Homozygous ALS-linked mutations in TARDBP/TDP-43 lead to hypoactivity and synaptic abnormalities in human iPSC-derived motor neurons

Sarah Lépine; Angela Nauleau-Javaudin; Eric Deneault; Carol X-Q Chen; Narges Abdian; Anna Krystina Franco-Flores; Ghazal Haghi; María José Castellanos-Montiel; Gilles Maussion; Mathilde Chaineau; Thomas Martin Durcan

doi:10.1016/j.isci.2024.109166

Homozygous ALS-linked mutations in TARDBP/TDP-43 lead to hypoactivity and synaptic abnormalities in human iPSC-derived motor neurons

iScience. 2024 Feb 9;27(3):109166. doi: 10.1016/j.isci.2024.109166. eCollection 2024 Mar 15.

Affiliations

¹ Early Drug Discovery Unit (EDDU), The Neuro-Montreal Neurological Institute and Hospital, Department of Neurology and Neurosurgery, McGill University, Montreal, QC H3A 1A1, Canada.
² Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3G 2M1, Canada.
³ Faculty of Medicine, Université de Montréal, Montreal, QC H3C 3J7, Canada.
⁴ Centre for Oncology, Radiopharmaceuticals and Research; Biologic and Radiopharmaceutical Drugs Directorate, Health Products and Food Branch, Health Canada, Ottawa, ON K1A 0K9, Canada.

Abstract

Cytoplasmic mislocalization and aggregation of the RNA-binding protein TDP-43 is a pathological hallmark of the motor neuron (MN) disease amyotrophic lateral sclerosis (ALS). Furthermore, while mutations in TARDBP (encoding TDP-43) have been associated with ALS, the pathogenic consequences of these mutations remain poorly understood. Using CRISPR-Cas9, we engineered two homozygous knock-in induced pluripotent stem cell lines carrying mutations in TARDBP encoding TDP-43^A382T and TDP-43^G348C, two common yet understudied ALS TDP-43 variants. Motor neurons (MNs) differentiated from knock-in iPSCs had normal viability and displayed no significant changes in TDP-43 subcellular localization, phosphorylation, solubility, or aggregation compared with isogenic control MNs. However, our results highlight synaptic impairments in both TDP-43^A382T and TDP-43^G348C MN cultures, as reflected in synapse abnormalities and alterations in spontaneous neuronal activity. Collectively, our findings suggest that MN dysfunction may precede the occurrence of TDP-43 pathology and neurodegeneration in ALS and further implicate synaptic and excitability defects in the pathobiology of this disease.

Keywords: Cellular neuroscience; Molecular neuroscience.