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Purkinje neuron Ca2+ influx reduction rescues ataxia in SCA28 model
Journal article   Open access   Peer reviewed

Purkinje neuron Ca2+ influx reduction rescues ataxia in SCA28 model

Francesca Maltecca, Elisa Baseggio, Francesco Consolato, Davide Mazza, Paola Podini, Samuel M Young, Ilaria Drago, Ben A Bahr, Aldamaria Puliti, Franca Codazzi, …
The Journal of clinical investigation, Vol.125(1), pp.263-274
01/02/2015
DOI: 10.1172/JCI74770
PMCID: PMC4382234
PMID: 25485680
url
https://doi.org/10.1172/JCI74770View
Published (Version of record) Open Access

Abstract

Spinocerebellar ataxia type 28 (SCA28) is a neurodegenerative disease caused by mutations of the mitochondrial protease AFG3L2. The SCA28 mouse model, which is haploinsufficient for Afg3l2 , exhibits a progressive decline in motor function and displays dark degeneration of Purkinje cells (PC-DCD) of mitochondrial origin. Here, we determined that mitochondria in cultured Afg3l2 -deficient PCs ineffectively buffer evoked Ca 2+ peaks, resulting in enhanced cytoplasmic Ca 2+ concentrations, which subsequently triggers PC-DCD. This Ca 2+ -handling defect is the result of negative synergism between mitochondrial depolarization and altered organelle trafficking to PC dendrites in Afg3l2 -mutant cells. In SCA28 mice, partial genetic silencing of the metabotropic glutamate receptor mGluR1 decreased Ca 2+ influx in PCs and reversed the ataxic phenotype. Moreover, administration of the β-lactam antibiotic ceftriaxone, which promotes synaptic glutamate clearance, thereby reducing Ca 2+ influx, improved ataxia-associated phenotypes in SCA28 mice when given either prior to or after symptom onset. Together, the results of this study indicate that ineffective mitochondrial Ca 2+ handling in PCs underlies SCA28 pathogenesis and suggest that strategies that lower glutamate stimulation of PCs should be further explored as a potential treatment for SCA28 patients.

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