A04: Consequences of age-related G-quadruplex formation for the fidelity of mammalian transcription

Epigenetic alterations and genome instability are hallmarks of aging and cancer but their potential interlinkage and impact on transcriptional fidelity is not known. By developing specialized high-throughput sequencing technologies, we uncovered for the first time an association of DNA G-quadruplex (G4) structures with DNA accessibility in highly transcribed regulatory regions. Sirtuin activity is critically lost during aging. Some sirtuins have been shown to control the activity of helicases that can resolve G4 and R-loop structures. Failure of helicases to resolve G4s results in genome instability and DNA/RNA polymerase stalling. We provide preliminary evidence that loss of sirtuin function causes elevated G4 formation occupied by inactivated helicases in human and murine accelerated aging models. We hypothesize that sirtuin dysfunction promotes increased G4 and R-loop levels through inactivation of DNA and RNA helicases, leading to compromised transcription and misfolding of proteins. Our goal here is to unravel this novel aging-related mechanism for the fidelity of mRNA and protein homeostasis and demonstrate its proof-of-principle significance for a replicative senescence model. To achieve this, we will systematically perturb sirtuins, identify regulated helicases and determine the resulting G4 and R-loop structures genome-wide. We will assess their relationships to fidelity of RNA transcription and protein production by examining system-wide changes in transcriptional errors and protein folding.