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Enns CA, Weiskopf T, Zhang RH, Wu J, Jue S, Kawaguchi M, Kataoka H, Zhang AS. Matriptase-2 regulates iron homeostasis primarily by setting the basal levels of hepatic hepcidin expression through a nonproteolytic mechanism. J Biol Chem 2023; 299:105238. [PMID: 37690687 PMCID: PMC10551898 DOI: 10.1016/j.jbc.2023.105238] [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: 06/23/2023] [Revised: 08/07/2023] [Accepted: 08/23/2023] [Indexed: 09/12/2023] Open
Abstract
Matriptase-2 (MT2), encoded by TMPRSS6, is a membrane-anchored serine protease. It plays a key role in iron homeostasis by suppressing the iron-regulatory hormone, hepcidin. Lack of functional MT2 results in an inappropriately high hepcidin and iron-refractory iron-deficiency anemia. Mt2 cleaves multiple components of the hepcidin-induction pathway in vitro. It is inhibited by the membrane-anchored serine protease inhibitor, Hai-2. Earlier in vivo studies show that Mt2 can suppress hepcidin expression independently of its proteolytic activity. In this study, our data indicate that hepatic Mt2 was a limiting factor in suppressing hepcidin. Studies in Tmprss6-/- mice revealed that increases in dietary iron to ∼0.5% were sufficient to overcome the high hepcidin barrier and to correct iron-deficiency anemia. Interestingly, the increased iron in Tmprss6-/- mice was able to further upregulate hepcidin expression to a similar magnitude as in wild-type mice. These results suggest that a lack of Mt2 does not impact the iron induction of hepcidin. Additional studies of wild-type Mt2 and the proteolytic-dead form, fMt2S762A, indicated that the function of Mt2 is to lower the basal levels of hepcidin expression in a manner that primarily relies on its nonproteolytic role. This idea is supported by the studies in mice with the hepatocyte-specific ablation of Hai-2, which showed a marginal impact on iron homeostasis and no significant effects on iron regulation of hepcidin. Together, these observations suggest that the function of Mt2 is to set the basal levels of hepcidin expression and that this process is primarily accomplished through a nonproteolytic mechanism.
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Affiliation(s)
- Caroline A Enns
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Tyler Weiskopf
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Richard H Zhang
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Jeffrey Wu
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Shall Jue
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Makiko Kawaguchi
- Faculty of Medicine, Section of Oncopathology and Regenerative Biology, Department of Pathology, University of Miyazaki, Miyazaki, Japan
| | - Hiroaki Kataoka
- Faculty of Medicine, Section of Oncopathology and Regenerative Biology, Department of Pathology, University of Miyazaki, Miyazaki, Japan
| | - An-Sheng Zhang
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA.
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Abstract
Background: Plummer-Vinson syndrome (PVS), a rare disorder characterized by dysphagia, iron deficiency anemia, and esophageal webs, has principally been described in middle-aged women. This disorder is uncommon in the 21st century because of the abundance of iron-fortified foods. Clotting factor deficiencies are also rare. Factor VII deficiency is a bleeding disorder characterized by the absence of a critical protein in the coagulation cascade. Case Report: We present a case of PVS associated with factor VII deficiency in a 26-year-old African American female. The patient had a history of anemia that was repeatedly attributed to menstrual bleeding and dysphagia for 10 years. She presented with symptomatic anemia requiring transfusion. She reported a history of food getting stuck in her chest, and workup revealed esophageal webs with no evidence of overt luminal gastrointestinal bleeding. Coagulation laboratory tests revealed the incidental finding of a borderline increased prothrombin time. Hematologic studies confirmed the presence of factor VII deficiency. Conclusion: To our knowledge, no case has been published about a patient diagnosed with PVS and concomitant factor VII deficiency. Our case illustrates several learning points: (1) PVS is an uncommon disorder that may still be diagnosed in a developed country in the 21st century; (2) PVS requires close follow-up and esophageal surveillance because of the increased risk of esophageal cancer; (3) factor VII exhibits a high degree of phenotypic variability; (4) phenotype in factor VII deficiency does not always correlate with factor VII activity, although life-threatening spontaneous bleeding is not expected with levels >2%.
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Frýdlová J, Rychtarčíková Z, Gurieva I, Vokurka M, Truksa J, Krijt J. Effect of erythropoietin administration on proteins participating in iron homeostasis in Tmprss6-mutated mask mice. PLoS One 2017; 12:e0186844. [PMID: 29073189 PMCID: PMC5658091 DOI: 10.1371/journal.pone.0186844] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 10/09/2017] [Indexed: 11/30/2022] Open
Abstract
Tmprss6-mutated mask mice display iron deficiency anemia and high expression of hepcidin. The aim of the study was to determine the effect of erythropoietin administration on proteins participating in the control of iron homeostasis in the liver and spleen in C57BL/6 and mask mice. Administration of erythropoietin for four days at 50 IU/mouse/day increased hemoglobin and hematocrit in C57BL/6 mice, no such increase was seen in mask mice. Erythropoietin administration decreased hepcidin expression in C57BL/6 mice, but not in mask mice. Erythropoietin treatment significantly increased the spleen size in both C57BL/6 and mask mice. Furthermore, erythropoietin administration increased splenic Fam132b, Fam132a and Tfr2 mRNA content. At the protein level, erythropoietin increased the amount of splenic erythroferrone and transferrin receptor 2 both in C57BL/6 and mask mice. Splenic ferroportin content was decreased in erythropoietin-treated mask mice in comparison with erythropoietin-treated C57BL/6 mice. In mask mice, the amount of liver hemojuvelin was decreased in comparison with C57BL/6 mice. The pattern of hemojuvelin cleavage was different between C57BL/6 and mask mice: In both groups, a main hemojuvelin band was detected at approximately 52 kDa; in C57BL/6 mice, a minor cleaved band was seen at 47 kDa. In mask mice, the 47 kDa band was absent, but additional minor bands were detected at approximately 45 kDa and 48 kDa. The results provide support for the interaction between TMPRSS6 and hemojuvelin in vivo; they also suggest that hemojuvelin could be cleaved by another as yet unknown protease in the absence of functional TMPRSS6. The lack of effect of erythropoietin on hepcidin expression in mask mice can not be explained by changes in erythroferrone synthesis, as splenic erythroferrone content increased after erythropoietin administration in both C57BL/6 and mask mice.
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Affiliation(s)
- Jana Frýdlová
- Institute of Pathological Physiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Zuzana Rychtarčíková
- Laboratory of Tumour Resistance, Institute of Biotechnology, BIOCEV Research Center, Czech Academy of Sciences, Vestec, Czech Republic
- Faculty of Pharmacy in Hradec Králové, Charles University, Hradec Králové, Czech Republic
| | - Iuliia Gurieva
- Institute of Pathological Physiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Martin Vokurka
- Institute of Pathological Physiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Jaroslav Truksa
- Laboratory of Tumour Resistance, Institute of Biotechnology, BIOCEV Research Center, Czech Academy of Sciences, Vestec, Czech Republic
- * E-mail: (JT); (JK)
| | - Jan Krijt
- Institute of Pathological Physiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
- * E-mail: (JT); (JK)
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Frýdlová J, Přikryl P, Truksa J, Falke LL, Du X, Gurieva I, Vokurka M, Krijt J. Effect of Erythropoietin, Iron Deficiency and Iron Overload on Liver Matriptase-2 (TMPRSS6) Protein Content in Mice and Rats. PLoS One 2016; 11:e0148540. [PMID: 26845567 PMCID: PMC4742081 DOI: 10.1371/journal.pone.0148540] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Accepted: 01/19/2016] [Indexed: 12/26/2022] Open
Abstract
Matriptase-2 (TMPRSS6) is an important negative regulator of hepcidin expression; however, the effects of iron overload or accelerated erythropoiesis on liver TMPRSS6 protein content in vivo are largely unknown. We determined TMPRSS6 protein content in plasma membrane-enriched fractions of liver homogenates by immunoblotting, using a commercial antibody raised against the catalytic domain of TMPRSS6. Plasma membrane-enriched fractions were obtained by centrifugation at 3000 g and washing. TMPRSS6 was detected in the 3000 g fraction as a 120 kDa full-length protein in both mice and rats. Feeding of iron-deficient diet as well as erythropoietin treatment increased TMPRSS6 protein content in rats and mice by a posttranscriptional mechanism; the increase in TMPRSS6 protein by erythropoietin was also observed in Bmp6-mutant mice. Administration of high doses of iron to mice (200, 350 and 700 mg/kg) decreased TMPRSS6 protein content. Hemojuvelin was detected in the plasma membrane-enriched fractions of control animals as a full length protein of approximately 52 kDa; in iron deficient animals, the full length protein was partially cleaved at the N-terminus, resulting in an additional weak band of approximately 47 kDa. In livers from hemojuvelin-mutant mice, TMPRSS6 protein content was strongly decreased, suggesting that intact hemojuvelin is necessary for stable TMPRSS6 expression in the membrane. Overall, the results demonstrate posttranscriptional regulation of liver TMPRSS6 protein by iron status and erythropoietin administration, and provide support for the interaction of TMPRSS6 and hemojuvelin proteins in vivo.
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Affiliation(s)
- Jana Frýdlová
- Institute of Pathophysiology, Charles University in Prague, First Faculty of Medicine, Prague, Czech Republic
| | - Petr Přikryl
- Institute of Pathophysiology, Charles University in Prague, First Faculty of Medicine, Prague, Czech Republic
| | - Jaroslav Truksa
- Institute of Biotechnology, Laboratory of Tumour Resistance, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Lucas L. Falke
- Department of Pathology, Kidney Group, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Xin Du
- Division of Medical Genetics, Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Iuliia Gurieva
- Institute of Pathophysiology, Charles University in Prague, First Faculty of Medicine, Prague, Czech Republic
| | - Martin Vokurka
- Institute of Pathophysiology, Charles University in Prague, First Faculty of Medicine, Prague, Czech Republic
| | - Jan Krijt
- Institute of Pathophysiology, Charles University in Prague, First Faculty of Medicine, Prague, Czech Republic
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Rausa M, Ghitti M, Pagani A, Nai A, Campanella A, Musco G, Camaschella C, Silvestri L. Identification of TMPRSS6 cleavage sites of hemojuvelin. J Cell Mol Med 2015; 19:879-88. [PMID: 25704252 PMCID: PMC4395201 DOI: 10.1111/jcmm.12462] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 09/19/2014] [Indexed: 12/11/2022] Open
Abstract
Hemojuvelin (HJV), the coreceptor of the BMP-SMAD pathway that up-regulates hepcidin transcription, is a repulsive guidance molecule (RGMc) which undergoes a complex intracellular processing. Following autoproteolysis, it is exported to the cell surface both as a full-length and a heterodimeric protein. In vitro membrane HJV (m-HJV) is cleaved by the transmembrane serine protease TMPRSS6 to attenuate signalling and to inhibit hepcidin expression. In this study, we investigated the number and position of HJV cleavage sites by mutagenizing arginine residues (R), potential TMPRSS6 targets, to alanine (A). We analysed translation and membrane expression of HJV R mutants and the pattern of fragments they release in the culture media in the presence of TMPRSS6. Abnormal fragments were observed for mutants at arginine 121, 176, 218, 288 and 326. Considering that all variants, except HJVR121A, lack autoproteolytic activity and some (HJVR176A and HJVR288A) are expressed at reduced levels on cell surface, we identified the fragments originating from either full-length or heterodimeric proteins and defined the residues 121 and 326 as the TMPRSS6 cleavage sites in both isoforms. Using the N-terminal FLAG-tagged HJV, we showed that residue 121 is critical also in the rearrangement of the N-terminal heterodimeric HJV. Exploiting the recently reported RGMb crystallographic structure, we generated a model of HJV that was used as input structure for all-atoms molecular dynamics simulation in explicit solvent. As assessed by in silico studies, we concluded that some arginines in the von Willebrand domain appear TMPRSS6 insensitive, likely because of partial protein structure destabilization.
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Affiliation(s)
- Marco Rausa
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy; Vita Salute University, Milan, Italy
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Wang CY, Meynard D, Lin HY. The role of TMPRSS6/matriptase-2 in iron regulation and anemia. Front Pharmacol 2014; 5:114. [PMID: 24966834 PMCID: PMC4053654 DOI: 10.3389/fphar.2014.00114] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 04/29/2014] [Indexed: 01/12/2023] Open
Abstract
Matriptase-2, encoded by the TMPRSS6 gene, is a member of the type II transmembrane serine protease family. Matriptase-2 has structural and enzymatic similarities to matriptase-1, which has been implicated in cancer progression. Matriptase-2 was later established to be essential in iron homeostasis based on the phenotypes of iron-refractory iron deficiency anemia identified in mouse models as well as in human patients with TMPRSS6 mutations. TMPRSS6 is expressed mainly in the liver and negatively regulates the production of hepcidin, the systemic iron regulatory hormone. This review focuses on the current understanding of matriptase-2 biochemistry, and its role in iron metabolism and cancer progression. In light of recent investigations, the function of matriptase-2 in hepcidin regulation, how it is being regulated, as well as the therapeutic potential of matriptase-2 are also discussed.
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Affiliation(s)
- Chia-Yu Wang
- Program in Anemia Signaling Research, Division of Nephrology, Program in Membrane Biology, Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School Boston, MA, USA
| | - Delphine Meynard
- INSERM, U1043, CNRS, U5282, Université Paul Sabatier, Centre de Physiopathologie de Toulouse Purpan Toulouse, France
| | - Herbert Y Lin
- Program in Anemia Signaling Research, Division of Nephrology, Program in Membrane Biology, Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School Boston, MA, USA
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