Matriptase-2, a serine protease expressed in hepatocytes, is a negative regulator of hepcidin expression. The purpose of the study was to investigate the interaction of matriptase-2 with hemojuvelin protein in vivo. Mice lacking the matriptase-2 proteolytic activity (mask mice) display decreased content of hemojuvelin protein. Vice versa, the absence of hemojuvelin results in decreased liver content of matriptase-2, indicating that the two proteins interact. To further characterize the role of matriptase-2, we investigated iron metabolism in mask mice fed experimental diets. Administration of iron-enriched diet increased liver iron stores as well as hepcidin expression. Treatment of iron-overloaded mask mice with erythropoietin increased hemoglobin and hematocrit, indicating that the response to erythropoietin is intact in mask mice. Feeding of an iron-deficient diet to mask mice significantly increased spleen weight as well as the splenic content of erythroferrone and transferrin receptor proteins, indicating stress erythropoiesis. Liver hepcidin expression was decreased; expression of Id1 was not changed. Overall, the results suggest a complex interaction between matriptase-2 and hemojuvelin, and demonstrate that hepcidin can to some extent be regulated even in the absence of matriptase-2 proteolytic activity.

• Klíčová slova
• Hjv, Tfr2, Tfrc, Tmprss6, hepcidin, neogenin, transferrin receptor,
• MeSH
• deficit železa MeSH
• dietní železo farmakologie   MeSH
• erythropoetin farmakologie   MeSH
• GPI-vázané proteiny biosyntéza   nedostatek   genetika   fyziologie   MeSH
• hepcidiny biosyntéza   genetika   MeSH
• inhibitor diferenciace 1 biosyntéza   genetika   MeSH
• játra metabolismus   MeSH
• kostní morfogenetický protein 6 biosyntéza   genetika   MeSH
• membránové proteiny nedostatek   genetika   fyziologie   MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• orgánová specificita MeSH
• přetížení železem metabolismus   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• protein hemochromatózy biosyntéza   nedostatek   genetika   fyziologie   MeSH
• proteinové domény MeSH
• regulace genové exprese účinky léků   MeSH
• rekombinantní proteiny metabolismus   MeSH
• serinové endopeptidasy nedostatek   genetika   fyziologie   MeSH
• slezina metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• Bmp6 protein, mouse MeSH Prohlížeč
• dietní železo MeSH
• erythropoetin MeSH
• GPI-vázané proteiny MeSH
• Hamp protein, mouse MeSH Prohlížeč
• hepcidiny MeSH
• HJV protein, mouse MeSH Prohlížeč
• Idb1 protein, mouse MeSH Prohlížeč
• inhibitor diferenciace 1 MeSH
• kostní morfogenetický protein 6 MeSH
• matriptase 2 MeSH Prohlížeč
• membránové proteiny MeSH
• protein hemochromatózy MeSH
• rekombinantní proteiny MeSH
• serinové endopeptidasy MeSH

Mutations in HFE, the most common cause of hereditary hemochromatosis, lead to iron overload. The iron overload is characterized by increased iron uptake due to lower levels of the hepatic, iron regulatory hormone hepcidin. HFE was cloned 21 years ago, but the signaling pathway is still unknown. Because bone morphogenetic protein (BMP) signaling is impaired in patients with hereditary hemochromatosis, and the interaction of HFE and the BMP type I receptor ALK3 was suggested in vitro, in vivo experiments were performed. In vivo, hepatocyte-specific Alk3-deficient and control mice were injected with either AAV2/8-Hfe-Flag or PBS. HFE overexpression in control mice results in increased hepatic hepcidin levels, p-Smad1/5 levels, and iron deficiency anemia, whereas overexpression of HFE in hepatocyte-specific Alk3-deficient mice results in no change in hepcidin, p-Smad1/5 levels, or blood parameters. These results indicate that HFE signals predominantly via ALK3 to induce hepcidin in vivo.

• Publikační typ
• časopisecké články MeSH

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.

• MeSH
• cytokiny genetika   metabolismus   MeSH
• erythropoetin genetika   farmakologie   MeSH
• GPI-vázané proteiny MeSH
• hepcidiny genetika   metabolismus   MeSH
• játra metabolismus   patologie   MeSH
• membránové proteiny genetika   metabolismus   MeSH
• mutantní kmeny myší MeSH
• myši MeSH
• protein hemochromatózy MeSH
• proteiny vázající RNA genetika   metabolismus   MeSH
• regulace genové exprese účinky léků   genetika   MeSH
• serinové endopeptidasy genetika   metabolismus   MeSH
• slezina metabolismus   patologie   MeSH
• svalové proteiny genetika   metabolismus   MeSH
• velikost orgánu účinky léků   genetika   MeSH
• železo metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• Ankrd17 protein, mouse MeSH Prohlížeč
• cytokiny MeSH
• Erfe protein, mouse MeSH Prohlížeč
• erythropoetin MeSH
• GPI-vázané proteiny MeSH
• Hamp protein, mouse MeSH Prohlížeč
• hepcidiny MeSH
• HJV protein, mouse MeSH Prohlížeč
• matriptase 2 MeSH Prohlížeč
• membránové proteiny MeSH
• protein hemochromatózy MeSH
• proteiny vázající RNA MeSH
• serinové endopeptidasy MeSH
• svalové proteiny MeSH
• železo MeSH

INTRODUCTION: Hemojuvelin (Hjv) is a key component of the signaling cascade that regulates liver hepcidin (Hamp) expression. The purpose of this study was to determine Hjv protein levels in mice and rats subjected to iron overload and iron deficiency. METHODS: C57BL/6 mice were injected with iron (200 mg/kg); iron deficiency was induced by feeding of an iron-deficient diet, or by repeated phlebotomies. Erythropoietin (EPO)-treated mice were administered recombinant EPO at 50 U/mouse. Wistar rats were injected with iron (1200 mg/kg), or fed an iron-deficient diet. Hjv protein was determined by immunoblotting, liver samples from Hjv-/- mice were used as negative controls. Mouse plasma Hjv content was determined by a commercial ELISA kit. RESULTS: Liver crude membrane fraction from both mice and rats displayed a major Hjv-specific band at 35 kDa, and a weaker band of 20 kDa. In mice, the intensity of these bands was not changed following iron injection, repeated bleeding, low iron diet or EPO administration. No change in liver crude membrane Hjv protein was observed in iron-treated or iron-deficient rats. ELISA assay for mouse plasma Hjv did not show significant difference between Hjv+/+ and Hjv-/- mice. Liver Hamp mRNA, Bmp6 mRNA and Id1 mRNA displayed the expected response to iron overload and iron deficiency. EPO treatment decreased Id1 mRNA, suggesting possible participation of the bone morphogenetic protein pathway in EPO-mediated downregulation of Hamp mRNA. DISCUSSION: Since no differences between Hjv protein levels were found following various experimental manipulations of body iron status, the results indicate that, in vivo, substantial changes in Hamp mRNA can occur without noticeable changes of membrane hemojuvelin content. Therefore, modulation of hemojuvelin protein content apparently does not represent the limiting step in the control of Hamp gene expression.

• MeSH
• deficit železa MeSH
• dietní železo metabolismus   MeSH
• erythropoetin farmakologie   MeSH
• GPI-vázané proteiny MeSH
• játra účinky léků   metabolismus   MeSH
• kostní morfogenetické proteiny genetika   metabolismus   MeSH
• krysa rodu Rattus MeSH
• membránové proteiny genetika   metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• potkani Wistar MeSH
• přetížení železem genetika   metabolismus   MeSH
• protein hemochromatózy MeSH
• signální transdukce účinky léků   genetika   MeSH
• železo metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• dietní železo MeSH
• erythropoetin MeSH
• GPI-vázané proteiny MeSH
• HJV protein, mouse MeSH Prohlížeč
• kostní morfogenetické proteiny MeSH
• membránové proteiny MeSH
• protein hemochromatózy MeSH
• železo MeSH