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Dogaru CB, Muscurel C, Duță C, Stoian I. "Alphabet" Selenoproteins: Their Characteristics and Physiological Roles. Int J Mol Sci 2023; 24:15992. [PMID: 37958974 PMCID: PMC10650576 DOI: 10.3390/ijms242115992] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/29/2023] [Accepted: 11/04/2023] [Indexed: 11/15/2023] Open
Abstract
Selenium (Se) is a metalloid that is recognized as one of the vital trace elements in our body and plays multiple biological roles, largely mediated by proteins containing selenium-selenoproteins. Selenoproteins mainly have oxidoreductase functions but are also involved in many different molecular signaling pathways, physiological roles, and complex pathogenic processes (including, for example, teratogenesis, neurodegenerative, immuno-inflammatory, and obesity development). All of the selenoproteins contain one selenocysteine (Sec) residue, with only one notable exception, the selenoprotein P (SELENOP), which has 10 Sec residues. Although these mechanisms have been studied intensely and in detail, the characteristics and functions of many selenoproteins remain unknown. This review is dedicated to the recent data describing the identity and the functions of several selenoproteins that are less known than glutathione peroxidases (Gpxs), iodothyronine deiodinases (DIO), thioredoxin reductases (TRxRs), and methionine sulfoxide reductases (Msrs) and which are named after alphabetical letters (i.e., F, H, I, K, M, N, O, P, R, S, T, V, W). These "alphabet" selenoproteins are involved in a wide range of physiological and pathogenetic processes such as antioxidant defense, anti-inflammation, anti-apoptosis, regulation of immune response, regulation of oxidative stress, endoplasmic reticulum (ER) stress, immune and inflammatory response, and toxin antagonism. In selenium deficiency, the "alphabet" selenoproteins are affected hierarchically, both with respect to the particular selenoprotein and the tissue of expression, as the brain or endocrine glands are hardly affected by Se deficiency due to their equipment with LRP2 or LRP8.
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Affiliation(s)
| | | | - Carmen Duță
- Department of Biochemistry, Carol Davila University of Medicine and Pharmacy, 050474 Bucharest, Romania (I.S.)
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Pon A, Osinski A, Sreelatha A. Redefining pseudokinases: A look at the untapped enzymatic potential of pseudokinases. IUBMB Life 2023; 75:370-376. [PMID: 36602414 PMCID: PMC10050101 DOI: 10.1002/iub.2698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/19/2022] [Indexed: 01/06/2023]
Abstract
Catalytically inactive kinases, known as pseudokinases, are conserved in all three domains of life. Due to the lack of catalytic residues, pseudokinases are considered to act as allosteric regulators and scaffolding proteins with no enzymatic function. However, since these "dead" kinases are conserved along with their active counterparts, a role for pseudokinases may have been overlooked. In this review, we will discuss the recently characterized pseudokinases Selenoprotein O, Legionella effector SidJ, and the SARS-CoV2 protein nsp12 which catalyze AMPylation, glutamylation, and RNAylation, respectively. These studies provide structural and mechanistic insight into the versatility and diversity of the kinase fold.
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Affiliation(s)
- Alex Pon
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Adam Osinski
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Anju Sreelatha
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Nunes LGA, Pitts MW, Hoffmann PR. Selenoprotein I (selenoi) as a critical enzyme in the central nervous system. Arch Biochem Biophys 2022; 729:109376. [PMID: 36007576 PMCID: PMC11166481 DOI: 10.1016/j.abb.2022.109376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 08/12/2022] [Accepted: 08/14/2022] [Indexed: 11/02/2022]
Abstract
Selenoprotein I (selenoi) is a unique selenocysteine (Sec)-containing protein widely expressed throughout the body. Selenoi belongs to two different protein families: the selenoproteins that are characterized by a redox reactive Sec residue and the lipid phosphotransferases that contain the highly conserved cytidine diphosphate (CDP)-alcohol phosphotransferase motif. Selenoi catalyzes the third reaction of the CDP-ethanolamine branch of the Kennedy pathway within the endoplasmic reticulum membrane. This is not a redox reaction and does not directly involve the Sec residue, making selenoi quite distinct among selenoproteins. Selenoi is also unique among lipid phosphotransferases as the only family member containing a Sec residue near its C-terminus that serves an unknown function. The reaction catalyzed by selenoi involves the transfer of the ethanolamine phosphate group from CDP-ethanolamine to one of two lipid donors, 1,2-diacylglycerol (DAG) or 1-alkyl-2-acylglycerol (AAG), to produce PE or plasmanyl PE, respectively. Plasmanyl PE is subsequently converted to plasmenyl PE by plasmanylethanolamine desaturase. Both PE and plasmenyl PE are critical phospholipids in the central nervous system (CNS), as demonstrated through clinical studies involving SELENOI mutations as well as studies in cell lines and mice. Deletion of SELENOI in mice is embryonic lethal, while loss-of-function mutations in the human SELENOI gene have been found in rare cases leading to a form of hereditary spastic paraplegia (HSP). HSP is an upper motor disease characterized by spasticity of the lower limbs, which is often manifested with other symptoms such as impaired vision/hearing, ataxia, cognitive/intellectual impairment, and seizures. This article will summarize the current understanding of selenoi as a metabolic enzyme and discuss its role in the CNS physiology and pathophysiology.
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Affiliation(s)
- Lance G A Nunes
- Department of Anatomy, Physiology and Biochemistry, Honolulu, HI, 96813, USA
| | - Matthew W Pitts
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, 96813, USA
| | - Peter R Hoffmann
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, 96813, USA.
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Zhang ZH, Song GL. Roles of Selenoproteins in Brain Function and the Potential Mechanism of Selenium in Alzheimer's Disease. Front Neurosci 2021; 15:646518. [PMID: 33762907 PMCID: PMC7982578 DOI: 10.3389/fnins.2021.646518] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 02/16/2021] [Indexed: 12/13/2022] Open
Abstract
Selenium (Se) and its compounds have been reported to have great potential in the prevention and treatment of Alzheimer's disease (AD). However, little is known about the functional mechanism of Se in these processes, limiting its further clinical application. Se exerts its biological functions mainly through selenoproteins, which play vital roles in maintaining optimal brain function. Therefore, selenoproteins, especially brain function-associated selenoproteins, may be involved in the pathogenesis of AD. Here, we analyze the expression and distribution of 25 selenoproteins in the brain and summarize the relationships between selenoproteins and brain function by reviewing recent literature and information contained in relevant databases to identify selenoproteins (GPX4, SELENOP, SELENOK, SELENOT, GPX1, SELENOM, SELENOS, and SELENOW) that are highly expressed specifically in AD-related brain regions and closely associated with brain function. Finally, the potential functions of these selenoproteins in AD are discussed, for example, the function of GPX4 in ferroptosis and the effects of the endoplasmic reticulum (ER)-resident protein SELENOK on Ca2+ homeostasis and receptor-mediated synaptic functions. This review discusses selenoproteins that are closely associated with brain function and the relevant pathways of their involvement in AD pathology to provide new directions for research on the mechanism of Se in AD.
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Affiliation(s)
- Zhong-Hao Zhang
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China.,Shenzhen Bay Laboratory, Shenzhen, China
| | - Guo-Li Song
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China.,Shenzhen Bay Laboratory, Shenzhen, China.,Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
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Yan J, Fei Y, Han Y, Lu S. Selenoprotein O deficiencies suppress chondrogenic differentiation of ATDC5 cells. Cell Biol Int 2016; 40:1033-40. [PMID: 27425444 DOI: 10.1002/cbin.10644] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 07/07/2016] [Indexed: 01/16/2023]
Abstract
Selenoprotein O (Sel O) is a selenium-containing protein, but its function is still unclear. In the present study, we observed that the mRNA and protein expression levels of Sel O increased during chondrogenic induction of ATDC5 cells. The effects of Sel O on chondrocyte differentiation were then examined through shRNA-mediated gene silencing technique. The expression of Sel O was significantly suppressed at both mRNA and protein levels in a stable cell line transfected with a Sel O-specific target shRNA construct. Thereafter, we demonstrated that Sel O deficiencies suppress chondrogenic differentiation of ATDC5 cells. Sel O deficiencies inhibited expression of chondrogenic gene Sox9, Col II, and aggrecan. Sel O-deficient cells also accumulated a few cartilage glycosaminoglycans (GAGs) and decreased the activity of alkaline phosphatase (ALP). In addition, Sel O deficiencies inhibited chondrocyte proliferation through delayed cell cycle progression by suppression of cyclin D1 expression. Moreover, Sel O deficiencies induced chondrocyte death through cell apoptosis. In summary, we describe the expression patterns and the essential roles of Sel O in chondrocyte viability, proliferation, and chondrogenic differentiation. Additionally, Sel O deficiency-mediated impaired chondrogenesis may illustrate the mechanisms of Se deficiency in the pathophysiological process of the endemic osteoarthropathy.
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Affiliation(s)
- Jidong Yan
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, 710061, China
| | - Yao Fei
- College of Life Sciences, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Yan Han
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Yanta West Road 76, Xi'an, Shaanxi, 710061, China
| | - Shemin Lu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Yanta West Road 76, Xi'an, Shaanxi, 710061, China. .,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, China.
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Han SJ, Lee BC, Yim SH, Gladyshev VN, Lee SR. Characterization of mammalian selenoprotein o: a redox-active mitochondrial protein. PLoS One 2014; 9:e95518. [PMID: 24751718 PMCID: PMC3994087 DOI: 10.1371/journal.pone.0095518] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 03/26/2014] [Indexed: 11/30/2022] Open
Abstract
Selenoproteins exhibit diverse biological functions, most of which are associated with redox control. However, the functions of approximately half of mammalian selenoproteins are not known. One such protein is Selenoprotein O (SelO), the largest mammalian selenoprotein with orthologs found in a wide range of organisms, including bacteria and yeast. Here, we report characterization of mammalian SelO. Expression of this protein could be verified in HEK 293T cells by metabolic labeling of cells with 75Se, and it was abolished when selenocysteine was replaced with serine. A CxxU motif was identified in the C-terminal region of SelO. This protein was reversibly oxidized in a time- and concentration-dependent manner in HEK 293T cells when cells were treated with hydrogen peroxide. This treatment led to the formation of a transient 88 kDa SelO-containing complex. The formation of this complex was enhanced by replacing the CxxU motif with SxxC, but abolished when it was replaced with SxxS, suggesting a redox interaction of SelO with another protein through its Sec residue. SelO was localized to mitochondria and expressed across mouse tissues. Its expression was little affected by selenium deficiency, suggesting it has a high priority for selenium supply. Taken together, these results show that SelO is a redox-active mitochondrial selenoprotein.
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Affiliation(s)
- Seong-Jeong Han
- Department of Biochemistry, Research Center for Aging and Geriatrics, Research Institute of Medical Sciences, Chonnam National University Medical School, Gwangju, Republic of Korea
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
- Division of Genetics, Department of Medicine, Brigham & Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Byung Cheon Lee
- Division of Genetics, Department of Medicine, Brigham & Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sun Hee Yim
- Division of Genetics, Department of Medicine, Brigham & Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Vadim N. Gladyshev
- Division of Genetics, Department of Medicine, Brigham & Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Seung-Rock Lee
- Department of Biochemistry, Research Center for Aging and Geriatrics, Research Institute of Medical Sciences, Chonnam National University Medical School, Gwangju, Republic of Korea
- Division of Genetics, Department of Medicine, Brigham & Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Hawkes WC, Richter D, Alkan Z. Dietary selenium supplementation and whole blood gene expression in healthy North American men. Biol Trace Elem Res 2013; 155:201-8. [PMID: 23955482 DOI: 10.1007/s12011-013-9786-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 08/06/2013] [Indexed: 01/17/2023]
Abstract
Selenium (Se) is a trace nutrient required in microgram amounts, with a recommended dietary allowance of 55 μg/day in humans. The nutritional functions of Se are performed by a group of 25 selenoproteins containing the unusual amino acid selenocysteine at their active sites. The selenoproteins with known activities are oxidation-reduction enzymes with roles in antioxidant protection, redox homeostasis and signaling, and thyroid hormone metabolism. Both deficiencies and excesses of Se are associated with impaired innate and adaptive immune responses. We supplemented 16 healthy men for 1 year with 300 μg Se/day as high-Se yeast or placebo yeast and measured whole blood gene expression with DNA microarrays before and after supplementation. Protein phosphorylation was the main biological process in common among the Se-responsive genes, which included a prominent cluster of protein kinases, suggesting that protein phosphorylation in leukocytes is sensitive to Se supplementation. We found highly ranked clusters of genes associated with RNA processing and protein transport, suggesting that dietary Se may regulate protein expression in leukocytes at both the posttranscriptional and posttranslational levels. The main functional pathway affected by Se supplementation was FAS apoptosis signaling, and expression of genes associated with T cell and natural killer cell cytotoxicity was increased. At the same time, the numbers of circulating natural killer and T cells expressing activation markers decreased. These changes are consistent with an anti-inflammatory effect of Se supplementation exerted through regulation of protein phosphorylation.
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Affiliation(s)
- Wayne Chris Hawkes
- United States Department of Agriculture, Agricultural Research Service, Western Human Nutrition Research Center, University of California Davis, 430 West Health Sciences Drive, Davis, CA, 95616, USA,
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