ASO therapy rescues NOTCH2NLC GGC repeat expansion-induced genomic damage, 3D chromatin structural abnormalities, and senescence

Neuronal intranuclear inclusion disease is caused by abnormal GGC repeat expansion in the NOTCH2NLC gene, though its pathogenic mechanism remains incompletely understood. This study shows that the abnormally expanded polyG-uN2C protein, encoded by the repeat sequence, contains intrinsically disordered regions and forms aggregates, leading to mislocalization of nucleophosmin and downregulation of fibrillarin. PolyG aggregates interact with nucleophosmin and rRNA, disrupting ribosomal homeostasis. Furthermore, polyG facilitates the downregulation of chromatin structural proteins CTCF and RAD21, thereby impairing chromatin organization. This pathological manifestation can be mitigated by restoring CTCF/RAD21 expression. Furthermore, in brain organoids derived from neuronal intranuclear inclusion disease patients, we observe nucleolar stress accompanied by genome-wide chromatin structural alterations. These changes correlate with increased DNA damage and cellular senescence phenotypes. Notably, antisense oligonucleotides targeting GGC effectively reduce polyG aggregation and ameliorate related molecular defects, ultimately alleviating senescence-associated phenotypes. These findings establish key mechanisms underlying neuronal intranuclear inclusion disease pathogenesis and provide proof-of-concept for targeted therapy.