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Role of the small subunit processome in the maintenance of pluripotent stem cells.

ABSTRACT: RNA-binding proteins (RBPs) play integral roles in gene regulation, yet only a small fraction of RBPs has been studied in the context of stem cells. Here we applied an RNAi screen for RBPs in mouse embryonic stem cells (ESCs) and identified 16 RBPs involved in pluripotency maintenance. Interestingly, six identified RBPs, including Krr1 and Ddx47, are part of a complex called small subunit processome (SSUP) that mediates 18S rRNA biogenesis. The SSUP components are preferentially expressed in stem cells and enhance the global translational rate, which is critical to sustain the protein levels of labile pluripotency factors such as Nanog and Esrrb. Furthermore, the SSUP proteins are required for efficient reprogramming of induced pluripotent stem cells. Our study uncovers the role of the SSUP and the importance of translational control in stem cell fate decision.

SUBMITTER: You KT

PROVIDER: S-EPMC4604342 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

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Role of the small subunit processome in the maintenance of pluripotent stem cells.

You Kwon Tae KT Park Joha J Kim V Narry VN

Genes & development 20151001 19

RNA-binding proteins (RBPs) play integral roles in gene regulation, yet only a small fraction of RBPs has been studied in the context of stem cells. Here we applied an RNAi screen for RBPs in mouse embryonic stem cells (ESCs) and identified 16 RBPs involved in pluripotency maintenance. Interestingly, six identified RBPs, including Krr1 and Ddx47, are part of a complex called small subunit processome (SSUP) that mediates 18S rRNA biogenesis. The SSUP components are preferentially expressed in ste ...[more]

PMID: 26443847

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Role of the Small Subunit Processome in the Maintenance of Pluripotent Stem Cells

Project description:RNA-binding proteins (RBPs) play integral roles in gene regulation, yet only a small fraction of RBPs has been studied in the context of stem cells. We here apply RNA interference screen for RBPs in mouse embryonic stem cells (ESCs) and identify 16 RBPs involved in pluripotency maintenance. Interestingly, six identified RBPs including Krr1 and Ddx47 are part of a complex called Small Subunit Processome (SSUP) that mediates 18S rRNA biogenesis. The SSUP components are preferentially expressed in stem cells and enhance global translational rate, which is critical to sustain the protein levels of labile pluripotency factors such as Nanog and Esrrb. Furthermore, the SSUP proteins are required for efficient reprogramming of induced pluripotent stem cells. Our study uncovers the role of SSUP and the importance of translational control in stem cell fate decision. R1 cells were transfected with 3 different control siRNAs and 3 different siRNAs targeting Krr1 for 48 hrs. Transcriptome profiles were generated by deep sequencing using illumina HiSeq 2000.

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Small-subunit rRNA processome proteins are translationally regulated during differentiation of Trypanosoma cruzi.

Project description:We used differential display to select genes differentially expressed during differentiation of epimastigotes into metacyclic trypomastigotes in the protozoan parasite Trypanosoma cruzi. One of the selected clones had a sequence similar to that of the small-subunit (SSU) processome protein Sof1p, which is involved in rRNA processing. The corresponding T. cruzi protein, TcSof1, displayed a nuclear localization and is downregulated during metacyclogenesis. Heterologous RNA interference assays showed that depletion of this protein impaired growth but did not affect progression through the cell cycle, suggesting that ribosome synthesis regulation and the cell cycle are uncoupled in this parasite. Quantitative PCR (qPCR) assays of several SSU processome-specific genes in T. cruzi also showed that most of them were regulated posttranscriptionally. This process involves the accumulation of mRNA in the polysome fraction of metacyclic trypomastigotes, where TcSof1 cannot be detected. Metacyclic trypomastigote polysomes were purified and separated by sucrose gradient sedimentation. Northern blot analysis of the sucrose gradient fractions showed the association of TcSof1 mRNA with polysomes, confirming the qPCR data. The results suggest that the mechanism of regulation involves the blocking of translation elongation and/or termination.

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