Fisiopatología de la ataxia de Friedreich: Transporte y degeneración axonal

Muñoz Lasso, DC. (2017). Fisiopatología de la ataxia de Friedreich: Transporte y degeneración axonal [Tesis doctoral no publicada]. Universitat Politècnica de València. doi:10.4995/Thesis/10251/92842

Friedreich ataxia (FRDA) is a recessive human disease of central and peripheral nervous system that affects children and young adults. FRDA is a peripheral neuropathy characterized by a initial degeneration of the large neurons of the dorsal root ganglia (DRG) or proprioceptive neurons. Most of the patients with FRDA have a homozygous guanine-adenine-adenine (GAA) expansion within the first intron of the gen that codifies for a small mitochondrial protein, frataxin (FXN). This mutation leads to a reduction of frataxin expression in all human cells, which produces changes in both the cell and mitochondrial physiology, resulting in a dysfunction of the mitochondrial energetic metabolism linked to the increase of oxidative stress and calcium dyshomeostasis. These cellular proceses are tightly related with the regulation of the actin and microtubule cytoskeletons and with vesicle trafficking. Here, we show how the absence of frataxin in the mouse models YG8R and YG8sR affects the axonal cytoskeleton of adult sensory neurons. Changes of actin and microtubule cytoskeletons and the failure of Ca 2+ signaling induce alterations of dynamics growth cones of sensory neurons, which in turn produce a reduction of their capacity to grow and regenerate their axons. This study shows how these events can lead to the neurodegeneration in Friedreich's ataxia.