Project description:Whether RNA G-quadruplexes (rG4) form extensively in vivo and what roles they play remain actively debated. Among their proposed functions is recognition of Polycomb repressive complex 2 (PRC2), but how the interaction results in epigenetic regulation is not understood. Here we demonstrate that rG4s form dynamically during ES cell differentiation and require ATRX’s helicase function to unwind competing secondary structures. Mutating ATRX causes rG4 depletion on a transcriptome-wide basis and dramatically increases gene expression. We identify and mutate rG4s within Xist RNA and mechanistically separate PRC2’s recruitment versus catalysis. Surprisingly, although rG4s recruit PRC2, unfolding the rG4 structure causes PRC2 hyperactivation, entrapment of PRC2 in the S1 chromosomal compartment, and loss of gene silencing. Thus, we link dynamic rG4 folding and unfolding to PRC2 recruitment, trans-compartmental Xist migration, regulated activation of PRC2, and whole-chromosome gene silencing.
Project description:Whether RNA G-quadruplexes (rG4) form extensively in vivo and what roles they play remain actively debated. Among their proposed functions is recognition of Polycomb repressive complex 2 (PRC2), but how the interaction results in epigenetic regulation is not understood. Here we demonstrate that rG4s form dynamically during ES cell differentiation and require ATRX’s helicase function to unwind competing secondary structures. Mutating ATRX causes rG4 depletion on a transcriptome-wide basis and dramatically increases gene expression. We identify and mutate rG4s within Xist RNA and mechanistically separate PRC2’s recruitment versus catalysis. Surprisingly, although rG4s recruit PRC2, unfolding the rG4 structure causes PRC2 hyperactivation, entrapment of PRC2 in the S1 chromosomal compartment, and loss of gene silencing. Thus, we link dynamic rG4 folding and unfolding to PRC2 recruitment, trans-compartmental Xist migration, regulated activation of PRC2, and whole-chromosome gene silencing.
Project description:Whether RNA G-quadruplexes (rG4) form extensively in vivo and what roles they play remain actively debated. Among their proposed functions is recognition of Polycomb repressive complex 2 (PRC2), but how the interaction results in epigenetic regulation is not understood. Here we demonstrate that rG4s form dynamically during ES cell differentiation and require ATRX’s helicase function to unwind competing secondary structures. Mutating ATRX causes rG4 depletion on a transcriptome-wide basis and dramatically increases gene expression. We identify and mutate rG4s within Xist RNA and mechanistically separate PRC2’s recruitment versus catalysis. Surprisingly, although rG4s recruit PRC2, unfolding the rG4 structure causes PRC2 hyperactivation, entrapment of PRC2 in the S1 chromosomal compartment, and loss of gene silencing. Thus, we link dynamic rG4 folding and unfolding to PRC2 recruitment, trans-compartmental Xist migration, regulated activation of PRC2, and whole-chromosome gene silencing.
Project description:Whether RNA G-quadruplexes (rG4) form extensively in vivo and what roles they play remain actively debated. Among their proposed functions is recognition of Polycomb repressive complex 2 (PRC2), but how the interaction results in epigenetic regulation is not understood. Here we demonstrate that rG4s form dynamically during ES cell differentiation and require ATRX’s helicase function to unwind competing secondary structures. Mutating ATRX causes rG4 depletion on a transcriptome-wide basis and dramatically increases gene expression. We identify and mutate rG4s within Xist RNA and mechanistically separate PRC2’s recruitment versus catalysis. Surprisingly, although rG4s recruit PRC2, unfolding the rG4 structure causes PRC2 hyperactivation, entrapment of PRC2 in the S1 chromosomal compartment, and loss of gene silencing. Thus, we link dynamic rG4 folding and unfolding to PRC2 recruitment, trans-compartmental Xist migration, regulated activation of PRC2, and whole-chromosome gene silencing.
Project description:Guanine (G)-rich nucleic acids can fold into G-quadruplex (G4) structures under permissive conditions. Although many RNAs contain sequences that fold into RNA G4s (rG4s) in vitro, their folding and functions in vivo are not well understood. Here, we showed that the folding of putative rG4s in human cells into rG4 structures was dynamically induced by stress. By using high-throughput dimethylsulfate probing, we identified hundreds of endogenous stress-induced rG4s. Our results demonstrated that stress-induced rG4s were enriched in mRNA 3′-untranslated regions and enhanced mRNA stability. Furthermore, stress-induced rG4 folding was readily reversible upon stress removal. In summary, our study revealed the dynamic regulation of rG4 folding in living human cells and suggests suggested that widespread rG4 motifs may have a global regulatory impact on mRNA stability and cellular stress response.