Human INT6/eIF3e is required for nonsense‐mediated mRNA decay

Morris, Christelle; Wittmann, Jürgen; Jäck, Hans‐Martin; Jalinot, Pierre

doi:10.1038/sj.embor.7400955

Cited by 49 publications

(57 citation statements)

References 34 publications

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“…NMD assays with HeLa cells with the GlNS39 and GlWT constructs were performed as described previously (47), and mRNAs were measured by quantitative reverse transcription-PCR (qRT-PCR) using the QuantiTect SYBR green qRT-PCR kit (Qiagen) and ␤-globin primers. Similarly, for the analysis of GADD45␣, SLIT2, BAG1, ATF4, and MAP3K14 mRNA half-lives, total RNA was extracted by using the Nucleospin RNA kit (Macherey-Nagel).…”

Section: Methodsmentioning

confidence: 99%

“…In mammalian cells, the silencing of INT6 seems to marginally affect general translation, but evidence for a role of INT6 in the translation of specific genes was recently obtained (26,67). Regarding its role in association with eIF3, we have previously shown that INT6 was important for the degradation of cellular mRNAs by nonsensemediated mRNA decay (NMD) (47). The latter is a quality control process leading to the degradation of mRNAs, including a premature stop codon (PTC), which can arise from mutation or aberrant alternative splicing and eventually prevents the synthesis of a truncated protein, which could serve as a dominant negative protein against an intact protein (3).…”

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confidence: 99%

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The Human T-Lymphotropic Virus Type 1 Tax Protein Inhibits Nonsense-Mediated mRNA Decay by Interacting with INT6/EIF3E and UPF1

Mocquet

Neusiedler

Rende

et al. 2012

J Virol

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In this report, we analyzed whether the degradation of mRNAs by the nonsense-mediated mRNA decay (NMD) pathway was affected in human T-lymphotropic virus type 1 (HTLV-1)-infected cells. This pathway was indeed strongly inhibited in C91PL, HUT102, and MT2 cells, and such an effect was also observed by the sole expression of the Tax protein in Jurkat and HeLa cells. In line with this activity, Tax binds INT6/EIF3E (here called INT6), which is a subunit of the translation initiation factor eukaryotic initiation factor 3 (eIF3) required for efficient NMD, as well as the NMD core factor upstream frameshift protein 1 (UPF1). It was also observed that Tax expression alters the morphology of processing bodies (P-bodies), the cytoplasmic structures which concentrate RNA degradation factors. The presence of UPF1 in these subcellular compartments was increased by Tax, whereas that of INT6 was decreased. In line with these effects, the level of the phosphorylated form of UPF1 was increased in the presence of Tax. Analysis of several mutants of the viral protein showed that the interaction with INT6 is necessary for NMD inhibition. The alteration of mRNA stability was observed to affect viral transcripts, such as that coding for the HTLV-1 basic leucine zipper factor (HBZ), and also several cellular mRNAs sensitive to the NMD pathway. Our data indicate that the effect of Tax on viral and cellular gene expression is not restricted to transcriptional control but can also involve posttranscriptional regulation. Human T-lymphotropic virus type 1 (HTLV-1) infection is associated with the onset of severe diseases, mainly adult Tcell leukemia (ATL) and tropical spastic paraparesis, also named HTLV-1-associated myelopathy, in 2 to 5% of patients (for a review, see reference 44). These conditions are characterized by a long latency, with infection often occurring in childhood and disease development at an adult age. Accordingly, it is estimated that the development of ATL involves several phases, ending in the acute proliferation of monoclonal ATL cells. At the initial stage, lymphocytes are infected by viral particles, leading to provirus integration and the expression of various viral proteins. Among them, Tax plays an important role both by inducing the transcription of the provirus and by stimulating the proliferation of the host cell. Tax, which is present in both the nucleus and the cytoplasm, exerts these functions by directly binding or by modulating the expression of several key cellular proteins involved in transcriptional control, cell cycle progression, genomic stability, cell adherence and migration, protein degradation, and RNA metabolism (7).Among these various cellular proteins bound by Tax, we have previously characterized INT6, also known as EIF3E, one the 13 subunits of the translation initiation factor eukaryotic initiation factor 3 (eIF3) (16). The complex between both proteins was found to be cytoplasmic, whereas in normal cells, INT6 is present in both the cytoplasm and the nucleus (16,27,64). In mammalian cell...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

The Human T-Lymphotropic Virus Type 1 Tax Protein Inhibits Nonsense-Mediated mRNA Decay by Interacting with INT6/EIF3E and UPF1

Mocquet

Neusiedler

Rende

et al. 2012

J Virol

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“…Thus, the phosphorylation status of Upf1 was assessed with a phospho-(Ser) ATM/ATX substrate antibody after immunoprecipitation of Upf1 (49,50). As shown in Fig.…”

Section: Pata Enhances the Interaction Of Upf1 With Other Components mentioning

confidence: 99%

Inhibition of Nonsense-mediated mRNA Decay by the Natural Product Pateamine A through Eukaryotic Initiation Factor 4AIII

Dang¹,

Low²,

Xu³

et al. 2009

Journal of Biological Chemistry

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Nonsense-mediated mRNA decay (NMD) in mammalian cells is a key mechanism for the removal of mRNA containing premature stop codons and is mediated by the coordinated function of numerous proteins that dynamically associate with the exon junction complex. The information communicated by these interactions and the functional consequences from a mechanistic perspective, however, are not completely documented. Herein, we report that the natural product pateamine A (PatA) is capable of inhibiting NMD through direct interaction with eIF4AIII, which is independent of its inhibition of translation initiation. Furthermore, we have characterized the mechanisms by which PatA and cycloheximide modulate NMD. Unlike CHX, PatA was found to inhibit NMD by a novel mechanism that is independent of the phosphorylation of Up-frameshift protein 1.In mammalian cells, nonsense-mediated mRNA decay (NMD) 2 is one of the key RNA surveillance mechanisms to specifically degrade mRNA with premature stop codons (PTCs) located more than 50 -55 nucleotides upstream of the final exon-exon junction. PTCs can be formed in genes containing a nonsense mutation or frameshift mutation or as a result of errors that occur during transcription or RNA splicing (1-4). After splicing, the exon junction complex (EJC) imprints mature mRNAs 20 -24 nucleotides upstream of the exon-exon junction (5). The EJC is a dynamic multiprotein complex that plays an essential role in NMD. The core EJC proteins eIF4AIII, Y14, Magoh, and MLN51 form a platform to interact with several other proteins in a dynamic fashion to regulate NMD (6). The spatial-temporal regulation of NMD by the EJC and its partner proteins has been extensively investigated, leading to the proposition of the "linear interaction model" (4, 7). According to this model, deposition of the EJC onto mRNA causes the Y14-Magoh and eIF4AIII complex to effectively recruit Upf3 that interacts with Upf2. Although the mechanism of loading Upf1 onto EJC is poorly understood, it has been shown that phosphorylation and dephosphorylation of Upf1 by SMG-1, -5, -6, and -7 affect the interaction with the EJC complex through

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“…For plasmids and siRNA transfections, the amount of FCS used in the culture medium was reduced to 5%, and antibiotics were omitted for siRNA transfection, which was performed using the Lipofectamine 2000 reagent according to the manufacturer's instructions (Invitrogen). siRNA duplexes I6.1, I6.3, I6.4, and anti-EIF3B have been described previously (Morris and Jalinot 2005;Morris et al 2007). For endogenous histone labeling experiments, a Luc siRNA duplex was used.…”

Section: Cell Culture and Transfectionmentioning

confidence: 99%

INT6 interacts with MIF4GD/SLIP1 and is necessary for efficient histone mRNA translation

Neusiedler¹,

Mocquet²,

Limousin³

et al. 2012

RNA

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The INT6/EIF3E protein has been implicated in mouse and human breast carcinogenesis. This subunit of the eIF3 translation initiation factor that includes a PCI domain exhibits specific features such as presence in the nucleus and ability to interact with other important cellular protein complexes like the 26S proteasome and the COP9 signalosome. It has been previously shown that INT6 was not essential for bulk translation, and this protein is considered to regulate expression of specific mRNAs. Based on the results of a two-hybrid screen performed with INT6 as bait, we characterize in this article the MIF4GD/SLIP1 protein as an interactor of this eIF3 subunit. MIF4GD was previously shown to associate with SLBP, which binds the stem-loop located at the 39 end of the histone mRNAs, and to be necessary for efficient translation of these cell cycle-regulated mRNAs that lack a poly(A) tail. In line with the interaction of both proteins, we show using the RNA interference approach that INT6 is also essential to S-phase histone mRNA translation. This was observed by analyzing expression of endogenous histones and by testing heterologous constructs placing the luciferase reporter gene under the control of the stem-loop element of various histone genes. With such a reporter plasmid, silencing and overexpression of INT6 exerted opposite effects. In agreement with these results, INT6 and MIF4GD were observed to colocalize in cytoplasmic foci. We conclude from these data that INT6, by establishing interactions with MIF4GD and SLBP, plays an important role in translation of poly(A) minus histone mRNAs.

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Human INT6/eIF3e is required for nonsense‐mediated mRNA decay

Cited by 49 publications

References 34 publications

The Human T-Lymphotropic Virus Type 1 Tax Protein Inhibits Nonsense-Mediated mRNA Decay by Interacting with INT6/EIF3E and UPF1

The Human T-Lymphotropic Virus Type 1 Tax Protein Inhibits Nonsense-Mediated mRNA Decay by Interacting with INT6/EIF3E and UPF1

Inhibition of Nonsense-mediated mRNA Decay by the Natural Product Pateamine A through Eukaryotic Initiation Factor 4AIII

INT6 interacts with MIF4GD/SLIP1 and is necessary for efficient histone mRNA translation

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