title: SMN deficiency does not induce oxidative stress in SMA iPSC-derived astrocytes or motor neurons.
abstract: Spinal muscular atrophy (SMA) is a genetic disorder characterized by loss of motor neurons in the spinal cord leading to muscle atrophy and death. Although motor neurons (MNs) are the most obviously affected cells in SMA, recent evidence suggest dysfunction in multiple cell types. Astrocytes are a crucial component of the motor circuit and are intimately involved with MN health and maintenance. We have previously shown that SMA astrocytes are altered both morphologically and functionally early in disease progression, though it is unclear what causes astrocytes to become reactive. Oxidative stress is a common feature among neurodegenerative diseases. Oxidative stress can both induce apoptosis in neurons and can cause astrocytes to become reactive, which are features observed in the SMA induced pluripotent stem cell (iPSC) cultures. Therefore, we asked if oxidative stress contributes to SMA astrocyte pathology. We examined mitochondrial bioenergetics, transcript and protein levels of oxidative and anti-oxidant factors, and reactive oxygen species (ROS) production and found little evidence of oxidative stress. We did observe a significant increase in endogenous catalase expression in SMA iPSCs. While catalase knockdown in SMA iPSCs increased ROS production above basal levels, levels of ROS remained lower than in controls, further arguing against robust oxidative stress in this system. Viral delivery of survival motor neuron (SMN) reversed astrocyte activation and restored catalase levels to normal, without changing mitochondrial respiration or expression of oxidative stress markers. Taken together, these data indicate that SMN deficiency induces astrocyte reactivity, but does not do so through an oxidative stress-mediated process.
authors.affiliation: Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, USA.
authors.forename: Teresa N
authors.initials: TN
authors.lastname: Patitucci
authors.affiliation: Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, USA aebert@mcw.edu.
authors.forename: Allison D
authors.initials: AD
authors.lastname: Ebert
mesh_terms: D001253:Astrocytes / Q000378:metabolism* / Q000473:pathology; D002374:Catalase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D005786:Gene Expression Regulation; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000378:metabolism* / Q000473:pathology; D008928:Mitochondria / Q000378:metabolism*; D009046:Motor Neurons / Q000378:metabolism* / Q000473:pathology; D009134:Muscular Atrophy, Spinal / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D058953:Neural Stem Cells / Q000378:metabolism* / Q000473:pathology; D010085:Oxidative Phosphorylation; D018384:Oxidative Stress; D061251:Primary Cell Culture; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013116:Spinal Cord / Q000378:metabolism / Q000473:pathology; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000094765:Glutathione Peroxidase GPX1
chemical_list: D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; C000609392:GCLC protein, human; D005721:Glutamate-Cysteine Ligase; D000094765:Glutathione Peroxidase GPX1; C000722067:GPX1 protein, human