Project description:Cell fate transitions depend on balanced rewiring of transcription and translation programmes to enable ordered developmental progression. We identified a feedback loop between nonsense-mediated mRNA decay (NMD) and translation initiation, in which NMD controls the translation initiation factor Eif4a2 and its premature termination codon encoding isoform (Eif4a2-PTC). This leads to translation of a specific truncated protein, which elicits increased translation rates and is causative for significant delays in mouse embryonic stem cell differentiation. Using immunoprecipitation coupled with mass spectrometry, we identified the interactome of full length Eif4a2 (Eif4a2-iso1) and Eif4a2-PTC. We find that Eif4a2-iso1 is mainly involved in translation initiation, while unstable Eif4a2-PTC shows little interaction with translation initiation factors. Both isoforms can bind to mRNA, as indicated by the interaction with mRNA binding protein, such as NMD factors and Ago2. Finally, Eif4a2-iso1 and Eif4a2-PTC interact with key pluripotency factors, providing a potential explanation for how Eif4a2 controls ESC differentiation.
Project description:RNA-immunoprecipitation can be used to identify transcripts bound by RNA binding proteins. Here we identified transcripts bound by the translation initiation factor Eif4a2 in ESCs. We found that several pluripotency transcription factor encoding mRNAs and factors regulating ESC differentiation show binding to Eif4a2 stronger than expected by transcript abundance.
Project description:Stemness is a defining feature in embryonic and cancer stem cells. How stemness is regulated at the mRNA translational initiation remains undefined. We carried out an RNAi screen for key translation initiation factors that maintain the stemness in mouse embryonic stem cells (ESCs). We identified eIF4A2 and defined its mechanistic action through Rps26-depleted and -containing ribosomes in translational initiation activation of mRNAs encoding pluripotency factors and H3.3 for embryonic and extraembryonic lineage repression, respectively. eIF4A2 also mediates translation initiation activation of Ddx6, which acts together with eIF4A2 to restrict the totipotent 2-cell (2C) transcription program in ESCs through Zscan4 mRNA degradation and translation repression. Knockdown of eIF4A2 disrupts ESC proteome causing the loss of stemness in ESCs as well as in human glioblastomas where eIF4A2 is highly enriched. Collectively, our study establishes an eIF4A2-mediated translation initiation control of stemness and provides insight into cancer therapeutics targeting the translation initiation machinery.
Project description:Stemness is a defining feature in embryonic and cancer stem cells. How stemness is regulated at the mRNA translational initiation remains undefined. We carried out an RNAi screen for key translation initiation factors that maintain the stemness in mouse embryonic stem cells (ESCs). We identified eIF4A2 and defined its mechanistic action through Rps26-depleted and -containing ribosomes in translational initiation activation of mRNAs encoding pluripotency factors and H3.3 for embryonic and extraembryonic lineage repression, respectively. eIF4A2 also mediates translation initiation activation of Ddx6, which acts together with eIF4A2 to restrict the totipotent 2-cell (2C) transcription program in ESCs through Zscan4 mRNA degradation and translation repression. Knockdown of eIF4A2 disrupts ESC proteome causing the loss of stemness in ESCs as well as in human glioblastomas where eIF4A2 is highly enriched. Collectively, our study establishes an eIF4A2-mediated translation initiation control of stemness and provides insight into cancer therapeutics targeting the translation initiation machinery.
Project description:Stemness is a defining feature in embryonic and cancer stem cells. How stemness is regulated at the mRNA translational initiation remains undefined. We carried out an RNAi screen for key translation initiation factors that maintain the stemness in mouse embryonic stem cells (ESCs). We identified eIF4A2 and defined its mechanistic action through Rps26-depleted and -containing ribosomes in translational initiation activation of mRNAs encoding pluripotency factors and H3.3 for embryonic and extraembryonic lineage repression, respectively. eIF4A2 also mediates translation initiation activation of Ddx6, which acts together with eIF4A2 to restrict the totipotent 2-cell (2C) transcription program in ESCs through Zscan4 mRNA degradation and translation repression. Knockdown of eIF4A2 disrupts ESC proteome causing the loss of stemness in ESCs as well as in human glioblastomas where eIF4A2 is highly enriched. Collectively, our study establishes an eIF4A2-mediated translation initiation control of stemness and provides insight into cancer therapeutics targeting the translation initiation machinery.
Project description:TAF4 directed immunoprecipitation of the the Pre-initiation complex from mouse embryonic stem cells with or without depletion of TATA-box binding protein (TBP).