Dataset Information

Distinct roles for motor neuron autophagy early and late in the SOD1G93A mouse model of ALS.

ABSTRACT: Mutations in autophagy genes can cause familial and sporadic amyotrophic lateral sclerosis (ALS). However, the role of autophagy in ALS pathogenesis is poorly understood, in part due to the lack of cell type-specific manipulations of this pathway in animal models. Using a mouse model of ALS expressing mutant superoxide dismutase 1 (SOD1G93A), we show that motor neurons form large autophagosomes containing ubiquitinated aggregates early in disease progression. To investigate whether this response is protective or detrimental, we generated mice in which the critical autophagy gene Atg7 was specifically disrupted in motor neurons (Atg7 cKO). Atg7 cKO mice were viable but exhibited structural and functional defects at a subset of vulnerable neuromuscular junctions. By crossing Atg7 cKO mice to the SOD1G93A mouse model, we found that autophagy inhibition accelerated early neuromuscular denervation of the tibialis anterior muscle and the onset of hindlimb tremor. Surprisingly, however, lifespan was extended in Atg7 cKO; SOD1G93A double-mutant mice. Autophagy inhibition did not prevent motor neuron cell death, but it reduced glial inflammation and blocked activation of the stress-related transcription factor c-Jun in spinal interneurons. We conclude that motor neuron autophagy is required to maintain neuromuscular innervation early in disease but eventually acts in a non-cell-autonomous manner to promote disease progression.

SUBMITTER: Rudnick ND

PROVIDER: S-EPMC5625902 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Distinct roles for motor neuron autophagy early and late in the SOD1<sup>G93A</sup> mouse model of ALS.

Rudnick Noam D ND Griffey Christopher J CJ Guarnieri Paolo P Gerbino Valeria V Wang Xueyong X Piersaint Jason A JA Tapia Juan Carlos JC Rich Mark M MM Maniatis Tom T

Proceedings of the National Academy of Sciences of the United States of America 20170913 39

Mutations in autophagy genes can cause familial and sporadic amyotrophic lateral sclerosis (ALS). However, the role of autophagy in ALS pathogenesis is poorly understood, in part due to the lack of cell type-specific manipulations of this pathway in animal models. Using a mouse model of ALS expressing mutant superoxide dismutase 1 (SOD1<sup>G93A</sup>), we show that motor neurons form large autophagosomes containing ubiquitinated aggregates early in disease progression. To investigate whether th ...[more]

PMID: 28904095

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Project description:BACKGROUND:The development of new therapeutic strategies to treat amyotrophic lateral sclerosis (ALS) is of utmost importance. The use of cyclic nitroxides such as tempol may provide neuroprotection and improve lifespan. We investigated whether tempol (50 mg/kg) presents therapeutic potential in SOD1G93A transgenic mice. METHODS:Tempol treatment began at the asymptomatic phase of the disease (10th week) and was administered every other day until week 14, after which it was administered twice a week until the final stage of the disease. The animals were sacrificed at week 14 (initial stage of symptoms-ISS) and at the end stage (ES) of the disease. The lumbar spinal cord of the animals was dissected and processed for use in the following techniques: Nissl staining to evaluate neuronal survival; immunohistochemistry to evaluate astrogliosis and microgliosis (ISS and ES); qRT-PCR to evaluate the expression of neurotrophic factors and pro-inflammatory cytokines (ISS); and transmission electron microscopy to evaluate the alpha-motoneurons (ES). Behavioral analyses considering the survival of animals, bodyweight loss, and Rotarod motor performance test started on week 10 and were performed every 3 days until the end-stage of the disease. RESULTS:The results revealed that treatment with tempol promoted greater neuronal survival (23%) at ISS compared to untreated animals, which was maintained until ES. The intense reactivity of astrocytes and microglia observed in vehicle animals was reduced in the lumbar spinal cords of the animals treated with tempol. In addition, the groups treated with tempol showed reduced expression of proinflammatory cytokines (IL1β and TNFα) and a three-fold decrease in the expression of TGFβ1 at ISS compared with the group treated with vehicle. CONCLUSIONS:Altogether, our results indicate that treatment with tempol has beneficial effects, delaying the onset of the disease by enhancing neuronal survival and decreasing glial cell reactivity during ALS progression in SOD1G93A mice.

Dataset Information

Distinct roles for motor neuron autophagy early and late in the SOD1G93A mouse model of ALS.

Publications

Distinct roles for motor neuron autophagy early and late in the SOD1<sup>G93A</sup> mouse model of ALS.

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