015.127902] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 12/01/2015] [Indexed: 12/13/2022] Open
Abstract
Iron overload results in significant morbidity and mortality in β-thalassemic patients. Insufficient hepcidin is implicated in parenchymal iron overload in β-thalassemia and approaches to increase hepcidin have therapeutic potential. We have previously shown that exogenous apo-transferrin markedly ameliorates ineffective erythropoiesis and increases hepcidin expression in Hbb(th1/th1) (thalassemic) mice. We utilize in vivo and in vitro systems to investigate effects of exogenous apo-transferrin on Smad and ERK1/2 signaling, pathways that participate in hepcidin regulation. Our results demonstrate that apo-transferrin increases hepcidin expression in vivo despite decreased circulating and parenchymal iron concentrations and unchanged liver Bmp6 mRNA expression in thalassemic mice. Hepatocytes from apo-transferrin-treated mice demonstrate decreased ERK1/2 pathway and increased serum BMP2 concentration and hepatocyte BMP2 expression. Furthermore, hepatocyte ERK1/2 phosphorylation is enhanced by neutralizing anti-BMP2/4 antibodies and suppressed in vitro in a dose-dependent manner by BMP2, resulting in converse effects on hepcidin expression, and hepatocytes treated with MEK/ERK1/2 inhibitor U0126 in combination with BMP2 exhibit an additive increase in hepcidin expression. Lastly, bone marrow erythroferrone expression is normalized in apo-transferrin treated thalassemic mice but increased in apo-transferrin injected wild-type mice. These findings suggest that increased hepcidin expression after exogenous apo-transferrin is in part independent of erythroferrone and support a model in which apo-transferrin treatment in thalassemic mice increases BMP2 expression in the liver and other organs, decreases hepatocellular ERK1/2 activation, and increases nuclear Smad to increase hepcidin expression in hepatocytes.
Collapse
Affiliation(s)
- Huiyong Chen
- Erythropoiesis Laboratory, LFKRI, New York Blood Center, NY, USA
| | - Tenzin Choesang
- Erythropoiesis Laboratory, LFKRI, New York Blood Center, NY, USA
| | - Huihui Li
- Erythropoiesis Laboratory, LFKRI, New York Blood Center, NY, USA Central South University, Changsha, PR China
| | - Shuming Sun
- Erythropoiesis Laboratory, LFKRI, New York Blood Center, NY, USA
| | - Petra Pham
- Flow Cytometry Core Laboratory, LFKRI, New York Blood Center, NY, USA
| | - Weili Bao
- Erythropoiesis Laboratory, LFKRI, New York Blood Center, NY, USA
| | - Maria Feola
- Erythropoiesis Laboratory, LFKRI, New York Blood Center, NY, USA University of Piemonte Orientale, Amedeo Avogadro, Novara, Italy
| | | | - Guiyuan Li
- Central South University, Changsha, PR China
| | - Antonia Follenzi
- University of Piemonte Orientale, Amedeo Avogadro, Novara, Italy
| | - Lionel Blanc
- The Feinstein Institute for Medical Research, Manhasset, NY, USA
| | | | | | | |
Collapse
|
16
|
Combined treatment of 3-hydroxypyridine-4-one derivatives and green tea extract to induce hepcidin expression in iron-overloaded β-thalassemic mice. Asian Pac J Trop Biomed 2015. [DOI: 10.1016/j.apjtb.2015.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
|
17
|
Song B, Bian Q, Shao CH, Liu AA, Jing W, Liu R, Zhang YJ, Zhou YQ, Li G, Jin G. Sox2 function as a negative regulator to control HAMP expression. Biol Res 2015; 48:23. [PMID: 25943891 PMCID: PMC4440282 DOI: 10.1186/s40659-015-0013-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Accepted: 04/16/2015] [Indexed: 11/24/2022] Open
Abstract
Background Hepcidin, encoding by HAMP gene, is the pivotal regulator of iron metabolism, controlling the systemic absorption and transportation of irons from intracellular stores. Abnormal levels of HAMP expression alter plasma iron parameters and lead to iron metabolism disorders. Therefore, it is an important goal to understand the mechanisms controlling HAMP gene expression. Results Overexpression of Sox2 decrease basal expression of HAMP or induced by IL-6 or BMP-2, whereas, knockdown of Sox2 can increase HAMP expression, furthermore, two potential Sox2-binding sites were identified within the human HAMP promoter. Indeed, luciferase experiments demonstrated that deletion of any Sox2-binding site impaired the negative regulation of Sox2 on HAMP promoter transcriptional activity in basal conditions. ChIP experiments showed that Sox2 could directly bind to these sites. Finally, we verified the role of Sox2 to negatively regulate HAMP expression in human primary hepatocytes. Conclusion We found that Sox2 as a novel factor to bind with HAMP promoter to negatively regulate HAMP expression, which may be further implicated as a therapeutic option for the amelioration of HAMP-overexpression-related diseases, including iron deficiency anemia. Electronic supplementary material The online version of this article (doi:10.1186/s40659-015-0013-z) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Bin Song
- Department of General Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| | - Qi Bian
- Department of Nephrology, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| | - Cheng-Hao Shao
- Department of General Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| | - An-An Liu
- Department of General Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| | - Wei Jing
- Department of General Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| | - Rui Liu
- Department of General Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| | - Yi-Jie Zhang
- Department of General Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| | - Ying-Qi Zhou
- Department of General Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| | - Gang Li
- Department of General Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| | - Gang Jin
- Department of General Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
| |
Collapse
|
18
|
Bu JT, Bartnikas TB. The use of hypotransferrinemic mice in studies of iron biology. Biometals 2015; 28:473-80. [PMID: 25663418 DOI: 10.1007/s10534-015-9833-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/04/2015] [Indexed: 12/15/2022]
Abstract
The hypotransferrinemic (hpx) mouse is a model of inherited transferrin deficiency that originated several decades ago in the BALB/cJ mouse strain. Also known as the hpx mouse, this line is almost completely devoid of transferrin, an abundant serum iron-binding protein. Two of the most prominent phenotypes of the hpx mouse are severe anemia and tissue iron overload. These phenotypes reflect the essential role of transferrin in iron delivery to bone marrow and regulation of iron homeostasis. Over the years, the hpx mouse has been utilized in studies on the role of transferrin, iron and other metals in a variety of organ systems and biological processes. This review summarizes the lessons learned from these studies and suggests possible areas of future exploration using this versatile yet complex mouse model.
Collapse
Affiliation(s)
- Julia T Bu
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Providence, RI, 02912, USA
| | | |
Collapse
|
19
|
Abstract
Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-beta (TGF-β) superfamily of signaling molecules. In addition to protean roles in embryonic development, germ-line specification, and cellular differentiation, a central role in iron homeostasis has recently been demonstrated for certain BMPs. Specifically, BMP6 serves to relate hepatic iron stores to the hepatocellular expression of the iron-regulatory hormone hepcidin. This regulation occurs via cellular SMAD-signaling molecules and is strongly modulated by the BMP coreceptor hemojuvelin (HJV). Mutations in certain genes influencing signaling to hepcidin via the BMP/SMAD pathway are associated with human disorders of iron metabolism, such as hereditary hemochromatosis and iron-refractory iron-deficiency anemia. Evidence suggests that signals in addition to iron stores influence hepcidin expression via the BMP/SMAD pathway. This review summarizes the details of BMP/SMAD signaling, with a particular focus on its role in iron homeostasis and iron-related diseases.
Collapse
Affiliation(s)
- Nermi L Parrow
- Division of Molecular and Clinical Nutrition, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | | |
Collapse
|
20
|
Waldvogel-Abramowski S, Waeber G, Gassner C, Buser A, Frey BM, Favrat B, Tissot JD. Physiology of iron metabolism. Transfus Med Hemother 2014; 41:213-21. [PMID: 25053935 DOI: 10.1159/000362888] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 12/04/2013] [Indexed: 12/12/2022] Open
Abstract
A revolution occurred during the last decade in the comprehension of the physiology as well as in the physiopathology of iron metabolism. The purpose of this review is to summarize the recent knowledge that has accumulated, allowing a better comprehension of the mechanisms implicated in iron homeostasis. Iron metabolism is very fine tuned. The free molecule is very toxic; therefore, complex regulatory mechanisms have been developed in mammalian to insure adequate intestinal absorption, transportation, utilization, and elimination. 'Ironomics' certainly will be the future of the understanding of genes as well as of the protein-protein interactions involved in iron metabolism.
Collapse
Affiliation(s)
| | - Gérard Waeber
- Service de médecine interne, CHUV, Lausanne, Switzerland
| | | | | | | | - Bernard Favrat
- Department of Ambulatory Care and Community Medicine, Lausanne, Switzerland
| | - Jean-Daniel Tissot
- Service régional vaudois de transfusion sanguine, Epalinges, Switzerland
| |
Collapse
|
21
|
Patel N, Varghese J, Masaratana P, Latunde-Dada GO, Jacob M, Simpson RJ, McKie AT. The transcription factor ATOH8 is regulated by erythropoietic activity and regulates HAMP transcription and cellular pSMAD1,5,8 levels. Br J Haematol 2013; 164:586-96. [PMID: 24236640 PMCID: PMC4232863 DOI: 10.1111/bjh.12649] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 09/30/2013] [Indexed: 12/21/2022]
Abstract
ATOH8 has previously been shown to be an iron-regulated transcription factor, however its role in iron metabolism is not known. ATOH8 expression in HEK293 cells resulted in increased endogenous HAMP mRNA levels as well as HAMP promoter activity. Mutation of the E-box or SMAD response elements within the HAMP promoter significantly reduced the effects of ATOH8, indicating that ATOH8 activates HAMP transcription directly as well as through bone morphogenic protein (BMP) signalling. In support of the former, Chromatin immunoprecipitation assays provided evidence that ATOH8 binds to E-box regions within the HAMP promoter while the latter was supported by the finding that ATOH8 expression in HEK293 cells led to increased phosphorylated SMAD1,5,8 levels. Liver Atoh8 levels were reduced in mice under conditions associated with increased erythropoietic activity such as hypoxia, haemolytic anaemia, hypotransferrinaemia and erythropoietin treatment and increased by inhibitors of erythropoiesis. Hepatic Atoh8mRNA levels increased in mice treated with holo transferrin, suggesting that Atoh8 responds to changes in plasma iron. ATOH8 is therefore a novel transcriptional regulator of HAMP, which is responsive to changes in plasma iron and erythroid activity and could explain how changes in erythroid activity lead to regulation of HAMP.
Collapse
Affiliation(s)
- Neeta Patel
- Division of Diabetes and Nutritional Sciences, Kings College London, London, UK
| | | | | | | | | | | | | |
Collapse
|
22
|
Abstract
PURPOSE OF REVIEW The circulating peptide hepcidin modulates systemic iron balance by limiting the absorption of dietary iron and the release of iron from macrophage stores. Recent studies conducted in humans, animal models, and tissue culture systems have enhanced our understanding of the molecular mechanisms by which hepcidin levels are altered in response to iron stores, inflammation, and erythropoietic activity. RECENT FINDINGS The bone morphogenetic protein (BMP) type I receptors ALK2 and ALK3 play key, nonredundant roles in mediating hepcidin synthesis through the BMP signaling pathway. Actions of the hereditary hemochromatosis proteins HFE and transferrin receptor 2 may intersect with the BMP pathway. Hepcidin induction in response to inflammation requires cooperative BMP signaling. A variety of innate immune and infectious stimuli induce hepcidin expression. The hypoxia inducible factor pathway appears to suppress hepcidin indirectly through the capacity of erythropoietin to stimulate erythropoiesis. SUMMARY Study of the molecular mechanisms underlying the regulation of hepcidin synthesis has revealed complex biology. Improved understanding of the signaling pathways involved in hepcidin regulation may contribute to improved therapeutic outcomes for patients with genetic and acquired disorders that impact systemic iron balance.
Collapse
|
23
|
Out of balance--systemic iron homeostasis in iron-related disorders. Nutrients 2013; 5:3034-61. [PMID: 23917168 PMCID: PMC3775241 DOI: 10.3390/nu5083034] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 07/16/2013] [Accepted: 07/19/2013] [Indexed: 02/06/2023] Open
Abstract
Iron is an essential element in our daily diet. Most iron is required for the de novo synthesis of red blood cells, where it plays a critical role in oxygen binding to hemoglobin. Thus, iron deficiency causes anemia, a major public health burden worldwide. On the other extreme, iron accumulation in critical organs such as liver, heart, and pancreas causes organ dysfunction due to the generation of oxidative stress. Therefore, systemic iron levels must be tightly balanced. Here we focus on the regulatory role of the hepcidin/ferroportin circuitry as the major regulator of systemic iron homeostasis. We discuss how regulatory cues (e.g., iron, inflammation, or hypoxia) affect the hepcidin response and how impairment of the hepcidin/ferroportin regulatory system causes disorders of iron metabolism.
Collapse
|
24
|
Advantages and disadvantages of the animal models v. in vitro studies in iron metabolism: a review. Animal 2013; 7:1651-8. [PMID: 23790319 DOI: 10.1017/s1751731113001134] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Iron deficiency is the most common nutritional deficiency in the world. Special molecules have evolved for iron acquisition, transport and storage in soluble, nontoxic forms. Studies about the effects of iron on health are focused on iron metabolism or nutrition to prevent or treat iron deficiency and anemia. These studies are focused in two main aspects: (1) basic studies to elucidate iron metabolism and (2) nutritional studies to evaluate the efficacy of iron supplementation to prevent or treat iron deficiency and anemia. This paper reviews the advantages and disadvantages of the experimental models commonly used as well as the methods that are more used in studies related to iron. In vitro studies have used different parts of the gut. In vivo studies are done in humans and animals such as mice, rats, pigs and monkeys. Iron metabolism is a complex process that includes interactions at the systemic level. In vitro studies, despite physiological differences to humans, are useful to increase knowledge related to this essential micronutrient. Isotopic techniques are the most recommended in studies related to iron, but their high cost and required logistic, making them difficult to use. The depletion-repletion of hemoglobin is a method commonly used in animal studies. Three depletion-repletion techniques are mostly used: hemoglobin regeneration efficiency, relative biological values (RBV) and metabolic balance, which are official methods of the association of official analytical chemists. These techniques are well-validated to be used as studies related to iron and their results can be extrapolated to humans. Knowledge about the main advantages and disadvantages of the in vitro and animal models, and methods used in these studies, could increase confidence of researchers in the experimental results with less costs.
Collapse
|
25
|
Abstract
Hepcidin is the major regulatory peptide hormone of iron metabolism, encoded by the HAMP (hepcidin antimicrobial peptide) gene. Hepcidin is expressed mainly in hepatocytes, but is also found in the blood in both a mature and prohormone form. Although, the function of mature hepcidin and the regulation of the HAMP gene have been extensively studied, the intracellular localization and the fate of prohepcidin remains controversial. In the present study, we propose a novel role for prohepcidin in the regulation of its own transcription. Using indirect immunofluorescence and mCherry tagging, a portion of prohepcidin was detected in the nucleus of hepatocytes. Prohepcidin was found to specifically bind to the STAT3 (signal transducer and activator of transcription 3) site in the promoter of HAMP. Overexpression of prohepcidin in WRL68 cells decreased HAMP promoter activity, whereas decreasing the amount of prohepcidin caused increased promoter activity measured by a luciferase reporter-gene assay. Moreover, overexpression of the known prohepcidin-binding partner, α-1 antitrypsin caused increased HAMP promoter activity, suggesting that only the non-α-1 antitrypsin-bound prohepcidin affects the expression of its own gene. The results of the present study indicate that prohepcidin can bind to and transcriptionally regulate the expression of HAMP, suggesting a novel autoregulatory pathway of hepcidin gene expression in hepatocytes.
Collapse
|
26
|
Qian J, Chen S, Huang Y, Shi X, Liu C. PGC-1α regulates hepatic hepcidin expression and iron homeostasis in response to inflammation. Mol Endocrinol 2013; 27:683-92. [PMID: 23438894 DOI: 10.1210/me.2012-1345] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Systemic iron homeostasis is finely regulated by the liver through synthesis of the peptide hormone hepcidin (HAMP), which plays an important role in duodenal iron absorption and macrophage iron release. Clinical investigations have shown that chronic and low-grade inflammation leads to the increase of serum HAMP levels and the development of various diseases such as anemia of inflammation. However, gaps remain to fully elucidate the mechanism linking inflammation and iron dysregulation. Here we show that although inflammatory stimuli increase hepatic HAMP expression and cause systemic iron deficiency in mice, they inhibit the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a transcriptional coactivator actively involved in metabolic regulation. Liver-specific overexpression of PGC-1α antagonizes lipopolysaccharide-induced HAMP expression and alleviates various pathophysiological changes similar to anemia of inflammation. Consistently, overexpression of PGC-1α in HepG2 or HuH7 cells also suppresses HAMP expression and reduces iron accumulation. In contrast, knockdown of PGC-1α exaggerates LPS-induced HAMP expression and iron dysregulation. At the molecular level, PGC-1α suppresses HAMP transcription via the interaction with hepatocyte nuclear factor 4α. In addition, PGC-1α is present near hepatocyte nuclear factor 4α-binding site on the proximal HAMP promoter and turns the chromatin structure into an inactive state. Our data suggest a critical role for PGC-1α in the regulation of hepatic HAMP expression and iron homeostasis under inflammatory circumstances.
Collapse
Affiliation(s)
- Jinchun Qian
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology and College of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, Jiangsu 210023, China
| | | | | | | | | |
Collapse
|
27
|
Known and potential roles of transferrin in iron biology. Biometals 2012; 25:677-86. [PMID: 22294463 DOI: 10.1007/s10534-012-9520-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 01/06/2012] [Indexed: 12/13/2022]
Abstract
Transferrin is an abundant serum metal-binding protein best known for its role in iron delivery. The human disease congenital atransferrinemia and animal models of this disease highlight the essential role of transferrin in erythropoiesis and iron metabolism. Patients and mice deficient in transferrin exhibit anemia and a paradoxical iron overload attributed to deficiency in hepcidin, a peptide hormone synthesized largely by the liver that inhibits dietary iron absorption and macrophage iron efflux. Studies of inherited human disease and model organisms indicate that transferrin is an essential regulator of hepcidin expression. In this paper, we review current literature on transferrin deficiency and present our recent findings, including potential overlaps between transferrin, iron and manganese in the regulation of hepcidin expression.
Collapse
|
28
|
Guillem F, Kannengiesser C, Oudin C, Lenoir A, Matak P, Donadieu J, Isidor B, Méchinaud F, Aguilar-Martinez P, Beaumont C, Vaulont S, Grandchamp B, Nicolas G. Inactive matriptase-2 mutants found in IRIDA patients still repress hepcidin in a transfection assay despite having lost their serine protease activity. Hum Mutat 2012; 33:1388-96. [PMID: 22581667 DOI: 10.1002/humu.22116] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 05/02/2012] [Indexed: 12/21/2022]
Abstract
Mutations of the TMPRSS6 gene, which encodes Matriptase-2, are responsible for iron-refractory iron-deficiency anemia. Matriptase-2 is a transmembrane protease that downregulates hepcidin expression. We report one frameshift (p.Ala605ProfsX8) and four novel missense mutations (p.Glu114Lys, p.Leu235Pro, p.Tyr418Cys, p.Pro765Ala) found in IRIDA patients. These mutations lead to changes in both the catalytic and noncatalytic domains of Matriptase-2. Analyses of the mutant proteins revealed a reduction of autoactivating cleavage and the loss of N-Boc-Gln-Ala-Arg-p-nitroanilide hydrolysis. This resulted either from a direct modification of the active site or from the lack of the autocatalytic cleavage that transforms the zymogen into an active protease. In a previously described transfection assay measuring the ability of Matriptase-2 to repress the hepcidin gene (HAMP) promoter, all mutants retained some, if not all, of their transcriptional repression activity. This suggests that caution is called for in interpreting the repression assay in assessing the functional relevance of Matriptase-2 substitutions. We propose that Matriptase-2 activity should be measured directly in the cell medium of transfected cells using the chromogenic substrate. This simple test can be used to determine whether a sequence variation leading to an amino acid substitution is functionally relevant or not.
Collapse
|