RNA G-quadruplex(rG4) exacerbates cellular senescence by mediating ribosome pausing [RNA-seq]

Ribosome pausing plays a crucial role in the collapse of proteostasis, which is a prominent characteristic of cellular senescence. However, the understanding of ribosome pausing in senescent cells remains limited. In this study, we utilized ribosome profiling and G-quadruplex RNA immunoprecipitation sequencing techniques to investigate the impact of RNA G-quadruplex (rG4) on the translation efficiency of genes in senescent cells. Our findings reveal a decrease in the translation efficiency of genes enriched with rG4 in senescent cells. Meanwhile, we developed a dual fluorescence reporter system to demonstrate the ability of rG4 to halt ribosome translation both in vivo and in vitro. Moreover, a noteworthy augmentation in the prevalence of rG4 abundance was observed in senescent cells, and the reinforcement of the rG4 structure further exacerbates the process of cellular senescence. Additionally, the RNA helicase DHX9 was identified as a crucial regulator of rG4 abundance, and its reduced expression in senescent cells exacerbates the occurrence of ribosome pausing. Intriguingly, we also observed an augmented abundance of rG4, an imbalance in protein homeostasis, and a decrease in DHX9 expression in the fibroblast cells and highly aged tissues of aging mice. In summary, our findings reveal a novel biological role of rG4 and DHX9 in the regulation of ribosome translation and proteostasis, potentially providing implications for the postponement of cellular senescence and ageing.