Translational control of cell viability downstreams of eIF4E, using polyribosome RNA
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE2094 | GEO | 2006/10/16
SECONDARY ACCESSION(S): PRJNA91785
REPOSITORIES: GEO
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Project description:Aberrant activation of the translation initiation machinery is a common property of malignant cells, and is essential for breast carcinoma cells to manifest a malignant phenotype. How does sustained activation of the rate limiting step in protein synthesis so fundamentally alter a cell? In this report, we test the post transcriptional operon theory as a possible mechanism, employing a model system in which apoptosis resistance is conferred on NIH 3T3 cells by ectopic expression of eIF4E. We show (i) there is a set of 255 transcripts that manifest an increase in translational efficiency during eIF4E-mediated escape from apoptosis; (ii) there is a novel prototype 55 nt RNA consensus hairpin structure that is overrepresented in the 5'-untranslated region of translationally activated transcripts; (iii) the identified consensus hairpin structure is sufficient to target a reporter mRNA for translational activation under pro-apoptotic stress, but only when eIF4E is deregulated; and (iv) that osteopontin, one of the translationally activated transcripts harboring the identified consensus hairpin structure functions as one mediator of the apoptosis resistance seen in our model. Our findings offer genome-wide insights into the mechanism of eIF4E-mediated apoptosis resistance and provide a paradigm for the systematic study of posttranscriptional control in normal biology and disease. To globally address the issue of which transcripts mediate the anti-apoptotic functions of eIF4E, we used a model in which NIH 3T3 cells ectopically overexpress translation initiation factor 4E (eIF4E) resulting in an apoptosis-resistant and tumorigenic phenotype. We performed a comprehensive study of apoptosis resistance in the NIH 3T3/4E model using an array containing 15k cDNAs and ESTs (NIH 15k collection printed at The Ontario Cancer Institute). To facilitate data analysis in the two-color competitive hybridization microarray approach employed, we used a universal standard mRNA [non-stratified poly(A) selected RNA derived from NIH 3T3 cells cultured in full growth medium]. We compared signals generated from this standard to both the light (fractions 4â6, <1 ribosome/transcript) and the heavy (fractions 7â10, >1 ribosomes/transcript) polyribosome fractions of RNA from NIH 3T3 and NIH 3T3/4E cells cultured either in complete growth medium or after 16 h of serum starvation, a time point before any evidence of cytochrome c release from the mitochondria, a signature step at the apex of the cell death program. We selected the 16 h time point in order to identify genes that might govern the decision to enter the apoptotic pathway, and exclude those involved in the actual process of cell execution.
2010-06-10 | E-GEOD-2094 | biostudies-arrayexpress
Project description:Background: Translation deregulation is an important mechanism that causes aberrant cell growth, proliferation and survival. eIF4E, the mRNA 5 prime cap–binding protein, plays a major role in translational control. To understand how eIF4E affects cellular proliferation and cell survival, we identified mRNA targets that are translationally responsive to eIF4E. Methodology/ principal findings: Microarray analysis of polysomal mRNA from an eIF4E-inducible NIH 3T3 cell line was performed. Induction of eIF4E expression resulted in increased translation of a defined set of mRNAs; many of the mRNAs are novel targets, including those that encode large- and small-subunit ribosomal proteins and cell growth–related factors. eIF4E overexpression also led to augmented translation of mRNAs encoding anti-apoptotic proteins, which conferred resistance to endoplasmic reticulum–mediated apoptosis. Conclusions/ significance: Our results shed new light on the mechanisms by which eIF4E prevents apoptosis and transforms cells. Downregulation of eIF4E and its downstream targets is a therapeutic option for the development of novel anti-cancer drugs. Keywords: time course
2007-04-21 | GSE6639 | GEO
Project description:Background: Translation deregulation is an important mechanism that causes aberrant cell growth, proliferation and survival. eIF4E, the mRNA 5 prime capâ??binding protein, plays a major role in translational control. To understand how eIF4E affects cellular proliferation and cell survival, we identified mRNA targets that are translationally responsive to eIF4E. Methodology/ principal findings: Microarray analysis of polysomal mRNA from an eIF4E-inducible NIH 3T3 cell line was performed. Induction of eIF4E expression resulted in increased translation of a defined set of mRNAs; many of the mRNAs are novel targets, including those that encode large- and small-subunit ribosomal proteins and cell growthâ??related factors. eIF4E overexpression also led to augmented translation of mRNAs encoding anti-apoptotic proteins, which conferred resistance to endoplasmic reticulumâ??mediated apoptosis. Conclusions/ significance: Our results shed new light on the mechanisms by which eIF4E prevents apoptosis and transforms cells. Downregulation of eIF4E and its downstream targets is a therapeutic option for the development of novel anti-cancer drugs. Keywords: time course Comparison of total and polysomal RNA upon eIF4E iinduction in NIH3T3/parental and NIH3T3/eIF4E cells Each of the following pairs were generated from one hybridization: GSM153931 GSM153932 GSM153933 GSM153934 GSM153935 GSM153936 GSM153937 GSM153938 GSM153939 GSM153940 GSM153941 GSM153942 GSM153943 GSM153944 GSM153945 GSM153946 GSM153947 GSM153948 GSM153949 GSM153950 GSM153951 GSM153952 GSM153953 GSM153954 GSM153955 GSM153956 GSM153957 GSM153958 GSM153959 GSM153960 GSM153961 GSM153962
2010-06-11 | E-GEOD-6639 | biostudies-arrayexpress
Project description:Translation initiation factor eIF4E is overexpressed early in breast cancers in association with disease progression and reduced survival. Much remains to be understood regarding the role of eIF4E in human cancer. Using immortalized human breast epithelial cells, we report that elevated expression of elF4E translationally activates the TGFβ pathway, promoting cell invasion, loss of cell polarity, increased cell survival and other hallmarks of early neoplasia. Overexpression of eIF4E is shown to facilitate selective translation of integrin β1 mRNA, which drives the translationally controlled assembly of a TGFβ receptor signaling complex containing α3β1 integrins, β-catenin, TGFβ receptor I, E-cadherin and phosphorylated Smads2/3. This receptor complex acutely sensitizes non-malignant breast epithelial cells to activation by typically sub-stimulatory levels of activated TGFβ. TGFβ can promote cellular differentiation or invasion and transformation. As a translational coactivator of TGFβ, eIF4E confers selective mRNA translation, reprogramming non-malignant cells to an invasive phenotype by reducing the set-point for stimulation by activated TGFβ. Overexpression of eIF4E may be a pro-invasive facilitator of TGFβ activity.
2015-06-19 | GSE69780 | GEO
Project description:Aggressive double and triple hit (DH/TH) DLBCL feature activation of Hsp90 stress pathways. Herein, we show that Hsp90 controls post-transcriptional dynamics of key mRNA species including those encoding BCL6, MYC and BCL2. Using a proteomics approach, we found that Hsp90 binds to and maintains activity of eIF4E (eukaryotic translation initiation factor 4E). EIF4E drives nuclear export and translation of BCL6, MYC and BCL2 mRNA. eIF4E RIP-sequencing in DLBCL suggests that nuclear eIF4E controls an extended program that includes BCR signaling, cellular metabolism and epigenetic regulation. Accordingly, eIF4E was required for survival of DLBCL including the most aggressive subtypes DH/TH lymphomas. Indeed, eIF4E inhibition induces tumor regression in cell line and patient-derived tumorgrafts of TH-DLBCL, even in the presence of elevated Hsp90 activity. Targeting Hsp90 is typically limited by counter-regulatory elevation of Hsp70B, which induces resistance to Hsp90 inhibitors. Surprisingly, we identify Hsp70 mRNA as an eIF4E target. In this way, eIF4E inhibition can overcome drug resistance to Hsp90 inhibitors. Accordingly, rational combinatorial inhibition of eIF4E and Hsp90 inhibitors resulted in cooperative anti-lymphoma activity in DH/TH DLBCL in vitro and in vivo. We found that eIF4E activity regulates the nuclear export of BCL6, MYC, and BCL2 in DH/TH DLBCLs. To determine the extent of nuclear eIF4E activity in DH/TH DLBCLs and how these programs can support the oncogenic activity of BCL6, MYC and/or BCL2 transcripts, we conducted eIF4E-RIP of nuclear RNA followed by RNA-sequencing in OCI-Ly1 cells in triplicates. To understand the changes in gene expression after ribavarin in a clinically relevant sample, we generated a patient-derived xenograft (PDX) in NSG mice from a de-identified specimen isolated from a patient prior to treatment harboring a triple-hit ABC-type DLBCL. PDX cells from passage four (PDX-4) were implanted into NSG mice. When tumors were palpable, mice were randomized to receive vehicle or 80 mg/kg/b.i.d. ribavarin intraperitoneally for 10 days. We isolated RNA from tumors treated with vehicle (n=2) or ribavarin (n=2) and performed mRNA-seq.
2016-01-11 | E-GEOD-63265 | biostudies-arrayexpress
Project description:Translation initiation factor eIF4E is overexpressed early in breast cancers in association with disease progression and reduced survival. Much remains to be understood regarding the role of eIF4E in human cancer. Using immortalized human breast epithelial cells, we report that elevated expression of elF4E translationally activates the TGFβ pathway, promoting cell invasion, loss of cell polarity, increased cell survival and other hallmarks of early neoplasia. Overexpression of eIF4E is shown to facilitate selective translation of integrin β1 mRNA, which drives the translationally controlled assembly of a TGFβ receptor signaling complex containing α3β1 integrins, β-catenin, TGFβ receptor I, E-cadherin and phosphorylated Smads2/3. This receptor complex acutely sensitizes non-malignant breast epithelial cells to activation by typically sub-stimulatory levels of activated TGFβ. TGFβ can promote cellular differentiation or invasion and transformation. As a translational coactivator of TGFβ, eIF4E confers selective mRNA translation, reprogramming non-malignant cells to an invasive phenotype by reducing the set-point for stimulation by activated TGFβ. Overexpression of eIF4E may be a pro-invasive facilitator of TGFβ activity. MCF10A cells were subjected to consitutive silencing with a non-silencing control shRNA or an shRNA to eIF4E. Total RNA, light polysomal RNA (2-3 ribosome fraction) and heavy polysomal RNA (greater than or equal to 4 ribosome fraction) were purified and used for hybridization to Affymetrix 133 2.0 Plus arrays. Data analysis was conducted using MicroArray Suite Software from Affymetrix. To remove probe sets with insignificant differences between perfect match and mismatch data, which creates a more robust data set of greater clarity without a high level of background noise, discrimination values for each probe pair were calculated for low intensity ratios using Wilcoxon signed rank test to assess significance and data re-assigned as either changed or unchanged mRNAs. Data sets were compared using Expressionist Suite software. Significance of mRNAs were assessed using fold changes and the FDRs estimated based on t-tests.
2015-06-19 | E-GEOD-69780 | biostudies-arrayexpress
Project description:Translational regulation plays a critical role in cell growth and proliferation, and its dysregulation results in cancer. Aberrant expression of the mRNA 5’cap-binding protein, eIF4E, has been implicated in cancer development and progression. eIF4E activity is promoted by phosphorylation. Here we show that “knock-in” mice in which eIF4E cannot be phosphorylated are resistant to tumorigenesis in a prostate cancer model. We identify multiple candidate genes involved in the resistance to oncogenic transformation. Importantly, phosphorylation of eIF4E is increased in hormone-refractory prostate cancer, the deadliest stage of the disease. Our results highlight eIF4E phosphorylation as a critical event in tumorigenesis. Comaparison of total RNA and polysomal RNA from mouse embryo fibroblasts derived from WT and eIF4E-KI (non phosphorylatable eIF4E) mice
2010-08-17 | E-GEOD-17451 | biostudies-arrayexpress
Project description:Polyribosome sedimentation velocity centrifugation can be used to identify differential regulation of the translation of mRNAs. However, ultracentrifugation presents practical limitations on the number of sedimentation velocity gradients that can be run simultaneously. A method for sedimentation velocity analysis of polyribosomes is presented that is based on low-speed centrifugation of sucrose gradients prepared in deep 96-well plates, the advantage of which is that hundreds of polyribosome fractionations can be performed simultaneously in a tabletop centrifuge.
| S-EPMC434456 | biostudies-literature
Project description:Aggressive double and triple hit (DH/TH) DLBCL feature activation of Hsp90 stress pathways. Herein, we show that Hsp90 controls post-transcriptional dynamics of key mRNA species including those encoding BCL6, MYC and BCL2. Using a proteomics approach, we found that Hsp90 binds to and maintains activity of eIF4E (eukaryotic translation initiation factor 4E). EIF4E drives nuclear export and translation of BCL6, MYC and BCL2 mRNA. eIF4E RIP-sequencing in DLBCL suggests that nuclear eIF4E controls an extended program that includes BCR signaling, cellular metabolism and epigenetic regulation. Accordingly, eIF4E was required for survival of DLBCL including the most aggressive subtypes DH/TH lymphomas. Indeed, eIF4E inhibition induces tumor regression in cell line and patient-derived tumorgrafts of TH-DLBCL, even in the presence of elevated Hsp90 activity. Targeting Hsp90 is typically limited by counter-regulatory elevation of Hsp70B, which induces resistance to Hsp90 inhibitors. Surprisingly, we identify Hsp70 mRNA as an eIF4E target. In this way, eIF4E inhibition can overcome drug resistance to Hsp90 inhibitors. Accordingly, rational combinatorial inhibition of eIF4E and Hsp90 inhibitors resulted in cooperative anti-lymphoma activity in DH/TH DLBCL in vitro and in vivo.
2016-01-11 | GSE63265 | GEO
Project description:One of the most regulated steps of translation initiation is the recruitment of an mRNA by the translation machinery. In eukaryotes, this step is mediated by the 5M-BM-4end cap-binding factor eIF4E bound to the bridge protein eIF4G and forming the eIF4F complex. In plants, different isoforms of eIF4E and eIF4G form the antigenically distinct eIF4F and eIF(iso)4F complexes proposed to mediate selective translation. Using a microarray analysis of polyribosome- and non-polyribosome-purified mRNAs from 15 day-old Arabidopsis thaliana wild type [WT] and eIF(iso)4E knockout mutant [AteIF(iso)4E-1] seedlings we found 79 transcripts shifted from polyribosomes toward non-polyribosomes, and 47 mRNAs with the opposite behavior in the mutant. The translationally decreased mRNAs were overrepresented in root-preferentially expressed genes and proteins from the endomembrane system, including several transporters such as the phosphate transporter PHOSPHATE1 (PHO1), Sucrose transporter 3 (SUC3), the ABC transporter-like with ATPase activity (MRP11) and five electron transporters, as well as signal transduction-, protein modification- and transcription-related proteins. For transcriptional analysis used total RNA of AteIF(iso)4E-1 seedlings of 15 days old to known the changes on transcripts leves by the eIF(iso)4E absence, using as control Wt seedlings. The experiments were performed in duplicate, and swap analysis were done. For translational analysis, used non-polysomal and polysomal RNA of AteIF(iso)4E-1 seedlings of 15 days old in order to known the transcripts that are modified in their translational levels by the eIF(iso)4E absence, using as control non polysomal and polysomal RNA of Wt seddlings.
2013-07-26 | E-GEOD-29386 | biostudies-arrayexpress