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.
- 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
- železo MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články 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
- 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
- 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
AIMS: The skeletal manifestations of sickle cell disease are the result of changes in bone and bone marrow caused by chronic tissue hypoxia that is exacerbated by episodic occlusion of the microcirculation by the abnormal sickle cells. Furthermore, the occurrence of osteonecrosis is under the control of some modifier gene. BMP6 (Bone morphogenetic protein) has been reported as associated with osteonecrosis in sickle cell anemia (SCA). Herein, we intend to study the impact of rs267196, rs267201, rs408505 and rs449853 of BMP6 gene in the occurrence of osteonecrosis among sickle cell patients in Tunisia. METHODS: Our study involved 100 SCA patients among whom 19 have osteonecrosis of the head of the femur. The latter polymorphisms of BMP6 gene were analyzed for all subjects by PCR/sequencing. To test for trait association with the candidate SNPs, genotype and allele frequencies between cases (osteonecrosis group) and controls (non-osteonecrosis group) were compared using Pearson's chi_square test with a significance threshold of P<0.05 (compare 2, version 1.02). RESULTS: Our findings showed that the patients carried genotype TA of rs 267196 and genotype AG of rs267201 present a high risk factor for developing osteonecrosis RR=1.317 and RR=1.3 respectively. The results showed a significant association between the alleles A of rs 267196 and G of rs267201 and osteonecrosis P=0.0023; RR=2.42 and P=0.041; RR=2.24 respectively. Interestingly, SCA patients with the combined genotype TA/AG were found to be at higher risk of developing osteonecrosis (P=0.009). As for rs408505 and rs449853 of BMP6 gene no significant association was found among SCA patients.
- MeSH
- dospělí MeSH
- fenotyp MeSH
- frekvence genu MeSH
- genetická predispozice k nemoci * MeSH
- kostní morfogenetický protein 6 genetika metabolismus MeSH
- lidé MeSH
- osteonekróza etiologie genetika metabolismus MeSH
- polymerázová řetězová reakce MeSH
- polymorfismus genetický * MeSH
- regulace genové exprese * MeSH
- rizikové faktory MeSH
- RNA nádorová genetika MeSH
- srpkovitá anemie komplikace genetika metabolismus MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
x
- MeSH
- časové faktory MeSH
- exprese genu MeSH
- fraktury femuru farmakoterapie radiografie MeSH
- hojení fraktur * účinky léků MeSH
- kostní morfogenetické proteiny genetika terapeutické užití MeSH
- kostní morfogenetický protein 2 * aplikace a dávkování genetika MeSH
- kostní morfogenetický protein 4 genetika MeSH
- kostní morfogenetický protein 6 genetika MeSH
- kostní morfogenetický protein 7 genetika MeSH
- kostní svalek MeSH
- krysa rodu rattus MeSH
- kvantitativní polymerázová řetězová reakce statistika a číselné údaje MeSH
- messenger RNA MeSH
- mezibuněčné signální peptidy a proteiny genetika MeSH
- osteogeneze účinky léků MeSH
- potkani Sprague-Dawley MeSH
- regenerace kostí genetika účinky léků MeSH
- rekombinantní proteiny MeSH
- stanovení celkové genové exprese MeSH
- TNF-alfa genetika MeSH
- uzavřené fraktury MeSH
- výzkum MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- ženské pohlaví MeSH
- zvířata MeSH
Transcription of the hepcidin (Hamp) gene is controlled by iron stores and the rate of erythropoiesis. Functional hierarchy between these two stimuli has not yet been completely established. It is also not known whether the erythropoiesis-related downregulation of Hamp expression utilises the bone morphogenetic protein/hemojuvelin (Bmp/Hjv) pathway. Hemojuvelin-mutant (Hjv-/-) mice treated with erythropoietin (EPO) at 50IU/mouse/day for three days displayed marked decrease in Hamp mRNA, demonstrating that hemojuvelin is not an indispensable component in EPO-induced Hamp gene downregulation. Irradiation of Hjv-/- mice prevented the EPO-induced decrease of Hamp mRNA, highlighting the role of erythropoiesis in Hamp gene regulation by EPO. After a single injection of EPO, Hamp mRNA levels were not significantly changed at 6h, but decreased at 10 and 24h. Chronic bleeding decreased hepatic Bmp6 mRNA levels; however, repeated EPO treatment did not change Bmp6 mRNA, suggesting that the erythropoietic regulator(s) act independently of the Bmp/Hjv pathway. Pretreatment of C57BL/6 mice with iron (5mg/mouse) almost completely inhibited the EPO-induced decrease of Hamp mRNA. This result suggests that administration of EPO to patients with transfusional iron overload is probably not associated with the risk of additional absorption of substantial amounts of iron from the diet.
- MeSH
- down regulace účinky léků MeSH
- erythropoetin farmakologie MeSH
- erytropoéza účinky léků genetika MeSH
- genetická transkripce účinky léků MeSH
- játra účinky léků metabolismus MeSH
- kationické antimikrobiální peptidy biosyntéza genetika MeSH
- kostní morfogenetický protein 6 biosyntéza genetika MeSH
- membránové proteiny nedostatek genetika fyziologie MeSH
- messenger RNA biosyntéza MeSH
- myši inbrední C57BL MeSH
- myši knockoutované MeSH
- myši MeSH
- polysacharidy farmakologie toxicita MeSH
- přetížení železem chemicky indukované metabolismus MeSH
- regulace genové exprese účinky léků MeSH
- rekombinantní proteiny MeSH
- železité sloučeniny farmakologie toxicita MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
