DEAD-box RNA helicases eIF4A and Ded1 are believed to promote translation initiation by resolving mRNA secondary structures that impede ribosome attachment at the mRNA 5' end or subsequent scanning of the 5'UTR, but whether they perform distinct functions or act redundantly in vivo is poorly understood. We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling. Despite similar reductions in bulk translation, inactivation of a cold-sensitive Ded1 mutant substantially reduced the TEs of >600 mRNAs, whereas inactivation of a temperature-sensitive eIF4A mutant yielded <40 similarly impaired mRNAs. The broader requirement for Ded1 did not reflect more pervasive secondary structures at low temperature, as inactivation of temperature-sensitive and cold-sensitive ded1 mutants gave highly correlated results. Interestingly, Ded1-dependent mRNAs exhibit greater than average 5'UTR length and propensity for secondary structure, implicating Ded1 in scanning though structured 5' UTRs. Reporter assays confirmed that cap- distal stem-loop insertions increase dependence on Ded1 but not eIF4A for efficient translation. While only a small fraction of mRNAs is strongly dependent on eIF4A, this dependence is significantly correlated with requirements for Ded1 and 5'UTR features characteristic of Ded1- dependent mRNAs. Our findings suggest that Ded1 is critically required to promote scanning through secondary structures within 5'UTRs; and while eIF4A cooperates with Ded1 in this function, it also promotes a step of initiation common to virtually all yeast mRNAs. Overall design: We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling.The study includes 32 samples, comprised of 16 mRNA-Seq samples and 16 ribosome footprint profiling samples, derived from biological replicates of 3 mutant strains, ded1-cs, ded1-ts and tif1-ts, and the corresponding wild-type strains. The tif1-ts mutant and its wild-type counterpart were analyzed at 30°C and 37°C.
Functional interplay between DEAD-box RNA helicases Ded1 and Dbp1 in preinitiation complex attachment and scanning on structured mRNAs in vivo.
Subject
View SamplesSpinal muscular atrophy (SMA) is one of the most common inherited forms of neurological disease leading to infant mortality. Patients exhibit selective loss of lower motor neurons resulting in muscle weakness, paralysis, and often death. Although patient fibroblasts have been used extensively to study SMA, motor neurons have a unique anatomy and physiology which may underlie their vulnerability to the disease process. Here we report the generation of induced pluripotent stem (iPS) cells from skin fibroblast samples taken from a child with SMA. These cells expanded robustly in culture, maintained the disease genotype, and generated motor neurons that showed selective deficits compared to those derived from the childs unaffected mother. This is the first study to show human iPS cells can be used to model the specific pathology seen in a genetically inherited disease. As such, it represents a promising resource to study disease mechanisms, screen novel drug compounds, and develop new therapies.
Induced pluripotent stem cells from a spinal muscular atrophy patient.
No sample metadata fields
View SamplesAim of this experiment was to look at the gene expression differences in the benzyladenine-treated and untreated Arabidopsis seedlings grown in light
Identification of cytokinin-responsive genes using microarray meta-analysis and RNA-Seq in Arabidopsis.
Age, Specimen part, Compound
View SamplesAim was to look at the gene profile changes in 10 days old Arabidopsis seedlings grown in light and treated with either Zeatin or BA and compared to non-treatment
Identification of cytokinin-responsive genes using microarray meta-analysis and RNA-Seq in Arabidopsis.
Age, Compound
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Combined Gene Expression and RNAi Screening to Identify Alkylation Damage Survival Pathways from Fly to Human.
Specimen part, Treatment
View SamplesDespite the high toxicity, alkylating agents are still at the forefront of several clinical protocols used to treat cancers. In this study, we investigated the mechanisms underlying alkylation damage responses, aiming to identify novel strategies to augment alkylating therapy efficacy. In this pursuit, we compared gene expression profiles of evolutionary distant cell types (D. melanogaster Kc167 cells, mouse embryonic fibroblasts and human cancer cells) in response to the alkylating agent methyl-methanesulfonate (MMS). We found that many responses to alkylation damage are conserved across species independent on their tumor/normal phenotypes. Key amongst these observations was the protective role of NRF2-induced GSH production primarily regulating GSH pools essential for MMS detoxification but also controlling activation of unfolded protein response (UPR) needed for mounting survival responses across species. An interesting finding emerged from a non-conserved mammalian-specific induction of mitogen activated protein kinase (MAPK)-dependent inflammatory responses following alkylation, which was not directly related to cell survival but stimulated the production of a pro-inflammatory, invasive and angiogenic secretome in cancer cells. Appropriate blocking of this inflammatory component blocked the invasive phenotype and angiogenesis in vitro and facilitated a controlled tumor killing by alkylation in vivo through inhibition of alkylation-induced angiogenic response, and induction of tumor healing.
Combined Gene Expression and RNAi Screening to Identify Alkylation Damage Survival Pathways from Fly to Human.
Specimen part, Treatment
View SamplesDespite the high toxicity, alkylating agents are still at the forefront of several clinical protocols used to treat cancers. In this study, we investigated the mechanisms underlying alkylation damage responses, aiming to identify novel strategies to augment alkylating therapy efficacy. In this pursuit, we compared gene expression profiles of evolutionary distant cell types (D. melanogaster Kc167 cells, mouse embryonic fibroblasts and human cancer cells) in response to the alkylating agent methyl-methanesulfonate (MMS). We found that many responses to alkylation damage are conserved across species independent on their tumor/normal phenotypes. Key amongst these observations was the protective role of NRF2-induced GSH production primarily regulating GSH pools essential for MMS detoxification but also controlling activation of unfolded protein response (UPR) needed for mounting survival responses across species. An interesting finding emerged from a non-conserved mammalian-specific induction of mitogen activated protein kinase (MAPK)-dependent inflammatory responses following alkylation, which was not directly related to cell survival but stimulated the production of a pro-inflammatory, invasive and angiogenic secretome in cancer cells. Appropriate blocking of this inflammatory component blocked the invasive phenotype and angiogenesis in vitro and facilitated a controlled tumor killing by alkylation in vivo through inhibition of alkylation-induced angiogenic response, and induction of tumor healing.
Combined Gene Expression and RNAi Screening to Identify Alkylation Damage Survival Pathways from Fly to Human.
Specimen part, Treatment
View SamplesUnderstanding the mechanisms by which cells respond to chemotherapeutics is key to identifying means to improve therapy effiicacy while reducing systemic toxicity of these widely used classes of drugs. While determining the role of NRF2-GSH and ER stress in cells exposed to alkylating compounds such as methyl-methanesulfonate (MMS), we asked if these pathways could also be a general cell damage response relevant to other clinically used chemotherapeutics or if it is an alkylation specific response. With this intent, we performed RNA sequencing of MDA-MB231 breast cancer and U2OS osteosarcoma cells lines treated for 8 hours with a topoisomerase II inhibitor etoposide (20 µM), the antimitotic beta-tubulin-interacting drug paclitaxel (0.2 µM), doxorubicin (1 µM) and compared to MMS (40 µg/mL) treated cells. Doses represent IC50 level after 72 hours exposure. We observed that even though non-alkylating drugs, especially etoposide, caused an increase in the mRNA expression of some NRF2 and ER stress signaling markers, the number and magnitude of upregulation of genes markers in either pathway was more pronounced in alkylation treatments compared to other drugs. This indicates that alterations in NRF2 and ER stress pathways could be more likely associated with differential sensitivity to alkylating chemotherapies. Overall design: MDA-MB231 breast cancer and U2OS osteosarcoma cells lines were treated with the 72 h IC50 dose of etoposide (20 µM), paclitaxel (0.2 µM), doxorubicin (1 µM) or MMS (40 µg/mL) for 8 h, and RNA was extracted and analyzed.
Alkylating Agent-Induced NRF2 Blocks Endoplasmic Reticulum Stress-Mediated Apoptosis via Control of Glutathione Pools and Protein Thiol Homeostasis.
Specimen part, Cell line, Treatment, Subject
View SamplesAlthough many genes have been proposed to be involved in prostate carcinogenesis, no single gene or gene profile has shown to have prognostic value. The main challenge for clinical management is to distinguish slowly growing tumors from those that will relapse. In this study, we compared expression profiles of 18 prostate samples (7 with Gleason 6, 8 with Gleason 7 and 3 with Gleason score equal or higher than 8) and 5 non-neoplastic prostate samples, using the GeneChip Human Exon Array 1.0 ST of Affymetrix. Microarray analysis revealed 99 genes showing statistically significant differences among tumors with Gleason score 6, 7 and 8. In addition, mRNA expression of 29 selected genes was analyzed by qRT-PCR with microfluidic cards in an extended series of 30 prostate tumors. From these, 29 were selected to be validated and the differential expression of 18 of them (62%) was independently confirmed by quantitative real-time RT-PCR (14 upregulated and 4 downregulated in higher Gleason scores) in the extended series. This list was further narrowed down to 12 genes that were differentially expressed in tumors with Gleason score of 6-7 vs 8. Finally, the protein levels of two genes from the 12-gene signature (SEC14L1 and TCEB1) were additionally validated by immunohistochemistry. Strong protein levels of both genes were correlated with Gleason score, stage, and PSA progression.
A 12-gene expression signature is associated with aggressive histological in prostate cancer: SEC14L1 and TCEB1 genes are potential markers of progression.
Specimen part
View SamplesMolecular targeted compounds are emerging as important component to improve the efficacy of classical chemotherapeutics. In this study, we tested whether using low dose sorafenib to reduce off target inhibitions of kinases impacts the antitumor effect of alkylating agents in breast cancer models. Overall design: MDA-MB231 cells were treated with 1 µM sorafenib, 40 µg/mL MMS, or pre-incubated with 1 µM sorafenib for 12 h followed by 40 µg/mL MMS, each in two independent experiments. RNA was harvested 8 and 24 h, or post MMS treatment for combination treatment.
Sorafenib improves alkylating therapy by blocking induced inflammation, invasion and angiogenesis in breast cancer cells.
Specimen part, Cell line, Subject
View Samples