Saposin C, Key Regulator in the Alpha-Synuclein Degradation Mediated by Lysosome

Lysosomal dysfunction has been proposed as one of the most important pathogenic molecular mechanisms in Parkinson disease (PD). The most significant evidence lies in the GBA gene, which encodes for the lysosomal enzyme beta-glucocerebrosidase (beta-GCase), considered the main genetic risk factor for sporadic PD. The loss of beta-GCase activity results in the formation of alpha-synuclein deposits. The present study was aimed to determine the activity of the main lysosomal enzymes and the cofactors Prosaposin (PSAP) and Saposin C in PD and healthy controls, and their contribution to alpha-synuclein (alpha-Syn) aggregation. 42 PD patients and 37 age-matched healthy controls were included in the study. We first analyzed the beta-GCase, beta-galactosidase (beta-gal), beta-hexosaminidase (Hex B) and Cathepsin D (CatD) activities in white blood cells. We also measured the GBA, beta-GAL, beta-HEX, CTSD, PSAP, Saposin C and alpha-Syn protein levels by Western-blot. We found a 20% reduced beta-GCase and beta-gal activities in PD patients compared to controls. PSAP and Saposin C protein levels were significantly lower in PD patients and correlated with increased levels of alpha-synuclein. CatD, in contrast, showed significantly increased activity and protein levels in PD patients compared to controls. Increased CTSD protein levels in PD patients correlated, intriguingly, with a higher concentration of alpha-Syn. Our findings suggest that lysosomal dysfunction in sporadic PD is due, at least in part, to an alteration in Saposin C derived from reduced PSAP levels. That would lead to a significant decrease in the beta-GCase activity, resulting in the accumulation of alpha-syn. The accumulation of monohexosylceramides might act in favor of CTSD activation and, therefore, increase its enzymatic activity. The evaluation of lysosomal activity in the peripheral blood of patients is expected to be a promising approach to investigate pathological mechanisms and novel therapies aimed to restore the lysosomal function in sporadic PD.Foundation "Progreso y Salud" of the Junta de Andalucia PI-0424-2014FEDER/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades/Proyecto B-CTS-702-UGR20German Research Foundation (DFG) FPU14/03473 EST16/0080

Genetic variation within genes associated with mitochondrial function is significantly associated with later age at onset of Parkinson disease and contributes to disease risk

Mitochondrial dysfunction has been implicated in the aetiology of monogenic Parkinson’s disease (PD). Yet the role that mitochondrial processes play in the most common form of the disease; sporadic PD, is yet to be fully established. Here we comprehensively assessed the role of mitochondrial function associated genes in sporadic PD by leveraging improvements in the scale and analysis of PD GWAS data with recent advances in our understanding of the genetics of mitochondrial disease. First, we identified that a proportion of the “missing heritability” of the PD can be explained by common variation within genes implicated in mitochondrial disease (primary gene list) and mitochondrial function (secondary gene list). Next we calculated a mitochondrial-specific polygenic risk score (PRS) and showed that cumulative small effect variants within both our primary and secondary gene lists are significantly associated with increased PD risk. Most significantly we further report that the PRS of the secondary mitochondrial gene list was significantly associated with later age at onset. Finally, to identify possible functional genomic associations we implemented Mendelian randomisation, which showed that 14 of these mitochondrial function associated genes showed functional consequence associated with PD risk. Further analysis suggested that the 14 identified genes are not only involved in mitophagy but implicate new mitochondrial processes. Our data suggests that therapeutics targeting mitochondrial bioenergetics and proteostasis pathways distinct from mitophagy could be beneficial to treating the early stage of PD

Fundamentos genéticos de la enfermedad del parkinson en el sur de España

Premio Sociedad Andaluza de Neurología al proyecto “Polimorfismos genéticos, biomarcadores plasmáticos y estrés oxidativo en la Enfermedad de Parkinson”.In the last decades, we have witnessed a revolution in the field of genetics of Parkinson’s disease (PD), a movement disorder caused by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The discovery of deleterious mutations and genetic risk variants in familial and sporadic PD cases respectively, has increased our knowledge about the possible molecular pathways involved on its pathogenesis. This substantial progress has helped us to better understand such devastating disease, and although the route to PD diseasemodifying drugs is still long, it will hopefully be an achievable future goal. This study aims to elucidate the genetic architecture of familial and sporadic PD in Southern Spain, assessing in detail a population that has so far been poorly studied in this context.Tesis Univ. Granada. Programa Oficial de Doctorado en: BiomedicinaFPU12-01885. Beca-Contrato del Programa de Formación de Profesorado Universitario (FPU) (2013-2017)Project WT089698/Z/09/Z: Medical Research Council (London, UK) and Welcome Trust Strategic Award.Project ZO1 AG000949: Intramural Research Program of the National Institute on Aging, National Institutes of Health (NIH) (part of the Department of Health and Human Services, USA)

Mitochondria function associated genes contribute to Parkinson's Disease risk and later age at onset.

Mitochondrial dysfunction has been implicated in the etiology of monogenic Parkinson's disease (PD). Yet the role that mitochondrial processes play in the most common form of the disease; sporadic PD, is yet to be fully established. Here, we comprehensively assessed the role of mitochondrial function-associated genes in sporadic PD by leveraging improvements in the scale and analysis of PD GWAS data with recent advances in our understanding of the genetics of mitochondrial disease. We calculated a mitochondrial-specific polygenic risk score (PRS) and showed that cumulative small effect variants within both our primary and secondary gene lists are significantly associated with increased PD risk. We further reported that the PRS of the secondary mitochondrial gene list was significantly associated with later age at onset. Finally, to identify possible functional genomic associations we implemented Mendelian randomization, which showed that 14 of these mitochondrial function-associated genes showed functional consequence associated with PD risk. Further analysis suggested that the 14 identified genes are not only involved in mitophagy, but implicate new mitochondrial processes. Our data suggests that therapeutics targeting mitochondrial bioenergetics and proteostasis pathways distinct from mitophagy could be beneficial to treating the early stage of PD

Mitochondria function associated genes contribute to Parkinson’s Disease risk and later age at onset

Abstract Mitochondrial dysfunction has been implicated in the etiology of monogenic Parkinson’s disease (PD). Yet the role that mitochondrial processes play in the most common form of the disease; sporadic PD, is yet to be fully established. Here, we comprehensively assessed the role of mitochondrial function-associated genes in sporadic PD by leveraging improvements in the scale and analysis of PD GWAS data with recent advances in our understanding of the genetics of mitochondrial disease. We calculated a mitochondrial-specific polygenic risk score (PRS) and showed that cumulative small effect variants within both our primary and secondary gene lists are significantly associated with increased PD risk. We further reported that the PRS of the secondary mitochondrial gene list was significantly associated with later age at onset. Finally, to identify possible functional genomic associations we implemented Mendelian randomization, which showed that 14 of these mitochondrial function-associated genes showed functional consequence associated with PD risk. Further analysis suggested that the 14 identified genes are not only involved in mitophagy, but implicate new mitochondrial processes. Our data suggests that therapeutics targeting mitochondrial bioenergetics and proteostasis pathways distinct from mitophagy could be beneficial to treating the early stage of PD.Additional information International Parkinson’s Disease Genomics Consortium (IPDGC) Members A. Noyce13, A. Tucci14, B. Middlehurst1, D. Kia15, M. Tan16, H. Houlden14, H. R. Morris16, H. Plun-Favreau14, P. Holmans17, J. Hardy14, D. Trabzuni14,18, J. Bras19, K. Mok14, K. Kinghorn20, N. Wood15, P. Lewis21, R. Guerreiro14,19, R. Lovering22, L. R’Bibo14, M. Rizig14, V. Escott-Price22,23, V. Chelban14, T. Foltynie6, N. Williams24, A. Brice25, F. Danjou25, S. Lesage25, M. Martinez26, A. Giri27,28, C. Schulte27,28, K. Brockmann27,28, J. Simón-Sánchez27,28, P. Heutink27,28, P. Rizzu28, M. Sharma29, T. Gasser27,28, A. Nicolas2, M. Cookson2, F. Faghri2,30, D. Hernandez2, J. Shulman31,32, L. Robak33, S. Lubbe34, S. Finkbeiner35,36,37, N. Mencacci38, C. Lungu39, S. Scholz40, X. Reed2, H. Leonard2, G. Rouleau7, L. Krohan41, J. van Hilten42, J. Marinus42, A. Adarmes-Gómez43, M. Aguilar44, I. Alvarez44, V. Alvarez45, F. Javier Barrero46, J. Bergareche Yarza47, I. Bernal-Bernal43, M. Blazquez45, M. Bonilla-Toribio Bernal43, M. Boungiorno44, Dolores Buiza-Rueda43, A. Cámara48, M. Carcel44, F. Carrillo43, M. Carrión-Claro43, D. Cerdan49, J. Clarimón50,51, Y. Compta48, M. Diez-Fairen44, O. Dols-Icardo50,51, J. Duarte49, R. l. Duran52, F. Escamilla-Sevilla53, M. Ezquerra48, M. Fernández48, R. Fernández-Santiago48, C. Garcia45, P. García-Ruiz54, P. Gómez-Garre43, M. Gomez Heredia55, I. Gonzalez-Aramburu56, A. Gorostidi Pagola57, J. Hoenicka58, J. Infante51,56, S. Jesús43, A. Jimenez-Escrig59, J. Kulisevsky51,60, M. Labrador-Espinosa43, J. Lopez-Sendon59, A. López de Munain Arregui59, D. Macias43, I. Martínez Torres61, J. Marín51,60, M. Jose Marti48, J. Martínez-Castrillo59, C. Méndez-del-Barrio43, M. Menéndez González43, A. Mínguez53, P. Mir43, E. Mondragon Rezola57, E. Muñoz48, J. Pagonabarraga51,60, P. Pastor44, F. Perez Errazquin55, T. Periñán-Tocino43, J. Ruiz-Martínez57, C. Ruz52, A. Sanchez Rodriguez56, M. Sierra56, E. Suarez-Sanmartin4, C. Tabernero59, J. Pablo Tartari44, C. Tejera-Parrado43, E. Tolosa48, F. Valldeoriola48, L. Vargas-González43, L. Vela62, F. Vives52, A. Zimprich63, L. Pihlstrom64, P. Taba65, K. Majamaa66,67, A. Siitonen66, N. Okubadejo68, O. Ojo68 1 Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK 2Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, 20892, USA 3Department of Medical and Molecular Genetics, King’s College London School of Basic and Medical Biosciences, London, SE1 9RT, UK 4Clinical Genetics Unit, Guys and St. Thomas’ NHS Foundation Trust, London, SE1 9RT, UK 5Departamento de Ingeniería de la Información y las Comunicaciones, Universidad de Murcia, 30100, Murcia, Spain 6Department of Neurodegenerative Disease, UCL Institute of Neurology, 10-12 Russell Square House, London, UK 7Montreal Neurological Institute, McGill University, Montréal, QC, Canada 8Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada 9Department of Human Genetics, McGill University, Montréal, QC, Canada 10Data Tecnica International, Glen Echo, MD, 20812, USA 11The Perron Institute for Neurological and Translational Science, 8 Verdun Street, Nedlands, WA, 6009, Australia 12Centre for Comparative Genomics, Murdoch University, Murdoch, 6150, Australia 13Preventive Neurology Unit, Wolfson Institute of Preventive Medicine, QMUL, London, UK 14Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK 15UCL Genetics Institute; and Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK 16Department of Clinical Neuroscience, University College London, London, UK 17Biostatistics & Bioinformatics Unit, Institute of Psychological Medicine and Clinical Neuroscience, MRC Centre for Neuropsychiatric Genetics & Genomics, Cardiff, UK 18Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia 19UK Dementia Research Institute at UCL and Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK 20Institute of Healthy Ageing, University College London, London, UK 21University of Reading, Reading, UK 22University College London, London, UK 23MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff, UK 24Cardiff University School of Medicine, Cardiff, UK 25Institut du Cerveau et de la Moelle épinière, ICM, Inserm U 1127, CNRS, UMR 7225, Sorbonne Universités, UPMC University Paris 06, UMR S 1127, AP-HP, Pitié-Salpêtrière Hospital, Paris, France 26INSERM UMR 1220; and Paul Sabatier University, Toulouse, France 27Department for Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany 28DZNE, German Center for Neurodegenerative Diseases, Tübingen, Germany 29Centre for Genetic Epidemiology, Institute for Clinical Epidemiology and Applied Biometry, University of Tubingen, Tubingen, Germany 30Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL, USA 31Departments of Neurology, Neuroscience, and Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA 32Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX, USA 33Baylor College of Medicine, Houston, TX, USA 34Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA 35Departments of Neurology and Physiology, University of California, San Francisco, CA, USA 36Gladstone Institute of Neurological Disease, San Francisco, CA, USA 37Taube/Koret Center for Neurodegenerative Disease Research, San Francisco, CA, USA) 38 (Northwestern University Feinberg School of Medicine, Chicago, IL, USA) 39 (National Institutes of Health Division of Clinical Research, NINDS, National Institutes of Health, Bethesda, MD, USA) 40Neurodegenerative Diseases Research Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA 41Department of Human Genetics, McGill University, Montréal, QC H3A 0G4, Canada 42Department of Neurology, Leiden University Medical Center, Leiden, Netherlands 43Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/ Universidad de Sevilla, Seville, Spain 44Fundació Docència i Recerca Mútua de Terrassa and Movement Disorders Unit, Department of Neurology, University Hospital Mutua de Terrassa, Terrassa, Barcelona, Spain 45Hospital Universitario Central de Asturias, Oviedo, Spain 46Hospital Universitario Parque Tecnologico de la Salud, Granada, Spain 47Instituto de Investigación Sanitaria Biodonostia, San Sebastián, Spain 48Hospital Clinic de Barcelona, Barcelona, Spain 49Hospital General de Segovia, Segovia, Spain 50Memory Unit, Department of Neurology, IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain 51Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain 52Centro de Investigacion Biomedica, Universidad de Granada, Granada, Spain 53Hospital Universitario Virgen de las Nieves, Instituto de Investigación Biosanitaria de Granada, Granada, Spain 54Instituto de Investigación Sanitaria Fundación Jiménez Díaz, Madrid, Spain 55Hospital Universitario Virgen de la Victoria, Malaga, Spain 56Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain 57Instituto de Investigación Sanitaria Biodonostia, San Sebastián, Spain 58Institut de Recerca Sant Joan de Déu, Barcelona, Spain 59Hospital Universitario Ramón y Cajal Madrid, Madrid, Spain 60Movement Disorders Unit, Department of Neurology, IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain 61Department of Neurology, Instituto de Investigación Sanitaria La Fe, Hospital Universitario y Politécnico La Fe, Valencia, Spain 62Department of Neurology, Hospital Universitario Fundación Alcorcón, Madrid, Spain 63Department of Neurology, Medical University of Vienna, Vienna, Austria 64Department of Neurology, Oslo University Hospital, Oslo, Norway 65Department of Neurology and Neurosurgery, University of Tartu, Tartu, Estonia 66Institute of Clinical Medicine, Department of Neurology, University of Oulu, Oulu, Finland 67Department of Neurology and Medical Research Center, Oulu University Hospital, Oulu, Finland 68University of Lagos, Yaba, Lagos State, Nigeri