Novel proteomics and neuropathology of NOTCH2NLC-related neuronal intranuclear inclusion disease.

BACKGROUND

Nucleotide repeat expansion disorders constitute a group of clinically and genetically heterogeneous diseases, pathologically characterized by the misfolding, aggregation, and accumulation of proteins. The expanded GGC repeats in the 5' untranslated region (5'UTR) of the NOTCH2NLC gene translate into uN2CpolyG, a toxic polyglycine protein that leads to neuronal intranuclear inclusion disease (NIID). However, the precise composition of uN2CpolyG and its pathogenic mechanisms remain fully unclear.

OBJECTIVES

We aimed to investigate the proteomic profile of uN2CpolyG and explore the novel neuropathology in NIID patients, which may underlie the disease pathogenesis.

METHODS

Mass spectrometry analysis was performed on purified intranuclear inclusions to investigate the proteomic profile. Three patients with genetically confirmed NIID were enrolled; two participants underwent skin biopsy, and one underwent brain autopsy. Skin and brain tissues derived from these patients were used to examine NOTCH2NLC-related pathological changes.

RESULTS

A group of enriched proteins interacting with uN2CpolyG were identified, characterized by significant intrinsically disordered regions (IDRs). Among these, we detected the co-localization of uN2CpolyG with PML and FUS in notably distinct patterns, causing significant DNA damage and impaired stress response. Furthermore, FUS- and PML-positive inclusions were confirmed in NIID patients' tissues.

CONCLUSION

Our findings provide novel insights into the proteomic profile and neuropathology of NIID, potentially enlightening the pathogenesis and therapeutic strategies for protein aggregation-related neurodegenerative diseases.