title: Frataxin silencing alters microtubule stability in motor neurons: implications for Friedreich's ataxia.
abstract: To elucidate the pathogenesis of axonopathy in Friedreich's Ataxia (FRDA), a neurodegenerative disease characterized by axonal retraction, we analyzed the microtubule (MT) dynamics in an in vitro frataxin-silenced neuronal model (shFxn). A typical feature of MTs is their "dynamic instability", in which they undergo phases of growth (polymerization) and shrinkage (depolymerization). MTs play a fundamental role in the physiology of neurons and every perturbation of their dynamicity is highly detrimental for neuronal functions. The aim of this study is to determine whether MTs are S-glutathionylated in shFxn and if the glutathionylation triggers MT dysfunction. We hypothesize that oxidative stress, determined by high GSSG levels, induces axonal retraction by interfering with MT dynamics. We propose a mechanism of the axonopathy in FRDA where GSSG overload and MT de-polymerization are strictly interconnected. Indeed, using a frataxin-silenced neuronal model we show a significant reduction of neurites extension, a shift of tubulin toward the unpolymerized fraction and a consistent increase of glutathione bound to the cytoskeleton. The live cell imaging approach further reveals a significant decrease in MT growth lifetime due to frataxin silencing, which is consistent with the MT destabilization. The in vitro antioxidant treatments trigger the axonal re-growth and the increase in stable MTs in shFxn, thus contributing to identify new neuronal targets of oxidation in this disease and providing a novel approach for antioxidant therapies.
authors: Unit of Muscular and Neurodegenerative Diseases.
authors: Emanuela
authors: E
authors: Piermarini
authors: Department of Biosciences.
authors: Daniele
authors: D
authors: Cartelli
authors: Laboratory of Biochemistry.
authors: Anna
authors: A
authors: Pastore
authors: Unit of Muscular and Neurodegenerative Diseases.
authors: Giulia
authors: G
authors: Tozzi
authors: Unit of Muscular and Neurodegenerative Diseases.
authors: Claudia
authors: C
authors: Compagnucci
authors: Unit of Flow Cytometry.
authors: Ezio
authors: E
authors: Giorda
authors: Unit of Muscular and Neurodegenerative Diseases.
authors: Jessica
authors: J
authors: D'Amico
authors: Department of Biosciences.
authors: Stefania
authors: S
authors: Petrini
authors: Unit of Muscular and Neurodegenerative Diseases.
authors: Enrico
authors: E
authors: Bertini
authors: Department of Biosciences.|Center of Excellence on Neurodegenerative Diseases, University of Milan, Via Celoria 26, Milan, Italy.
authors: Graziella
authors: G
authors: Cappelletti
authors: Unit of Muscular and Neurodegenerative Diseases fiorella.piemonte@opbg.net.
authors: Fiorella
authors: F
authors: Piemonte
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage; D001369:Axons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000235:genetics / Q000378:metabolism; D005621:Friedreich Ataxia / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D020868:Gene Silencing; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D033862:Iron-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics*; D051379:Mice; D008870:Microtubules / Q000235:genetics / Q000473:pathology; D009046:Motor Neurons / Q000378:metabolism* / Q000473:pathology; D016501:Neurites / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D000096923:Frataxin
chemical_list: D000975:Antioxidants; D019803:Glutathione Disulfide; D033862:Iron-Binding Proteins; D000096923:Frataxin