037 | Analysis of the activation of the unfolded protein response pathways in cellular models of TDP-43 proteinopathies

Cellular and Molecular Neurobiology

Author: Mauricio Norman Montenegro | Email: mauricio.montenegro909@gmail.com

Mauricio Montenegro 1°2°, Analia Amante , Antonella Vila , Matías Blaustein , Lionel Muller Igaz 1°2°

1° Universidad de Buenos Aires, Facultad de Ciencias Médicas, Departamento de Ciencias Fisiológicas. Grupo de Neurociencia de Sistemas. Buenos Aires, Argentina.
2° CONICET – Universidad de Buenos Aires. Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay). Buenos Aires, Argentina.
3° Instituto de Biociencias, Biotecnología y Biología traslacional (iB3), Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires.

The abnormal aggregation of TDP-43 into cytoplasmic inclusions in affected neurons is a pathological hallmark of a group of neurodegenerative diseases called TDP-43 proteinopathies, which include amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Recent evidence suggests that endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) are important players in ALS/FTD aetiology. The accumulation of unfolded proteins in the ER induces three signaling cascades initiated by the transmembrane proteins IRE1, ATF6 and PERK. To study the role of the UPR in TDP-43-mediated pathogenesis we used HEK293 cells overexpressing wild-type, nuclear TDP-43 or a cytoplasmic form of TDP-43 which recapitulate key ALS/FTD features. Biochemical analysis of endogenous UPR components were performed to study the effects of TDP-43 dysregulation on UPR activity. Our Western Blot results using the ER stressor tunicamycin (Tn) show the activation of the UPR branches IRE1/xBP1 and PERK/ATF4. However, expression of TDP-43 variants does not significantly alter the activation of these UPR pathways under basal and Tn-induced conditions. We are currently performing immunocytochemistry experiments to analyze UPR activation combined with TDP-43 overexpression on a cell-by-cell fashion. Lastly, we also want to pursue these studies in neuroblastoma Neuro2a cells, which show neuronal-like features. These experiments will contribute to understand the role of UPR activation in ALS/FTD.