Mutations in the SPAST gene, that encodes the microtubule-severing protein called Spastin, are the most common cause of autosomal dominant hereditary spastic paraplegia (HSP). HSP is characterized by axonal degeneration of corticospinal tracts. In vitro and in vivo models showed that depletion of Spastin causes excessive stabilization of microtubules, morphological alterations of lysosomes and defects of Lipid Droplets (LDs) biogenesis. Furthermore, lack of Spastin in Drosophila induced a partial lethality of flies at pupal stage and a reduction of locomotor activity. Lysosomes and LDs biogenesis are implicated in autophagic process but the role of Spastin in this pathway and its implications in neurodegeneration mechanism of HSP still remain unknown. In this work, we analyzed the effects of loss of DSpastin on autophagy by using the RNAi (RNA interference) approach. We investigated the formation of early and late autophagosomes, lysosomes and autolysosomes using the monomeric tandem construct GFP–mCherry-Atg8a, the fluorescent markers GFP-Lamp1 and mCherry-Atg8a in neuronal and muscle tissues in control and RNAi Spastin flies. Our data showed that loss of DSpastin impaired the autophagic flux, increasing the number of early/immature and late autophagosomes, and decreasing the autolysosomes number. Moreover, we showed that lack of DSpastin produces larger lysosomes, unable to fuse with the autophagosomes, leading to the accumulation of Ref(2)p (fly homolog of human p62). The administration to RNAi Spastin of naringenin, a flavanone known for its neuroprotective effects, partially rescued lethality phenotype, locomotor behavior and autophagy impairments, thus representing a promising strategy for the management of HSP symptoms.

Administration of naringenin ameliorates DSpastin loss of function phenotypes in Drosophila melanogaster

Salvador A.;Forgiarini A.;Martinuzzi A.;Orso G.
2019

Abstract

Mutations in the SPAST gene, that encodes the microtubule-severing protein called Spastin, are the most common cause of autosomal dominant hereditary spastic paraplegia (HSP). HSP is characterized by axonal degeneration of corticospinal tracts. In vitro and in vivo models showed that depletion of Spastin causes excessive stabilization of microtubules, morphological alterations of lysosomes and defects of Lipid Droplets (LDs) biogenesis. Furthermore, lack of Spastin in Drosophila induced a partial lethality of flies at pupal stage and a reduction of locomotor activity. Lysosomes and LDs biogenesis are implicated in autophagic process but the role of Spastin in this pathway and its implications in neurodegeneration mechanism of HSP still remain unknown. In this work, we analyzed the effects of loss of DSpastin on autophagy by using the RNAi (RNA interference) approach. We investigated the formation of early and late autophagosomes, lysosomes and autolysosomes using the monomeric tandem construct GFP–mCherry-Atg8a, the fluorescent markers GFP-Lamp1 and mCherry-Atg8a in neuronal and muscle tissues in control and RNAi Spastin flies. Our data showed that loss of DSpastin impaired the autophagic flux, increasing the number of early/immature and late autophagosomes, and decreasing the autolysosomes number. Moreover, we showed that lack of DSpastin produces larger lysosomes, unable to fuse with the autophagosomes, leading to the accumulation of Ref(2)p (fly homolog of human p62). The administration to RNAi Spastin of naringenin, a flavanone known for its neuroprotective effects, partially rescued lethality phenotype, locomotor behavior and autophagy impairments, thus representing a promising strategy for the management of HSP symptoms.
2019
Administration of naringenin ameliorates DSpastin loss of function phenotypes in Drosophila melanogaster
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3324882
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