scholarly journals Measles Virus N Protein Inhibits Host Translation by Binding to eIF3-p40

2007 ◽  
Vol 81 (21) ◽  
pp. 11569-11576 ◽  
Author(s):  
Hiroki Sato ◽  
Munemitsu Masuda ◽  
Moeko Kanai ◽  
Kyoko Tsukiyama-Kohara ◽  
Misako Yoneda ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Mammalian Cells ◽  
Measles Virus ◽  
Encephalomyocarditis Virus ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Translation System ◽  
Dependent Manner ◽  
Initiation Factors ◽  
Human T Cell

ABSTRACT The nonsegmented, negative-sense RNA genome of measles virus (MV) is encapsidated by the virus-encoded nucleocapsid protein (N). In this study, we searched for N-binding cellular proteins by using MV-N as bait and screening the human T-cell cDNA library by yeast two-hybrid assay and isolated the p40 subunit of eukaryotic initiation factor 3 (eIF3-p40) as a binding partner. The interaction between MV-N and eIF3-p40 in mammalian cells was confirmed by coimmunoprecipitation. Since eIF3-p40 is a translation initiation factor, we analyzed the potential inhibitory effect of MV-N on protein synthesis. Glutathione S-transferase (GST)-fused MV-N (GST-N) inhibited translation of reporter mRNAs in rabbit reticulocyte lysate translation system in a dose-dependent manner. Encephalomyocarditis virus internal ribosomal entry site-mediated translation, which requires canonical initiation factors to initiate translation, was also inhibited by GST-N. In contrast, a unique form of translation mediated by the intergenic region of Plautia stali intestine virus, which can assemble 80S ribosomes in the absence of canonical initiation factors, was scarcely affected by GST-N. In vivo expression of MV-N induced by the Cre/loxP switching system inhibited the synthesis of a transfected reporter protein, as well as overall protein synthesis. These results suggest that MV-N targets eIF3-p40 and may be involved in inhibiting MV-induced host translation.

scholarly journals Translation suppression promotes stress granule formation and cell survival in response to cold shock

2012 ◽  
Vol 23 (19) ◽  
pp. 3786-3800 ◽  
Author(s):  
Sarah Hofmann ◽  
Valeria Cherkasova ◽  
Peter Bankhead ◽  
Bernd Bukau ◽  
Georg Stoecklin
Keyword(s):  
Protein Synthesis ◽  
Mammalian Cells ◽  
Cold Shock ◽  
Optimal Growth ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Dependent Manner ◽  
Granule Formation ◽  
Cellular Survival ◽  
Compound C

Cells respond to different types of stress by inhibition of protein synthesis and subsequent assembly of stress granules (SGs), cytoplasmic aggregates that contain stalled translation preinitiation complexes. Global translation is regulated through the translation initiation factor eukaryotic initiation factor 2α (eIF2α) and the mTOR pathway. Here we identify cold shock as a novel trigger of SG assembly in yeast and mammals. Whereas cold shock–induced SGs take hours to form, they dissolve within minutes when cells are returned to optimal growth temperatures. Cold shock causes eIF2α phosphorylation through the kinase PERK in mammalian cells, yet this pathway is not alone responsible for translation arrest and SG formation. In addition, cold shock leads to reduced mitochondrial function, energy depletion, concomitant activation of AMP-activated protein kinase (AMPK), and inhibition of mTOR signaling. Compound C, a pharmacological inhibitor of AMPK, prevents the formation of SGs and strongly reduces cellular survival in a translation-dependent manner. Our results demonstrate that cells actively suppress protein synthesis by parallel pathways, which induce SG formation and ensure cellular survival during hypothermia.

scholarly journals IRE1α-Dependent Decay of CReP/Ppp1r15b mRNA Increases Eukaryotic Initiation Factor 2α Phosphorylation and Suppresses Protein Synthesis

2015 ◽  
Vol 35 (16) ◽  
pp. 2761-2770 ◽  
Author(s):  
Jae-Seon So ◽  
Sungyun Cho ◽  
Sang-Hyun Min ◽  
Scot R. Kimball ◽  
Ann-Hwee Lee
Keyword(s):  
Protein Synthesis ◽  
Er Stress ◽  
Translational Control ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Regulatory Subunit ◽  
Dependent Manner ◽  
Eukaryotic Translation ◽  
Eif2α Phosphorylation ◽  
The Unfolded Protein Response

The unfolded protein response (UPR) regulates endoplasmic reticulum (ER) homeostasis and protects cells from ER stress. IRE1α is a central regulator of the UPR that activates the transcription factor XBP1s through an unconventional splicing mechanism using its endoribonuclease activity. IRE1α also cleaves certain mRNAs containing XBP1-like secondary structures to promote the degradation of these mRNAs, a process known as regulated IRE1α-dependent decay (RIDD). We show here that the mRNA of CReP/Ppp1r15b, a regulatory subunit of eukaryotic translation initiation factor 2α (eIF2α) phosphatase, is a RIDD substrate. eIF2α plays a central role in the integrated stress response by mediating the translational attenuation to decrease the stress level in the cell. CReP expression was markedly suppressed in XBP1-deficient mice livers due to hyperactivated IRE1α. Decreased CReP expression caused the induction of eIF2α phosphorylation and the attenuation of protein synthesis in XBP1-deficient livers. ER stress also suppressed CReP expression in an IRE1α-dependent manner, which increased eIF2α phosphorylation and consequently attenuated protein synthesis. Taken together, the results of our study reveal a novel function of IRE1α in the regulation of eIF2α phosphorylation and the translational control.

Acute attenuation of translation initiation and protein synthesis by glucocorticoids in skeletal muscle

2000 ◽  
Vol 278 (1) ◽  
pp. E76-E82 ◽  
Author(s):  
O. Jameel Shah ◽  
Scot R. Kimball ◽  
Leonard S. Jefferson
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Translation Initiation ◽  
Intraperitoneal Administration ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Nucleotide Exchange ◽  
Α Subunit ◽  
Initiation Factors

Glucocorticoids are diabetogenic factors that not only antagonize the action of insulin in target tissues but also render these tissues catabolic. Therefore, in rats, we endeavored to characterize the effects in skeletal muscle of glucocorticoids on translation initiation, a regulated process that, in part, governs overall protein synthesis through the modulated activities of eukaryotic initiation factors (eIFs). Four hours after intraperitoneal administration of dexamethasone (100 μg/100 g body wt), protein synthesis in skeletal muscle was reduced to 59% of the value recorded in untreated control animals. Furthermore, translation initiation factor eIF4E preferred association with its endogenous inhibitor 4E-BP1 rather than eIF4G. Dexamethasone treatment resulted in dephosphorylation of both 4E-BP1 and the 40S ribosomal protein S6 kinase concomitant with enhanced phosphorylation of eIF4E. Moreover, the guanine nucleotide exchange activity of eIF2B was unaffected as was phosphorylation of the α-subunit of eIF2. Hence glucocorticoids negatively modulate the activation of a subset of the protein synthetic machinery, thereby contributing to the catabolic properties of this class of hormones in vivo.

scholarly journals mTORC1 signalling and eIF4E/4E-BP1 translation initiation factor stoichiometry influence recombinant protein productivity from GS-CHOK1 cells

2016 ◽  
Vol 473 (24) ◽  
pp. 4651-4664 ◽  
Author(s):  
Lyne Jossé ◽  
Jianling Xie ◽  
Christopher G. Proud ◽  
C. Mark Smales
Keyword(s):  
Protein Synthesis ◽  
Cell Growth ◽  
Recombinant Protein ◽  
Cell Lines ◽  
Translation Initiation ◽  
Mammalian Cells ◽  
Mrna Translation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Cho Cell

Many protein-based biotherapeutics are produced in cultured Chinese hamster ovary (CHO) cell lines. Recent reports have demonstrated that translation of recombinant mRNAs and global control of the translation machinery via mammalian target of rapamycin (mTOR) signalling are important determinants of the amount and quality of recombinant protein such cells can produce. mTOR complex 1 (mTORC1) is a master regulator of cell growth/division, ribosome biogenesis and protein synthesis, but the relationship between mTORC1 signalling, cell growth and proliferation and recombinant protein yields from mammalian cells, and whether this master regulating signalling pathway can be manipulated to enhance cell biomass and recombinant protein production (rPP) are not well explored. We have investigated mTORC1 signalling and activity throughout batch culture of a panel of sister recombinant glutamine synthetase-CHO cell lines expressing different amounts of a model monoclonal IgG4, to evaluate the links between mTORC1 signalling and cell proliferation, autophagy, recombinant protein expression, global protein synthesis and mRNA translation initiation. We find that the expression of the mTORC1 substrate 4E-binding protein 1 (4E-BP1) fluctuates throughout the course of cell culture and, as expected, that the 4E-BP1 phosphorylation profiles change across the culture. Importantly, we find that the eIF4E/4E-BP1 stoichiometry positively correlates with cell productivity. Furthermore, eIF4E amounts appear to be co-regulated with 4E-BP1 amounts. This may reflect a sensing of either change at the mRNA level as opposed to the protein level or the fact that the phosphorylation status, as well as the amount of 4E-BP1 present, is important in the co-regulation of eIF4E and 4E-BP1.

BIOCHEMICAL MECHANISM TO CONTROL PROTEIN SYNTHESIS mRNA SPECIFIC INITIATION FACTORS

1973 ◽  
Vol 74 (Suppl) ◽  
pp. S54-S74 ◽  
Author(s):  
M. Revel ◽  
Y. Groner ◽  
Y. Pollack ◽  
D. Cnaani ◽  
H. Zeller ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Mammalian Cells ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Interference Factor ◽  
E Coli ◽  
Initiation Factors ◽  
Virus Rna ◽  
Globin Synthesis

ABSTRACT Studies with cell fre systems of protein synthesis have shown that mRNAs are not translated uniformly by ribosomes. In particular the existence of mRNA specific initiation factors which stimulate or inhibit the translation of individual cistrons is now well recognized. We originally reported that E. coli initiation factor IF3 activity can be separated into subfractions differing in their activity toward MS2 and T4 mRNA. Our recent work, however, indicates that the specificity of IF3 for mRNAs actually results from its combination with "interference" protein factors. These proteins act in the presence of IF3 to stimulate the translation of certain cistrons while inhibiting that of others. We have isolated three interference factors from E. coli and characterized some of their cistron specificities on MS2 RNA, T4 and T7 early and late mRNAs. These factors can explain the heterogeneity of IF3 toward various mRNA. In vivo variations in the activity of ribosomes can result from changes either in IF3 or in an interference factor. We have also recently purified a mRNA-specific initiation factor from mammalian cells. This factor isolated from the ribosomal wash of rabbit reticulocytes stimulates haemoglobin mRNA translation but not that of Mengo virus RNA, in a crude extract from Krebs ascites cells. This factor stimulates a globin synthesis. Ribosome activity may be, therefore, regulated both quantitatively and qualitatively by such factors.

Expression of Translation Initiation Factors eIF-4E and eIF-2α and a Potential Physiologic Role of Continuous Protein Synthesis in Human Platelets

2001 ◽  
Vol 85 (01) ◽  
pp. 142-151 ◽  
Author(s):  
Anping Han ◽  
Linrong Lu ◽  
German Pihan ◽  
Bruce Woda ◽  
Jane-Jane Chen ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Translation Initiation ◽  
Ribosomal Subunit ◽  
Human Platelets ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Protein Synthesis Inhibitors ◽  
Initiation Factors ◽  
Translation Initiation Factors ◽  
Rate Limiting

SummaryIt is generally believed that platelets do not have a functionally significant protein synthetic machinery. However, our analysis demonstrated that normal bone marrow megakaryocytes express high levels of translation initiation factors eIF-4E and eIF-2α and the expression of these protein synthesis initiation factors is continued in platelets (as determined by immunohistochemistry and Western blot analysis). Both eIF-4E and eIF-2α are key regulators of protein synthesis. The eIF-4E is a rate-limiting part of a multisubunit complex, eIF-4F, that binds to the 5’ cap structure present in virtually all eukaryotic mRNAs, and carries out transfer of mRNAs to ribosomes for translation. Translation initiation factor eIF-2α is also a rate-limiting protein which associates with two other proteins to form an eIF-2 initiation factor complex responsible for the transfer of initiator methionyl-tRNA to the 40S ribosomal subunit. We confirm that expression of eIF-4E and eIF-2α is biologically relevant in that platelets continue protein synthesis, albeit at a 16 times lower rate than WBC (as determined by 35S-labeled amino acid incorporation, SDS-PAGE and scintillation counting). Finally, we determined that protein synthesis inhibitors (puromycin and emetine) attenuate the platelet aggregation response to a combination of ADP and epinephrine, but potentiate the response to collagen. Our data are consistent with the existence of different signal transducing pathways mediating the response to ADP/epinephrine and collagen. We suggest that the ADP/epinephrine response is positively affected by continuously synthesized proteins, while the response to collagen is modulated by continuously produced inhibitory proteins. Taken together, our results suggest that continuous protein synthesis is important for platelet function and its role in platelet physiology and pathophysiology deserves further study.

scholarly journals Correction of eIF2-dependent defects in brain protein synthesis, synaptic plasticity, and memory in mouse models of Alzheimer’s disease

2021 ◽  
Vol 14 (668) ◽  
pp. eabc5429
Author(s):  
Mauricio M. Oliveira ◽  
Mychael V. Lourenco ◽  
Francesco Longo ◽  
Nicole P. Kasica ◽  
Wenzhong Yang ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protein Synthesis ◽  
Synaptic Plasticity ◽  
Translation Initiation ◽  
Mrna Translation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Postmortem Brain Tissue ◽  
Phosphorylated Eif2α

Neuronal protein synthesis is essential for long-term memory consolidation, and its dysregulation is implicated in various neurodegenerative disorders, including Alzheimer’s disease (AD). Cellular stress triggers the activation of protein kinases that converge on the phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), which attenuates mRNA translation. This translational inhibition is one aspect of the integrated stress response (ISR). We found that postmortem brain tissue from AD patients showed increased phosphorylation of eIF2α and reduced abundance of eIF2B, another key component of the translation initiation complex. Systemic administration of the small-molecule compound ISRIB (which blocks the ISR downstream of phosphorylated eIF2α) rescued protein synthesis in the hippocampus, measures of synaptic plasticity, and performance on memory-associated behavior tests in wild-type mice cotreated with salubrinal (which inhibits translation by inducing eIF2α phosphorylation) and in both β-amyloid-treated and transgenic AD model mice. Thus, attenuating the ISR downstream of phosphorylated eIF2α may restore hippocampal protein synthesis and delay cognitive decline in AD patients.

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