RNA Exosome Complex-Mediated Control of Redox Status in Pluripotent Stem Cells.

Maria Skamagki,Hu Li,Jiguang Wang,Quanhua Mu,Zhong Liu,Christian A Ross,Uttiya Basu,Aparna Ananthanarayanan,Rui Zhao,Cheng Zhang,Kitai Kim

doi:10.1016/j.stemcr.2017.08.024

Abstract

SummaryThe RNA exosome complex targets AU-rich element (ARE)-containing mRNAs in eukaryotic cells. We identified a transcription factor, ZSCAN10, which binds to the promoters of multiple RNA exosome complex subunits in pluripotent stem cells to maintain subunit gene expression. We discovered that induced pluripotent stem cell clones generated from aged tissue donors (A-iPSC) show poor expression of ZSCAN10, leading to poor RNA exosome complex expression, and a subsequent elevation in ARE-containing RNAs, including glutathione peroxidase 2 (Gpx2). Excess GPX2 leads to excess glutathione-mediated reactive oxygen species scavenging activity that blunts the DNA damage response and apoptosis. Expression of ZSCAN10 in A-iPSC recovers RNA exosome gene expression, the DNA damage response, and apoptosis. These findings reveal the central role of ZSCAN10 and the RNA exosome complex in maintaining pluripotent stem cell redox status to support a normal DNA damage response.

Highlights

The RNA exosome complex is a central ring structure of six core proteins and three RNA-binding domain-containing core proteins (Kilchert et al, 2016; Makino et al, 2015) that removes aberrantly accumulated RNA transcripts to prevent events such as altered splicing (Coy et al, 2013), autoimmune response activation (Eckard et al, 2014), and genomic instability caused by RNA-DNA hybridization (Wahba et al, 2013)
We found that induced pluripotent stem cells (Takahashi and Yamanaka, 2006) derived from older donor cells (A-iPSCs; using mouse skin fibroblasts from donors 1.4 years of age) retain an aging-associated epigenetic signature that is not present in iPSCs derived from young donor cells (Y-iPSCs; using mouse skin fibroblasts from E15.5 embryos to 5-day-old neonates) (Skamagki et al, 2017; Kim et al, 2010, 2011)
We found that ZSCAN10 directly binds to the promoters of RNA exosome subunits to stimulate their expression, and that A-iPSCs show poor expression of core RNA exosome subunits due to poor ZSCAN10 expression, which could result in dysfunctional RNA exosome function in A-iPSCs (Figure S1)

Summary

Introduction

The RNA exosome complex is a central ring structure of six core proteins and three RNA-binding domain-containing core proteins (Kilchert et al, 2016; Makino et al, 2015) that removes aberrantly accumulated RNA transcripts to prevent events such as altered splicing (Coy et al, 2013), autoimmune response activation (Eckard et al, 2014), and genomic instability caused by RNA-DNA hybridization (Wahba et al, 2013). The RNA exosome complex is highly conserved in eukaryotic cells and functions in both the nucleus and the cytoplasm (Schmid and Jensen, 2008). Recent reports have shown that the RNA exosome complex targets specific RNA transcripts in response to environmental changes during embryo development (Kilchert et al, 2015). The targeting specificity of the RNA exosome complex was studied in embryonic stem cells (ESCs) by transcriptome analysis (Pefanis et al, 2015). That study showed that the exosome regulates long non-coding RNA transcripts that function as enhancer RNAs to control gene transcription. We utilized A-iPSCs to test the hypothesis that ZSCAN10 regulates gene transcription in PSCs via the RNA exosome complex, focusing on glutathione peroxidase 2 (GPX2) as a downstream target that influences the DNA damage response pathway

Results

Discussion

Conclusion