Project description:Translational control plays a central role in regulation of gene expression and can lead to significant divergence between mRNA- and protein-abundance. Here we used genome-wide approaches combined with time-course analysis to measure the mRNA-abundance, mRNA-translation rate and protein expression during the transition of naïve-to-primed mouse embryonic stem cells (ESCs). We find that the ground state ESCs cultured with GSK3-, MEK-inhibitors and LIF (2iL) display higher ribosome density on a selective set of mRNAs. This set of mRNAs undergo strong translational buffering to maintain stable protein expression levels in 2iL-ESCs. Importantly, we show that the global alteration of cellular proteome during the transition of naïve to primed pluripotency is largely accompanied by transcriptional rewiring. Thus, we provide a comprehensive and detailed overview of the global changes in gene expression in different states of ESCs and dissect the relative contributions of RNA-transcription, translation and regulation of protein stability in controlling protein abundance.
Project description:Translational control plays a central role in regulation of gene expression and can lead to significant divergence between mRNA- and protein-abundance. Here we used genome-wide approaches combined with time-course analysis to measure the mRNA-abundance, mRNA-translation rate and protein expression during the transition of naïve-to-primed mouse embryonic stem cells (ESCs). We find that the ground state ESCs cultured with GSK3-, MEK-inhibitors and LIF (2iL) display higher ribosome density on a selective set of mRNAs. This set of mRNAs undergo strong translational buffering to maintain stable protein expression levels in 2iL-ESCs. Importantly, we show that the global alteration of cellular proteome during the transition of naïve to primed pluripotency is largely accompanied by transcriptional rewiring. Thus, we provide a comprehensive and detailed overview of the global changes in gene expression in different states of ESCs and dissect the relative contributions of RNA-transcription, translation and regulation of protein stability in controlling protein abundance.
Project description:Translational control plays a central role in regulation of gene expression and can lead to significant divergence between mRNA- and protein-abundance. The translational landscape of early mammalian development and its impact on cellular proteome, however, remains largely un-explored. Here we used genome-wide approaches combined with time-course analysis to measure the mRNA-abundance, mRNA-translation rate and protein expression during the transition of naïve into primed embryonic stem cells (ESCs). We found that the ground state ESCs cultured with GSK3- and MEK-inhibitors and LIF (2iL) display higher ribosome density on a selective set of mRNAs. These mRNAs show reduced translation during the exit from ground state pluripotency and transition to serum/LIF (SL) culture or upon commitment to primed epiblast-like stem cells (EpiLSCs). Strikingly, integrative analysis with cellular proteome indicate a strong translational buffering of this set of mRNAs in 2iL-ESCs leading to stable protein expression levels. Our data reveal that the global alteration of cellular proteome is largely accompanied by transcriptional rewiring. Furthermore, we identified a set of genes (including UHRF1 and KRAS) that undergo selective post-translational regulation during the transition of naïve into primed pluripotency and linked the observed changes to upstream GSK- and MEK/MAPK-signaling pathways using single inhibitor treated ESCs. Thus, we provide a comprehensive and detailed overview of the global changes in gene expression during the transition of naïve to primed pluripotency and dissect the relative contributions of RNA-transcription, translation and regulation of protein stability in controlling protein abundance.
Project description:The ground state of pluripotency is defined as a minimal unrestricted state as present in the Inner Cell Mass (ICM). Mouse embryonic stem cells (ESCs) grown in a defined serum-free medium with two kinase inhibitors (‘2i’) reflect this state, whereas ESCs grown in the presence of serum (‘serum’) share more similarities with post implantation epiblast cells. Pluripotency results from an intricate interplay between cytoplasmic, nuclear and chromatin-associated proteins. Therefore, quantitative information on the (sub)cellular proteome is essential to gain insight in the molecular mechanisms driving different pluripotent states. Here, we describe a full SILAC workflow and quality controls for proteomic comparison of 2i and serum ESCs. We demonstrate that this workflow is applicable for subcellular proteomics of the cytoplasm, nuclear and chromatin. The obtained quantitative information revealed increased levels of naïve pluripotency factors on the chromatin of 2i ESCs. Further, we demonstrate that these pluripotent states are supported by distinct metabolic programs, which include upregulation of free radical buffering by the glutathione pathway in 2i ESCs. Through induction of intracellular radicals, we show that the altered metabolic environment renders 2i ESCs less sensitive to oxidative stress. Altogether, this work provides novel insights into the proteome landscape underlying ground state pluripotency.
Project description:Pluripotency is established in E4.5 preimplantation epiblast. Embryonic stem cells (ESCs) represent the immortalization of pluripotency, however, they only partially resemble the gene expression signature of developmental ground-state. Induced PRAMEL7 expression, a protein highly expressed in the ICM but lowly expressed in ESCs, reprograms developmentally advanced ESC+serum into ground-state pluripotency by inducing a gene expression signature close to developmental ground-state. However, how PRAMEL7 reprograms gene expression remains elusive. Here we show that PRAMEL7 associates with Cullin2 (CUL2) and this interaction is required to establish ground-state gene expression. PRAMEL7 recruits CUL2 to chromatin and targets for proteasomal degradation regulators of repressive chromatin, including NuRD complex. PRAMEL7 antagonizes NuRD-mediated repression of genes implicated in pluripotency by decreasing NuRD stability and promoter association in a CUL2-dependent manner. Our data link proteasome degradation pathways to ground-state gene expression, offering insights to generate in vitro models to reproduce the in vivo ground-state pluripotency.
Project description:Current human pluripotent stem cells lack the transcription factor circuitry that governs the ground state of mouse embryonic stem cells (ESC). Here we report that short-term expression of two components, NANOG and KLF2, is sufficient to ignite other elements of the network and reset the human pluripotent state. Inhibition of ERK and protein kinase C signalling sustains a transgene-independent rewired state. Reset cells self-renew continuously without ERK signalling, are phenotypically stable and karyotypically intact. They differentiate in vitro and form teratomas in vivo. Metabolism is reprogrammed in reset cells with activation of mitochondrial respiration as in ESC. DNA methylation is dramatically reduced and transcriptome state is globally realigned across multiple cell lines. Depletion of ground state transcription factors, TFCP2L1 or KLF4 has marginal impact on conventional human pluripotent stem cells, but collapses the reset state. These findings demonstrate feasibility of installing and propagating functional control circuitry for ground state pluripotency in human cells. DNA methylation analysis in Conventional and Reset human embryonic stem cells by whole genome bisulfite sequencing, in triplicate, using the Illumina platform
Project description:Current human pluripotent stem cells lack the transcription factor circuitry that governs the ground state of mouse embryonic stem cells (ESC). Here we report that short-term expression of two components, NANOG and KLF2, is sufficient to ignite other elements of the network and reset the human pluripotent state. Inhibition of ERK and protein kinase C signalling sustains a transgene-independent rewired state. Reset cells self-renew continuously without ERK signalling, are phenotypically stable and karyotypically intact. They differentiate in vitro and form teratomas in vivo. Metabolism is reprogrammed in reset cells with activation of mitochondrial respiration as in ESC. DNA methylation is dramatically reduced and transcriptome state is globally realigned across multiple cell lines. Depletion of ground state transcription factors, TFCP2L1 or KLF4 has marginal impact on conventional human pluripotent stem cells, but collapses the reset state. These findings demonstrate feasibility of installing and propagating functional control circuitry for ground state pluripotency in human cells.