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Onal G, Yalçın-Çakmaklı G, Özçelik CE, Boussaad I, Şeker UÖŞ, Fernandes HJR, Demir H, Krüger R, Elibol B, Dökmeci S, Salman MM. Variant-specific effects of GBA1 mutations on dopaminergic neuron proteostasis. J Neurochem 2024. [PMID: 38641924 DOI: 10.1111/jnc.16114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 03/26/2024] [Accepted: 04/05/2024] [Indexed: 04/21/2024]
Abstract
Glucocerebrosidase 1 (GBA1) mutations are the most important genetic risk factors for Parkinson's disease (PD). Clinically, mild (e.g., p.N370S) and severe (e.g., p.L444P and p.D409H) GBA1 mutations have different PD phenotypes, with differences in age at disease onset, progression, and the severity of motor and non-motor symptoms. We hypothesize that GBA1 mutations cause the accumulation of α-synuclein by affecting the cross-talk between cellular protein degradation mechanisms, leading to neurodegeneration. Accordingly, we tested whether mild and severe GBA1 mutations differentially affect the degradation of α-synuclein via the ubiquitin-proteasome system (UPS), chaperone-mediated autophagy (CMA), and macroautophagy and differentially cause accumulation and/or release of α-synuclein. Our results demonstrate that endoplasmic reticulum (ER) stress and total ubiquitination rates were significantly increased in cells with severe GBA1 mutations. CMA was found to be defective in induced pluripotent stem cell (iPSC)-derived dopaminergic neurons with mild GBA1 mutations, but not in those with severe GBA1 mutations. When examining macroautophagy, we observed reduced formation of autophagosomes in cells with the N370S and D409H GBA1 mutations and impairments in autophagosome-lysosome fusion in cells with the L444P GBA1 mutation. Accordingly, severe GBA1 mutations were found to trigger the accumulation and release of oligomeric α-synuclein in iPSC-derived dopaminergic neurons, primarily as a result of increased ER stress and defective macroautophagy, while mild GBA1 mutations affected CMA, which is mainly responsible for the degradation of the monomeric form of α-synuclein. Overall, our findings provide new insight into the molecular basis of the clinical variability in PD associated with different GBA1 mutations.
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Affiliation(s)
- G Onal
- Department of Physiology, Anatomy and Genetics, Kavli Institute for NanoScience Discovery, University of Oxford, Oxford, UK
- Oxford Parkinson's Disease Centre, University of Oxford, Oxford, UK
| | - G Yalçın-Çakmaklı
- Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - C E Özçelik
- National Nanotechnology Research Center, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey
| | - I Boussaad
- Translational Neuroscience, Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - U Ö Ş Şeker
- Interdisciplinary Neuroscience Program, National Nanotechnology Research Center, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey
| | - Hugo J R Fernandes
- Department of Physiology, Anatomy and Genetics, Kavli Institute for NanoScience Discovery, University of Oxford, Oxford, UK
- Oxford Parkinson's Disease Centre, University of Oxford, Oxford, UK
| | - H Demir
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - R Krüger
- Translational Neuroscience, Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Esch-sur-Alzette, Luxembourg
- Transversal Translational Medicine, Luxembourg Institute of Health (LIH), Strassen, Luxembourg
- Parkinson Research Clinic, Centre Hospitalier de Luxembourg (CHL), Luxembourg City, Luxembourg
| | - B Elibol
- Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - S Dökmeci
- Department of Medical Biology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - M M Salman
- Department of Physiology, Anatomy and Genetics, Kavli Institute for NanoScience Discovery, University of Oxford, Oxford, UK
- Oxford Parkinson's Disease Centre, University of Oxford, Oxford, UK
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Khan A, Özçelik CE, Begli O, Oguz O, Kesici MS, Kasırga TS, Özçubukcu S, Yuca E, Seker UOS. Highly Potent Peptide Therapeutics To Prevent Protein Aggregation in Huntington's Disease. ACS Med Chem Lett 2023; 14:1821-1826. [PMID: 38116434 PMCID: PMC10726468 DOI: 10.1021/acsmedchemlett.3c00415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 11/10/2023] [Accepted: 11/10/2023] [Indexed: 12/21/2023] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder resulting from a significant amplification of CAG repeats in exon 1 of the Huntingtin (Htt) gene. More than 36 CAG repeats result in the formation of a mutant Htt (mHtt) protein. These amino-terminal mHtt fragments lead to the formation of misfolded proteins, which then form aggregates in the relevant brain regions. Therapies that can delay the progression of the disease are imperative to halting the course of the disease. Peptide-based drug therapies provide such a platform. Inhibitory peptides were screened against monomeric units of both wild type (Htt(Q25)) and mHtt fragments, Htt(Q46) and Htt(Q103). Fibril kinetics was studied by utilizing the Thioflavin T (ThT) assay. Atomic force microscopy was also used to study the influence of the peptides on fibril formation. These experiments demonstrate that the chosen peptides suppress the formation of fibrils in mHtt proteins and can provide a therapeutic lead for further optimization and development.
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Affiliation(s)
- Anooshay Khan
- UNAM-Institute
of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
- Department
of Neurosciences, Bilkent University, 06800 Ankara, Turkey
| | - Cemile Elif Özçelik
- UNAM-Institute
of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Ozge Begli
- UNAM-Institute
of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Oguzhan Oguz
- UNAM-Institute
of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Mehmet Seçkin Kesici
- Department
of Chemistry, Faculty of Science, Middle
East Technical University, Ankara 06800, Turkey
| | - Talip Serkan Kasırga
- UNAM-Institute
of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Salih Özçubukcu
- Department
of Chemistry, Faculty of Science, Middle
East Technical University, Ankara 06800, Turkey
| | - Esra Yuca
- Department
of Molecular Biology and Genetics, Yildiz
Technical University, Istanbul 34349, Turkey
- Health
Biotechnology Joint Research and Application Center of Excellence, Esenler, Istanbul 34220, Turkey
| | - Urartu Ozgur Safak Seker
- UNAM-Institute
of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
- Department
of Neurosciences, Bilkent University, 06800 Ankara, Turkey
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