title: Complexity of astrocyte-motor neuron interactions in amyotrophic lateral sclerosis.
abstract: Neurons and surrounding glial cells compose a highly specialized functional unit. In amyotrophic lateral sclerosis (ALS) astrocytes interact with motor neurons in a complex manner to modulate neuronal survival. Experiments using chimeric mice expressing ALS-linked mutations to Cu,Zn superoxide dismutase (SOD-1) suggest a critical modulation exerted by neighboring non-neuronal cell types on disease phenotype. When perturbed by primary neuronal damage, e.g. expression of SOD-1 mutations, neurons can signal astrocytes to proliferate and become reactive. Fibroblast growth factor-1 (FGF-1) can be released by motor neurons in response to damage to induce astrocyte activation by signaling through the receptor FGFR1. FGF-1 stimulates nerve growth factor (NGF) expression and secretion, as well as activity of the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor. Nrf2 leads to the expression of antioxidant and cytoprotective enzymes such as heme oxygenase-1 and a group of enzymes involved in glutathione metabolism that prevent motor neuron degeneration. However, prolonged stimulation with FGF-1 or SOD-mediated oxidative stress in astrocytes may disrupt the normal neuron-glia interactions and lead to progressive neuronal degeneration. The re-expression of p75 neurotrophin receptor and neuronal NOS in motor neurons in parallel with increased NGF secretion by reactive astrocytes may be a mechanism to eliminate critically damaged neurons. Consequently, astrocyte activation in ALS may have a complex pathogenic role.
authors.affiliation: Departamento de Neurobiología Celular y Molecular, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay.
authors.forename: Mariana
authors.initials: M
authors.lastname: Pehar
authors.forename: Marcelo R
authors.initials: MR
authors.lastname: Vargas
authors.forename: Patricia
authors.initials: P
authors.lastname: Cassina
authors.forename: Ana G
authors.initials: AG
authors.lastname: Barbeito
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Beckman
authors.forename: Luis
authors.initials: L
authors.lastname: Barbeito
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000473:pathology / Q000503:physiopathology*; D000818:Animals; D001253:Astrocytes / Q000378:metabolism* / Q000473:pathology; D002450:Cell Communication / Q000502:physiology*; D016923:Cell Death / Q000502:physiology; D016220:Fibroblast Growth Factor 1 / Q000378:metabolism; D005911:Gliosis / Q000378:metabolism; D006801:Humans; D051379:Mice; D009046:Motor Neurons / Q000378:metabolism* / Q000473:pathology; D020932:Nerve Growth Factor / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics; D000072105:Superoxide Dismutase-1
chemical_list: C000606290:SOD1 protein, human; D016220:Fibroblast Growth Factor 1; D020932:Nerve Growth Factor; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1