scholarly journals Oligodendrocytes contribute to motor neuron death in ALS via SOD1-dependent mechanism

2016 ◽  
Vol 113 (42) ◽  
pp. E6496-E6505 ◽  
Author(s):  
Laura Ferraiuolo ◽  
Kathrin Meyer ◽  
Thomas W. Sherwood ◽  
Jonathan Vick ◽  
Shibi Likhite ◽  
...  
Keyword(s):  
Motor Neuron ◽  
Lactate Production ◽  
Chromosome 9 ◽  
Neuron Death ◽  
Motor Neuron Death ◽  
Repeat Expansions ◽  
Human Oligodendrocytes ◽  
Lateral Sclerosis ◽  
Dependent Mechanism

Oligodendrocytes have recently been implicated in the pathophysiology of amyotrophic lateral sclerosis (ALS). Here we show that, in vitro, mutant superoxide dismutase 1 (SOD1) mouse oligodendrocytes induce WT motor neuron (MN) hyperexcitability and death. Moreover, we efficiently derived human oligodendrocytes from a large number of controls and patients with sporadic and familial ALS, using two different reprogramming methods. All ALS oligodendrocyte lines induced MN death through conditioned medium (CM) and in coculture. CM-mediated MN death was associated with decreased lactate production and release, whereas toxicity in coculture was lactate-independent, demonstrating that MN survival is mediated not only by soluble factors. Remarkably, human SOD1 shRNA treatment resulted in MN rescue in both mouse and human cultures when knockdown was achieved in progenitor cells, whereas it was ineffective in differentiated oligodendrocytes. In fact, early SOD1 knockdown rescued lactate impairment and cell toxicity in all lines tested, with the exclusion of samples carrying chromosome 9 ORF 72 (C9orf72) repeat expansions. These did not respond to SOD1 knockdown nor did they show lactate release impairment. Our data indicate that SOD1 is directly or indirectly involved in ALS oligodendrocyte pathology and suggest that in this cell type, some damage might be irreversible. In addition, we demonstrate that patients with C9ORF72 represent an independent patient group that might not respond to the same treatment.

scholarly journals ALS mutations of FUS suppress protein translation and disrupt the regulation of nonsense-mediated decay

2018 ◽  
Vol 115 (51) ◽  
pp. E11904-E11913 ◽  
Author(s):  
Marisa Kamelgarn ◽  
Jing Chen ◽  
Lisha Kuang ◽  
Huan Jin ◽  
Edward J. Kasarskis ◽  
...  
Keyword(s):  
Motor Neuron ◽  
Protein Biosynthesis ◽  
Protein Composition ◽  
Protein Translation ◽  
Fibroblast Cells ◽  
Neuron Death ◽  
Nonsense Mediated Decay ◽  
Cytoplasmic Granules ◽  
Motor Neuron Death

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease characterized by preferential motor neuron death. Approximately 15% of ALS cases are familial, and mutations in the fused in sarcoma (FUS) gene contribute to a subset of familial ALS cases. FUS is a multifunctional protein participating in many RNA metabolism pathways. ALS-linked mutations cause a liquid–liquid phase separation of FUS protein in vitro, inducing the formation of cytoplasmic granules and inclusions. However, it remains elusive what other proteins are sequestered into the inclusions and how such a process leads to neuronal dysfunction and degeneration. In this study, we developed a protocol to isolate the dynamic mutant FUS-positive cytoplasmic granules. Proteomic identification of the protein composition and subsequent pathway analysis led us to hypothesize that mutant FUS can interfere with protein translation. We demonstrated that the ALS mutations in FUS indeed suppressed protein translation in N2a cells expressing mutant FUS and fibroblast cells derived from FUS ALS cases. In addition, the nonsense-mediated decay (NMD) pathway, which is closely related to protein translation, was altered by mutant FUS. Specifically, NMD-promoting factors UPF1 and UPF3b increased, whereas a negative NMD regulator, UPF3a, decreased, leading to the disruption of NMD autoregulation and the hyperactivation of NMD. Alterations in NMD factors and elevated activity were also observed in the fibroblast cells of FUS ALS cases. We conclude that mutant FUS suppresses protein biosynthesis and disrupts NMD regulation, both of which likely contribute to motor neuron death.

scholarly journals Deletion of Ripk3 Prevents Motor Neuron Death In Vitro but not In Vivo

eNeuro ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. ENEURO.0308-18.2018 ◽  
Author(s):  
Georgia Dermentzaki ◽  
Kristin A. Politi ◽  
Lei Lu ◽  
Vartika Mishra ◽  
Eduardo J. Pérez-Torres ◽  
...  
Keyword(s):  
Motor Neuron ◽  
Neuron Death ◽  
Motor Neuron Death

Ferroptosis mediates selective motor neuron death in amyotrophic lateral sclerosis

2021 ◽  
Author(s):  
Taide Wang ◽  
Doris Tomas ◽  
Nirma D. Perera ◽  
Brittany Cuic ◽  
Sophia Luikinga ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Motor Neuron ◽  
Neuron Death ◽  
Motor Neuron Death ◽  
Lateral Sclerosis

scholarly journals Ligand-independent activation of the P2X7 receptor by Hsp90 inhibition stimulates motor neuron apoptosis

2019 ◽  
Vol 244 (11) ◽  
pp. 901-914
Author(s):  
Amy L Strayer ◽  
Cassandra N Dennys-Rivers ◽  
Karina C Ricart ◽  
Narae Bae ◽  
Joseph S Beckman ◽  
...  
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
P2x7 Receptor ◽  
Receptor Activation ◽  
Neuron Death ◽  
Hsp90 Inhibition ◽  
Highly Sensitive ◽  
Motor Neuron Death ◽  
Lateral Sclerosis ◽  
Neuron Apoptosis

Activation of the extracellular ATP ionotropic receptor P2X7 stimulates motor neuron apoptosis, whereas its inhibition in cell and animal models of amyotrophic lateral sclerosis can be protective. These observations suggest that P2X7 receptor activation is relevant to motor neuron disease and that it could be targeted for therapeutic development. Heat shock protein 90 (Hsp90) is an integral regulatory component of the P2X7 receptor complex, antagonizing ligand-induced receptor activation. Here, we show that the repressive activity of Hsp90 on P2X7 receptor activation in primary motor neurons is highly sensitive to inhibition. Primary motor neurons in culture are 100-fold more sensitive to Hsp90 inhibition by geldanamycin than other neuronal populations. Pharmacological inhibition and down-regulation of the P2X7 receptor prevented motor neuron apoptosis triggered by Hsp90 inhibition, which occurred in the absence of extracellular ATP. These observations suggest that inhibition of a seemingly motor neuron specific pool of Hsp90 leads to ligand independent activation of P2X7 receptor and motor neuron death. Downstream of Hsp90 inhibition, P2X7 receptor activated the phosphatase and tensin homolog (TPEN), which in turn suppressed the pro-survival phosphatidyl inositol 3 kinase (PI3K)/Akt pathway, leading to Fas-dependent motor neuron apoptosis. Conditions altering the interaction between P2X7 receptor and Hsp90, such as recruitment of Hsp90 to other subcellular compartments under stress conditions, or nitration following oxidative stress can induce motor neuron death. These findings may have broad implications in neurodegenerative disorders, including amyotrophic lateral sclerosis, in which activation of P2X7 receptor may be involved in both autonomous and non-autonomous motor neurons death. Impact statement Here we show that a motor neuron specific pool of Hsp90 that is highly sensitive to geldanamycin inhibition represses ligand-independent activation of P2X7 receptor and is critical to motor neuron survival. Activation of P2X7 receptor by Hsp90 inhibition triggers motor neuron apoptosis through the activation of PTEN, which in turn inhibits the PI3 kinase/Akt survival pathway. Thus, inhibition of Hsp90 for therapeutic applications may have the unexpected negative consequence of decreasing the activity of trophic pathways in motor neurons. The inhibition of Hsp90 as a therapeutic approach may require the identification of the Hsp90 complexes involved in pathogenic processes and the development of inhibitors selective for these complexes.

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