Project description:Endogenous retrovirus MERVL is specifically expressed in a minority of embryonic stem cells. To determine the restrain mechanism of MERVL, we knocked out Ssrp1 and analyzed the effect on the expression of transposable elements and coding genes.
Project description:Endogenous retrovirus MERVL is specifically expressed in a minority of embryonic stem cells. To determine the restrain mechanism of MERVL, we knocked out Ssrp1 and analyzed the effect on the expression of transposable elements and coding genes. Ssrp1 further interacts with ubiquitin specific protease Usp7. We knocked down usp7 and analyzed the effect on the expression of MERVL. It turns out the deletion of ssrp1 or usp7 would lead to upregulation of MERVL. This study extends our understandings of the machanism by novel factors regulates MERVL.
Project description:Endogenous retroviruses (ERVs) were usually silenced by various histone modifications on histone H3 variants and respective histone chaperones in embryonic stem cells (ESCs). However, it is still unknown whether chaperones of other histones could repress ERVs. Here, we show that H2A/H2B histone chaperone FACT plays a critical role in silencing ERVs and ERV-derived cryptic promoters in ESCs. Loss of FACT component Ssrp1 activated MERVL whereas the re-introduction of Ssrp1 rescued the phenotype. Additionally, Ssrp1 interacted with MERVL and suppressed cryptic transcription of MERVL-fused genes. Remarkably, Ssrp1 interacted with and recruited H2B deubiquitinase Usp7 to Ssrp1 target genes. Suppression of Usp7 caused similar phenotypes as loss of Ssrp1. Furthermore, Usp7 acted by deubiquitinating H2Bub and thereby repressed the expression of MERVL-fused genes. Taken together, our study uncovers a unique mechanism by which FACT complex silences ERVs and ERV-derived cryptic promoters in ESCs.
Project description:We have examined the nuclear (nuc) and cytoplasmic (cyt) polyA+ transcriptomes of undifferentiated mouse embryonic stem cells (un) and cells differentiated to neural precursors (d5) using strand-specific RNA-Seq. The 46C mouse embryonic stem cell line was used for this study.
Project description:We have examined the nuclear (nuc) and cytoplasmic (cyt) polyA+ transcriptomes of undifferentiated mouse embryonic stem cells (un) and cells differentiated to neural precursors (d5) using strand-specific RNA-Seq. The 46C mouse embryonic stem cell line was used for this study. Two cell types were examined: undifferentiated mouse embryonic stem cells (un) and cells differentiated to neural precursors (d5). For each cell type, cells were fractionated to nuclear and cytoplasmic components. RNAs were extracted from each component and were fragmented enzymatically for library construction. For each cell type and component, strand-specific RNA-Seq libraries were generated using at least two different fragmentation protocols.
Project description:FACT was discovered to be a repressor of transcription in mES cells. In addition, the murine endogenous retrovirus were repressed by various mechanisms. Hence, we examined the possibility for Ssrp1 as a repressor of MT2/MERVL.