Alternative polyadenylation and nonsense-mediated decay coordinately regulate the human HFE mRNA levels.
Nonsense-mediated decay (NMD) is an mRNA surveillance pathway that selectively recognizes and degrades defective mRNAs carrying premature translation-termination codons. However, several studies have shown that NMD also targets physiological transcripts that encode full-length proteins, modulating t...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2012-01-01
|
| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC3329446?pdf=render |
| _version_ | 1819086879534874624 |
|---|---|
| author | Rute Martins Daniela Proença Bruno Silva Cristina Barbosa Ana Luísa Silva Paula Faustino Luísa Romão |
| author_facet | Rute Martins Daniela Proença Bruno Silva Cristina Barbosa Ana Luísa Silva Paula Faustino Luísa Romão |
| author_sort | Rute Martins |
| collection | DOAJ |
| description | Nonsense-mediated decay (NMD) is an mRNA surveillance pathway that selectively recognizes and degrades defective mRNAs carrying premature translation-termination codons. However, several studies have shown that NMD also targets physiological transcripts that encode full-length proteins, modulating their expression. Indeed, some features of physiological mRNAs can render them NMD-sensitive. Human HFE is a MHC class I protein mainly expressed in the liver that, when mutated, can cause hereditary hemochromatosis, a common genetic disorder of iron metabolism. The HFE gene structure comprises seven exons; although the sixth exon is 1056 base pairs (bp) long, only the first 41 bp encode for amino acids. Thus, the remaining downstream 1015 bp sequence corresponds to the HFE 3' untranslated region (UTR), along with exon seven. Therefore, this 3' UTR encompasses an exon/exon junction, a feature that can make the corresponding physiological transcript NMD-sensitive. Here, we demonstrate that in UPF1-depleted or in cycloheximide-treated HeLa and HepG2 cells the HFE transcripts are clearly upregulated, meaning that the physiological HFE mRNA is in fact an NMD-target. This role of NMD in controlling the HFE expression levels was further confirmed in HeLa cells transiently expressing the HFE human gene. Besides, we show, by 3'-RACE analysis in several human tissues that HFE mRNA expression results from alternative cleavage and polyadenylation at four different sites--two were previously described and two are novel polyadenylation sites: one located at exon six, which confers NMD-resistance to the corresponding transcripts, and another located at exon seven. In addition, we show that the amount of HFE mRNA isoforms resulting from cleavage and polyadenylation at exon seven, although present in both cell lines, is higher in HepG2 cells. These results reveal that NMD and alternative polyadenylation may act coordinately to control HFE mRNA levels, possibly varying its protein expression according to the physiological cellular requirements. |
| first_indexed | 2024-12-21T21:27:16Z |
| format | Article |
| id | doaj.art-eae36e35079341baa3bd60e5cee226fa |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-21T21:27:16Z |
| publishDate | 2012-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-eae36e35079341baa3bd60e5cee226fa2022-12-21T18:49:44ZengPublic Library of Science (PLoS)PLoS ONE1932-62032012-01-0174e3546110.1371/journal.pone.0035461Alternative polyadenylation and nonsense-mediated decay coordinately regulate the human HFE mRNA levels.Rute MartinsDaniela ProençaBruno SilvaCristina BarbosaAna Luísa SilvaPaula FaustinoLuísa RomãoNonsense-mediated decay (NMD) is an mRNA surveillance pathway that selectively recognizes and degrades defective mRNAs carrying premature translation-termination codons. However, several studies have shown that NMD also targets physiological transcripts that encode full-length proteins, modulating their expression. Indeed, some features of physiological mRNAs can render them NMD-sensitive. Human HFE is a MHC class I protein mainly expressed in the liver that, when mutated, can cause hereditary hemochromatosis, a common genetic disorder of iron metabolism. The HFE gene structure comprises seven exons; although the sixth exon is 1056 base pairs (bp) long, only the first 41 bp encode for amino acids. Thus, the remaining downstream 1015 bp sequence corresponds to the HFE 3' untranslated region (UTR), along with exon seven. Therefore, this 3' UTR encompasses an exon/exon junction, a feature that can make the corresponding physiological transcript NMD-sensitive. Here, we demonstrate that in UPF1-depleted or in cycloheximide-treated HeLa and HepG2 cells the HFE transcripts are clearly upregulated, meaning that the physiological HFE mRNA is in fact an NMD-target. This role of NMD in controlling the HFE expression levels was further confirmed in HeLa cells transiently expressing the HFE human gene. Besides, we show, by 3'-RACE analysis in several human tissues that HFE mRNA expression results from alternative cleavage and polyadenylation at four different sites--two were previously described and two are novel polyadenylation sites: one located at exon six, which confers NMD-resistance to the corresponding transcripts, and another located at exon seven. In addition, we show that the amount of HFE mRNA isoforms resulting from cleavage and polyadenylation at exon seven, although present in both cell lines, is higher in HepG2 cells. These results reveal that NMD and alternative polyadenylation may act coordinately to control HFE mRNA levels, possibly varying its protein expression according to the physiological cellular requirements.http://europepmc.org/articles/PMC3329446?pdf=render |
| spellingShingle | Rute Martins Daniela Proença Bruno Silva Cristina Barbosa Ana Luísa Silva Paula Faustino Luísa Romão Alternative polyadenylation and nonsense-mediated decay coordinately regulate the human HFE mRNA levels. PLoS ONE |
| title | Alternative polyadenylation and nonsense-mediated decay coordinately regulate the human HFE mRNA levels. |
| title_full | Alternative polyadenylation and nonsense-mediated decay coordinately regulate the human HFE mRNA levels. |
| title_fullStr | Alternative polyadenylation and nonsense-mediated decay coordinately regulate the human HFE mRNA levels. |
| title_full_unstemmed | Alternative polyadenylation and nonsense-mediated decay coordinately regulate the human HFE mRNA levels. |
| title_short | Alternative polyadenylation and nonsense-mediated decay coordinately regulate the human HFE mRNA levels. |
| title_sort | alternative polyadenylation and nonsense mediated decay coordinately regulate the human hfe mrna levels |
| url | http://europepmc.org/articles/PMC3329446?pdf=render |
| work_keys_str_mv | AT rutemartins alternativepolyadenylationandnonsensemediateddecaycoordinatelyregulatethehumanhfemrnalevels AT danielaproenca alternativepolyadenylationandnonsensemediateddecaycoordinatelyregulatethehumanhfemrnalevels AT brunosilva alternativepolyadenylationandnonsensemediateddecaycoordinatelyregulatethehumanhfemrnalevels AT cristinabarbosa alternativepolyadenylationandnonsensemediateddecaycoordinatelyregulatethehumanhfemrnalevels AT analuisasilva alternativepolyadenylationandnonsensemediateddecaycoordinatelyregulatethehumanhfemrnalevels AT paulafaustino alternativepolyadenylationandnonsensemediateddecaycoordinatelyregulatethehumanhfemrnalevels AT luisaromao alternativepolyadenylationandnonsensemediateddecaycoordinatelyregulatethehumanhfemrnalevels |