Rescue of lysosomal function as therapeutic strategy for SPG15 hereditary spastic paraplegia.

SPG15 is a hereditary spastic paraplegia subtype caused by mutations in Spastizin, a protein encoded by the ZFYVE26 gene. Spastizin is involved in autophagosome maturation and autophagic lysosome reformation and SPG15-related mutations lead to autophagic lysosome reformation defects with lysosome enlargement, free lysosome depletion and autophagosome accumulation. Symptomatic and rehabilitative treatments are the only therapy currently available for patients. Here, we targeted autophagy and lysosomes in SPG15 patient-derived cells by using a library of autophagy-modulating compounds. We identified a rose of compounds affecting intracellular calcium levels, the calcium-calpain pathway or lysosomal functions, which reduced autophagosome accumulation. The six most effective compounds were tested in vivo in a new SPG15 loss of function Drosophila model that mimicked the reported SPG15 phenotype, with autophagosome accumulation, enlarged lysosomes, reduced free lysosomes, autophagic lysosome reformation defects and locomotor deficit. These compounds, namely verapamil, Bay K8644, 2',5'-dideoxyadenosine, trehalose, Small-Molecule Enhancer of Rapamycin 28 and trifluoperazine, improved lysosome biogenesis and function in vivo, demonstrating that lysosomes are a key pharmacological target to rescue SPG15 phenotype. Among the others, the Small-Molecule Enhancer of Rapamycin 28 was the most effective, rescuing both autophagic lysosome reformation defects and locomotor deficit, and could be considered as a potential therapeutic compound for this hereditary spastic paraplegia subtype.

Targeting the multifaceted neurotoxicity of Alzheimer's disease by tailored functionalisation of the curcumin scaffold.

Simultaneous modulation of multifaceted toxicity arising from neuroinflammation, oxidative stress, and mitochondrial dysfunction represents a valuable therapeutic strategy to tackle Alzheimer's disease. Among the significant hallmarks of the disorder, Aß protein and its aggregation products are well-recognised triggers of the neurotoxic cascade. In this study, by tailored modification of the curcumin-based lead compound 1, we aimed at developing a small library of hybrid compounds targeting Aß protein oligomerisation and the consequent neurotoxic events. Interestingly, from in vitro studies, analogues 3 and 4, bearing a substituted triazole moiety, emerged as multifunctional agents able to counteract Aß aggregation, neuroinflammation and oxidative stress. In vivo proof-of-concept evaluations, performed in a Drosophila oxidative stress model, allowed us to identify compound 4 as a promising lead candidate.

Drosophila D-idua Reduction Mimics Mucopolysaccharidosis Type I Disease-Related Phenotypes.

Deficit of the IDUA (α-L-iduronidase) enzyme causes the lysosomal storage disorder mucopolysaccharidosis type I (MPS I), a rare pediatric neurometabolic disease, due to pathological variants in the IDUA gene and is characterized by the accumulation of the undegraded mucopolysaccharides heparan sulfate and dermatan sulfate into lysosomes, with secondary cellular consequences that are still mostly unclarified. Here, we report a new fruit fly RNAi-mediated knockdown model of a IDUA homolog (D-idua) displaying a phenotype mimicking some typical molecular features of Lysosomal Storage Disorders (LSD). In this study, we showed that D-idua is a vital gene in Drosophila and that ubiquitous reduction of its expression leads to lethality during the pupal stage, when the precise degradation/synthesis of macromolecules, together with a functional autophagic pathway, are indispensable for the correct development to the adult stage. Tissue-specific analysis of the D-idua model showed an increase in the number and size of lysosomes in the brain and muscle. Moreover, the incorrect acidification of lysosomes led to dysfunctional lysosome-autophagosome fusion and the consequent block of autophagy flux. A concomitant metabolic drift of glycolysis and lipogenesis pathways was observed. After starvation, D-idua larvae showed a quite complete rescue of both autophagy/lysosome phenotypes and metabolic alterations. Metabolism and autophagy are strictly interconnected vital processes that contribute to maintain homeostatic control of energy balance, and little is known about this regulation in LSDs. Our results provide new starting points for future investigations on the disease's pathogenic mechanisms and possible pharmacological manipulations.