In agreement with this, reduced mitochondrial membrane potential was observed in motor neurones cultured from G93A mSOD1 mice, this website suggesting mitochondrial functional defects may have secondary effects on the dynamic status of mitochondria, impacting on their morphology [115]. Accumulation of proteins is a hallmark pathology of ALS and is an indicator of defective axonal transport (Figure 3). Accumulations of neurofilaments

and peripherin occur as either perikaryal aggregations [hyaline conglomerate inclusions (HCIs)] or axonal spheroid swellings. HCIs occur in SOD1-mediated FALS patients and consist of both phosphorylated and nonphosphorylated neurofilaments [117,118]. Accumulations of neurofilaments and decreased transport of cytoskeletal proteins were shown in the G93A, G85R and G37R SOD1 mice [119]. Importantly, these defects in slow axonal transport were observed at least 6 months prior to disease onset [119]. Mutations in dynein and the dynactin complex have also been implicated

in FALS, suggesting disruption to dynein-mediated fast axonal transport may be pathogenic. Mutations in the p150 subunit of dynactin have been identified in several FALS cases [120,121]. KIF5A mutations have also been found in patients with a related motor neurone disorder, hereditary spastic paraplegia [122]. Pathogenic mutations in KIF5A were shown to perturb KIF5A-mediated motility [123]. Axonal transport of mitochondria was disrupted aminophylline in a mouse model of mutant spastin-induced hereditary spastic paraplegia [124]. These lines of evidence indicate that learn more defective mitochondrial axonal transport is an early and important event not only in ALS, but also in other motor disorders, and may be a common pathway in different complex disorders. In motor neurones from G93A mSOD1 mice and primary cortical neurones transfected with four different SOD1 mutants,

anterograde transport of mitochondria was selectively impaired [115]. This was associated with decreased mitochondrial membrane potential and rounding up of mitochondria, indicative of mitochondrial dysfunction [115]. In addition, mSOD1 targeted to the mitochondrial IMS is sufficient to cause axonal transport defects of mitochondria [109]. Redistribution of damaged mitochondria might serve as an additional insult to motor neurones, particularly in the distal axon segment. This agrees with data from in vivo models and human ALS patients [108], where dying back of the distal axon is an early and potentially catastrophic event. Motor proteins and their associated adaptor proteins may be damaged by mSOD1, impairing axonal transport. Although there has been no direct interaction found between kinesin and mSOD1, the adaptor proteins Milton and Miro may be important in the regulation of axonal transport of mitochondria via mSOD1-induced changes to calcium levels.