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Kim HY, Yoo YH. The Role of STAMP2 in Pathogenesis of Chronic Diseases Focusing on Nonalcoholic Fatty Liver Disease: A Review. Biomedicines 2022; 10:biomedicines10092082. [PMID: 36140186 PMCID: PMC9495648 DOI: 10.3390/biomedicines10092082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/16/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a major health issue. NAFLD can progress from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH). NASH can progress to cirrhosis or hepatocellular carcinoma. Unfortunately, there is no currently approved pharmacologic therapy for NAFLD patients. The six transmembrane protein of prostate 2 (STAMP2), a metalloreductase involved in iron and copper homeostasis, is well known for its critical role in the coordination of glucose/lipid metabolism and inflammation in metabolic tissues. We previously demonstrated that hepatic STAMP2 could be a suitable therapeutic target for NAFLD. In this review, we discuss the emerging role of STAMP2 in the dysregulation of iron metabolism events leading to NAFLD and suggest therapeutic strategies targeting STAMP2.
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Oosterheert W, van Bezouwen LS, Rodenburg RNP, Granneman J, Förster F, Mattevi A, Gros P. Cryo-EM structures of human STEAP4 reveal mechanism of iron(III) reduction. Nat Commun 2018; 9:4337. [PMID: 30337524 PMCID: PMC6194020 DOI: 10.1038/s41467-018-06817-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 09/19/2018] [Indexed: 01/28/2023] Open
Abstract
Enzymes of the six-transmembrane epithelial antigen of the prostate (STEAP) family reduce Fe3+ and Cu2+ ions to facilitate metal-ion uptake by mammalian cells. STEAPs are highly upregulated in several types of cancer, making them potential therapeutic targets. However, the structural basis for STEAP-catalyzed electron transfer through an array of cofactors to metals at the membrane luminal side remains elusive. Here, we report cryo-electron microscopy structures of human STEAP4 in absence and presence of Fe3+-NTA. Domain-swapped, trimeric STEAP4 orients NADPH bound to a cytosolic domain onto axially aligned flavin-adenine dinucleotide (FAD) and a single b-type heme that cross the transmembrane-domain to enable electron transfer. Substrate binding within a positively charged ring indicates that iron gets reduced while in complex with its chelator. These molecular principles of iron reduction provide a basis for exploring STEAPs as therapeutic targets. Enzymes of the six-transmembrane epithelial antigen of the prostate (STEAP) family reduce Fe3+ and Cu2+ ions to facilitate metal-ion uptake by mammalian cells. Here, authors employ single-particle cryo-EM to gain insights into the molecular principles of iron reduction by human STEAP4 .
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Affiliation(s)
- Wout Oosterheert
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Laura S van Bezouwen
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.,Cryo-Electron Microscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Remco N P Rodenburg
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Joke Granneman
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Friedrich Förster
- Cryo-Electron Microscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Andrea Mattevi
- Department of Biology and Biotechnology 'L. Spallanzani', University of Pavia, 27100, Pavia, Italy
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
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Scarl RT, Lawrence CM, Gordon HM, Nunemaker CS. STEAP4: its emerging role in metabolism and homeostasis of cellular iron and copper. J Endocrinol 2017; 234:R123-R134. [PMID: 28576871 PMCID: PMC6166870 DOI: 10.1530/joe-16-0594] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Accepted: 06/02/2017] [Indexed: 12/28/2022]
Abstract
Preserving energy homeostasis in the presence of stressors such as proinflammatory cytokines and nutrient overload is crucial to maintaining normal cellular function. Six transmembrane epithelial antigen of the prostate 4 (STEAP4), a metalloreductase involved in iron and copper homeostasis, is thought to play a potentially important role in the cellular response to inflammatory stress. Genome-wide association studies have linked various mutations in STEAP4 with the development of metabolic disorders such as obesity, metabolic syndrome and type 2 diabetes. Several studies have shown that expression of Steap4 is modulated by inflammatory cytokines, hormones and other indicators of cellular stress and that STEAP4 may protect cells from damage, helping to maintain normal metabolic function. STEAP4 appears to be particularly relevant in metabolically oriented cells, such as adipocytes, hepatocytes and pancreatic islet cells. These cells struggle to maintain their function in iron or copper overloaded states, presumably due to increased oxidative stress, suggesting STEAP4's role in metal homeostasis is critical to the maintenance of cellular homeostasis in general, and in preventing the onset of metabolic disease. In this review, we explore genetic associations of STEAP4 with metabolic disorders, and we examine STEAP4 tissue expression, subcellular localization, regulation, structure and function as it relates to metabolic diseases. We then examine how STEAP4's role as a regulator of cellular iron and copper may relate to type 2 diabetes.
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Affiliation(s)
- Rachel T Scarl
- Diabetes InstituteHeritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
- Department of Biomedical SciencesHeritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
| | - C Martin Lawrence
- Department of Chemistry and BiochemistryMontana State University, Bozeman, Montana, USA
| | - Hannah M Gordon
- Diabetes InstituteHeritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
- Department of Biomedical SciencesHeritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
| | - Craig S Nunemaker
- Diabetes InstituteHeritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
- Department of Biomedical SciencesHeritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
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4
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Gordon HM, Majithia N, MacDonald PE, Fox JEM, Sharma PR, Byrne FL, Hoehn KL, Evans-Molina C, Langman L, Brayman KL, Nunemaker CS. STEAP4 expression in human islets is associated with differences in body mass index, sex, HbA1c, and inflammation. Endocrine 2017; 56:528-537. [PMID: 28405880 PMCID: PMC6166871 DOI: 10.1007/s12020-017-1297-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/27/2017] [Indexed: 02/08/2023]
Abstract
OBJECTIVE STEAP4 (six-transmembrane epithelial antigen of the prostate 4) is a metalloreductase that has been shown previously to protect cells from inflammatory damage. Genetic variants in STEAP4 have been associated with numerous metabolic disorders related to obesity, including putative defects in the acute insulin response to glucose in type 2 diabetes. PURPOSE We examined whether obesity and/or type 2 diabetes altered STEAP4 expression in human pancreatic islets. METHODS Human islets were isolated from deceased donors at two medical centers and processed for quantitative polymerase chain reaction. Organ donors were selected by status as non-diabetic or having type 2 diabetes. Site 1 (Edmonton): N = 13 type 2 diabetes donors (7M, 6F), N = 20 non-diabetic donors (7M, 13F). Site 2 (Virginia): N = 6 type 2 diabetes donors (6F), N = 6 non-diabetic donors (3M, 3F). RESULTS STEAP4 showed reduced islet expression with increasing body mass index among all donors (P < 0.10) and non-diabetic donors (P < 0.05) from Site 1; STEAP4 showed reduced islet expression among type 2 diabetes donors with increasing hemoglobin A1c. Islet STEAP4 expression was also marginally higher in female donors (P < 0.10). Among type 2 diabetes donors from Site 2, islet insulin expression was reduced, STEAP4 expression was increased, and white blood cell counts were increased compared to non-diabetic donors. Islets from non-diabetic donors that were exposed overnight to 5 ng/ml IL-1β displayed increased STEAP4 expression, consistent with STEAP4 upregulation by inflammatory signaling. CONCLUSIONS These findings suggest that increased STEAP4 mRNA expression is associated with inflammatory stimuli, whereas lower STEAP4 expression is associated with obesity in human islets. Given its putative protective role, downregulation of STEAP4 by chronic obesity suggests a mechanism for reduced islet protection against cellular damage.
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Affiliation(s)
- Hannah M Gordon
- Department of Biomedical Sciences, Ohio University, Athens, OH, USA
- Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Neil Majithia
- Department of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Patrick E MacDonald
- Alberta Diabetes Institute and Department of Pharmacology, University of Alberta, Edmonton, AB, T6G 2R3, Canada
| | - Jocelyn E Manning Fox
- Alberta Diabetes Institute and Department of Pharmacology, University of Alberta, Edmonton, AB, T6G 2R3, Canada
| | - Poonam R Sharma
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Frances L Byrne
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Kyle L Hoehn
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Carmella Evans-Molina
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
- Richard L. Roudebush VA Medical Center, Indianapolis, IN, USA
| | - Linda Langman
- Department of Surgery, University of Virginia Health System, Charlottesville, VA, USA
| | - Kenneth L Brayman
- Department of Surgery, University of Virginia Health System, Charlottesville, VA, USA
| | - Craig S Nunemaker
- Department of Biomedical Sciences, Ohio University, Athens, OH, USA.
- Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA.
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Qi Y, Yu Y, Wu Y, Wang S, Yu Q, Shi J, Xu Z, Zhang Q, Fu Y, Fu Y, Kou C. Genetic Variants in Six-Transmembrane Epithelial Antigen of Prostate 4 Increase Risk of Developing Metabolic Syndrome in a Han Chinese Population. Genet Test Mol Biomarkers 2015; 19:666-72. [PMID: 26510124 DOI: 10.1089/gtmb.2015.0104] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Altered expression of six-transmembrane epithelial antigen of prostate 4 (STEAP4) is linked to obesity, insulin insensitivity, metabolic homeostasis, and inflammation. This study assessed STEAP4 single nucleotide polymorphisms (SNPs) for association with a risk in developing metabolic syndrome in a Han Chinese population. METHODS A total of 3375 Han Chinese subjects were included in this case-control study with 1583 metabolic syndrome (MetS) patients and 1792 healthy controls. Four SNPs (rs1981529, rs2040657, rs10263111, rs12386756) were genotyped using polymerase chain reaction and MALDI-TOF-MS. The associations between the STAMP4 SNPs and MetS were then analyzed statistically. RESULTS There was no statistical difference in allele frequency of these four SNPs between the case and control populations. The genotype of rs12386756 was shown to be significantly associated with MetS (p = 0.035). Compared with the AA/GG genotypes, the GA genotype of rs12386756 significantly decreased the risk of developing MetS (OR = 0.77; 95% CI, 0.63-0.94; p = 0.0098). There was also no haplotype that could be associated with the risk of developing MetS. Furthermore, the SNP rs1981529 of STEAP4 was associated with body-mass index, waist circumference, and systolic blood pressure, while SNP rs10263111 was associated with waist circumference and fasting glucose levels. SNP rs12386756 was associated with waist and hip circumferences. CONCLUSION Some SNPs of the STEAP4 gene altered the risk of developing a metabolic syndrome in the Han Chinese population. Further studies must be conducted to understand the role of the STEAP4 gene in the pathogenesis of metabolic syndrome.
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Affiliation(s)
- Yue Qi
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
| | - Yaqin Yu
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
| | - Yanhua Wu
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
| | - Shibin Wang
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
| | - Qiong Yu
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
| | - Jieping Shi
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
| | - Ziqi Xu
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
| | - Qingqing Zhang
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
| | - Yingli Fu
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
| | - Yao Fu
- 2 Chinese Jilin Provincial Center for Disease Control and Prevention , Changchun, China
| | - Changgui Kou
- 1 Department of Epidemiology and Biostatistics, School of Public Health, Jilin University , Changchun, China
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Chen X, Huang Z, Zhou B, Wang H, Jia G, Liu G, Zhao H. STEAP4 and insulin resistance. Endocrine 2014; 47:372-9. [PMID: 24627165 DOI: 10.1007/s12020-014-0230-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 02/26/2014] [Indexed: 12/31/2022]
Abstract
Obesity is a multifactorial disease that caused by the interactions between genetic susceptibility genes and environmental cues. Obesity is considered as a major risk factor of insulin resistance. STEAP4 is a novel anti-obesity gene that is significantly down-regulated in adipose tissue of obese patients. Over-expression of STEAP4 can improve glucose uptake and mitochondrial function, and increase insulin sensitivity. STEAP4 expression is regulated by a variety of inflammatory cytokines, hormones, or adipokines. In this review, we discuss function of STEAP4 in regulating insulin resistance in adipose tissue in vivo, as well as in adipocytes in vitro.
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Affiliation(s)
- Xiaoling Chen
- Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, 611130, Sichuan, People's Republic of China
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Brocato J, Sun H, Shamy M, Kluz T, Alghamdi MA, Khoder MI, Chen LC, Costa M. Particulate matter from Saudi Arabia induces genes involved in inflammation, metabolic syndrome and atherosclerosis. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2014; 77:751-66. [PMID: 24839929 PMCID: PMC4233653 DOI: 10.1080/15287394.2014.892446] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Airborne particulate matter (PM) exposure is a major environmental health concern and is linked to metabolic disorders, such as cardiovascular diseases (CVD) and diabetes, which are on the rise in the Kingdom of Saudi Arabia. This study investigated changes in mouse lung gene expression produced by administration of PM10 collected from Jeddah, Saudi Arabia. FVB/N mice were exposed to 100 μg PM10 or water by aspiration and euthanized 24 h later. The bronchoalveolar lavage fluid (BALF) was collected and analyzed for neutrophil concentration and tumor necrosis factor (TNF)-α and interleukin (IL)-6 levels. RNA was extracted from lungs and whole transcript was analyzed using Affymetrix Mouse Gene 1.0 ST Array. Mice exposed to PM10 displayed an increase in neutrophil concentration and elevated TNF-α and IL-6 levels. Gene expression analysis revealed that mice exposed to PM10 displayed 202 genes that were significantly upregulated and 40 genes that were significantly downregulated. PM10 induced genes involved in inflammation, cholesterol and lipid metabolism, and atherosclerosis. This is the first study to demonstrate that Saudi Arabia PM10 increases in vivo expression of genes located in pathways associated with diseases involving metabolic syndrome and atherosclerosis.
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Affiliation(s)
- Jason Brocato
- Department of Environmental Medicine, NYU School of Medicine, NY, NY, 10016 USA
| | - Hong Sun
- Department of Environmental Medicine, NYU School of Medicine, NY, NY, 10016 USA
| | - Magdy Shamy
- Department of Environmental Sciences, Faculty of Meteorology, Environmental and Arid Land Agriculture, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Thomas Kluz
- Department of Environmental Medicine, NYU School of Medicine, NY, NY, 10016 USA
| | - Mansour A. Alghamdi
- Department of Environmental Sciences, Faculty of Meteorology, Environmental and Arid Land Agriculture, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mamdouh I. Khoder
- Department of Environmental Sciences, Faculty of Meteorology, Environmental and Arid Land Agriculture, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Lung-Chi Chen
- Department of Environmental Medicine, NYU School of Medicine, NY, NY, 10016 USA
| | - Max Costa
- Department of Environmental Medicine, NYU School of Medicine, NY, NY, 10016 USA
- Corresponding author: Max Costa, 57 Old Forge Rd., Tuxedo, NY, 10987, Phone number: 845.731.3515,
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Zhang W, Tang M, Zhong M, Wang Z, Shang Y, Gong H, Zhang Y, Zhang W. Association of the six transmembrane protein of prostate 2 gene polymorphisms with metabolic syndrome in Han Chinese population. Diabetes Metab Syndr 2013; 7:138-142. [PMID: 23953178 DOI: 10.1016/j.dsx.2013.06.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
AIM The six-transmembrane protein of prostate 2 (STAMP2) has been demonstrated to play a potential role in the pathogenesis of metabolic syndrome (MetS). The present study was designed to investigate the association of STAMP2 gene polymorphisms with MetS in Han Chinese population. METHODS A case-control study enrolled 350 Han Chinese subjects in two groups: 182 MetS patients and 168 control subjects. The clinical and biochemical characteristics were determined. Three single nucleotide polymorphisms (SNPs), rs1981529, rs12386756 and rs10263111 in STAMP2 gene were genotyped. The association of STAMP2 gene polymorphisms with MetS was analyzed. RESULTS SNPs rs1981529 and rs10263111 were found to be significantly associated with MetS phenotype in male population (P=0.014 and 0.025). Moreover, SNP rs1981529 was found to be associated with high density lipoprotein-cholesterol in male cases and with body mass index in female cases (P=0.014 and 0.049). SNP rs10263111 was found to be associated with both waist circumference and diastolic blood pressure in total cases (P=0.044 and 0.033). Haplotype analysis yielded significant association of STAMP2 gene with MetS in total (global P=0.0109) and male population (global P=0.0004). CONCLUSION Our findings revealed that STAMP2 gene polymorphisms are likely to significantly contribute to the risk of MetS in male Han Chinese population.
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Affiliation(s)
- Wenchao Zhang
- Qilu Hospital of Shandong University, Jinan, Shandong 250012, PR China
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Gauss GH, Kleven MD, Sendamarai AK, Fleming MD, Lawrence CM. The crystal structure of six-transmembrane epithelial antigen of the prostate 4 (Steap4), a ferri/cuprireductase, suggests a novel interdomain flavin-binding site. J Biol Chem 2013; 288:20668-82. [PMID: 23733181 DOI: 10.1074/jbc.m113.479154] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Steap4 is a cell surface metalloreductase linked to obesity-associated insulin resistance. Initial characterization of its cell surface metalloreductase activity has been reported, but thorough biochemical characterization of this activity is lacking. Here, we report detailed kinetic analysis of the Steap4 cell surface metalloreductase activities. Steap4 shows physiologically relevant Km values for both Fe(3+) and Cu(2+) and retains activity at acidic pH, suggesting it may also function within intracellular organelles to reduce these metals. Flavin-dependent NADPH oxidase activity that was much greater than the equivalent Steap3 construct was observed for the isolated N-terminal oxidoreductase domain. The crystal structure of the Steap4 oxidoreductase domain was determined, providing a structural explanation for these differing activities. Structure-function work also suggested Steap4 utilizes an interdomain flavin-binding site to shuttle electrons between the oxidoreductase and transmembrane domains, and it showed that the disordered N-terminal residues do not contribute to enzymatic activity.
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Affiliation(s)
- George H Gauss
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
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Grunewald TGP, Bach H, Cossarizza A, Matsumoto I. The STEAP protein family: versatile oxidoreductases and targets for cancer immunotherapy with overlapping and distinct cellular functions. Biol Cell 2012; 104:641-57. [PMID: 22804687 DOI: 10.1111/boc.201200027] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 07/08/2012] [Indexed: 12/26/2022]
Abstract
The human six-transmembrane epithelial antigen of the prostate (STEAP) protein family contains at least five homologous members. The necessity of multiple homologous STEAP proteins is still unclear, but their peculiar and tissue-specific expression suggests that they are assigned to distinct functional tasks. This concept is supported by the fact that especially STEAP1, and to a lesser extent STEAP2 and -4, are highly over-expressed in many different cancer entities, while being only minimally expressed in a few normal tissues. Despite their very similar domain organisation, STEAP3 seems to act as a potent metalloreductase essential for physiological iron uptake and turnover, while in particular STEAP4 appears to be rather involved in responses to nutrients and inflammatory stress, fatty acid and glucose metabolism. Moreover, individual STEAP proteins possess overlapping functions important for growth and survival of cancer cells. Due to their membrane-bound localisation and their high expression in many different cancers such as prostate, breast and bladder carcinoma as well as Ewing's sarcoma, STEAP proteins have been recognised and utilised as promising targets for cell- and antibody-based immunotherapy. This review summarises our present knowledge of the individual members of the human STEAP family and highlights the functional differences between them.
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Affiliation(s)
- Thomas G P Grunewald
- INSERM Unit 830 'Genetics and Biology of Cancer', Institut Curie Research Center, Paris, France.
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Gomes IM, Maia CJ, Santos CR. STEAP proteins: from structure to applications in cancer therapy. Mol Cancer Res 2012; 10:573-87. [PMID: 22522456 DOI: 10.1158/1541-7786.mcr-11-0281] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The human 6-transmembrane epithelial antigen of prostate (STEAP) family comprises STEAP1, STEAP2, STEAP3, and STEAP4. All of these proteins are unique to mammals and share an innate activity as metalloreductases, indicating their importance in metal metabolism. Overall, they participate in a wide range of biologic processes, such as molecular trafficking in the endocytic and exocytic pathways and control of cell proliferation and apoptosis. STEAP1 and STEAP2 are overexpressed in several types of human cancers, namely prostate, bladder, colon, pancreas, ovary, testis, breast, cervix, and Ewing sarcoma, but their clinical significance and role in cancer cells are not clear. Still, their localization in the cell membrane and differential expression in normal and cancer tissues make STEAP proteins potential candidates as biomarkers of several cancers, as well as potential targets for new immunotherapeutic strategies for disease attenuation or treatment. This review brings together the current knowledge about each STEAP protein, giving an overview of the roles of this family of proteins in human physiology and disease, and analyzes their potential as immunotherapeutic agents in cancer research.
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Affiliation(s)
- Inês M Gomes
- Health Sciences Research Centre--CICS, University of Beira Interior, Av Infante D. Henrique, Covilhã, 6200-506, Portugal
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