1
|
Qian Y, Ma S, Qiu R, Sun Z, Liu W, Wu F, Lam SM, Xia Z, Wang K, Fang L, Shui G, Cao X. Golgi protein ACBD3 downregulation sensitizes cells to ferroptosis. Cell Biol Int 2024. [PMID: 38953242 DOI: 10.1002/cbin.12213] [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: 05/31/2024] [Revised: 06/13/2024] [Accepted: 06/16/2024] [Indexed: 07/03/2024]
Abstract
Ferroptosis, a form of cell death driven by iron-dependent lipid peroxidation, is emerging as a promising target in cancer therapy. It is regulated by a network of molecules and pathways that modulate lipid metabolism, iron homeostasis and redox balance, and related processes. However, there are still numerous regulatory molecules intricately involved in ferroptosis that remain to be identified. Here, we indicated that suppression of Golgi protein acyl-coenzyme A binding domain A containing 3 (ACBD3) increased the sensitivity of Henrieta Lacks and PANC1 cells to ferroptosis. ACBD3 knockdown increases labile iron levels by promoting ferritinophagy. This increase in free iron, coupled with reduced levels of glutathione peroxidase 4 due to ACBD3 knockdown, leads to the accumulation of reactive oxygen species and lipid peroxides. Moreover, ACBD3 knockdown also results in elevated levels of polyunsaturated fatty acid-containing glycerophospholipids through mechanisms that remain to be elucidated. Furthermore, inhibition of ferrtinophagy in ACBD3 downregulated cells by knocking down the nuclear receptor co-activator 4 or Bafilomycin A1 treatment impeded ferroptosis. Collectively, our findings highlight the pivotal role of ACBD3 in governing cellular resistance to ferroptosis and suggest that pharmacological manipulation of ACBD3 levels is a promising strategy for cancer therapy.
Collapse
Affiliation(s)
- Ying Qian
- School of Life Sciences, Anhui Medical University, Hefei, China
| | - Shanchuan Ma
- School of Life Sciences, Anhui Medical University, Hefei, China
| | - Rong Qiu
- School of Life Sciences, Anhui Medical University, Hefei, China
| | - Zhiyang Sun
- School of Life Sciences, Anhui Medical University, Hefei, China
| | - Wei Liu
- School of Life Sciences, Anhui Medical University, Hefei, China
| | - Fan Wu
- School of Life Sciences, Anhui Medical University, Hefei, China
| | - Sin Man Lam
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Zhengguo Xia
- Department of Wound Repair and Plastic and Aesthetic Surgery, the First Affiliated Hospital of Anhui Medical University, Hefei, China
- Anhui Public Health Clinical Center, Hefei, China
| | - Kezhen Wang
- School of Life Sciences, Anhui Medical University, Hefei, China
- Anhui Provincial Institute of Translational Medicine, Anhui Medical University, Hefei, China
| | - Linshen Fang
- Department of Wound Repair and Plastic and Aesthetic Surgery, the First Affiliated Hospital of Anhui Medical University, Hefei, China
- Anhui Public Health Clinical Center, Hefei, China
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xinwang Cao
- School of Life Sciences, Anhui Medical University, Hefei, China
- Anhui Provincial Institute of Translational Medicine, Anhui Medical University, Hefei, China
| |
Collapse
|
2
|
Luteijn RD, van Terwisga SR, Ver Eecke JE, Onia L, Zaver SA, Woodward JJ, Wubbolts RW, Raulet DH, van Kuppeveld FJM. The activation of the adaptor protein STING depends on its interactions with the phospholipid PI4P. Sci Signal 2024; 17:eade3643. [PMID: 38470955 PMCID: PMC11003704 DOI: 10.1126/scisignal.ade3643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 02/22/2024] [Indexed: 03/14/2024]
Abstract
Activation of the endoplasmic reticulum (ER)-resident adaptor protein STING, a component of a cytosolic DNA-sensing pathway, induces the transcription of genes encoding type I interferons (IFNs) and other proinflammatory factors. Because STING is activated at the Golgi apparatus, control of the localization and activation of STING is important in stimulating antiviral and antitumor immune responses. Through a genome-wide CRISPR interference screen, we found that STING activation required the Golgi-resident protein ACBD3, which promotes the generation of phosphatidylinositol 4-phosphate (PI4P) at the trans-Golgi network, as well as other PI4P-associated proteins. Appropriate localization and activation of STING at the Golgi apparatus required ACBD3 and the PI4P-generating kinase PI4KB. In contrast, STING activation was enhanced when the lipid-shuttling protein OSBP, which removes PI4P from the Golgi apparatus, was inhibited by the US Food and Drug Administration-approved antifungal itraconazole. The increase in the abundance of STING-activating phospholipids at the trans-Golgi network resulted in the increased production of IFN-β and other cytokines in THP-1 cells. Furthermore, a mutant STING that could not bind to PI4P failed to traffic from the ER to the Golgi apparatus in response to a STING agonist, whereas forced relocalization of STING to PI4P-enriched areas elicited STING activation in the absence of stimulation with a STING agonist. Thus, PI4P is critical for STING activation, and manipulating PI4P abundance may therapeutically modulate STING-dependent immune responses.
Collapse
Affiliation(s)
- Rutger D Luteijn
- Virology Section, Infectious Diseases and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Sypke R van Terwisga
- Virology Section, Infectious Diseases and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Jill E Ver Eecke
- Virology Section, Infectious Diseases and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Liberty Onia
- Department of Molecular and Cell Biology, and Cancer Research Laboratory, Division of Immunology and Molecular Medicine, University of California, Berkeley, CA, USA
| | - Shivam A Zaver
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Joshua J Woodward
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Richard W Wubbolts
- Centre for Cell Imaging, Division of Cell Biology, Metabolism and Cancer, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - David H Raulet
- Department of Molecular and Cell Biology, and Cancer Research Laboratory, Division of Immunology and Molecular Medicine, University of California, Berkeley, CA, USA
| | - Frank J M van Kuppeveld
- Virology Section, Infectious Diseases and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| |
Collapse
|
3
|
Okazaki Y. Iron from the gut: the role of divalent metal transporter 1. J Clin Biochem Nutr 2024; 74:1-8. [PMID: 38292117 PMCID: PMC10822759 DOI: 10.3164/jcbn.23-47] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 10/10/2023] [Indexed: 02/01/2024] Open
Abstract
Mammalian cells contain thousands of metalloproteins and evolved systems to correctly incorporate metal cofactors into their designated sites. Among the transient metals in living cells, iron is the most abundant element that present as an iron sulfur cluster, mono- and dinuclear iron centers or heme for catalytic reactions. Iron homeostasis is tightly regulated by intestinal iron absorption in mammals owing to the lack of an iron excretive transport system, apart from superficial epithelial cell detachment and urinary outflow reabsorptive impairment. In mammals, the central site for iron absorption is in the duodenum, where the divalent metal transporter 1 is essential for iron uptake. The most notable manifestation of mutated divalent metal transporter 1 presents as iron deficiency anemia in humans. In contrast, the mutation of ferroportin, which exports iron, causes iron overload by either gain or loss of function. Furthermore, hepcidin secretion from the liver suppresses iron efflux by internalizing and degrading ferroportin; thus, the hepcidin/ferroportin axis is extensively investigated for its potential as a therapeutic target to treat iron overload. This review focuses on the divalent metal transporter 1-mediated intestinal iron uptake and hepcidin/ferroportin axis that regulate systemic iron homeostasis.
Collapse
Affiliation(s)
- Yasumasa Okazaki
- Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi 466-8550, Japan
| |
Collapse
|
4
|
ACBD3 Bioinformatic Analysis and Protein Expression in Breast Cancer Cells. Int J Mol Sci 2022; 23:ijms23168881. [PMID: 36012147 PMCID: PMC9408326 DOI: 10.3390/ijms23168881] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/28/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022] Open
Abstract
ACBD3 overexpression has previously been found to correlate with worse prognosis for breast cancer patients and, as an incredibly diverse protein in both function and cellular localisation, ACBD3 may have a larger role in breast cancer than previously thought. This study further investigated ACBD3′s role in breast cancer. Bioinformatic databases were queried to characterise ACBD3 expression and mutation in breast cancer and to investigate how overexpression affects breast cancer patient outcomes. Immunohistochemistry was carried out to examine ACBD3 location within cells and tissue structures. ACBD3 was more highly expressed in breast cancer than in any other cancer or matched normal tissue, and expression over the median level resulted in reduced relapse-free, overall, and distant metastasis-free survival for breast cancer patients as a whole, with some differences observed between subtypes. IHC analysis found that ACBD3 levels varied based on hormone receptor status, indicating that ACBD3 could be a candidate biomarker for poor patient prognosis in breast cancer and may possibly be a biomarker for ER signal reprogramming of precancerous breast tissue.
Collapse
|
5
|
Islinger M, Costello JL, Kors S, Soupene E, Levine TP, Kuypers FA, Schrader M. The diversity of ACBD proteins - From lipid binding to protein modulators and organelle tethers. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2020; 1867:118675. [PMID: 32044385 PMCID: PMC7057175 DOI: 10.1016/j.bbamcr.2020.118675] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/30/2020] [Accepted: 02/05/2020] [Indexed: 12/12/2022]
Abstract
Members of the large multigene family of acyl-CoA binding domain containing proteins (ACBDs) share a conserved motif required for binding of Coenzyme A esterified fatty acids of various chain length. These proteins are present in the three kingdoms of life, and despite their predicted roles in cellular lipid metabolism, knowledge about the precise functions of many ACBD proteins remains scarce. Interestingly, several ACBD proteins are now suggested to function at organelle contact sites, and are recognized as host interaction proteins for different pathogens including viruses and bacteria. Here, we present a thorough phylogenetic analysis of the ACBD family and discuss their structure and evolution. We summarize recent findings on the various functions of animal and fungal ACBDs with particular focus on peroxisomes, the role of ACBD proteins at organelle membranes, and their increasing recognition as targets for pathogens.
Collapse
Affiliation(s)
- Markus Islinger
- Institute of Neuroanatomy, Medical Faculty Manheim, University of Heidelberg, 68167 Mannheim, Germany
| | - Joseph L Costello
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Suzan Kors
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Eric Soupene
- Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA
| | | | - Frans A Kuypers
- Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA
| | - Michael Schrader
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK.
| |
Collapse
|
6
|
Yue X, Qian Y, Gim B, Lee I. Acyl-CoA-Binding Domain-Containing 3 (ACBD3; PAP7; GCP60): A Multi-Functional Membrane Domain Organizer. Int J Mol Sci 2019; 20:ijms20082028. [PMID: 31022988 PMCID: PMC6514682 DOI: 10.3390/ijms20082028] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/13/2019] [Accepted: 04/15/2019] [Indexed: 01/04/2023] Open
Abstract
Acyl-CoA-binding domain-containing 3 (ACBD3) is a multi-functional scaffolding protein, which has been associated with a diverse array of cellular functions, including steroidogenesis, embryogenesis, neurogenesis, Huntington’s disease (HD), membrane trafficking, and viral/bacterial proliferation in infected host cells. In this review, we aim to give a timely overview of recent findings on this protein, including its emerging role in membrane domain organization at the Golgi and the mitochondria. We hope that this review provides readers with useful insights on how ACBD3 may contribute to membrane domain organization along the secretory pathway and on the cytoplasmic surface of intracellular organelles, which influence many important physiological and pathophysiological processes in mammalian cells.
Collapse
Affiliation(s)
- Xihua Yue
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai 201210, China.
| | - Yi Qian
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai 201210, China.
| | - Bopil Gim
- School of Physical Science and Technology, ShanghaiTech University, Pudong, Shanghai 201210, China.
| | - Intaek Lee
- School of Life Science and Technology, ShanghaiTech University, Pudong, Shanghai 201210, China.
| |
Collapse
|
7
|
Channels, transporters and receptors for cadmium and cadmium complexes in eukaryotic cells: myths and facts. Biometals 2019; 32:469-489. [DOI: 10.1007/s10534-019-00176-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 01/21/2019] [Indexed: 12/21/2022]
|
8
|
Ma Y, Okazaki Y, Glass J. A fluorescent metal-sensor study provides evidence for iron transport by transcytosis in the intestinal epithelial cells. J Clin Biochem Nutr 2018; 62:49-55. [PMID: 29362518 PMCID: PMC5773836 DOI: 10.3164/jcbn.17-74] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 08/27/2017] [Indexed: 12/17/2022] Open
Abstract
Iron transport across the intestinal epithelium is facilitated by the divalent metal transporter 1 (DMT1) on the brush border membrane (BBM). The fluorescent metal sensor calcein, which is hydrophilic, membrane-impermeable and quenched by chelation with iron, was used to test our hypothesis that intestinal iron absorption is through the endocytic processes and is involved in a pathway where BBM-derived vesicles fuse with basolateral membrane (BLM)-derived vesicles. To monitor the flux of iron via transcytosis, Caco-2 cells were employed as a polarized cell layer in Transwell chambers. When calcein was added to the basal chamber along with apo-transferrin (apo-Tf), calcein rapidly underwent endocytosis and co-localized with apo-Tf. Calcein was quenched by adding an iron-ascorbate complex and then restored by adding 2,2'-dipyridyl into the apical chamber. These results were confirmed by live-cell imaging. When hemin from the apical surface and calcein from the basal chamber were added to the Caco-2 cells, internalization of DMT1 and quenching of calcein were not observed until 2 h later. These results indicated that absorbed hemin required processing before hemin-derived iron was available to BLM-derived vesicles. These studies suggest that iron is transported in Caco-2 cells by transcytosis with apical-derived vesicles that are fused to BLM-derived vesicles.
Collapse
Affiliation(s)
- Yuxiang Ma
- Feist-Weiller Cancer Center and the Department of Medicine, Louisiana State University Health Sciences Center-Shreveport, 1501 Kings Highway, Shreveport, LA 71130, USA
| | - Yasumasa Okazaki
- Feist-Weiller Cancer Center and the Department of Medicine, Louisiana State University Health Sciences Center-Shreveport, 1501 Kings Highway, Shreveport, LA 71130, USA
| | - Jonathan Glass
- Feist-Weiller Cancer Center and the Department of Medicine, Louisiana State University Health Sciences Center-Shreveport, 1501 Kings Highway, Shreveport, LA 71130, USA
| |
Collapse
|
9
|
Okazaki Y, Glass J. Protoporphyrin IX regulates peripheral benzodiazepine receptor associated protein 7 (PAP7) and divalent metal transporter 1 (DMT1) in K562 cells. Biochem Biophys Rep 2017; 10:26-31. [PMID: 28955733 PMCID: PMC5614651 DOI: 10.1016/j.bbrep.2017.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 02/17/2017] [Accepted: 02/25/2017] [Indexed: 11/28/2022] Open
Abstract
Background Protoporphyrin IX (PP IX), the immediate precursor to heme, combines with ferrous iron to make this product. The effects of exogenous PP IX on iron metabolism remain to be elucidated. Peripheral-type benzodiazepine receptor (PBR) is implicated in the transport of coproporphyrinogen into the mitochondria for conversion to PP IX. We have demonstrated that PBR-Associated Protein 7 (PAP7) bound to the Iron Responsive Element (IRE) isoform of divalent metal transporter 1 (DMT1). PP IX and PAP7 are ligands for PBR, thus, we hypothesized that PAP7 interact with PP IX via PBR. Methods We have examined in K562 cells, which can be induced to undergo erythroid differentiation by PP IX and hemin, the effects of PP IX on the expression of PAP7 and other proteins involved in cellular iron metabolism, transferrin receptor 1 (TfR1), DMT1, ferritin heavy chain (FTH), c-Myc and C/EBPα by western blot and quantitative real time PCR analyses. Results PP IX significantly decreased mRNA levels of DMT1 (IRE) and (non-IRE) from 4 h. PP IX markedly decreased protein levels of C/EBPα, PAP7 and DMT1. In contrast, hemin, which like PP IX also induces K562 cell differentiation, had no effect on PAP7 or DMT1 expression. Conclusion We hypothesize that PP IX binds to PBR displacing PAP7 protein, which is then degraded, decreasing the interaction of PAP7 with DMT1 (IRE) and resulting in increased turnover of DMT1. General significance These results suggest that exogenous PP IX disrupts iron metabolism by decreasing the protein expression levels of PAP7, DMT1 and C/EBPα. Protoporphyrin IX (PP IX) decreased protein levels of PAP7 and DMT1 in K562. PP IX decreased mRNA levels of DMT1 (IRE) and (non-IRE) isoforms in K562. PP IX decreased protein level of C/EBPα, which transcribes DMT1 mRNA, in K562.
Collapse
Affiliation(s)
- Yasumasa Okazaki
- Feist-Weiller Cancer Center and the Department of Medicine, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA 71130, USA
| | - Jonathan Glass
- Feist-Weiller Cancer Center and the Department of Medicine, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA 71130, USA
| |
Collapse
|
10
|
Xu H, Jiang H, Xie J. New Insights into the Crosstalk between NMDARs and Iron: Implications for Understanding Pathology of Neurological Diseases. Front Mol Neurosci 2017; 10:71. [PMID: 28360837 PMCID: PMC5352910 DOI: 10.3389/fnmol.2017.00071] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 03/01/2017] [Indexed: 12/11/2022] Open
Abstract
Both iron dyshomeostasis and N-methyl-D-aspartate receptors (NMDARs)-mediated neurotoxicity have been shown to have an important role in neurological diseases such as Parkinson’s disease (PD) and Alzheimer’s disease (AD). Evidence proved that activation of NMDARs could promote iron overload and iron-induced neurotoxicity by enhancing iron importer divalent metal transporter 1 (DMT1)-mediated iron uptake and iron releasing from lysosome. Also, iron overload could regulate NMDARs-mediated synaptic transmission. This indicates that there might be a possible relationship between iron and activation of NMDARs in neurological diseases. Understanding this interaction between iron and activation of NMDARs may provide new therapeutic avenues for a more targeted neurotherapeutic strategy for these diseases. Therefore, in this review article, we will describe the dysfunction of iron metabolism and NMDARs in neurological diseases including PD and AD, and summarize the new insight into the mechanisms underlying the interaction between iron and activation of NMDARs.
Collapse
Affiliation(s)
- Huamin Xu
- Collaborative Innovation Center for Brain Science, Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao UniversityQingdao, China; Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao UniversityQingdao, China
| | - Hong Jiang
- Collaborative Innovation Center for Brain Science, Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao UniversityQingdao, China; Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao UniversityQingdao, China
| | - Junxia Xie
- Collaborative Innovation Center for Brain Science, Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao UniversityQingdao, China; Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao UniversityQingdao, China
| |
Collapse
|
11
|
Regulation of divalent metal transporter-1 by serine phosphorylation. Biochem J 2016; 473:4243-4254. [PMID: 27681840 PMCID: PMC5103878 DOI: 10.1042/bcj20160674] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 09/22/2016] [Accepted: 09/28/2016] [Indexed: 01/14/2023]
Abstract
Divalent metal transporter-1 (DMT1) mediates dietary iron uptake across the intestinal mucosa and facilitates peripheral delivery of iron released by transferrin in the endosome. Here, we report that classical cannabinoids (Δ9-tetrahydrocannabinol, Δ9-THC), nonclassical cannabinoids (CP 55,940), aminoalkylindoles (WIN 55,212-2) and endocannabinoids (anandamide) reduce 55Fe and 54Mn uptake by HEK293T(DMT1) cells stably expressing the transporter. siRNA knockdown of cannabinoid receptor type 2 (CB2) abrogated inhibition. CB2 is a G-protein (GTP-binding protein)-coupled receptor that negatively regulates signal transduction cascades involving serine/threonine kinases. Immunoprecipitation experiments showed that DMT1 is serine-phosphorylated under basal conditions, but that treatment with Δ9-THC reduced phosphorylation. Site-directed mutation of predicted DMT1 phosphosites further showed that substitution of serine with alanine at N-terminal position 43 (S43A) abolished basal phosphorylation. Concordantly, both the rate and extent of 55Fe uptake in cells expressing DMT1(S43A) was reduced compared with those expressing wild-type DMT1. Among kinase inhibitors that affected DMT1-mediated iron uptake, staurosporine also reduced DMT1 phosphorylation confirming a role for serine phosphorylation in iron transport regulation. These combined data indicate that phosphorylation at serine 43 of DMT1 promotes transport activity, whereas dephosphorylation is associated with loss of iron uptake. Since anti-inflammatory actions mediated through CB2 would be associated with reduced DMT1 phosphorylation, we postulate that this pathway provides a means to reduce oxidative stress by limiting iron uptake.
Collapse
|
12
|
Soupene E, Kao J, Cheng DH, Wang D, Greninger AL, Knudsen GM, DeRisi JL, Kuypers FA. Association of NMT2 with the acyl-CoA carrier ACBD6 protects the N-myristoyltransferase reaction from palmitoyl-CoA. J Lipid Res 2016; 57:288-98. [PMID: 26621918 PMCID: PMC4727424 DOI: 10.1194/jlr.m065003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Indexed: 01/13/2023] Open
Abstract
The covalent attachment of a 14-carbon aliphatic tail on a glycine residue of nascent translated peptide chains is catalyzed in human cells by two N-myristoyltransferase (NMT) enzymes using the rare myristoyl-CoA (C(14)-CoA) molecule as fatty acid donor. Although, NMT enzymes can only transfer a myristate group, they lack specificity for C(14)-CoA and can also bind the far more abundant palmitoyl-CoA (C(16)-CoA) molecule. We determined that the acyl-CoA binding protein, acyl-CoA binding domain (ACBD)6, stimulated the NMT reaction of NMT2. This stimulatory effect required interaction between ACBD6 and NMT2, and was enhanced by binding of ACBD6 to its ligand, C(18:2)-CoA. ACBD6 also interacted with the second human NMT enzyme, NMT1. The presence of ACBD6 prevented competition of the NMT reaction by C(16)-CoA. Mutants of ACBD6 that were either deficient in ligand binding to the N-terminal ACBD or unable to interact with NMT2 did not stimulate activity of NMT2, nor could they protect the enzyme from utilizing the competitor C(16)-CoA. These results indicate that ACBD6 can locally sequester C(16)-CoA and prevent its access to the enzyme binding site via interaction with NMT2. Thus, the ligand binding properties of the NMT/ACBD6 complex can explain how the NMT reaction can proceed in the presence of the very abundant competitive substrate, C(16)-CoA.
Collapse
Affiliation(s)
- Eric Soupene
- Children's Hospital Oakland Research Institute, Oakland, CA
| | - Joseph Kao
- Children's Hospital Oakland Research Institute, Oakland, CA
| | - Daniel H Cheng
- Children's Hospital Oakland Research Institute, Oakland, CA
| | - Derek Wang
- Children's Hospital Oakland Research Institute, Oakland, CA
| | - Alexander L Greninger
- Department of Biochemistry and Biophysics, University of California at San Francisco and Howard Hughes Medical Institute, San Francisco, CA
| | - Giselle M Knudsen
- Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, CA
| | - Joseph L DeRisi
- Department of Biochemistry and Biophysics, University of California at San Francisco and Howard Hughes Medical Institute, San Francisco, CA
| | | |
Collapse
|
13
|
Shawki A, Anthony SR, Nose Y, Engevik MA, Niespodzany EJ, Barrientos T, Öhrvik H, Worrell RT, Thiele DJ, Mackenzie B. Intestinal DMT1 is critical for iron absorption in the mouse but is not required for the absorption of copper or manganese. Am J Physiol Gastrointest Liver Physiol 2015; 309:G635-47. [PMID: 26294671 PMCID: PMC4609933 DOI: 10.1152/ajpgi.00160.2015] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 08/18/2015] [Indexed: 01/31/2023]
Abstract
Divalent metal-ion transporter-1 (DMT1) is a widely expressed iron-preferring membrane-transport protein that serves a critical role in erythroid iron utilization. We have investigated its role in intestinal metal absorption by studying a mouse model lacking intestinal DMT1 (i.e., DMT1(int/int)). DMT1(int/int) mice exhibited a profound hypochromic-microcytic anemia, splenomegaly, and cardiomegaly. That the anemia was due to iron deficiency was demonstrated by the following observations in DMT1(int/int) mice: 1) blood iron and tissue nonheme-iron stores were depleted; 2) mRNA expression of liver hepcidin (Hamp1) was depressed; and 3) intraperitoneal iron injection corrected the anemia, and reversed the changes in blood iron, nonheme-iron stores, and hepcidin expression levels. We observed decreased total iron content in multiple tissues from DMT1(int/int) mice compared with DMT1(+/+) mice but no meaningful change in copper, manganese, or zinc. DMT1(int/int) mice absorbed (64)Cu and (54)Mn from an intragastric dose to the same extent as did DMT1(+/+) mice but the absorption of (59)Fe was virtually abolished in DMT1(int/int) mice. This study reveals a critical function for DMT1 in intestinal nonheme-iron absorption for normal growth and development. Further, this work demonstrates that intestinal DMT1 is not required for the intestinal transport of copper, manganese, or zinc.
Collapse
Affiliation(s)
- Ali Shawki
- 1Department of Molecular & Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio; ,2Systems Biology & Physiology Program, University of Cincinnati College of Medicine, Cincinnati, Ohio;
| | - Sarah R. Anthony
- 1Department of Molecular & Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio;
| | - Yasuhiro Nose
- 3Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, North Carolina;
| | - Melinda A. Engevik
- 1Department of Molecular & Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio; ,2Systems Biology & Physiology Program, University of Cincinnati College of Medicine, Cincinnati, Ohio;
| | - Eric J. Niespodzany
- 1Department of Molecular & Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio;
| | - Tomasa Barrientos
- 3Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, North Carolina;
| | - Helena Öhrvik
- 3Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, North Carolina; ,4Department of Medical Biochemistry & Microbiology, Uppsala University, Uppsala, Sweden; and
| | - Roger T. Worrell
- 1Department of Molecular & Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio; ,2Systems Biology & Physiology Program, University of Cincinnati College of Medicine, Cincinnati, Ohio;
| | - Dennis J. Thiele
- 3Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, North Carolina; ,5Department of Biochemistry, Duke University Medical Center, Durham, North Carolina
| | - Bryan Mackenzie
- Department of Molecular & Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio; Systems Biology & Physiology Program, University of Cincinnati College of Medicine, Cincinnati, Ohio;
| |
Collapse
|
14
|
Soupene E, Kuypers FA. Ligand binding to the ACBD6 protein regulates the acyl-CoA transferase reactions in membranes. J Lipid Res 2015; 56:1961-71. [PMID: 26290611 PMCID: PMC4583085 DOI: 10.1194/jlr.m061937] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 08/18/2015] [Indexed: 12/17/2022] Open
Abstract
The binding determinants of the human acyl-CoA binding domain-containing protein (ACBD) 6 and its function in lipid renewal of membranes were investigated. ACBD6 binds acyl-CoAs of a chain length of 6 to 20 carbons. The stoichiometry of the association could not be fitted to a 1-to-1 model. Saturation of ACBD6 by C16:0-CoA required higher concentration than less abundant acyl-CoAs. In contrast to ACBD1 and ACBD3, ligand binding did not result in the dimerization of ACBD6. The presence of fatty acids affected the binding of C18:1-CoA to ACBD6, dependent on the length, the degree of unsaturation, and the stereoisomeric conformation of their aliphatic chain. ACBD1 and ACBD6 negatively affected the formation of phosphatidylcholine (PC) and phosphatidylethanolamine in the red blood cell membrane. The acylation rate of lysophosphatidylcholine into PC catalyzed by the red cell lysophosphatidylcholine-acyltransferase 1 protein was limited by the transfer of the acyl-CoA substrate from ACBD6 to the acyltransferase enzyme. These findings provide evidence that the binding properties of ACBD6 are adapted to prevent its constant saturation by the very abundant C16:0-CoA and protect membrane systems from the detergent nature of free acyl-CoAs by controlling their release to acyl-CoA-utilizing enzymes.
Collapse
Affiliation(s)
- Eric Soupene
- Children’s Hospital Oakland Research Institute, Oakland, CA 94609
| | - Frans A. Kuypers
- Children’s Hospital Oakland Research Institute, Oakland, CA 94609
| |
Collapse
|
15
|
Gastrointestinal absorption of uranium compounds--a review. Regul Toxicol Pharmacol 2014; 71:125-33. [PMID: 25263405 DOI: 10.1016/j.yrtph.2014.08.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 07/14/2014] [Accepted: 08/21/2014] [Indexed: 01/18/2023]
Abstract
Uranium occurs naturally in soil and rocks, and therefore where it is present in water-soluble form it also occurs naturally in groundwater as well as in drinking water obtained from groundwater. Animal studies suggest that the toxicity of uranium is mainly due to its damage to kidney tubular cells following exposure to soluble uranium compounds. The assessments of the absorption of uranium via the gastrointestinal tract vary, and this has consequences for regulation, in particular the derivation of e.g. drinking water limit values. Absorption rates vary according to the nature and solubility of the compound in which uranium is presented to the test animals and depending on the animal species used in the test. No differences for sex have been observed for absorption in either animals or humans. However, human biomonitoring data do show that boys excrete significantly more uranium than girls. In animal studies neonates took up more uranium than adults or older children. Nutritional status, and in particular the iron content of the diet, have a marked influence on absorption, and higher uranium levels in food intake also appear to increase the absorption rate. If the pointers to an absorption mechanism competing with iron are correct, these mechanisms could also explain the relatively high concentration and chemical toxicity of uranium in the kidneys. It is here (and in the duodenum) that divalent metal transporter 1 (DMT1), which is primarily responsible for the passage of iron (or uranium?) through the cell membranes, is most strongly expressed.
Collapse
|
16
|
Okazaki Y, Wang Y, Tanaka H, Mizuno M, Nakamura K, Kajiyama H, Kano H, Uchida K, Kikkawa F, Hori M, Toyokuni S. Direct exposure of non-equilibrium atmospheric pressure plasma confers simultaneous oxidative and ultraviolet modifications in biomolecules. J Clin Biochem Nutr 2014; 55:207-15. [PMID: 25411528 PMCID: PMC4227828 DOI: 10.3164/jcbn.14-40] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 06/09/2014] [Indexed: 12/19/2022] Open
Abstract
Thermal plasmas and lasers are used in medicine to cut and ablate tissues and for coagulation. Non-equilibrium atmospheric pressure plasma (NEAPP) is a recently developed, non-thermal technique with possible biomedical applications. Although NEAPP reportedly generates reactive oxygen/nitrogen species, electrons, positive ions, and ultraviolet radiation, little research has been done into the use of this technique for conventional free radical biology. Recently, we developed a NEAPP device with high electron density. Electron spin resonance spin-trapping revealed •OH as a major product. To obtain evidence of NEAPP-induced oxidative modifications in biomolecules and standardize them, we evaluated lipid peroxidation and DNA modifications in various in vitro and ex vivo experiments. Conjugated dienes increased after exposure to linoleic and α-linolenic acids. An increase in 2-thiobarbituric acid-reactive substances was also observed after exposure to phosphatidylcholine, liposomes or liver homogenate. Direct exposure to rat liver in saline produced immunohistochemical evidence of 4-hydroxy-2-nonenal- and acrolein-modified proteins. Exposure to plasmid DNA induced dose-dependent single/double strand breaks and increased the amounts of 8-hydroxy-2'-deoxyguanosine and cyclobutane pyrimidine dimers. These results indicate that oxidative biomolecular damage by NEAPP is dose-dependent and thus can be controlled in a site-specific manner. Simultaneous oxidative and UV-specific DNA damage may be useful in cancer treatment.
Collapse
Affiliation(s)
- Yasumasa Okazaki
- Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Yue Wang
- Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hiromasa Tanaka
- Plasma Nanotechnology Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan ; Center for Advanced Medicine and Clinical Research, Nagoya University Hospital, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Masaaki Mizuno
- Center for Advanced Medicine and Clinical Research, Nagoya University Hospital, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Kae Nakamura
- Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hiroaki Kajiyama
- Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hiroyuki Kano
- NU Eco-Engineering Co. Ltd, 2-3-8 Kurozasaizumi, Miyoshi-shi, Nagoya 470-0232, Japan
| | - Koji Uchida
- Laboratory of Food and Biodyamics, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Fumitaka Kikkawa
- Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Masaru Hori
- Plasma Nanotechnology Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Shinya Toyokuni
- Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya 466-8550, Japan
| |
Collapse
|
17
|
Dostalikova-Cimburova M, Balusikova K, Kratka K, Chmelikova J, Hejda V, Hnanicek J, Neubauerova J, Vranova J, Kovar J, Horak J. Role of duodenal iron transporters and hepcidin in patients with alcoholic liver disease. J Cell Mol Med 2014; 18:1840-50. [PMID: 24894955 PMCID: PMC4196659 DOI: 10.1111/jcmm.12310] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 03/28/2014] [Indexed: 02/06/2023] Open
Abstract
Patients with alcoholic liver disease (ALD) often display disturbed iron indices. Hepcidin, a key regulator of iron metabolism, has been shown to be down-regulated by alcohol in cell lines and animal models. This down-regulation led to increased duodenal iron transport and absorption in animals. In this study, we investigated gene expression of duodenal iron transport molecules and hepcidin in three groups of patients with ALD (with anaemia, with iron overload and without iron overload) and controls. Expression of DMT1, FPN1, DCYTB, HEPH, HFE and TFR1 was measured in duodenal biopsies by using real-time PCR and Western blot. Serum hepcidin levels were measured by using ELISA. Serum hepcidin was decreased in patients with ALD. At the mRNA level, expressions of DMT1, FPN1 and TFR1 genes were significantly increased in ALD. This pattern was even more pronounced in the subgroups of patients without iron overload and with anaemia. Protein expression of FPN1 paralleled the increase at the mRNA level in the group of patients with ALD. Serum ferritin was negatively correlated with DMT1 mRNA. The down-regulation of hepcidin expression leading to up-regulation of iron transporters expression in the duodenum seems to explain iron metabolism disturbances in ALD. Alcohol consumption very probably causes suppression of hepcidin expression in patients with ALD.
Collapse
Affiliation(s)
- Marketa Dostalikova-Cimburova
- Department of Cell and Molecular Biology, Third Faculty of Medicine, Charles University PraguePrague, Czech Republic
| | - Kamila Balusikova
- Department of Cell and Molecular Biology, Third Faculty of Medicine, Charles University PraguePrague, Czech Republic
| | - Karolina Kratka
- Department of Medicine I, Third Faculty of Medicine, Charles University PraguePrague, Czech Republic
| | - Jitka Chmelikova
- Department of Cell and Molecular Biology, Third Faculty of Medicine, Charles University PraguePrague, Czech Republic
| | - Vaclav Hejda
- 1st Dept. of Medicine, Charles University in Prague, Medical School and Teaching Hospital in PilsenPilsen, Czech Republic
| | - Jan Hnanicek
- Department of Medicine II, Third Faculty of Medicine, Charles University PraguePrague, Czech Republic
| | - Jitka Neubauerova
- Department of Cell and Molecular Biology, Third Faculty of Medicine, Charles University PraguePrague, Czech Republic
| | - Jana Vranova
- Department of Medical Biophysics and Informatics, Third Faculty of Medicine, Charles University PraguePrague, Czech Republic
| | - Jan Kovar
- Department of Cell and Molecular Biology, Third Faculty of Medicine, Charles University PraguePrague, Czech Republic
- *Correspondence to: Prof. Jan KOVAR, Department of Cell and Molecular Biology, Third Faculty of Medicine, Charles University Prague, Ruska 87, 100 00 Prague 10, Czech Republic. Tel.: +420 2 67102 658 Fax: +420 2 67102 650 E-mail:
| | - Jiri Horak
- Department of Medicine I, Third Faculty of Medicine, Charles University PraguePrague, Czech Republic
| |
Collapse
|
18
|
Konietzka R, Heinze R, Seiwert M, Dieter HH. The ex-vivo intestinal absorption rate of uranium is a two-phase function of supply. Regul Toxicol Pharmacol 2014; 69:256-62. [DOI: 10.1016/j.yrtph.2014.04.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 03/21/2014] [Accepted: 04/23/2014] [Indexed: 11/26/2022]
|
19
|
Shinoda S, Yoshizawa S, Nozaki E, Tadai K, Arita A. Marginally excessive iron loading transiently blocks mucosal iron uptake in iron-deficient rats. Am J Physiol Gastrointest Liver Physiol 2014; 307:G89-97. [PMID: 24833704 DOI: 10.1152/ajpgi.00305.2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Regular "mucosal block" is characterized by decreased uptake of a normal iron load 3-72 h after the administration of excess iron (generally 10 mg) to iron-deficient animals. We found that short-acting mucosal block could be induced by much lower iron concentration and much shorter induction time than previously reported, without affecting levels of gene expression. A rapid endocytic mechanism was reported to decrease intestinal iron absorption after a high iron load, but the activating iron load and the time to decreased absorption were undetermined. We assessed the effects of 30-2,000 μg iron load on iron uptake in the duodenal loop of iron-deficient and iron-sufficient rats under anesthesia. One hour later, mucosal cellular iron uptake in iron-deficient rats administered 30 μg iron was 76.1%, decreasing 25% to 50.7% in rats administered 2,000 μg iron. In contrast, iron uptake by iron-sufficient rats was 63% (range 60.3-65.5%) regardless of iron load. Duodenal mucosal iron concentration was significantly lower in iron-deficient than in iron-sufficient rats. Iron levels in portal blood were consistently higher in iron-deficient rats regardless of iron load, in contrast to the decreased iron uptake on the luminal side. Iron loading blocked mucosal uptake of marginally excess iron (1,000 μg), with a greater effect at 15 min than at 30 min. The rapid induction of short-acting mucosal block only in iron-deficient rats suggests DMT1 internalization.
Collapse
Affiliation(s)
- Shoko Shinoda
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan; and
| | - Shiho Yoshizawa
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan; and
| | - Eriko Nozaki
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan; and
| | - Kouki Tadai
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan; and
| | - Anna Arita
- Department of Food and Nutrition, Jumonji University Niiza, Saitama, Japan
| |
Collapse
|
20
|
Shawki A, Knight PB, Maliken BD, Niespodzany EJ, Mackenzie B. H(+)-coupled divalent metal-ion transporter-1: functional properties, physiological roles and therapeutics. CURRENT TOPICS IN MEMBRANES 2012. [PMID: 23177986 DOI: 10.1016/b978-0-12-394316-3.00005-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Divalent metal-ion transporter-1 (DMT1) is a widely expressed, iron-preferring membrane transport protein. Animal models establish that DMT1 plays indispensable roles in intestinal nonheme-iron absorption and iron acquisition by erythroid precursor cells. Rare mutations in human DMT1 result in severe microcytic-hypochromic anemia. When we express DMT1 in RNA-injected Xenopus oocytes, we observe rheogenic Fe(2+) transport that is driven by the proton electrochemical potential gradient. In that same preparation, DMT1 also transports cadmium and manganese but not copper. Whether manganese metabolism relies upon DMT1 remains unclear but DMT1 contributes to the effects of overexposure to cadmium and manganese in some tissues. There exist at least four DMT1 isoforms that arise from variant transcription of the SLC11A2 gene. Whereas these isoforms display identical functional properties, N- and C-terminal variations contain cues that direct the cell-specific targeting of DMT1 isoforms to discrete subcellular compartments (plasma membrane, endosomes, and lysosomes). An iron-responsive element (IRE) in the mRNA 3'-untranslated region permits the regulation of some isoforms by iron status, and additional mechanisms by which DMT1 is regulated are emerging. Natural-resistance-associated macrophage protein-1 (NRAMP1)-the only other member of the mammalian SLC11 gene family-contributes to antimicrobial function by extruding from the phagolysosome divalent metal ions (e.g. Mn(2+)) that may be essential cofactors for bacteria-derived enzymes or required for bacterial growth. The principal or only intestinal nonheme-iron transporter, DMT1 is a validated therapeutic target in hereditary hemochromatosis (HHC) and other iron-overload disorders.
Collapse
Affiliation(s)
- Ali Shawki
- Department of Molecular & Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | | | | | | | | |
Collapse
|
21
|
|