title: A Drosophila Model of Neuronopathic Gaucher Disease Demonstrates Lysosomal-Autophagic Defects and Altered mTOR Signalling and Is Functionally Rescued by Rapamycin.
abstract: Glucocerebrosidase (GBA1) mutations are associated with Gaucher disease (GD), an autosomal recessive disorder caused by functional deficiency of glucocerebrosidase (GBA), a lysosomal enzyme that hydrolyzes glucosylceramide to ceramide and glucose. Neuronopathic forms of GD can be associated with rapid neurological decline (Type II) or manifest as a chronic form (Type III) with a wide spectrum of neurological signs. Furthermore, there is now a well-established link between GBA1 mutations and Parkinson's disease (PD), with heterozygote mutations in GBA1 considered the commonest genetic defect in PD. Here we describe a novel Drosophila model of GD that lacks the two fly GBA1 orthologs. This knock-out model recapitulates the main features of GD at the cellular level with severe lysosomal defects and accumulation of glucosylceramide in the fly brain. We also demonstrate a block in autophagy flux in association with reduced lifespan, age-dependent locomotor deficits and accumulation of autophagy substrates in dGBA-deficient fly brains. Furthermore, mechanistic target of rapamycin (mTOR) signaling is downregulated in dGBA knock-out flies, with a concomitant upregulation of Mitf gene expression, the fly ortholog of mammalian TFEB, likely as a compensatory response to the autophagy block. Moreover, the mTOR inhibitor rapamycin is able to partially ameliorate the lifespan, locomotor, and oxidative stress phenotypes. Together, our results demonstrate that this dGBA1-deficient fly model is a useful platform for the further study of the role of lysosomal-autophagic impairment and the potential therapeutic benefits of rapamycin in neuronopathic GD. These results also have important implications for the role of autophagy and mTOR signaling in GBA1-associated PD SIGNIFICANCE STATEMENT: We developed a Drosophila model of neuronopathic GD by knocking-out the fly orthologs of the GBA1 gene, demonstrating abnormal lysosomal pathology in the fly brain. Functioning lysosomes are required for autophagosome-lysosomal fusion in the autophagy pathway. We show in vivo that autophagy is impaired in dGBA-deficient fly brains. In response, mechanistic target of rapamycin (mTOR) activity is downregulated in dGBA-deficient flies and rapamycin ameliorates the lifespan, locomotor, and oxidative stress phenotypes. dGBA knock-out flies also display an upregulation of the Drosophila ortholog of mammalian TFEB, Mitf, a response that is unable to overcome the autophagy block. Together, our results suggest that rapamycin may have potential benefits in the treatment of GD, as well as PD linked to GBA1 mutations.
authors.affiliation: Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom, k.kinghorn@ucl.ac.uk l.partridge@ucl.ac.uk.|Institute of Neurology, University College London, London WC1N 3BG, United Kingdom.
authors.forename: Kerri J
authors.identifier: 0000-0003-2048-4332
authors.initials: KJ
authors.lastname: Kinghorn
authors.affiliation: Max Planck Institute for Biology of Ageing, D-50931 Köln, Germany.
authors.forename: Sebastian
authors.identifier: 0000-0002-1539-5346
authors.initials: S
authors.lastname: Grönke
authors.affiliation: Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom.|Institute of Neurology, University College London, London WC1N 3BG, United Kingdom.|Max Planck Institute for Biology of Ageing, D-50931 Köln, Germany.
authors.forename: Jorge Iván
authors.identifier: 0000-0002-6324-2854
authors.initials: JI
authors.lastname: Castillo-Quan
authors.affiliation: Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom.
authors.forename: Nathaniel S
authors.identifier: 0000-0002-0298-3800
authors.initials: NS
authors.lastname: Woodling
authors.affiliation: Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom.|Institute of Neurology, University College London, London WC1N 3BG, United Kingdom.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Centre for Translational Omics, Institute of Child Health, University College London, London WC1N 1EH, United Kingdom.
authors.forename: Ernestas
authors.identifier: 0000-0001-8500-5406
authors.initials: E
authors.lastname: Sirka
authors.affiliation: Clinical Neuroscience, Institute of Neurology, University College London, London NW3 2PF, United Kingdom, and.
authors.forename: Matthew
authors.identifier: 0000-0001-8093-0723
authors.initials: M
authors.lastname: Gegg
authors.affiliation: Centre for Translational Omics, Institute of Child Health, University College London, London WC1N 1EH, United Kingdom.
authors.forename: Kevin
authors.initials: K
authors.lastname: Mills
authors.affiliation: Institute of Neurology, University College London, London WC1N 3BG, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Hardy
authors.affiliation: University College London Cancer Institute, London WC1E 6DD, United Kingdom.
authors.forename: Ivana
authors.initials: I
authors.lastname: Bjedov
authors.affiliation: Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom, k.kinghorn@ucl.ac.uk l.partridge@ucl.ac.uk.|Max Planck Institute for Biology of Ageing, D-50931 Köln, Germany.
authors.forename: Linda
authors.identifier: 0000-0001-9615-0094
authors.initials: L
authors.lastname: Partridge
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001343:Autophagy / Q000187:drug effects; D004195:Disease Models, Animal; D004330:Drosophila; D005776:Gaucher Disease / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control*; D055786:Gene Knockout Techniques; D005962:Glucosylceramidase / Q000235:genetics*; D008247:Lysosomes / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000008:administration & dosage*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D058570:TOR Serine-Threonine Kinases; D005962:Glucosylceramidase; D020123:Sirolimus
keywords: Drosophila; Gaucher disease; autophagy; glucocerebrosidase; mTOR; rapamycin