V-089 | Modelling UBQLN2-linked or related neurodegeneration with patient-derived induced pluripotent stem cells

Disorders of the Nervous System
Author: Micaela Nievas | Email: micnievas@gmail.com

Micaela Nievas^1°, Barbara Weil^1°,Mercedes Vautier^1°, Ana Czerniczyniec^1°, Nahuel Magrath-Guimet^2°, Ricardo Allegri^2°, Tatiana Itzcovich^3°, Gustavo Sevlever^1°3°, Ezequiel Surace^3°, Mariela Marazita^1°

^1° Laboratorios de Investigación Aplicada en Neurociencias, Instituto de Neurociencias, Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (LIAN-INEU-Fleni-CONICET), Escobar, Provincia de Buenos Aires, Argentina.
^2° Department of Cognitive Neurology, Neuropsychiatry and Neuropsychology (Fleni), Buenos Aires, Argentina.
^3° Laboratory of Neurodegenerative Diseases- Institute of Neurosciences (INEU-Fleni- CONICET), Buenos Aires, Argentin

Ubiquilin-2 (UBQLN2) pathogenic variants are implicated in hereditary Frontotemporal Dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS). However, the molecular mechanisms by which UBQLN2 variants contribute to neurodegeneration remain largely unknown. This study aimed to establish an in vitro model of FTD/ALS by reprogramming patient somatic cells and differentiating them into a neural lineage. Fibroblasts were obtained from a male patient carrying two novel hemizygous UBQLN2 variants. Using the EF1a-hSTEMCCA-loxP lentiviral vector expressing OCT4, SOX2, c-MYC, and KLF4, we reprogrammed the cells in a feeder- and xeno-free protocol. Sequencing confirmed the presence of the variants in the selected iPSC clone (FFDU), which exhibited a normal karyotype (46, XY). Stemness was validated by established protocols. We further differentiated FFDU and iPSCs from a healthy donor into neural stem cells (NSCs). Western blot and IF studies revealed higher UBQLN2 protein levels and cytoplasmic inclusions in FFDU-NSCs, while levels of SOD2, HSP70, and SIRT1—essential proteins involved in oxidative stress management, protein folding, and cellular survival—were lower compared to WT cells. Our data suggest that these novel variants result in UBQLN2 accumulation and disruption in protective mechanisms against cellular stress that may contribute to neurodegeneration. This model is a valuable tool for exploring FTD/ALS pathogenic mechanisms and potential therapeutic approaches.