Dataset Information

The effect of heterogeneous Transcription Start Sites (TSS) on the translatome: implications for the mammalian cellular phenotype.

ABSTRACT:

Background

The genetic program, as manifested as the cellular phenotype, is in large part dictated by the cell's protein composition. Since characterisation of the proteome remains technically laborious it is attractive to define the genetic expression profile using the transcriptome. However, the transcriptional landscape is complex and it is unclear as to what extent it reflects the ribosome associated mRNA population (the translatome). This is particularly pertinent for genes using multiple transcriptional start sites (TSS) generating mRNAs with heterogeneous 5' transcript leaders (5'TL). Furthermore, the relative abundance of the TSS gene variants is frequently cell-type specific. Indeed, promoter switches have been reported in pathologies such as cancer. The consequences of this 5'TL heterogeneity within the transcriptome for the translatome remain unresolved. This is not a moot point because the 5'TL plays a key role in regulating mRNA recruitment onto polysomes.

Results

In this article, we have characterised both the transcriptome and translatome of the MCF7 (tumoural) and MCF10A (non-tumoural) cell lines. We identified ~550 genes exhibiting differential translation efficiency (TE). In itself, this is maybe not surprising. However, by focusing on genes exhibiting TSS heterogeneity we observed distinct differential promoter usage patterns in both the transcriptome and translatome. Only a minor fraction of these genes belonged to those exhibiting differential TE. Nonetheless, reporter assays demonstrated that the TSS variants impacted on the translational readout both quantitatively (the overall amount of protein expressed) and qualitatively (the nature of the proteins expressed).

Conclusions

The results point to considerable and distinct cell-specific 5'TL heterogeneity within both the transcriptome and translatome of the two cell lines analysed. This observation is in-line with the ribosome filter hypothesis which posits that the ribosomal machine can selectively filter information from within the transcriptome. As such it cautions against the simple extrapolation transcriptome???proteome. Furthermore, polysomal occupancy of specific gene 5'TL variants may also serve as novel disease biomarkers.

SUBMITTER: Dieudonne FX

PROVIDER: S-EPMC4654819 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Publications

The effect of heterogeneous Transcription Start Sites (TSS) on the translatome: implications for the mammalian cellular phenotype.

Dieudonné Francois-Xavier FX O'Connor Patrick B F PB Gubler-Jaquier Pascale P Yasrebi Haleh H Conne Beatrice B Nikolaev Sergey S Antonarakis Stylianos S Baranov Pavel V PV Curran Joseph J

BMC genomics 20151121

<h4>Background</h4>The genetic program, as manifested as the cellular phenotype, is in large part dictated by the cell's protein composition. Since characterisation of the proteome remains technically laborious it is attractive to define the genetic expression profile using the transcriptome. However, the transcriptional landscape is complex and it is unclear as to what extent it reflects the ribosome associated mRNA population (the translatome). This is particularly pertinent for genes using mu ...[more]

PMID: 26589636

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Project description:Bacteria rely on efficient gene regulatory mechanisms to switch between genetic programs when they are facing new environments. Although this regulation can occur at many different levels, one of the key steps is the initiation of transcription. Identification of the first nucleotide transcribed by the RNA polymerase is therefore essential to understand the underlying regulatory processes, since this provides insight on promoter strength and binding sites for transcriptional regulators, and additionally reveals the exact 5' untranslated region of the transcripts, which often contains elements that regulate translation.Here we present data from a novel TSS-EMOTE assay (Transcription Start Specific Exact Mapping Of Transcriptome Ends) to precisely map the transcription initiation sites of four entire transcriptomes. TSS-EMOTE is a variation of the dRNA-seq method, which has been combined with the EMOTE protocol, in order to increase detection of longer transcripts and limit biases introduced by PCR amplification of the Illumina sequencing library. Using TSS-EMOTE, 2018 promoters were detected in the opportunistic pathogen Staphylococcus aureus, and detailed consensus sequences could be obtained for the RNA polymerase recognition elements (e.g. sigma factor binding sites). The data also revealed a 94 nt median length of the 5' untranslated region in S. aureus, giving important insights for future work on translational regulation. Additionally, the transcriptomes of three other opportunistic pathogens, Staphylococcus epidermidis, Acinetobacter baumannii and Enterobacter aerogenes, were examined, and the identified promoter locations were then used to generate a map of the operon structure for each of the four organisms.Mapping transcription start sites, and subsequent correlation with the genomic sequence, provides a multitude of important information about the regulation of gene expression, both at the transcriptional and translational level, by defining 5' untranslated regions and sigma-factor binding sites. We have here mapped transcription start sites in four important pathogens using TSS-EMOTE, a method that works with both long and 3'-phosphorylated RNA molecules, and which incorporates Unique Molecular Identifiers (UMIs) to allow unbiased quantification.

Dataset Information

The effect of heterogeneous Transcription Start Sites (TSS) on the translatome: implications for the mammalian cellular phenotype.

Background

Results

Conclusions

Publications

The effect of heterogeneous Transcription Start Sites (TSS) on the translatome: implications for the mammalian cellular phenotype.

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