The Experts below are selected from a list of 441 Experts worldwide ranked by ideXlab platform

Gregory J. Anderson - One of the best experts on this subject based on the ideXlab platform.

  • Ceruloplasmin and Hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux.
    Redox biology, 2018
    Co-Authors: Min Chen, Brie K Fuqua, Gregory J. Anderson, Chris D. Vulpe, Jiashuo Zheng, Guohao Liu, Junzhuo Wang, Huijun Chen
    Abstract:

    Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used Hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls' Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage.

  • Ceruloplasmin and Hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux
    Elsevier, 2018
    Co-Authors: Min Chen, Brie K Fuqua, Gregory J. Anderson, Chris D. Vulpe, Jiashuo Zheng, Guohao Liu, Junzhuo Wang, Huijun Chen
    Abstract:

    Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used Hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls’ Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage. Keywords: Multicopper ferroxidase, Hephaestin, Ceruloplasmin, Pancreas, Oxidative damage, Iron efflu

  • large scale expression and purification of secreted mouse Hephaestin
    PLOS ONE, 2017
    Co-Authors: Gregory J. Anderson, Chandrika N Deshpande, Vicky Xin, Tom Savage, Mika Jormakka
    Abstract:

    Hephaestin is a large membrane-anchored multicopper ferroxidase involved in mammalian iron metabolism. Newly absorbed dietary iron is exported across the enterocyte basolateral membrane by the ferrous iron transporter ferroportin, but Hephaestin increases the efficiency of this process by oxidizing the transported iron to its ferric form and promoting its release from ferroportin. Deletion or mutation of the Hephaestin gene leads to systemic anemia with iron accumulation in the intestinal epithelium. The crystal structure of human ceruloplasmin, another multicopper ferroxidase with 50% sequence identity to Hephaestin, has provided a framework for comparative analysis and modelling. However, detailed structural information for Hephaestin is still absent, leaving questions relating to metal coordination and binding sites unanswered. To obtain structural information for Hephaestin, a reliable protocol for large-scale purification is required. Here, we present an expression and purification protocol of soluble mouse Hephaestin, yielding milligram amounts of enzymatically active, purified protein using the baculovirus/insect cell system.

  • intestinal Hephaestin potentiates iron absorption in weanling adult and pregnant mice under physiological conditions
    Blood Advances, 2017
    Co-Authors: Caglar Doguer, Gregory J. Anderson, Chris D. Vulpe, Sukru Gulec, James F Collins
    Abstract:

    Regulation of intestinal iron absorption is crucial to maintain body iron levels because humans have no regulated iron-excretory system. Elucidating molecular events that mediate intestinal iron transport is thus important for the development of therapeutic approaches to modify iron absorption in pathological states. The process of iron uptake into duodenal enterocytes is relatively well understood, but less is known about the functional coupling between the iron exporter ferroportin 1 and the basolateral membrane iron oxidase Hephaestin (Heph). Initial characterization of intestine-specific Heph knockout (Hephint) mice demonstrated that adult male mice were mildly iron deficient; however, the specific role of intestinal Heph has not been determined in weanling mice, in female mice, or during physiological states which stimulate iron absorption. Furthermore, because ferroportin 1-mediated iron export from some tissues (eg, liver) is impaired in the absence of the Heph homolog, ceruloplasmin, we hypothesized that Heph is rate limiting for intestinal iron absorption, especially when iron demands increase. Our experimental approach was to assess various physiological parameters and iron (59Fe) absorption and tissue distribution in weanling, adult, and pregnant Hephint mice (and controls) under physiological conditions and in adult Hephint mice after dietary iron deprivation or acute hemolysis. Results demonstrate that intestinal Heph is essential for optimal iron transport in weanlings and adults of both sexes and during pregnancy, but not in adult mice with iron-deficiency or hemolytic anemia. Moreover, activation of unidentified, intestinal ferroxidases was noted, which may explain why intestinal Heph is not always required for optimal iron absorption.

  • Hephaestin and ceruloplasmin play distinct but interrelated roles in iron homeostasis in mouse brain
    Journal of Nutrition, 2015
    Co-Authors: Ruiwei Jiang, Brie K Fuqua, Gregory J. Anderson, Joshua L Dunaief, Jiashuo Zheng, Bo Jiang, Chao Hua, Yike Wan, Samuel David, Chris D. Vulpe
    Abstract:

    BACKGROUND Iron accumulation in the central nervous system (CNS) is a common feature of many neurodegenerative diseases. Multicopper ferroxidases (MCFs) play an important role in cellular iron metabolism. However, the role of MCFs in the CNS in health and disease remains poorly characterized. OBJECTIVE The aim was to study the role of Hephaestin (HEPH) and ceruloplasmin (CP) in CNS iron metabolism and homeostasis. METHODS Iron concentrations and L-ferritin protein levels of selected brain regions were determined in global Hephaestin knockout (Heph KO), global ceruloplasmin knockout (Cp KO), and wild-type (WT) male mice at 6-7 mo of age. Gene expression of divalent metal transporter 1 (Dmt1), ferroportin 1 (Fpn1), Heph, Cp, and transferrin receptor 1 (Tfrc) and HEPH protein level was quantitated in the same brain regions. RESULTS Iron and L-ferritin protein levels were significantly increased in Heph KO mouse brain cortex (iron: 30%, P < 0.05; L-ferritin: 200%, P < 0.05), hippocampus (iron: 80%, P < 0.05; L-ferritin: 300%, P < 0.05), brainstem (iron: 20%, P < 0.05; L-ferritin: 150%, P < 0.05), and cerebellum (iron: 20%, P < 0.05; L-ferritin: 100%, P < 0.05) regions than in WT and Cp KO mouse brain regions at 6 mo of age. Expression of the Heph gene was significantly increased in the Cp KO mouse cortex (100%; P < 0.01), hippocampus (350%; P < 0.001), brainstem (30%; P < 0.01), and cerebellum (150%; P < 0.001) than in WT controls, and Cp gene expression was significantly decreased in the Heph KO mouse hippocampus (20%; P < 0.05) than in WT control mice at 6 mo of age. CONCLUSIONS Ablation of HEPH or CP results in disordered brain iron homeostasis in mice. Heph KO may provide a novel model for neurodegenerative disorders.

Huijun Chen - One of the best experts on this subject based on the ideXlab platform.

  • deletion of Hephaestin and ceruloplasmin induces a serious systemic iron deficiency and disrupts iron homeostasis
    Biochemical and Biophysical Research Communications, 2018
    Co-Authors: Min Chen, Jiashuo Zheng, Zaitunamu Maimaitiming, Tianjiao Zhong, Huijun Chen
    Abstract:

    Multi-copper ferroxidases (MCFs) play important roles in cellular iron metabolism and homeostasis. In this study, we generated the Hephaestin (Heph), ceruloplasmin (Cp) single and Heph/Cp double knockout (KO) mice to investigate the roles of MCFs in iron transport among system and vital organs in mice at 4 weeks and 6 months of age. Compared with wild-type (WT) mice, Heph/Cp mice at both ages presented with severe anemia and significantly lower iron level in the serum and spleen, but with significantly higher iron level in the liver, heart, kidney, and duodenal enterocytes. Furthermore, Heph/Cp mice displayed significantly lower level of hepcidin mRNA and transferrin receptor 1 (TFR1) protein expression, but significantly higher level of ferroportin 1 (FPN1) protein expression in the liver than WT mice at 6 months of age. Liver superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzyme activities were significantly lower in Heph/Cp KO mice than WT mice at 6 months of age. Together, our results suggest that ablation of HEPH and CP could lead to severe systemic iron deficiency and local tissue iron overload, which disrupt the whole body iron homeostasis and impact on tissue functions.

  • Ceruloplasmin and Hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux.
    Redox biology, 2018
    Co-Authors: Min Chen, Brie K Fuqua, Gregory J. Anderson, Chris D. Vulpe, Jiashuo Zheng, Guohao Liu, Junzhuo Wang, Huijun Chen
    Abstract:

    Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used Hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls' Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage.

  • ablation of Hephaestin and ceruloplasmin results in iron accumulation in adipocytes and type 2 diabetes
    FEBS Letters, 2018
    Co-Authors: Jiashuo Zheng, Min Chen, Guohao Liu, Huijun Chen
    Abstract:

    Little is known about the iron efflux mechanism in adipocytes. Here, we used Hephaestin (Heph) and ceruloplasmin (Cp) single-knockout (KO) mice and Heph/Cp double-KO mice to investigate the roles of multicopper ferroxidases (MCFs) in this process. We show that both HEPH and CP are expressed in subcutaneous adipose tissue. Ablation of either MCF leads to a compensatory increase in the other, which contributes to the balance of iron status. However, ablation of both MCFs together induces severe iron deposition in adipocytes which is associated with decreased adiponectin and leptin mRNA expression. Furthermore, Heph/Cp KO mice display disordered carbohydrate metabolism characterized as type 2 diabetes. Together, these results demonstrate the protective roles of HEPH and CP in preventing iron overload in adipocytes.

  • Ceruloplasmin and Hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux
    Elsevier, 2018
    Co-Authors: Min Chen, Brie K Fuqua, Gregory J. Anderson, Chris D. Vulpe, Jiashuo Zheng, Guohao Liu, Junzhuo Wang, Huijun Chen
    Abstract:

    Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used Hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls’ Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage. Keywords: Multicopper ferroxidase, Hephaestin, Ceruloplasmin, Pancreas, Oxidative damage, Iron efflu

  • severe iron metabolism defects in mice with double knockout of the multicopper ferroxidases Hephaestin and ceruloplasmin
    Cellular and molecular gastroenterology and hepatology, 2018
    Co-Authors: Brie K Fuqua, Sarah J. Wilkins, Pavle Matak, Deepak Darshan, David M. Frazer, Linda A Dunn, Alex Loguinov, Scott C Kogan, Huijun Chen
    Abstract:

    BACKGROUND & AIMS: Multicopper ferroxidases (MCFs) facilitate intestinal iron absorption and systemic iron recycling, likely by a mechanism involving the oxidization of Fe2+ from the iron exporter ferroportin 1 for delivery to the circulating Fe3+ carrier transferrin. Hephaestin (HEPH), the only MCF known to be expressed in enterocytes, aids in the basolateral transfer of dietary iron to the blood. Mice lacking HEPH in the whole body (Heph(-/-)) or intestine alone (Heph(int/int)) exhibit defects in dietary iron absorption but still survive and grow. Circulating ceruloplasmin (CP) is the only other known MCF likely to interact with enterocytes. Our aim was to assess the effects of combined deletion of HEPH and CP on intestinal iron absorption and homeostasis in mice.METHODS: Mice lacking both HEPH and CP (Heph(-/-)Cp(-/-)) and mice with whole-body knockout of CP and intestine-specific deletion of HEPH (Heph(int/int)Cp(-/-)) were generated and phenotyped.RESULTS: Heph(-/-)Cp(-/-) mice were severely anemic and had low serum iron, but they exhibited marked iron loading in duodenal enterocytes, the liver, heart, pancreas, and other tissues. Heph(int/int)Cp(-/-) mice were moderately anemic (similar to Cp-/- mice) but were iron loaded only in the duodenum and liver, as in Heph(int/int) and Cp-/- mice, respectively. Both double knockout models absorbed iron in radiolabeled intestinal iron absorption studies, but the iron was inappropriately distributed, with an abnormally high percentage retained in the liver.CONCLUSIONS: These studies indicate that HEPH and CP, and likely MCFs in general, are not essential for intestinal iron absorption but are required for proper systemic iron distribution. They also point to important extra-intestinal roles for HEPH in maintaining whole-body iron homeostasis.

Chris D. Vulpe - One of the best experts on this subject based on the ideXlab platform.

  • Ceruloplasmin and Hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux.
    Redox biology, 2018
    Co-Authors: Min Chen, Brie K Fuqua, Gregory J. Anderson, Chris D. Vulpe, Jiashuo Zheng, Guohao Liu, Junzhuo Wang, Huijun Chen
    Abstract:

    Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used Hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls' Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage.

  • Ceruloplasmin and Hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux
    Elsevier, 2018
    Co-Authors: Min Chen, Brie K Fuqua, Gregory J. Anderson, Chris D. Vulpe, Jiashuo Zheng, Guohao Liu, Junzhuo Wang, Huijun Chen
    Abstract:

    Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used Hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls’ Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage. Keywords: Multicopper ferroxidase, Hephaestin, Ceruloplasmin, Pancreas, Oxidative damage, Iron efflu

  • intestinal Hephaestin potentiates iron absorption in weanling adult and pregnant mice under physiological conditions
    Blood Advances, 2017
    Co-Authors: Caglar Doguer, Gregory J. Anderson, Chris D. Vulpe, Sukru Gulec, James F Collins
    Abstract:

    Regulation of intestinal iron absorption is crucial to maintain body iron levels because humans have no regulated iron-excretory system. Elucidating molecular events that mediate intestinal iron transport is thus important for the development of therapeutic approaches to modify iron absorption in pathological states. The process of iron uptake into duodenal enterocytes is relatively well understood, but less is known about the functional coupling between the iron exporter ferroportin 1 and the basolateral membrane iron oxidase Hephaestin (Heph). Initial characterization of intestine-specific Heph knockout (Hephint) mice demonstrated that adult male mice were mildly iron deficient; however, the specific role of intestinal Heph has not been determined in weanling mice, in female mice, or during physiological states which stimulate iron absorption. Furthermore, because ferroportin 1-mediated iron export from some tissues (eg, liver) is impaired in the absence of the Heph homolog, ceruloplasmin, we hypothesized that Heph is rate limiting for intestinal iron absorption, especially when iron demands increase. Our experimental approach was to assess various physiological parameters and iron (59Fe) absorption and tissue distribution in weanling, adult, and pregnant Hephint mice (and controls) under physiological conditions and in adult Hephint mice after dietary iron deprivation or acute hemolysis. Results demonstrate that intestinal Heph is essential for optimal iron transport in weanlings and adults of both sexes and during pregnancy, but not in adult mice with iron-deficiency or hemolytic anemia. Moreover, activation of unidentified, intestinal ferroxidases was noted, which may explain why intestinal Heph is not always required for optimal iron absorption.

  • Hephaestin and ceruloplasmin play distinct but interrelated roles in iron homeostasis in mouse brain
    Journal of Nutrition, 2015
    Co-Authors: Ruiwei Jiang, Brie K Fuqua, Gregory J. Anderson, Joshua L Dunaief, Jiashuo Zheng, Bo Jiang, Chao Hua, Yike Wan, Samuel David, Chris D. Vulpe
    Abstract:

    BACKGROUND Iron accumulation in the central nervous system (CNS) is a common feature of many neurodegenerative diseases. Multicopper ferroxidases (MCFs) play an important role in cellular iron metabolism. However, the role of MCFs in the CNS in health and disease remains poorly characterized. OBJECTIVE The aim was to study the role of Hephaestin (HEPH) and ceruloplasmin (CP) in CNS iron metabolism and homeostasis. METHODS Iron concentrations and L-ferritin protein levels of selected brain regions were determined in global Hephaestin knockout (Heph KO), global ceruloplasmin knockout (Cp KO), and wild-type (WT) male mice at 6-7 mo of age. Gene expression of divalent metal transporter 1 (Dmt1), ferroportin 1 (Fpn1), Heph, Cp, and transferrin receptor 1 (Tfrc) and HEPH protein level was quantitated in the same brain regions. RESULTS Iron and L-ferritin protein levels were significantly increased in Heph KO mouse brain cortex (iron: 30%, P < 0.05; L-ferritin: 200%, P < 0.05), hippocampus (iron: 80%, P < 0.05; L-ferritin: 300%, P < 0.05), brainstem (iron: 20%, P < 0.05; L-ferritin: 150%, P < 0.05), and cerebellum (iron: 20%, P < 0.05; L-ferritin: 100%, P < 0.05) regions than in WT and Cp KO mouse brain regions at 6 mo of age. Expression of the Heph gene was significantly increased in the Cp KO mouse cortex (100%; P < 0.01), hippocampus (350%; P < 0.001), brainstem (30%; P < 0.01), and cerebellum (150%; P < 0.001) than in WT controls, and Cp gene expression was significantly decreased in the Heph KO mouse hippocampus (20%; P < 0.05) than in WT control mice at 6 mo of age. CONCLUSIONS Ablation of HEPH or CP results in disordered brain iron homeostasis in mice. Heph KO may provide a novel model for neurodegenerative disorders.

  • Hephaestin and ceruloplasmin play distinct but interrelated roles in iron homeostasis
    2015
    Co-Authors: Ruiwei Jiang, Brie K Fuqua, Gregory J. Anderson, Joshua L Dunaief, Jiashuo Zheng, Bo Jiang, Chao Hua, Yike Wan, Samuel David, Chris D. Vulpe
    Abstract:

    Background: Iron accumulation in the central nervous system (CNS) is a common feature of many neurodegenerative diseases. Multicopperferroxidases (MCFs) play an important role in cellular iron metabolism. However, the role of MCFs in the CNS in health and disease remains poorly characterized. Objective: The aim was to study the role of Hephaestin (HEPH) and ceruloplasmin (CP) in CNS iron metabolism and homeostasis. Methods: Iron concentrations and L-ferritin protein levels of selected brain regions were determined in global Hephaestin knockout (Heph KO), global ceruloplasmin knockout (Cp KO), and wild-type (WT) male mice at 6–7 mo of age. Gene expression of divalent metal transporter 1 (Dmt1), ferroportin 1 (Fpn1), Heph, Cp, and transferrin receptor 1 (Tfrc )a nd HEPH protein level was quantitated in the same brain regions. Results: Iron and L-ferritin protein levels were significantly increased in Heph KO mouse brain cortex (iron: 30% greater, P < 0.05; L-ferritin: 200% greater, P < 0.05), hippocampus (iron: 80% greater, P < 0.05; L-ferritin: 300% greater, P < 0.05), brainstem (iron: 20% greater, P < 0.05; L-ferritin: 150% greater, P < 0.05), and cerebellum (iron: 20% greater, P < 0.05; L-ferritin: 100% greater, P < 0.05) regions than in WT and Cp KO mouse brain regions at 6 mo of age. Expression of the Heph gene was significantly increased in the Cp KO mouse cortex (100% greater; P < 0.01), hippocampus (350% greater; P < 0.001), brainstem (30% greater;P < 0.01), and cerebellum (150% greater;P < 0.001) than in WT controls, and Cp gene expression was significantly decreased in the Heph KO mouse hippocampus (20% less; P < 0.05) than in WT control mice at 6 mo of age. Conclusions: Ablation of HEPH or CP results in disordered brain iron homeostasis in mice. Heph KO may provide a novel model for neurodegenerative disorders. J Nutr doi: 10.3945/jn.114.207316.

Brie K Fuqua - One of the best experts on this subject based on the ideXlab platform.

  • Biallelic HEPHL1 variants impair ferroxidase activity and cause an abnormal hair phenotype
    2019
    Co-Authors: Prashant Sharma, Brie K Fuqua, Marie Reichert, Thomas C. Markello, David R. Adams, Peter J. Steinbach, Xenia Parisi, Stephen G. Kaler, Christopher D. Vulpe
    Abstract:

    Maintenance of the correct redox status of iron is functionally important for critical biological processes. Multicopper ferroxidases play an important role in oxidizing ferrous iron, released from the cells, into ferric iron, which is subsequently distributed by transferrin. Two well-characterized ferroxidases, ceruloplasmin (CP) and Hephaestin (HEPH) facilitate this reaction in different tissues. Recently, a novel ferroxidase, Hephaestin like 1 (HEPHL1), also known as zyklopen, was identified. Here we report a child with compound heterozygous mutations in HEPHL1 (NM_001098672) who presented with abnormal hair (pili torti and trichorrhexis nodosa) and cognitive dysfunction. The maternal missense mutation affected mRNA splicing, leading to skipping of exon 5 and causing an in-frame deletion of 85 amino acids (c.809_1063del; p.Leu271_ala355del). The paternal mutation (c.3176T>C; p.Met1059Thr) changed a highly conserved methionine that is part of a typical type I copper binding site in HEPHL1. We demonstrated that HEPHL1 has ferroxidase activity and that the patient’s two mutations exhibited loss of this ferroxidase activity. Consistent with these findings, the patient’s fibroblasts accumulated intracellular iron and exhibited reduced activity of the copper-dependent enzyme, lysyl oxidase. These results suggest that the patient’s biallelic variants are loss-of-function mutations. Hence, we generated a Hephl1 knockout mouse model that was viable and had curly whiskers, consistent with the hair phenotype in our patient. These results enhance our understanding of the function of HEPHL1 and implicate altered ferroxidase activity in hair growth and hair disorders.

  • Ceruloplasmin and Hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux.
    Redox biology, 2018
    Co-Authors: Min Chen, Brie K Fuqua, Gregory J. Anderson, Chris D. Vulpe, Jiashuo Zheng, Guohao Liu, Junzhuo Wang, Huijun Chen
    Abstract:

    Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used Hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls' Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage.

  • Ceruloplasmin and Hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux
    Elsevier, 2018
    Co-Authors: Min Chen, Brie K Fuqua, Gregory J. Anderson, Chris D. Vulpe, Jiashuo Zheng, Guohao Liu, Junzhuo Wang, Huijun Chen
    Abstract:

    Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used Hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls’ Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage. Keywords: Multicopper ferroxidase, Hephaestin, Ceruloplasmin, Pancreas, Oxidative damage, Iron efflu

  • severe iron metabolism defects in mice with double knockout of the multicopper ferroxidases Hephaestin and ceruloplasmin
    Cellular and molecular gastroenterology and hepatology, 2018
    Co-Authors: Brie K Fuqua, Sarah J. Wilkins, Pavle Matak, Deepak Darshan, David M. Frazer, Linda A Dunn, Alex Loguinov, Scott C Kogan, Huijun Chen
    Abstract:

    BACKGROUND & AIMS: Multicopper ferroxidases (MCFs) facilitate intestinal iron absorption and systemic iron recycling, likely by a mechanism involving the oxidization of Fe2+ from the iron exporter ferroportin 1 for delivery to the circulating Fe3+ carrier transferrin. Hephaestin (HEPH), the only MCF known to be expressed in enterocytes, aids in the basolateral transfer of dietary iron to the blood. Mice lacking HEPH in the whole body (Heph(-/-)) or intestine alone (Heph(int/int)) exhibit defects in dietary iron absorption but still survive and grow. Circulating ceruloplasmin (CP) is the only other known MCF likely to interact with enterocytes. Our aim was to assess the effects of combined deletion of HEPH and CP on intestinal iron absorption and homeostasis in mice.METHODS: Mice lacking both HEPH and CP (Heph(-/-)Cp(-/-)) and mice with whole-body knockout of CP and intestine-specific deletion of HEPH (Heph(int/int)Cp(-/-)) were generated and phenotyped.RESULTS: Heph(-/-)Cp(-/-) mice were severely anemic and had low serum iron, but they exhibited marked iron loading in duodenal enterocytes, the liver, heart, pancreas, and other tissues. Heph(int/int)Cp(-/-) mice were moderately anemic (similar to Cp-/- mice) but were iron loaded only in the duodenum and liver, as in Heph(int/int) and Cp-/- mice, respectively. Both double knockout models absorbed iron in radiolabeled intestinal iron absorption studies, but the iron was inappropriately distributed, with an abnormally high percentage retained in the liver.CONCLUSIONS: These studies indicate that HEPH and CP, and likely MCFs in general, are not essential for intestinal iron absorption but are required for proper systemic iron distribution. They also point to important extra-intestinal roles for HEPH in maintaining whole-body iron homeostasis.

  • Severe Iron Metabolism Defects in Mice With Double Knockout of the Multicopper Ferroxidases Hephaestin and CeruloplasminSummary
    'Elsevier BV', 2018
    Co-Authors: Brie K Fuqua, Sarah J. Wilkins, Pavle Matak, Deepak Darshan, David M. Frazer, Alex Loguinov, Scott C Kogan, Linda Dunn, Huijun Chen
    Abstract:

    Background & Aims: Multicopper ferroxidases (MCFs) facilitate intestinal iron absorption and systemic iron recycling, likely by a mechanism involving the oxidization of Fe2+ from the iron exporter ferroportin 1 for delivery to the circulating Fe3+ carrier transferrin. Hephaestin (HEPH), the only MCF known to be expressed in enterocytes, aids in the basolateral transfer of dietary iron to the blood. Mice lacking HEPH in the whole body (Heph-/-) or intestine alone (Hephint/int) exhibit defects in dietary iron absorption but still survive and grow. Circulating ceruloplasmin (CP) is the only other known MCF likely to interact with enterocytes. Our aim was to assess the effects of combined deletion of HEPH and CP on intestinal iron absorption and homeostasis in mice. Methods: Mice lacking both HEPH and CP (Heph-/-Cp-/-) and mice with whole-body knockout of CP and intestine-specific deletion of HEPH (Hephint/intCp-/-) were generated and phenotyped. Results: Heph-/-Cp-/- mice were severely anemic and had low serum iron, but they exhibited marked iron loading in duodenal enterocytes, the liver, heart, pancreas, and other tissues. Hephint/intCp-/- mice were moderately anemic (similar to Cp-/- mice) but were iron loaded only in the duodenum and liver, as in Hephint/int and Cp-/- mice, respectively. Both double knockout models absorbed iron in radiolabeled intestinal iron absorption studies, but the iron was inappropriately distributed, with an abnormally high percentage retained in the liver. Conclusions: These studies indicate that HEPH and CP, and likely MCFs in general, are not essential for intestinal iron absorption but are required for proper systemic iron distribution. They also point to important extra-intestinal roles for HEPH in maintaining whole-body iron homeostasis. Keywords: Iron Deficiency Anemia, Iron Overload, Intestinal Iron Absorption, Non-Transferrin Bound Iro

Andrew T. Mckie - One of the best experts on this subject based on the ideXlab platform.

  • decreased Hephaestin activity in the intestine of copper deficient mice causes systemic iron deficiency
    Journal of Nutrition, 2006
    Co-Authors: Huijun Chen, Gregory J. Anderson, Andrew T. Mckie, Zouhair K. Attieh, Hua Gao, Gang Huang, Chris D. Vulpe
    Abstract:

    Copper and iron metabolism intersect in mammals. Copper deficiency simultaneously leads to decreased iron levels in some tissues and iron deficiency anemia, whereas it results in iron overload in other tissues such as the intestine and liver. The copper requirement of the multicopper ferroxidases Hephaestin and ceruloplasmin likely explains this link between copper and iron homeostasis in mammals. We investigated the effect of in vivo and in vitro copper deficiency on Hephaestin (Heph) expression and activity. C57BL/6J mice were separated into 2 groups on the day of parturition. One group was fed a copper-deficient diet and another was fed a control diet for 6 wk. Copper-deficient mice had significantly lower Hephaestin and ceruloplasmin (~50% of controls) ferroxidase activity. Liver hepcidin expression was significantly downregulated by copper deficiency (~60% of controls), and enterocyte mRNA and protein levels of ferroportin1 were increased to 2.5 and 10 times, respectively, relative to controls, by copper deficiency, indicating a systemic iron deficiency in the copper-deficient mice. Interestingly, Hephaestin protein levels were significantly decreased to ~40% of control, suggesting that decreased enterocyte copper content leads to decreased Hephaestin synthesis and/or stability. We also examined the effect of copper deficiency on Hephaestin in vitro in the HT29 cell line and found dramatically decreased Hephaestin synthesis and activity. Both in vivo and in vitro studies indicate that copper is required for the proper processing and/or stability of Hephaestin.

  • decreased Hephaestin activity in the intestine of copper deficient mice causes systemic iron deficiency
    Scopus, 2006
    Co-Authors: Huijun Chen, Gregory J. Anderson, Andrew T. Mckie, Zouhair K. Attieh, Hua Gao, Gang Huang, Chris D. Vulpe
    Abstract:

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  • mislocalisation of Hephaestin a multicopper ferroxidase involved in basolateral intestinal iron transport in the sex linked anaemia mouse
    Gut, 2004
    Co-Authors: Yienming Kuo, Gregory J. Anderson, Andrew T. Mckie, Huijun Chen, Zouhair K. Attieh, Basharut A. Syed, Jane Gitschier, Chris D. Vulpe
    Abstract:

    Background: Hephaestin is a multicopper ferroxidase required for basolateral transport of iron from enterocytes. Sex linked anaemia (sla) mice have a defect in the release of iron from intestinal enterocytes into the circulation due to an interstitial deletion in the Hephaestin gene (heph). Results: We have demonstrated that Hephaestin is primarily localised to a supranuclear compartment in both intestinal enterocytes and in cultured cells. In normal intestinal enterocytes, Hephaestin was also present on the basolateral surface. In sla mice, Hephaestin was present only in the supranuclear compartment. In contrast, the iron permease Ireg1 localised to the basolateral membrane in both control and sla mice. Conclusion: We suggest that mislocalisation of Hephaestin likely contributes to the functional defect in sla intestinal epithelium.

  • systemic regulation of Hephaestin and ireg1 revealed in studies of genetic and nutritional iron deficiency
    Blood, 2003
    Co-Authors: Huijun Chen, Gregory J. Anderson, Andrew T. Mckie, Zouhair K. Attieh, Tama C. Fox
    Abstract:

    Hephaestin is a membrane-bound multicopper ferroxidase necessary for iron egress from intestinal enterocytes into the circulation. Mice with sex-linked anemia (sla) have a mutant form of Hephaestin and a defect in intestinal basolateral iron transport, which results in iron deficiency and anemia. Ireg1 (SLC11A3, also known as Ferroportin1 or Mtp1) is the putative intestinal basolateral iron transporter. We compared iron levels and expression of genes involved in iron uptake and storage in sla mice and C57BL/6J mice fed iron-deficient, iron-overload, or control diets. Both iron-deficient wild-type mice and sla mice showed increased expression of Heph and Ireg1 mRNA, compared to controls, whereas only iron-deficient wild-type mice had increased expression of the brush border transporter Dmt1. Unlike iron-deficient mice, sla mouse enterocytes accumulated nonheme iron and ferritin. These results indicate that Dmt1 can be modulated by the enterocyte iron level, whereas Hephaestin and Ireg1 expression respond to systemic rather than local signals of iron status. Thus, the basolateral transport step appears to be the primary site at which the small intestine responds to alterations in body iron requirements.

  • Duodenal cytochrome b and Hephaestin expression in patients with iron deficiency and hemochromatosis.
    Gastroenterology, 2003
    Co-Authors: Heinz Zoller, Igor Theurl, Robert Koch, Andrew T. Mckie, Wolfgang Vogel, Günter Weiss
    Abstract:

    Abstract Background & Aims: An increased duodenal expression of the iron transporters, divalent-metal-transporter-1, and ferroportin is observed in patients with iron deficiency or hereditary hemochromatosis. Two oxidoreductases, termed duodenal cytochrome b and Hephaestin, are proposed to co-operate with divalent-metal-transporter-1 and FPN1, respectively, to transfer iron from the duodenal lumen to the circulation. Methods: In the present study, we investigated the mRNA and protein expression of Dcytb and Hephaestin in duodenal biopsies from patients with iron deficiency, HFE, and non-HFE-associated hemochromatosis and in control subjects by means of real-time polymerase chain reaction, Western blot, and immunofluorescence. Results: In iron deficiency a coordinated upregulation of the iron transporters divalent-metal-transporter-1 and ferroportin and of duodenal-cytochrome b and Hephaestin was found, whereas in patients with HFE and non-HFE-associated hemochromatosis duodenal-cytochrome b and Hephaestin protein and mRNA expression were not significantly different from control subjects. However, HFE but not non-HFE hemochromatosis patients presented with an increased duodenal ferric reductase activity. Spearman rank correlations showed that Dcytb, Hephaestin, FPN1, and DMT1 mRNA expression are positively related to each other independently of the underlying disease, which ensures an efficient transepithelial transport of absorbed iron. Conclusions: Our data show that duodenal-cytochrome b activity in iron deficiency is stimulated via enhanced protein expression, whereas in HFE hemochromatosis it is up-regulated post-translationally. This points to different kinetics of intestinal iron uptake between iron deficiency and HFE hemochromatosis and also indicates that duodenal iron accumulation in HFE and non-HFE hemochromatosis is pathophysiologically different.