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Alternative Transcripts and 3′UTR Elements Govern the Incorporation of Selenocysteine into Selenoprotein S

Selenoprotein S (SelS) is a 189 amino acid trans-membrane protein that plays an important yet undefined role in the unfolded protein response. It has been proposed that SelS may function as a reductase, with the penultimate selenocysteine (Sec(188)) residue participating in a selenosulfide bond with...

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Autores principales: Bubenik, Jodi L., Miniard, Angela C., Driscoll, Donna M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3628699/
https://www.ncbi.nlm.nih.gov/pubmed/23614019
http://dx.doi.org/10.1371/journal.pone.0062102
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author Bubenik, Jodi L.
Miniard, Angela C.
Driscoll, Donna M.
author_facet Bubenik, Jodi L.
Miniard, Angela C.
Driscoll, Donna M.
author_sort Bubenik, Jodi L.
collection PubMed
description Selenoprotein S (SelS) is a 189 amino acid trans-membrane protein that plays an important yet undefined role in the unfolded protein response. It has been proposed that SelS may function as a reductase, with the penultimate selenocysteine (Sec(188)) residue participating in a selenosulfide bond with cysteine (Cys(174)). Cotranslational incorporation of Sec into SelS depends on the recoding of the UGA codon, which requires a Selenocysteine Insertion Sequence (SECIS) element in the 3′UTR of the transcript. Here we identify multiple mechanisms that regulate the expression of SelS. The human SelS gene encodes two transcripts (variants 1 and 2), which differ in their 3′UTR sequences due to an alternative splicing event that removes the SECIS element from the variant 1 transcript. Both transcripts are widely expressed in human cell lines, with the SECIS-containing variant 2 mRNA being more abundant. In vitro experiments demonstrate that the variant 1 3′UTR does not allow readthrough of the UGA/Sec codon. Thus, this transcript would produce a truncated protein that does not contain Sec and cannot make the selenosulfide bond. While the variant 2 3′UTR does support Sec insertion, its activity is weak. Bioinformatic analysis revealed two highly conserved stem-loop structures, one in the proximal part of the variant 2 3′UTR and the other immediately downstream of the SECIS element. The proximal stem-loop promotes Sec insertion in the native context but not when positioned far from the UGA/Sec codon in a heterologous mRNA. In contrast, the 140 nucleotides downstream of the SECIS element inhibit Sec insertion. We also show that endogenous SelS is enriched at perinuclear speckles, in addition to its known localization in the endoplasmic reticulum. Our results suggest the expression of endogenous SelS is more complex than previously appreciated, which has implications for past and future studies on the function of this protein.
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spelling pubmed-36286992013-04-23 Alternative Transcripts and 3′UTR Elements Govern the Incorporation of Selenocysteine into Selenoprotein S Bubenik, Jodi L. Miniard, Angela C. Driscoll, Donna M. PLoS One Research Article Selenoprotein S (SelS) is a 189 amino acid trans-membrane protein that plays an important yet undefined role in the unfolded protein response. It has been proposed that SelS may function as a reductase, with the penultimate selenocysteine (Sec(188)) residue participating in a selenosulfide bond with cysteine (Cys(174)). Cotranslational incorporation of Sec into SelS depends on the recoding of the UGA codon, which requires a Selenocysteine Insertion Sequence (SECIS) element in the 3′UTR of the transcript. Here we identify multiple mechanisms that regulate the expression of SelS. The human SelS gene encodes two transcripts (variants 1 and 2), which differ in their 3′UTR sequences due to an alternative splicing event that removes the SECIS element from the variant 1 transcript. Both transcripts are widely expressed in human cell lines, with the SECIS-containing variant 2 mRNA being more abundant. In vitro experiments demonstrate that the variant 1 3′UTR does not allow readthrough of the UGA/Sec codon. Thus, this transcript would produce a truncated protein that does not contain Sec and cannot make the selenosulfide bond. While the variant 2 3′UTR does support Sec insertion, its activity is weak. Bioinformatic analysis revealed two highly conserved stem-loop structures, one in the proximal part of the variant 2 3′UTR and the other immediately downstream of the SECIS element. The proximal stem-loop promotes Sec insertion in the native context but not when positioned far from the UGA/Sec codon in a heterologous mRNA. In contrast, the 140 nucleotides downstream of the SECIS element inhibit Sec insertion. We also show that endogenous SelS is enriched at perinuclear speckles, in addition to its known localization in the endoplasmic reticulum. Our results suggest the expression of endogenous SelS is more complex than previously appreciated, which has implications for past and future studies on the function of this protein. Public Library of Science 2013-04-16 /pmc/articles/PMC3628699/ /pubmed/23614019 http://dx.doi.org/10.1371/journal.pone.0062102 Text en © 2013 Bubenik et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Bubenik, Jodi L.
Miniard, Angela C.
Driscoll, Donna M.
Alternative Transcripts and 3′UTR Elements Govern the Incorporation of Selenocysteine into Selenoprotein S
title Alternative Transcripts and 3′UTR Elements Govern the Incorporation of Selenocysteine into Selenoprotein S
title_full Alternative Transcripts and 3′UTR Elements Govern the Incorporation of Selenocysteine into Selenoprotein S
title_fullStr Alternative Transcripts and 3′UTR Elements Govern the Incorporation of Selenocysteine into Selenoprotein S
title_full_unstemmed Alternative Transcripts and 3′UTR Elements Govern the Incorporation of Selenocysteine into Selenoprotein S
title_short Alternative Transcripts and 3′UTR Elements Govern the Incorporation of Selenocysteine into Selenoprotein S
title_sort alternative transcripts and 3′utr elements govern the incorporation of selenocysteine into selenoprotein s
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3628699/
https://www.ncbi.nlm.nih.gov/pubmed/23614019
http://dx.doi.org/10.1371/journal.pone.0062102
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