Abrogation of translation initiation factor eIF-2 phosphorylation causes malignant transformation of NIH 3T3 cells.

Donzé, Olivier; Jagus, Rosemary; Koromilas, Antonis E.; Hershey, John W.B.; Sonenberg, Nahum

doi:10.1002/j.1460-2075.1995.tb00052.x

Cited by 269 publications

(223 citation statements)

References 47 publications

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“…Within this group of genes, we identified the translation initiation factor eIF-4A1 (Eberle et al, 1997), found consistently upregulated at the mRNA level. As the oncogenic potential of other translation initiation factors (e.g., eIF-4E and eIF-2, had already been described in other cells; Lazaris-Karatzas et al, 1990;Donze et al, 1995), we suggested that eIF-4A1 upregulation may contribute specifically to the malignant phenotype of melanoma. In the present paper, we addressed the question whether we can confer inhibitory effects on melanoma cells by obstructing eIF-4A1 gene expression using transient and stable transfection of antisense constructs against eIF-4A1.…”

supporting

confidence: 52%

Decreased proliferation of human melanoma cell lines caused by antisense RNA against translation factor eIF-4A1

Eberle

et al. 2002

Br J Cancer

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Control of translation initiation was recognised as a critical checkpoint for cell proliferation and tumorigenesis. In human melanoma cells, we have previously reported consistent overexpression of translation initiation factor eIF-4A1. Here, we investigated by transfection of antisense constructs its significance for the control of melanoma cell growth. The tetracyclineinducible expression system was established in melanoma cells, and three fragments of the 5'-, central-, and 3'-portion of the eIF-4A1 cDNA were subcloned in antisense and in sense orientation after a tetracycline inducible promoter. Significant proliferation decrease was obtained after transient transfection and induction of antisense RNA directed against the 5'-and the central portion (up to 10%), whereas, no effects were seen after induction of the 3'-fragment and the sense controls. Cell clones stably transfected with the central antisense fragment revealed after doxycycline induction reduced expression of endogeneous eIF-4A1 mRNA correlated with decreased proliferation rates (up to 6%). These data demonstrate the applicability of antisense strategies against translation factors in melanoma cells. Translation initiation factor eIF-4A1 contributes to the control of melanoma cell proliferation and may be taken into consideration when scheduling new therapeutic approaches targeting the translational control.

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supporting

confidence: 52%

Decreased proliferation of human melanoma cell lines caused by antisense RNA against translation factor eIF-4A1

Eberle

et al. 2002

Br J Cancer

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“…Transformation could be driven in part by a deregulation of protein synthesis initiation since mutant forms of eIF2a, a PKR substrate, are also transforming oncogenes in this assay (Donze et al, 1995). Since dominant negative mutants of PKR also inactivate its activities as a signal transducer, other mechanisms of transformation can be envisaged including a failure to maintain the homeostasis and inhibition of apoptosis.…”

Section: Pkr and P38 Mapkmentioning

confidence: 99%

PKR; a sentinel kinase for cellular stress

1999

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“…Although previous work has determined that PKR is not essential for translational repression during the UPR (Harding et al, 1999), these experiments were not performed in a PERK null background. Because mice harboring deletion of both PERK and PKR are not currently available, we used a documented PKR dominant negative allele (Donze et al, 1995) to assess its contribution to the regulation of cyclin D1 translation after UPR activation. PERKϪ/Ϫ cells were transiently transfected with an empty vector or a plasmid encoding a dominant negative PKR (K296D) and subsequently treated with tunicamycin.…”

Section: Functional Cooperativity Among Eif2␣ Kinasesmentioning

confidence: 99%

PERK and GCN2 Contribute to eIF2α Phosphorylation and Cell Cycle Arrest after Activation of the Unfolded Protein Response Pathway

Hamanaka

Bennett

Cullinan

et al. 2005

MBoC

232

180

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Exposure of cells to endoplasmic reticulum (ER) stress leads to activation of PKR-like ER kinase (PERK), eukaryotic translation initiation factor 2␣ (eIF2␣) phosphorylation, repression of cyclin D1 translation, and subsequent cell cycle arrest in G 1 phase. However, whether PERK is solely responsible for regulating cyclin D1 accumulation after unfolded protein response pathway (UPR) activation has not been assessed. Herein, we demonstrate that repression of cyclin D1 translation after UPR activation occurs independently of PERK, but it remains dependent on eIF2␣ phosphorylation. Although phosphorylation of eIF2␣ in PERK؊/؊ fibroblasts is attenuated in comparison with wild-type fibroblasts, it is not eliminated. The residual eIF2␣ phosphorylation correlates with the kinetics of cyclin D1 loss, suggesting that another eIF2␣ kinase functions in the absence of PERK. In cells harboring targeted deletion of both PERK and GCN2, cyclin D1 loss is attenuated, suggesting GCN2 functions as the redundant kinase. Consistent with these results, cyclin D1 translation is also stabilized in cells expressing a nonphosphorylatable allele of eIF2␣; in contrast, repression of global protein translation still occurs in these cells, highlighting a high degree of specificity in transcripts targeted for translation inhibition by phosphorylated eIF2␣. Our results demonstrate that PERK and GCN2 function to cooperatively regulate eIF2␣ phosphorylation and cyclin D1 translation after UPR activation. INTRODUCTIONIntegral membrane proteins and secreted proteins are synthesized, folded, and posttranslationally modified in the endoplasmic reticulum (ER). When the integrity of protein folding in the ER is compromised and misfolded proteins accumulate, a signaling network referred to as the unfolded protein response pathway (UPR) is activated (Kaufman, 1999). Stresses that activate the UPR include disruption of proper protein glycosylation (glucose deprivation or treatment of cells with drugs that directly inhibit glycosylation such as tunicamycin), perturbations in ER calcium homeostasis (thapsigargin), perturbations in ER redox status (dithiothreitol [DTT]), and hypoxia (Kaufman, 1999;Koumenis et al., 2002).Activation of the UPR triggers a checkpoint that provides cells with the opportunity to adapt and survive, or under conditions of chronic stress, to commit to a program of cell death. The proximal effectors of the mammalian UPR include the three homologous, ER-resident transmembrane protein kinases Ire1 (␣ and ␤) and PKR-like ER kinase (PERK); the ER-resident transmembrane protease caspase 12; and the ER-resident transmembrane bZIP transcription factor ATF6 (Cox et al., 1993;Shi et al., 1998;Tirasophon et al., 1998;Wang et al., 1998;Harding et al., 1999;Haze et al., 1999;Nakagawa et al., 2000). Ire1 and PERK both have luminal, ER stress-sensing domains that regulate their dimerization and activation of their protein kinase activity. Activation of ATF6 occurs via a proteolytic cleavage that allows its translocation to the nucleus where it fun...

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Abrogation of translation initiation factor eIF-2 phosphorylation causes malignant transformation of NIH 3T3 cells.

Cited by 269 publications

References 47 publications

Decreased proliferation of human melanoma cell lines caused by antisense RNA against translation factor eIF-4A1

Decreased proliferation of human melanoma cell lines caused by antisense RNA against translation factor eIF-4A1

PKR; a sentinel kinase for cellular stress

PERK and GCN2 Contribute to eIF2α Phosphorylation and Cell Cycle Arrest after Activation of the Unfolded Protein Response Pathway

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