NuSEN · Persistent rDNA damage in senescence: Linking nucleolar dysfunction to genome instability and inflammatory signaling

Ribosomal DNA (rDNA) encodes the ribosomal RNAs essential for protein synthesis and thus for cell growth and maintenance. Owing to its repetitive nature, high GC content, and intense transcriptional activity, rDNA is among the most fragile genomic regions and is normally safeguarded by a specialized nucleolar DNA damage response (n-DDR). In senescent cells, however, persistent rDNA damage accumulates, coinciding with genomic instability and the chronic activation of inflammatory signaling pathways that drive the senescence-associated secretory phenotype (SASP). SASP has strong tumour-promoting effects and contributes to malignancy and therapy resistance. Despite these observations, the causes of persistent rDNA damage in senescence and its connection to genome instability and SASP remain poorly understood.This project will address this critical gap by investigating whether the profound remodeling of the nucleolus during senescence, including structural reorganization and rRNA hyper-transcription, impairs the fidelity of n-DDR and compromises rDNA stability. Using an oncogene-induced senescence model, I will pursue three objectives: (1) test how nucleolar reorganization and elevated rRNA transcription affect n-DDR fidelity using advanced imaging and quantitative proteomics, (2) identify structural alterations and mutational signatures that accumulate at rDNA loci through long-read sequencing and computational analysis, and (3) establish the causal link between rDNA damage and SASP activation by applying genomic approaches and targeted perturbations.This project will deliver the first mechanistic framework for nucleolar genome instability in senescence. Beyond advancing our understanding of genome maintenance, it may reveal novel biomarkers of senescence and uncover therapeutic opportunities to reprogram or suppress the pro-cancerous activities of senescent cells, thereby contributing to strategies that reduce cancer burden.