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

Expression of hepcidin, the hormone regulating iron homeostasis, is increased by iron overload and decreased by accelerated erythropoiesis or iron deficiency. The purpose of the study was to examine the effect of these stimuli, either alone or in combination, on the main signaling pathway controlling hepcidin biosynthesis in the liver, and on the expression of splenic modulators of hepcidin biosynthesis. Liver phosphorylated SMAD 1 and 5 proteins were determined by immunoblotting in male mice treated with iron dextran, kept on an iron deficient diet, or administered recombinant erythropoietin for four consecutive days. Administration of iron increased liver phosphorylated SMAD protein content and hepcidin mRNA content; subsequent administration of erythropoietin significantly decreased both the iron-induced phosphorylated SMAD proteins and hepcidin mRNA. These results are in agreement with the recent observation that erythroferrone binds and inactivates the BMP6 protein. Administration of erythropoietin substantially increased the amount of erythroferrone and transferrin receptor 2 proteins in the spleen; pretreatment with iron did not influence the erythropoietin-induced content of these proteins. Erythropoietin-treated iron-deficient mice displayed smaller spleen size in comparison with erythropoietin-treated mice kept on a control diet. While the erythropoietin-induced increase in splenic erythroferrone protein content was not significantly affected by iron deficiency, the content of transferrin receptor 2 protein was lower in the spleens of erythropoietin-treated mice kept on iron-deficient diet, suggesting posttranscriptional regulation of transferrin receptor 2. Interestingly, iron deficiency and erythropoietin administration had additive effect on hepcidin gene downregulation in the liver. In mice subjected both to iron deficiency and erythropoietin administration, the decrease of hepcidin expression was much more pronounced than the decrease in phosphorylated SMAD protein content or the decrease in the expression of the SMAD target genes Id1 and Smad7. These results suggest the existence of another, SMAD-independent pathway of hepcidin gene downregulation.

• MeSH
• deficit železa * MeSH
• erythropoetin aplikace a dávkování   MeSH
• erytropoéza účinky léků   MeSH
• fosforylace MeSH
• hepcidiny genetika   metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• přetížení železem metabolismus   patologie   MeSH
• proteiny Smad genetika   metabolismus   MeSH
• regulace genové exprese účinky léků   MeSH
• železo aplikace a dávkování   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• erythropoetin MeSH
• Hamp protein, mouse MeSH Prohlížeč
• hepcidiny MeSH
• proteiny Smad MeSH
• železo 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

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.

• MeSH
• anemie z nedostatku železa metabolismus   MeSH
• deficit železa * MeSH
• erythropoetin metabolismus   farmakologie   MeSH
• GPI-vázané proteiny MeSH
• játra účinky léků   metabolismus   MeSH
• kostní morfogenetický protein 6 genetika   MeSH
• krysa rodu Rattus MeSH
• membránové proteiny metabolismus   MeSH
• modely nemocí na zvířatech MeSH
• mutace MeSH
• myši knockoutované MeSH
• myši MeSH
• přetížení železem metabolismus   MeSH
• protein hemochromatózy MeSH
• serinové endopeptidasy metabolismus   MeSH
• sodíko-draslíková ATPasa metabolismus   MeSH
• železo metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• erythropoetin MeSH
• GPI-vázané proteiny MeSH
• HJV protein, mouse MeSH Prohlížeč
• kostní morfogenetický protein 6 MeSH
• matriptase 2 MeSH Prohlížeč
• membránové proteiny MeSH
• protein hemochromatózy MeSH
• serinové endopeptidasy MeSH
• sodíko-draslíková ATPasa 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