title: Endothelin-1 is over-expressed in amyotrophic lateral sclerosis and induces motor neuron cell death.
abstract: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by progressive loss of motor neurons (MNs) and astrogliosis. Recent evidence suggests that factors secreted by activated astrocytes might contribute to degeneration of MNs. We focused on endothelin-1 (ET-1), a peptide which is strongly up-regulated in reactive astrocytes under different pathological conditions. We show that ET-1 is abundantly expressed by reactive astrocytes in the spinal cord of the SOD1-G93A mouse model and sporadic ALS patients. To test if ET-1 might play a role in degeneration of MNs, we investigated its effect on MN survival in an in vitro model of mixed rat spinal cord cultures (MSCs) enriched of astrocytes exhibiting a reactive phenotype. ET-1 exerted a toxic effect on MNs in a time- and concentration-dependent manner, with an exposure to 100-200nM ET-1 for 48h resulting in 40-50% MN cell death. Importantly, ET-1 did not induce MN degeneration when administered on cultures treated with AraC (5μM) or grown in a serum-free medium that did not favor astrocyte proliferation and reactivity. We found that both ETA and ETB receptors are enriched in astrocytes in MSCs. The ET-1 toxic effect was mimicked by ET-3 (100nM) and sarafotoxin S6c (10nM), two selective agonists of endothelin-B receptors, and was not additive with that of ET-3 suggesting the involvement of ETB receptors. Surprisingly, however, the ET-1 effect persisted in the presence of the ETB receptor antagonist BQ-788 (200nM-2μM) and was slightly reversed by the ETA receptor antagonist BQ-123 (2μM), suggesting an atypical pharmacological profile of the astrocytic receptors responsible for ET-1 toxicity. The ET-1 effect was not undone by the ionotropic glutamate receptor AMPA antagonist GYKI 52466 (20μM), indicating that it is not caused by an increased glutamate release. Conversely, a 48-hour ET-1 treatment increased MN cell death induced by acute exposure to AMPA (50μM), which is indicative of two distinct pathways leading to neuronal death. Altogether these results indicate that ET-1 exerts a toxic effect on cultured MNs through mechanisms mediated by reactive astrocytes and suggest that ET-1 may contribute to MN degeneration in ALS. Thus, a treatment aimed at lowering ET-1 levels or antagonizing its effect might be envisaged as a potential therapeutic strategy to slow down MN degeneration in this devastating disease.
authors.affiliation: Institute of Neurological Sciences, National Research Council (ISN-CNR), Catania, Italy; PhD Program in Neurobiology, University of Catania, Catania, Italy.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Ranno
authors.affiliation: Institute of Neurological Sciences, National Research Council (ISN-CNR), Catania, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: D'Antoni
authors.affiliation: Institute of Neurological Sciences, National Research Council (ISN-CNR), Catania, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Spatuzza
authors.affiliation: Institute of Neurological Sciences, National Research Council (ISN-CNR), Catania, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Berretta
authors.affiliation: Department of Biomedical Sciences, Section of Physiology, University of Catania, Catania, Italy.
authors.forename: Floriana
authors.initials: F
authors.lastname: Laureanti
authors.affiliation: IRCCS Oasi Maria SS, Troina (EN), Italy.
authors.forename: Carmela M
authors.initials: CM
authors.lastname: Bonaccorso
authors.affiliation: Institute of Neurological Sciences, National Research Council (ISN-CNR), Catania, Italy.
authors.forename: Rosalia
authors.initials: R
authors.lastname: Pellitteri
authors.affiliation: Molecular Neurobiology Unit, Experimental Neurology, Fondazione Santa Lucia, Rome, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Longone
authors.affiliation: Molecular Neurobiology Unit, Experimental Neurology, Fondazione Santa Lucia, Rome, Italy.
authors.forename: Alida
authors.initials: A
authors.lastname: Spalloni
authors.affiliation: Department of (Neuro) Pathology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Anand M
authors.initials: AM
authors.lastname: Iyer
authors.affiliation: Department of (Neuro) Pathology, Academic Medical Center, Amsterdam, The Netherlands; Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, The Netherlands.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Aronica
authors.affiliation: Institute of Neurological Sciences, National Research Council (ISN-CNR), Catania, Italy; IRCCS Oasi Maria SS, Troina (EN), Italy. Electronic address: mariavincenza.catania@cnr.it.
authors.forename: Maria Vincenza
authors.initials: MV
authors.lastname: Catania
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000473:pathology*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian; D019332:Endothelin-1 / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008875:Middle Aged; D009046:Motor Neurons / Q000187:drug effects*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000166:cytology; D013482:Superoxide Dismutase / Q000235:genetics; D013997:Time Factors
chemical_list: D019332:Endothelin-1; C109415:SOD1 G93A protein; D013482:Superoxide Dismutase
keywords: Amyotrophic lateral sclerosis; Astrocyte; Endothelin; Motor neuron; Reactive gliosis