Cell culture models to investigate the selective vulnerability of motoneuronal mitochondria to familial ALS‐linked G93ASOD1

Abstract

Mitochondrial damage induced by superoxide dismutase (SOD1) mutants has been proposed to have a causative role in the selective degeneration of motoneurons in amyotrophic lateral sclerosis (ALS). In order to investigate the basis of the tissue specificity of mutant SOD1 we compared the effect of the continuous expression of wild-type or mutant (G93A) human SOD1 on mitochondrial morphology in the NSC-34 motoneuronal-like, the N18TG2 neuroblastoma and the non-neuronal Madin-Darby Canine Kidney (MDCK) cell lines. Morphological alterations of mitochondria were observed in NSC-34 expressing the G93A mutant (NSC-G93A) but not the wild-type SOD1, whereas a ten-fold greater level of total expression of the mutant had no effect on mitochondria of non-motoneuronal cell lines. Fragmented network, swelling and cristae remodelling but not vacuolization of mitochondria or other intracellular organelles were observed only in NSC-G93A cells. The mitochondrial alterations were not explained by a preferential localization of the mutant within NSC-G93A mitochondria, as a higher amount of the mutant SOD1 was found in mitochondria of MDCK-G93A cells. Our results suggest that mitochondrial vulnerability of motoneurons to G93ASOD1 is recapitulated in NSC-34 cells, and that peculiar features in network dynamics may account for the selective alterations of motoneuronal mitochondria.

Mitochondrial dysfunction in familial amyotrophic lateral sclerosis

“…The first evidence of mitochondrial abnormalities came from ultrastructural studies showing aggregates of mitochondria in muscles and spinal cord motor neurons (Sasaki and Iwata 1996) and increased mitochondrial volume in motor nerve terminals of ALS patients (Siklos et al 1996). Consistent with these findings, observations of mitochondrial morphology in cell or animal models of familial ALS showed aggregated, swollen, vacuolated or fragmented mitochondria (Bendotti et al 2001;Coussee et al 2011;Damiano et al 2006;Jaarsma et al 2001;Jung et al 2002;Menzies et al 2002;Raimondi et al 2006;Xu et al 2004).…”

Hypoxia causes autophagic stress and derangement of metabolic adaptation in a cell model of amyotrophic lateral sclerosis

“…Mitochondrial dysfunction is present in models expressing a low amount of G93ASOD1 including the one used in this study (Menzies et al 2002;Rizzardini et al 2005;Raimondi et al 2006). Hypoxia might impinge on antecedent mitochondrial dysfunction; toxic interactions of G93ASOD1 with functional molecules linked to apoptosis and control of mitochondrial membrane potential such as Bcl-2 and voltage-dependent anion channel have been described (Tan et al 2013).…”

“…The G93A-NSC cell line expresses a low level of G93ASOD1 (lower than murine SOD1) and therefore it appears a good model of motor neurons in the disease in terms of expression level since only one allele is mutant in FALS patients with SOD1 mutations. Furthermore, this line has been shown to reproduce aspects of the oxidative and mitochondrial toxicity of this mutant SOD1 (Raimondi et al 2006;Rizzardini et al 2006). The cell lines were grown in high-glucose Dulbecco's modified Eagle's medium supplemented with 5% heat-inactivated fetal bovine serum, 1 mM glutamine (all from Lonza, Verviers, Belgium), 1 mM pyruvate, and antibiotics (100 IU/mL penicillin and 100 lg/mL streptomycin) (all from Invitrogen, Carlsbad, CA, USA).…”

Mitochondria in Neurodegeneration

“…Extensive mitochondrial fragmentation occurs in cell models of mutant SOD1 overexpression (Raimondi et al, 2006;Menzies et al, 2002). Mitochondrial vacuolation is another abnormal morphologic feature characteristic of SOD1 ALS models.…”