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Faes L.,Research Group Neurodegeneration | Callewaert G.,Research Group Neurodegeneration
Journal of Bioenergetics and Biomembranes | Year: 2011

A growing body of evidence suggests that mitochondrial dysfunctions play a crucial role in the pathogenesis of various neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), a neurodegenerative disease affecting both upper and lower motor neurons. Although ALS is predominantly a sporadic disease, approximately 10% of cases are familial. The most frequent familial form is caused by mutations in the gene encoding Cu/Zn superoxide dismutase 1 (SOD1). A dominant toxic gain of function of mutant SOD1 has been considered as the cause of the disease and mitochondria are thought to be key players in the pathogenesis. However, the exact nature of the link between mutant SOD1 and mitochondrial dysfunctions remains to be established. Here, we briefly review the evidence for mitochondrial dysfunctions in familial ALS and discuss a possible link between mutant SOD1 and mitochondrial dysfunction. © 2011 Springer Science+Business Media, LLC. Source

Maurin H.,Experimental Genetics Group LEGTEGG | Chong S.-A.,Experimental Genetics Group LEGTEGG | Kraev I.,Open University Milton Keynes | Davies H.,Open University Milton Keynes | And 10 more authors.
PLoS ONE | Year: 2014

The stratum lacunosum moleculare (SLM) is the connection hub between entorhinal cortex and hippocampus, two brain regions that are most vulnerable in Alzheimer's disease. We recently identified a specific synaptic deficit of Nectin-3 in transgenic models for tauopathy. Here we defined cognitive impairment and electrophysiological problems in the SLM of Tau.P301L mice, which corroborated the structural defects in synapses and dendritic spines. Reduced diffusion of DiI from the ERC to the hippocampus indicated defective myelinated axonal pathways. Ultrastructurally, myelinated axons in the temporoammonic pathway (TA) that connects ERC to CA1 were damaged in Tau.P301L mice at young age. Unexpectedly, the myelin defects were even more severe in bigenic biGT mice that co-express GSK3β with Tau.P301L in neurons. Combined, our data demonstrate that neuronal expression of protein Tau profoundly affected the functional and structural organization of the entorhinal-hippocampal complex, in particular synapses and myelinated axons in the SLM. White matter pathology deserves further attention in patients suffering from tauopathy and Alzheimer's disease. © 2014 Maurin et al. Source

Coussee E.,Research Group Neurodegeneration | De Smet P.,Research Group Neurodegeneration | Bogaert E.,Catholic University of Leuven | Bogaert E.,Vesalius Research Center | And 8 more authors.
Cell Calcium | Year: 2011

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by selective death of motor neurons. Mutations in Cu/Zn superoxide dismutase-1 (SOD1) cause familial ALS but the molecular mechanisms whereby these mutations induce motor neuron death remain controversial. Here, we show that stable overexpression of mutant human SOD1 (G37R) - but not wild-type SOD1 (wt-SOD1) - in mouse neuroblastoma cells (N2a) results in morphological abnormalities of mitochondria accompanied by several dysfunctions. Activity of the oxidative phosphorylation complex I was significantly reduced in G37R cells and correlated with lower mitochondrial membrane potential and reduced levels of cytosolic ATP. Using targeted chimeric aequorin we further analyzed the consequences of mitochondrial dysfunction on cellular Ca2+ handling. Mitochondrial Ca2+ uptake, elicited by IP3-induced Ca2+ release from endoplasmic reticulum (ER) was significantly reduced in G37R cells, while uptake induced by a brief Ca2+ pulse was not affected in permeabilized cells. The decreased mitochondrial Ca2+ uptake resulted in increased cytosolic Ca2+ transients, whereas ER Ca2+ load and resting cytosolic Ca2+ levels were not affected. Together, these findings suggest that the mechanism linking mutant G37R SOD1 and ALS involves mitochondrial respiratory chain deficiency resulting in ATP loss and impairment of mitochondrial and cytosolic Ca2+ homeostasis. © 2011 Elsevier Ltd. Source

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