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Cell Chemical Biology Nov 2018Selenoproteins, defined by the presence of selenocysteines (Sec), play important roles in a wide range of biological processes. All known selenoproteins are marked by...
Selenoproteins, defined by the presence of selenocysteines (Sec), play important roles in a wide range of biological processes. All known selenoproteins are marked by the presence of Sec insertion sequence (SECIS) at their mRNA. The lack of an effective analytical method has hindered our ability to explore the selenoproteome and new selenoproteins beyond SECIS. Here, we develop a Sec-specific mass spectrometry-based technique, termed "SecMS," which allows the systematic profiling of selenoproteomes by selective alkylation of Sec. Using SecMS, we quantitatively characterized the age- and stress-regulated selenoproteomes for nine tissues from mice of different ages and mammalian cells, demonstrating tissue-specific selenoproteomes and an age-dependent decline in specific selenoproteins in brains and hearts. We established an integrated platform using SecMS and SECIS-independent selenoprotein (SIS) database and further identified five candidate selenoproteins. The application of this integrated platform provides an effective strategy to explore the selenoproteome independent of SECIS.
Topics: Aging; Alkylation; Amino Acid Sequence; Animals; Brain; Brain Chemistry; Cell Line; Female; HEK293 Cells; Humans; Male; Mass Spectrometry; Mice, Inbred C57BL; Myocardium; Proteome; Proteomics; Selenocysteine; Selenoproteins; Stress, Physiological
PubMed: 30174312
DOI: 10.1016/j.chembiol.2018.08.006 -
Molecular and Biochemical Parasitology Apr 2013Selenium (Se) is an essential trace element primarily found in selenoproteins as the 21st amino acid (selenocysteine, Sec, or U). Selenoproteins play an important role...
Selenium (Se) is an essential trace element primarily found in selenoproteins as the 21st amino acid (selenocysteine, Sec, or U). Selenoproteins play an important role in growth and proliferation and are typically involved in cellular redox balance. Selenocysteine is encoded by an in-frame UGA codon specified by a stem-loop structure, the Sec insertion sequence element (SECIS), which, in eukaryotes, is located in the 3'-untranslated region (UTR). The availability of the Naegleria gruberi (ATCC 30224) genome sequence and the use of this organism as a model system for the pathogenic amoeba N. fowleri allowed us to investigate the Sec incorporation pathway in this primitive eukaryote. Using bioinformatics tools, we identified gene sequences encoding PSTK (O-phosphoseryl-tRNA(Sec) kinase), SepSecS (O-phosphoseryl-tRNA:selenocysteinyl-tRNA synthase), SelD/SPS2 (selenophosphate synthetase), EFSec (selenocysteine-specific elongation factor) and SBP (SECIS binding protein). These findings were confirmed by RT-PCR and by sequencing. A potential tRNA(Ser)Sec (SelC) gene and a putative selenoprotein with sequence similarity to a mitochondrial thioredoxin reductase (TR3) were also identified. Our results show that the selenocysteine incorporation machinery is indeed present in N. gruberi. Interestingly, the SelD/SPS2 gene is 2214 bp in length and contains two distinct domains. The N-terminal region shows sequence similarity to predicted methyltransferase proteins, and the C-terminal region is homologous to prokaryotic SelD/SPS2. Our results suggest the possibility of novel selenoproteins.
Topics: Amino Acid Sequence; Base Sequence; Biosynthetic Pathways; Computational Biology; Gene Expression Profiling; Genes, Protozoan; Models, Molecular; Molecular Sequence Data; Naegleria; Nucleic Acid Conformation; Reverse Transcriptase Polymerase Chain Reaction; Selenocysteine; Selenoproteins; Sequence Alignment; Sequence Analysis, DNA
PubMed: 23603359
DOI: 10.1016/j.molbiopara.2013.04.002 -
Journal of Neurochemistry Jul 2003Over the past three decades, selenium has been intensively investigated as an antioxidant trace element. It is widely distributed throughout the body, but is... (Review)
Review
Over the past three decades, selenium has been intensively investigated as an antioxidant trace element. It is widely distributed throughout the body, but is particularly well maintained in the brain, even upon prolonged dietary selenium deficiency. Changes in selenium concentration in blood and brain have been reported in Alzheimer's disease and brain tumors. The functions of selenium are believed to be carried out by selenoproteins, in which selenium is specifically incorporated as the amino acid, selenocysteine. Several selenoproteins are expressed in brain, but many questions remain about their roles in neuronal function. Glutathione peroxidase has been localized in glial cells, and its expression is increased surrounding the damaged area in Parkinson's disease and occlusive cerebrovascular disease, consistent with its protective role against oxidative damage. Selenoprotein P has been reported to possess antioxidant activities and the ability to promote neuronal cell survival. Recent studies in cell culture and gene knockout models support a function for selenoprotein P in delivery of selenium to the brain. mRNAs for other selenoproteins, including selenoprotein W, thioredoxin reductases, 15-kDa selenoprotein and type 2 iodothyronine deiodinase, are also detected in the brain. Future research directions will surely unravel the important functions of this class of proteins in the brain.
Topics: Animals; Blood-Brain Barrier; Brain; Brain Diseases; Glutathione Peroxidase; Humans; Proteins; Selenium; Selenocysteine; Selenoprotein P; Selenoprotein W; Selenoproteins
PubMed: 12807419
DOI: 10.1046/j.1471-4159.2003.01854.x -
Nutrients Mar 2020Selenium is a micronutrient which is found in many foods, with redox status modulation activity. Our aim was to evaluate the effects of two chemical forms of selenoamino...
Selenium is a micronutrient which is found in many foods, with redox status modulation activity. Our aim was to evaluate the effects of two chemical forms of selenoamino acids, Seleno-L-methionine and Seleno-L-cystine (a diselenide derived from selenocysteine), at different concentrations on cell viability, hydrogen peroxide production, antioxidant enzymes, UCP2 protein expression, as well as lipid and protein oxidative damage in MCF-7 breast cancer cells. Results showed that Seleno-L-methionine did not cause an increase in hydrogen peroxide production at relatively low concentrations, accompanied by a rise in the antioxidant enzymes catalase and MnSOD, and UCP2 protein expression levels. Furthermore, a decrease in protein and lipid oxidative damage was observed at 10 µM concentration. Otherwise, Seleno-L-cystine increased hydrogen peroxide production from relatively low concentrations (100 nM) to a large increase at high concentrations. Moreover, at 10 µM, Seleno-L-cystine decreased UCP2 and MnSOD protein expression. In conclusion, the chemical form of selenoamino acid and their incorporation to selenoproteins could affect the regulation of the breast cancer cell redox status. Taken together, the results obtained in this study imply that it is important to control the type of selenium-enriched nutrient consumption, taking into consideration their composition and concentration.
Topics: Antioxidants; Breast Neoplasms; Cell Survival; Female; Humans; Hydrogen Peroxide; Lipid Metabolism; MCF-7 Cells; Micronutrients; Oxidation-Reduction; Oxidative Stress; Reactive Oxygen Species; Selenocysteine; Selenomethionine; Uncoupling Protein 2
PubMed: 32213883
DOI: 10.3390/nu12030865 -
Biochimica Et Biophysica Acta Sep 2012Selenium (Se) is an essential micronutrient. Its biological functions are associated with selenoproteins, which contain this trace element in the form of the 21st amino... (Review)
Review
Selenium (Se) is an essential micronutrient. Its biological functions are associated with selenoproteins, which contain this trace element in the form of the 21st amino acid, selenocysteine. Genetic defects in selenocysteine insertion into proteins are associated with severe health issues. The consequences of selenoprotein deficiency are more variable, with several selenoproteins being essential, and several showing no clear phenotypes. Much of these functional studies benefited from the use of rodent models and diets employing variable levels of Se. This review summarizes the data obtained with these models, focusing on mouse models with targeted expression of individual selenoproteins and removal of individual, subsets or all selenoproteins in a systemic or organ-specific manner. This article is part of a Special Issue entitled: Cell Biology of Metals.
Topics: Animals; Food, Formulated; Gene Expression Regulation; Humans; Mice; Mice, Transgenic; Models, Animal; RNA, Transfer, Amino Acyl; Rodentia; Selenocysteine; Selenoproteins
PubMed: 22440326
DOI: 10.1016/j.bbamcr.2012.02.018 -
Molecular Medicine Reports Dec 2018Selenocysteine, a sulfur‑containing amino acid, can modulate cellular oxidative stress defense systems by incorporating into anti‑oxidant enzymes such as glutathione...
Selenocysteine, a sulfur‑containing amino acid, can modulate cellular oxidative stress defense systems by incorporating into anti‑oxidant enzymes such as glutathione peroxidase and thioredoxin reductase. Selenocysteine can also prevent cancer, neurodegenerative diseases and cardiovascular diseases. A recent study revealed that dietary supplementation with selenocysteine can increase the resistance of Caenorhabditis elegans to environmental stressors and its lifespan. The objective of the present study was to identify the underlying mechanism involved in the lifespan‑extending effect of selenocysteine and the effect of selenocysteine on age‑associated pathophysiological changes. Lifespan assays with known long‑lived mutants of age‑1 (the ortholog of the phosphoinositide 3-kinase), clk‑1 (the ortholog of demethoxyubiquinone hydroxylase) and eat‑2 (a ligand-gated ion channel subunit) revealed that the effect of selenocysteine on lifespan specifically overlapped with that of the eat‑2 mutation, a genetic model of dietary restriction (DR). Selenocysteine mimicked the effect of DR on the bacterial dilution method. It required SKN-1 (the ortholog of mammalian nuclear factor-erythroid-related factor) for lifespan extension. In addition, selenocysteine significantly delayed the paralysis induced by human amyloid‑β gene, positively correlated with the incidence of Alzheimer's disease. The effect of selenocysteine on amyloid‑β‑induced toxicity was dependent on the nuclear localization of DAF‑16. Reduced survival caused by high‑glucose‑diet was recovered by selenocysteine. Selenocysteine also reduced the cellular level of reactive oxygen species known to be increased by high‑glucose‑diet. The results of the present study suggested that selenocysteine can mimic the effect of DR on lifespan and age‑associated pathophysiological alterations, providing scientific evidence for the development of DR mimetics using selenocysteine.
Topics: Aging; Amyloid beta-Peptides; Animals; Biomarkers; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Caloric Restriction; Dose-Response Relationship, Drug; Glucose; Humans; Longevity; Mutation; Oxidative Stress; Protein Transport; Reactive Oxygen Species; Selenocysteine
PubMed: 30365103
DOI: 10.3892/mmr.2018.9590 -
International Journal of Molecular... Feb 2022The review presents the latest data on the role of selenium-containing agents in the regulation of diseases of the immune system. We mainly considered the contributions... (Review)
Review
The review presents the latest data on the role of selenium-containing agents in the regulation of diseases of the immune system. We mainly considered the contributions of selenium-containing compounds such as sodium selenite, methylseleninic acid, selenomethionine, and methylselenocysteine, as well as selenoproteins and selenium nanoparticles in the regulation of defense mechanisms against various viral infections, including coronavirus infection (COVID-19). A complete description of the available data for each of the above selenium compounds and the mechanisms underlying the regulation of immune processes with the active participation of these selenium agents, as well as their therapeutic and pharmacological potential, is presented. The main purpose of this review is to systematize the available information, supplemented by data obtained in our laboratory, on the important role of selenium compounds in all of these processes. In addition, the presented information makes it possible to understand the key differences in the mechanisms of action of these compounds, depending on their chemical and physical properties, which is important for obtaining a holistic picture and prospects for creating drugs based on them.
Topics: Anti-Inflammatory Agents, Non-Steroidal; Antiviral Agents; Humans; Immune System; Immunomodulating Agents; Organoselenium Compounds; Selenium Compounds; Selenocysteine; Selenomethionine; Sodium Selenite; COVID-19 Drug Treatment
PubMed: 35216476
DOI: 10.3390/ijms23042360 -
Journal of the American Chemical Society Mar 2017Employing selenocysteine-containing protein fragments to form the amide bond between respective protein fragments significantly extends the current capabilities of the...
Employing selenocysteine-containing protein fragments to form the amide bond between respective protein fragments significantly extends the current capabilities of the widely used protein engineering method, expressed protein ligation. Selenocysteine-mediated ligation is noteworthy for its high yield and efficiency. However, it has so far been restricted to solid-phase synthesized seleno-peptides and thus constrained by where the selenocysteine can be positioned. Here we employ heterologously expressed seleno-fragments to overcome the placement and size restrictions in selenocysteine-mediated chemical ligation. Following ligation, the selenocysteine can be deselenized into an alanine or serine, resulting in nonselenoproteins. This greatly extends the flexibility in selecting the conjugation site in expressed protein ligations with no influence on native cysteines. Furthermore, the selenocysteine can be used to selectively introduce site-specific protein modifications. Therefore, selenocysteine-mediated expressed protein ligation simplifies incorporation of post-translational modifications into the protein scaffold.
Topics: Gene Expression; Molecular Structure; Protein Engineering; Protein Processing, Post-Translational; Proteins; Selenocysteine
PubMed: 28186733
DOI: 10.1021/jacs.6b10991 -
IUBMB Life Jan 2009Selenocysteine (Sec) is the 21st genetically encoded amino acid found in organisms from all three domains of life. Sec biosynthesis is unique in that it always proceeds... (Review)
Review
Selenocysteine (Sec) is the 21st genetically encoded amino acid found in organisms from all three domains of life. Sec biosynthesis is unique in that it always proceeds from an aminoacyl-tRNA precursor. Even though Sec biosynthesis in bacteria was established almost two decades ago, only recently the pathway was elucidated in archaea and eukaryotes. While other aspects of Sec biology have been reviewed previously (Allmang and Krol, Biochimie 2006;88:1561-1571, Hatfield et al., Prog Nucleic Acid Res Mol Biol 2006;81:97-142, Squires and Berry, IUBMB Life 2008;60:232-235), here we review the biochemistry and evolution of Sec biosynthesis and coding and show how the knowledge of an archaeal cysteine biosynthesis pathway helped to uncover the route to Sec formation in archaea and eukaryotes.
Topics: Archaea; Cysteine; Evolution, Molecular; Genetic Code; Genetics; History, 20th Century; History, 21st Century; Humans; Selenocysteine
PubMed: 18798524
DOI: 10.1002/iub.136 -
Molekuliarnaia Biologiia 2016The main problem in studying mammalian selenocysteine-containing proteins is that the proteins are difficult to obtain in a recombinant form because the amino acid... (Review)
Review
The main problem in studying mammalian selenocysteine-containing proteins is that the proteins are difficult to obtain in a recombinant form because the amino acid selenocysteine (Sec), which is their component, is encoded by TGA, which is one of the stop codons. When only the open reading frame of a target protein is cloned in a plasmid, translation is prematurely terminated at the TGA codon. An intricate natural mechanism allows the codon to be recognized as a selenocysteine codon and involves various cis- and trans-acting factors, such as the selenocysteine insertion sequence (SECIS), mRNA secondary structure, selenocysteine tRNA Sec-tRNA^( [Ser]Sec), SECIS-binding protein 2 (SBP2), selenocysteine-specific elongation factor EFsec, and others. Generation of recombinant selenoproteins in preparative amounts directly depends on the expression levels of the cis- and trans-acting transcription and translation factors to further complicate the problem, and cysteine homologs of selenoproteins are consequently used in many studies. Several methods designed to express mammalian selenoproteins in vitro are considered in the review.
Topics: Animals; In Vitro Techniques; Protein Biosynthesis; RNA, Messenger; Selenocysteine; Selenoproteins
PubMed: 27028810
DOI: 10.7868/S0026898416010213