A dominant mutation in the gene coding for the vesicle-associated membrane protein-associated protein B (VAPB) was associated with amyotrophic lateral sclerosis, a fatal paralytic disorder characterized by the selective loss of motoneurons in the brain and spinal cord. Adeno-associated viral vectors that we show to transduce up to 90% of motoneurons in vitro were used to model VAPB-associated neurodegenerative process. We observed that Adeno-associated viral-mediated over-expression of both wild-type and mutated form of human VAPB selectively induces death of primary motoneurons, albeit with different kinetics. We provide evidence that ER stress and impaired homeostatic regulation of calcium (Ca2+) are implicated in the death process. Finally, we found that completion of the motoneuron death program triggered by the over-expression of wild-type and mutant VAPB implicates calpains, caspase 12 and 3. Our viral-based in vitro model, which recapitulates the selective vulnerability of motoneurons to the presence of mutant VAPB and also to VAPB gene dosage effect, identifies aberrant Ca2+ signals and ER-derived death pathways as important events in the motoneuron degenerative process.
Bruno Lemaitre, Samuel Rommelaere, Florent François Masson, Juan Camilo Paredes Escobar, Mario Gonzalo Garcia Arraez
Christof Holliger, Julien Maillard, Mathilde Stéphanie Willemin, Lorenzo Cimmino
Didier Trono, Evaristo Jose Planet Letschert, Julien Léonard Duc, Alexandre Coudray, Julien Paul André Pontis, Delphine Yvette L Grun, Cyril David Son-Tuyên Pulver, Shaoline Sheppard