Specialized ribosomal protein genes promote drug resistance through modulation of translation
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ABSTRACT: Ribosomes are ubiquitous ribonucleoprotein complexes required for protein synthesis. We show that in budding yeast exposure to drugs alters ribosome composition leading to modification of translation pattern and increased resistance to drug. Exposure to staurosporine repressed translation of cell wall protein genes. Expression of the major paralog of uL30/RPL7 increased cell sensitivity to staurosporine while expression of the minor paralog induced resistance. Remarkably, we found that differences in paralogs function was due to difference in the translation pattern. The minor paralog promoted the translation of cell wall genes with long open reading frames (ORFs), which are normally under-translated in the presence of the major paralog, leading to drug resistance. Reducing the ORF length repressed the minor paralog and staurosporine effects on translation. Together the data reveal a natural mechanism for the optimization of translation through changes in the identity of ribosomal protein genes.
Project description:Ribosomes are often seen as monolithic machines produced from uniformly regulated genes. However, in yeast most ribosomal proteins come from duplicated genes. Here, we demonstrate that gene duplication may serve as an adaption mechanism modulating the global proteome through the differential expression of ribosomal proteins paralogs after exposure to stress. Our data indicate that the yeast paralog pair of the ribosomal protein L7/uL30 produces two differentially acetylated proteins. Under normal conditions most ribosomes incorporate the hypo-acetylated major form favoring the translation of genes with short open reading frames. Exposure to drugs, on the other hand, increases the production of ribosomes carrying the hyper-acetylated minor paralog that increases translation of long reading frames. Many of these long genes encode cell wall proteins that increase drug resistance in a programed change in translation equilibrium. Together the data reveal a mechanism of translation control through the differential fates of near-identical ribosomal protein isoforms.
Project description:In Saccharomyces cerevisiae, most ribosomal proteins are produced from duplicated genes. These nearly identical protein pairs are expressed at varying levels, with one ‘major paralog’ usually predominating. The minor paralog is highly transcribed but held in check through reduced intron removal, but the mechanism and purpose of this copy-specific repression remains unclear. In this study, we searched for proteins that achieve copy-specific expression by acting through the intron of the minor paralog of the model duplicated small ribosomal subunit protein S9 genes. By mass spectrometry and gene deletion we demonstrate that the transcription factors Rim101 and Taf14 bind to the intron and inhibit the splicing of the minor RPS9 paralog. RPS9A is then specifically de-repressed during meiosis to ensure optimal expression of meiotic genes and efficient sporulation. Our results reveal a new regulatory paradigm where transcriptional factors can also modulate splicing rates to optimize the expression of duplicated ribosomal protein genes.
Project description:Ribosomes are often seen as monolithic machines produced from uniformly regulated genes. However, in yeast most ribosomal proteins come from duplicated genes. Here, we demonstrate that gene duplication may serve as a stress-adaptation mechanism modulating the global proteome through the differential expression of ribosomal protein paralogs. Our data indicate that the yeast paralog pair of the ribosomal protein L7/uL30 produces two differentially acetylated proteins. Under normal conditions most ribosomes incorporate the hypo-acetylated major form favoring the translation of genes with short open reading frames. Exposure to drugs, on the other hand, increases the production of ribosomes carrying the hyper-acetylated minor paralog that increases translation of long open reading frames. Many of these paralogs dependent genes encode cell wall proteins that could promote tolerance to drugs as their translation increases after exposure to drugs. Together the data reveal a mechanism of translation control through the differential use of near-identical ribosomal protein isoforms.
Project description:Purpose: Compare the transcriptional profile of staurosporine-treated cells in Neurospora crassa wild type and M-NM-^Tczt-1 (M-NM-^TNCU09974) cells Methods: Conidial suspensions were obtained and 1 x 106 cells/ml incubated in minimal medium for 6 hours (26M-BM-:C, 140 rpm, constant light) followed by the addition of staurosporine (or DMSO) and growth for 1 more hour. Cells were harvested using 0.45 M-NM-<m filters and immediately frozen in liquid nitrogen. Total RNA was isolated by the Trizol-Phenol-Chloroform method. After digestion of 25 M-NM-<g RNA with TURBO DNAse (Life Technologies), mRNA was purified using Dynabeads oligo(dT) magnetic beads (Life Technologies). The mRNA was chemically fragmented using the Ambion RNA fragmentation kit (Life Technologies). First and second strand cDNA synthesis was achieved using appropriate kits (Life Technologies). The illumina TruSeq kit was employed to generate the cDNA libraries with indexing adapters essentially following the manufacturerM-bM-^@M-^Ys protocol. After purification of the libraries with AMPure XP beads (Roche), the quality of the libraries was analysed in a Agilent 2100 Bioanalyzer. The cDNA libraries were sequenced in a illumina HiSeq2000 and single reads of 50 bp were obtained. Sequencing data was handled essentially with Tophat, Cufflinks and Cuffdiff. Expression levels are presented as Fragments/Reads Per Kilobase of transcript per Million mapped reads (FPKM/RPKM). Results: Transcriptional profiling of staurosporine-treated cells wild type by RNA-sequencing showed that genes encoding the machinery for protein synthesis are enriched among the genes repressed by the drug. Functional category enrichment analyses also show that genes encoding components of the mitochondrial respiratory chain are downregulated by staurosporine, whereas genes involved in endoplasmic reticulum activities are upregulated. In contrast, a staurosporine-treated czt-1 deletion strain is unable to repress the genes for the respiratory chain and to induce the genes related with the endoplasmic reticulum, indicating a role for CZT-1 on the regulation of activity of these organelles. Conclusions: This transcriptional profiling study is framed in a comprehensive study on the role of the novel transcription factor CZT-1 (NCU09974) in Neurospora crassa. Transcriptional profile of wild type and M-NM-^Tczt-1 cells staurosporine-treated cells in Neurospora crassa was compared using illumina HiSeq2000 and single reads of 50 bp.
Project description:Purpose: Compare the transcriptional profile of staurosporine-treated cells in Neurospora crassa wild type and Δczt-1 (ΔNCU09974) cells Methods: Conidial suspensions were obtained and 1 x 106 cells/ml incubated in minimal medium for 6 hours (26ºC, 140 rpm, constant light) followed by the addition of staurosporine (or DMSO) and growth for 1 more hour. Cells were harvested using 0.45 μm filters and immediately frozen in liquid nitrogen. Total RNA was isolated by the Trizol-Phenol-Chloroform method. After digestion of 25 μg RNA with TURBO DNAse (Life Technologies), mRNA was purified using Dynabeads oligo(dT) magnetic beads (Life Technologies). The mRNA was chemically fragmented using the Ambion RNA fragmentation kit (Life Technologies). First and second strand cDNA synthesis was achieved using appropriate kits (Life Technologies). The illumina TruSeq kit was employed to generate the cDNA libraries with indexing adapters essentially following the manufacturer’s protocol. After purification of the libraries with AMPure XP beads (Roche), the quality of the libraries was analysed in a Agilent 2100 Bioanalyzer. The cDNA libraries were sequenced in a illumina HiSeq2000 and single reads of 50 bp were obtained. Sequencing data was handled essentially with Tophat, Cufflinks and Cuffdiff. Expression levels are presented as Fragments/Reads Per Kilobase of transcript per Million mapped reads (FPKM/RPKM). Results: Transcriptional profiling of staurosporine-treated cells wild type by RNA-sequencing showed that genes encoding the machinery for protein synthesis are enriched among the genes repressed by the drug. Functional category enrichment analyses also show that genes encoding components of the mitochondrial respiratory chain are downregulated by staurosporine, whereas genes involved in endoplasmic reticulum activities are upregulated. In contrast, a staurosporine-treated czt-1 deletion strain is unable to repress the genes for the respiratory chain and to induce the genes related with the endoplasmic reticulum, indicating a role for CZT-1 on the regulation of activity of these organelles. Conclusions: This transcriptional profiling study is framed in a comprehensive study on the role of the novel transcription factor CZT-1 (NCU09974) in Neurospora crassa.
Project description:Processing (P)-bodies are cytoplasmic membrane-less condensates including translationally repressed mRNAs and proteins involved in the mRNA decay machinery. The mechanisms underlying P-bodies nucleation and mRNA decay have been largely described. However, the impact of signaling networks in P-bodies dynamics and mRNA translation is still not well understood. Here, we identify a ribonucleoprotein network assembled by the E3 ubiquitin ligase Praja2 at P-bodies that coordinates protein translation and mRNA turnover in human glioblastoma (GBM). Praja2 physically interacts and spatially colocalizes with the RNA helicase DDX6, a core component and nucleating factor of P-bodies. Stimulation of the G protein-coupled receptor (GPCR)-cAMP pathway in GBM cells induces a non-proteolytic polyubiquitylation of DDX6 by Praja2. DDX6 ubiquitylation is required for P-bodies assembly and mRNA translation repression. Interfering with DDX6 ubiquitylation or downregulation of expression markedly affects P-bodies assembly. Moreover, genetic deletion of praja2 dramatically impacts the assembly of DDX6/mRNA complexes and the amount of translating polysomes, leading to cellular senescence and GBM growth arrest. These findings identify a cAMP-driven post-transcriptional control mechanism operating at P-bodies by the ubiquitin system that profoundly impacts on mRNA translation and cancer cell growth. This regulatory system may, thus, contribute to the adaptive metabolic rewiring underlying cancer growth and drug resistance.
Project description:Processing (P)-bodies are cytoplasmic membrane-less condensates including translationally repressed mRNAs and proteins involved in the mRNA decay machinery. The mechanisms underlying P-bodies nucleation and mRNA decay have been largely described. However, the impact of signaling networks in P-bodies dynamics and mRNA translation is still not well understood. Here, we identify a ribonucleoprotein network assembled by the E3 ubiquitin ligase Praja2 at P-bodies that coordinates protein translation and mRNA turnover in human glioblastoma (GBM). Praja2 physically interacts and spaBally co-localizes with the RNA helicase DDX6, a core component and nucleating factor of P-bodies. Stimulation of the G protein-coupled receptor (GPCR)-cAMP pathway in GBM cells induces a non-proteolytic polyubiquitylation of DDX6 by Praja2. DDX6 ubiquitylation is required for P-bodies assembly and mRNA translation repression. Interfering with DDX6 ubiquitylation or downregulation of expression markedly affects P-bodies assembly. Moreover, geneBc deleBon of praja2 dramatically impacts the assembly of DDX6/mRNA complexes and the amount of translating polysomes, leading to cellular senescence and GBM growth arrest. These findings identify a cAMP-driven post-transcriptional control mechanism operating at P- bodies by the ubiquitin system that profoundly impacts on mRNA translation and cancer cell growth. This regulatory system may, thus, contribute to the adaptive metabolic rewiring underlying cancer growth and drug resistance.
Project description:Processing (P)-bodies are cytoplasmic membrane-less condensates including translationally repressed mRNAs and proteins involved in the mRNA decay machinery. The mechanisms underlying P-bodies nucleation and mRNA decay have been largely described. However, the impact of signaling networks in P-bodies dynamics and mRNA translation is still not well understood. Here, we identify a ribonucleoprotein network assembled by the E3 ubiquitin ligase Praja2 at P-bodies that coordinates protein translation and mRNA turnover in human glioblastoma (GBM). Praja2 physically interacts and spatially colocalizes with the RNA helicase DDX6, a core component and nucleating factor of P-bodies. Stimulation of the G protein-coupled receptor (GPCR)-cAMP pathway in GBM cells induces a non-proteolytic polyubiquitylation of DDX6 by Praja2. DDX6 ubiquitylation is required for P-bodies assembly and mRNA translation repression. Interfering with DDX6 ubiquitylation or downregulation of expression markedly affects P-bodies assembly. Moreover, genetic deletion of praja2 dramatically impacts the assembly of DDX6/mRNA complexes and the amount of translating polysomes, leading to cellular senescence and GBM growth arrest. These findings identify a cAMP-driven post-transcriptional control mechanism operating at P-bodies by the ubiquitin system that profoundly impacts on mRNA translation and cancer cell growth. This regulatory system may, thus, contribute to the adaptive metabolic rewiring underlying cancer growth and drug resistance.