title: Reactive oxygen species trigger motoneuron death in non-cell-autonomous models of ALS through activation of c-Abl signaling.
abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease in which pathogenesis and death of motor neurons are triggered by non-cell-autonomous mechanisms. We showed earlier that exposing primary rat spinal cord cultures to conditioned media derived from primary mouse astrocyte conditioned media (ACM) that express human SOD1(G93A) (ACM-hSOD1(G93A)) quickly enhances Nav channel-mediated excitability and calcium influx, generates intracellular reactive oxygen species (ROS), and leads to death of motoneurons within days. Here we examined the role of mitochondrial structure and physiology and of the activation of c-Abl, a tyrosine kinase that induces apoptosis. We show that ACM-hSOD1(G93A), but not ACM-hSOD1(WT), increases c-Abl activity in motoneurons, interneurons and glial cells, starting at 60 min; the c-Abl inhibitor STI571 (imatinib) prevents this ACM-hSOD1(G93A)-mediated motoneuron death. Interestingly, similar results were obtained with ACM derived from astrocytes expressing SOD1(G86R) or TDP43(A315T). We further find that co-application of ACM-SOD1(G93A) with blockers of Nav channels (spermidine, mexiletine, or riluzole) or anti-oxidants (Trolox, esculetin, or tiron) effectively prevent c-Abl activation and motoneuron death. In addition, ACM-SOD1(G93A) induces alterations in the morphology of neuronal mitochondria that are related with their membrane depolarization. Finally, we find that blocking the opening of the mitochondrial permeability transition pore with cyclosporine A, or inhibiting mitochondrial calcium uptake with Ru360, reduces ROS production and c-Abl activation. Together, our data point to a sequence of events in which a toxic factor(s) released by ALS-expressing astrocytes rapidly induces hyper-excitability, which in turn increases calcium influx and affects mitochondrial structure and physiology. ROS production, mediated at least in part through mitochondrial alterations, trigger c-Abl signaling and lead to motoneuron death.
authors.affiliation: Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello Santiago, Chile.
authors.forename: Fabiola
authors.initials: F
authors.lastname: Rojas
authors.affiliation: Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello Santiago, Chile.
authors.forename: David
authors.initials: D
authors.lastname: Gonzalez
authors.affiliation: Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello Santiago, Chile.
authors.forename: Nicole
authors.initials: N
authors.lastname: Cortes
authors.affiliation: Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello Santiago, Chile.
authors.forename: Estibaliz
authors.initials: E
authors.lastname: Ampuero
authors.affiliation: Faculty of Biological Sciences, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Diego E
authors.initials: DE
authors.lastname: Hernández
authors.affiliation: Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello Santiago, Chile.
authors.forename: Elsa
authors.initials: E
authors.lastname: Fritz
authors.affiliation: Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello Santiago, Chile.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Abarzua
authors.affiliation: Faculty of Biological Sciences, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Alexis
authors.initials: A
authors.lastname: Martinez
authors.affiliation: Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello Santiago, Chile ; Millennium Institute of Immunology and Immunotherapy Santiago, Chile.
authors.forename: Alvaro A
authors.initials: AA
authors.lastname: Elorza
authors.affiliation: Faculty of Biological Sciences, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Alvarez
authors.affiliation: Faculty of Biological Sciences, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Felipe
authors.initials: F
authors.lastname: Court
authors.affiliation: Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello Santiago, Chile.
authors.forename: Brigitte
authors.initials: B
authors.lastname: van Zundert
keywords: ALS; c-Abl; mitochondria; motor neuron; non-cell-autonomous; reactive oxygen species (ROS)