Calcium dysregulation, mitochondrial pathology and protein aggregation in a culture model of amyotrophic lateral sclerosis: Mechanistic relationship and differential sensitivity to intervention

The combination of Ca2+ influx during neurotransmission and low cytosolic Ca2+ buffering contributes to the preferential vulnerability of motor neurons in amyotrophic lateral sclerosis (ALS). This study investigated the relationship among Ca2+ accumulation in intracellular compartments, mitochondria...

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Main Authors: Miranda L. Tradewell, Laura A. Cooper, Sandra Minotti, Heather D. Durham
Format: Article
Language:English
Published: Elsevier 2011-06-01
Series:Neurobiology of Disease
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S0969996111000283
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author Miranda L. Tradewell
Laura A. Cooper
Sandra Minotti
Heather D. Durham
author_facet Miranda L. Tradewell
Laura A. Cooper
Sandra Minotti
Heather D. Durham
author_sort Miranda L. Tradewell
collection DOAJ
description The combination of Ca2+ influx during neurotransmission and low cytosolic Ca2+ buffering contributes to the preferential vulnerability of motor neurons in amyotrophic lateral sclerosis (ALS). This study investigated the relationship among Ca2+ accumulation in intracellular compartments, mitochondrial abnormalities, and protein aggregation in a model of familial ALS (fALS1). Human SOD1, wild type (SOD1WT) or with the ALS-causing mutation G93A (SOD1G93A), was expressed in motor neurons of dissociated murine spinal cord–dorsal root ganglia (DRG) cultures. Elevation of mitochondrial Ca2+ ([Ca2+]m), decreased mitochondrial membrane potential (Δψ) and rounding of mitochondria occurred early, followed by increased endoplasmic reticular Ca2+ ([Ca2+]ER), elevated cytosolic Ca2+ ([Ca2+]c), and subsequent appearance of SOD1G93A inclusions (a consequence of protein aggregation). [Ca2+]c was elevated to a greater extent in neurons with inclusions than in those with diffusely distributed SOD1G93A and promoted aggregation of mutant protein, not vice versa: both [Ca2+]c and the percentage of neurons with SOD1G93A inclusions were reduced by co-expressing the cytosolic Ca2+-buffering protein, calbindin D-28K; treatment with the heat shock protein inducer, geldanamycin, prevented inclusions but not the increase in [Ca2+]c, [Ca2+]m or loss of Δψ, and inhibiting proteasome activity with epoxomicin, known to promote aggregation of disease-causing mutant proteins including SOD1G93A, had no effect on Ca2+ levels. Both expression of SOD1G93A and epoxomicin-induced inhibition of proteasome activity caused mitochondrial rounding, independent of Ca2+ dysregulation and reduced Δψ. That geldanamycin prevented inclusions and mitochondrial rounding, but not Ca2+ dysregulation or loss of Δψ indicates that chaperone-based therapies to prevent protein aggregation may require co-therapy to address these other underlying mechanisms of toxicity.
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spelling doaj.art-ccc1c2872ff44652932f2c3aaa907a1b2022-12-21T22:08:40ZengElsevierNeurobiology of Disease1095-953X2011-06-01423265275Calcium dysregulation, mitochondrial pathology and protein aggregation in a culture model of amyotrophic lateral sclerosis: Mechanistic relationship and differential sensitivity to interventionMiranda L. Tradewell0Laura A. Cooper1Sandra Minotti2Heather D. Durham3Montreal Neurological Institute, McGill University, 3801 University St, Montreal, QC, Canada H3A 2B4Montreal Neurological Institute, McGill University, 3801 University St, Montreal, QC, Canada H3A 2B4Montreal Neurological Institute, McGill University, 3801 University St, Montreal, QC, Canada H3A 2B4Corresponding author.; Montreal Neurological Institute, McGill University, 3801 University St, Montreal, QC, Canada H3A 2B4The combination of Ca2+ influx during neurotransmission and low cytosolic Ca2+ buffering contributes to the preferential vulnerability of motor neurons in amyotrophic lateral sclerosis (ALS). This study investigated the relationship among Ca2+ accumulation in intracellular compartments, mitochondrial abnormalities, and protein aggregation in a model of familial ALS (fALS1). Human SOD1, wild type (SOD1WT) or with the ALS-causing mutation G93A (SOD1G93A), was expressed in motor neurons of dissociated murine spinal cord–dorsal root ganglia (DRG) cultures. Elevation of mitochondrial Ca2+ ([Ca2+]m), decreased mitochondrial membrane potential (Δψ) and rounding of mitochondria occurred early, followed by increased endoplasmic reticular Ca2+ ([Ca2+]ER), elevated cytosolic Ca2+ ([Ca2+]c), and subsequent appearance of SOD1G93A inclusions (a consequence of protein aggregation). [Ca2+]c was elevated to a greater extent in neurons with inclusions than in those with diffusely distributed SOD1G93A and promoted aggregation of mutant protein, not vice versa: both [Ca2+]c and the percentage of neurons with SOD1G93A inclusions were reduced by co-expressing the cytosolic Ca2+-buffering protein, calbindin D-28K; treatment with the heat shock protein inducer, geldanamycin, prevented inclusions but not the increase in [Ca2+]c, [Ca2+]m or loss of Δψ, and inhibiting proteasome activity with epoxomicin, known to promote aggregation of disease-causing mutant proteins including SOD1G93A, had no effect on Ca2+ levels. Both expression of SOD1G93A and epoxomicin-induced inhibition of proteasome activity caused mitochondrial rounding, independent of Ca2+ dysregulation and reduced Δψ. That geldanamycin prevented inclusions and mitochondrial rounding, but not Ca2+ dysregulation or loss of Δψ indicates that chaperone-based therapies to prevent protein aggregation may require co-therapy to address these other underlying mechanisms of toxicity.http://www.sciencedirect.com/science/article/pii/S0969996111000283Amyotrophic lateral sclerosis (ALS)CalciumMotor neuronMitochondriaProteasomeSOD1
spellingShingle Miranda L. Tradewell
Laura A. Cooper
Sandra Minotti
Heather D. Durham
Calcium dysregulation, mitochondrial pathology and protein aggregation in a culture model of amyotrophic lateral sclerosis: Mechanistic relationship and differential sensitivity to intervention
Neurobiology of Disease
Amyotrophic lateral sclerosis (ALS)
Calcium
Motor neuron
Mitochondria
Proteasome
SOD1
title Calcium dysregulation, mitochondrial pathology and protein aggregation in a culture model of amyotrophic lateral sclerosis: Mechanistic relationship and differential sensitivity to intervention
title_full Calcium dysregulation, mitochondrial pathology and protein aggregation in a culture model of amyotrophic lateral sclerosis: Mechanistic relationship and differential sensitivity to intervention
title_fullStr Calcium dysregulation, mitochondrial pathology and protein aggregation in a culture model of amyotrophic lateral sclerosis: Mechanistic relationship and differential sensitivity to intervention
title_full_unstemmed Calcium dysregulation, mitochondrial pathology and protein aggregation in a culture model of amyotrophic lateral sclerosis: Mechanistic relationship and differential sensitivity to intervention
title_short Calcium dysregulation, mitochondrial pathology and protein aggregation in a culture model of amyotrophic lateral sclerosis: Mechanistic relationship and differential sensitivity to intervention
title_sort calcium dysregulation mitochondrial pathology and protein aggregation in a culture model of amyotrophic lateral sclerosis mechanistic relationship and differential sensitivity to intervention
topic Amyotrophic lateral sclerosis (ALS)
Calcium
Motor neuron
Mitochondria
Proteasome
SOD1
url http://www.sciencedirect.com/science/article/pii/S0969996111000283
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