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Yuan Y, Wang Y, Liu M, Luo H, Liu X, Li L, Mao C, Yang T, Li S, Zhang X, Gao Y, Xu Y, Yang J. Peripheral cutaneous synucleinopathy characteristics in genetic Parkinson's disease. Front Neurol 2024; 15:1404492. [PMID: 38751879 PMCID: PMC11094647 DOI: 10.3389/fneur.2024.1404492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 04/16/2024] [Indexed: 05/18/2024] Open
Abstract
Background Cutaneous phosphorylated alpha-synuclein (p-α-syn) deposition is an important biomarker of idiopathic Parkinson's disease (iPD). Recent studies have reported synucleinopathies in patients with common genetic forms of PD. Objective This study aimed to detect p-α-syn deposition characteristic in rare genetic PD patients with CHCHD2 or RAB39B mutations. Moreover, this study also aimed to describe peripheral alpha-synuclein prion-like activity in genetic PD patients, and acquire whether the cutaneous synucleinopathy characteristics of genetic PD are consistent with central neuropathologies. Methods We performed four skin biopsy samples from the distal leg (DL) and proximal neck (C7) of 161 participants, including four patients with CHCHD2 mutations, two patients with RAB39B mutations, 16 patients with PRKN mutations, 14 patients with LRRK2 mutations, five patients with GBA mutations, 100 iPD patients, and 20 healthy controls. We detected cutaneous synucleinopathies using immunofluorescence staining and a seeding amplification assay (SAA). A systematic literature review was also conducted, involving 64 skin biopsies and 205 autopsies of genetic PD patients with synucleinopathy. Results P-α-syn was deposited in the peripheral cutaneous nerves of PD patients with CHCHD2, LRRK2, or GBA mutations but not in those with RAB39B or PRKN mutations. There were no significant differences in the location or rate of α-syn-positive deposits between genetic PD and iPD patients. Peripheral cutaneous synucleinopathy appears to well represent brain synucleinopathy of genetic PD, especially autosomal dominant PD (AD-PD). Cutaneous α-synuclein SAA analysis of iPD and LRRK2 and GBA mutation patients revealed prion-like activity. Conclusion P-α-syn deposition in peripheral cutaneous nerves, detected using SAA and immunofluorescence staining, may serve as an accurate biomarker for genetic PD and iPD in the future.
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Affiliation(s)
- Yanpeng Yuan
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
| | - Yangyang Wang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
| | - Minglei Liu
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Haiyang Luo
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
- NHC Key Laboratory of Prevention and Treatment of Cerebrovascular Disease, Zhengzhou, Henan, China
| | - Xiaojing Liu
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
| | - Lanjun Li
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
| | - Chengyuan Mao
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
- NHC Key Laboratory of Prevention and Treatment of Cerebrovascular Disease, Zhengzhou, Henan, China
| | - Ting Yang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
| | - Shuo Li
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
| | - Xiaoyun Zhang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Yuan Gao
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
- NHC Key Laboratory of Prevention and Treatment of Cerebrovascular Disease, Zhengzhou, Henan, China
| | - Yuming Xu
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
- NHC Key Laboratory of Prevention and Treatment of Cerebrovascular Disease, Zhengzhou, Henan, China
| | - Jing Yang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Henan Key Laboratory of Cerebrovascular Diseases, Zhengzhou University, Zhengzhou, Henan, China
- Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, China
- NHC Key Laboratory of Prevention and Treatment of Cerebrovascular Disease, Zhengzhou, Henan, China
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Abusrair A, Mititelu A, Pfeffer G, Rosenegger L, Aquino CC. Novel RAB39B variant associated intellectual disability and levodopa-responsive young-onset parkinsonism. Parkinsonism Relat Disord 2023; 116:105855. [PMID: 37844350 DOI: 10.1016/j.parkreldis.2023.105855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 10/18/2023]
Abstract
We report a 37-year-old Caucasian male with history of developmental delay, childhood onset Intellectual Disability (ID) and attention deficit hyperactivity disorder (ADHD) who presented at the age of 34 with tremor-dominant parkinsonism. Next Generation Sequencing (NGS) revealed pathogenic hemizygous sequence variant, c.200G > T, in the RAB39B gene. This report expands the number of described individuals with young onset PD associated with RAB39B mutation.
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Affiliation(s)
- Ali Abusrair
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Adriana Mititelu
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Gerald Pfeffer
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Child Health Research Institute, Department of Medical Genetics, University of Calgary, Calgary, Canada
| | - Lisa Rosenegger
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Canada
| | - Camila C Aquino
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
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Chiu CC, Weng YH, Yeh TH, Lu JC, Chen WS, Li AHR, Chen YL, Wei KC, Wang HL. Deficiency of RAB39B Activates ER Stress-Induced Pro-apoptotic Pathway and Causes Mitochondrial Dysfunction and Oxidative Stress in Dopaminergic Neurons by Impairing Autophagy and Upregulating α-Synuclein. Mol Neurobiol 2023; 60:2706-2728. [PMID: 36715921 DOI: 10.1007/s12035-023-03238-6] [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: 05/21/2022] [Accepted: 01/17/2023] [Indexed: 01/31/2023]
Abstract
Deletion and missense or nonsense mutation of RAB39B gene cause familial Parkinson's disease (PD). We hypothesized that deletion and mutation of RAB39B gene induce degeneration of dopaminergic neurons by decreasing protein level of functional RAB39B and causing RAB39B deficiency. Cellular model of deletion or mutation of RAB39B gene-induced PD was prepared by knocking down endogenous RAB39B in human SH-SY5Y dopaminergic cells. Transfection of shRNA-induced 90% reduction in RAB39B level significantly decreased viability of SH-SY5Y dopaminergic neurons. Deficiency of RAB39B caused impairment of macroautophagy/autophagy, which led to increased protein levels of α-synuclein and phospho-α-synucleinSer129 within endoplasmic reticulum (ER) and mitochondria. RAB39B deficiency-induced increase of ER α-synuclein and phospho-α-synucleinSer129 caused activation of ER stress, unfolded protein response, and ER stress-induced pro-apoptotic cascade. Deficiency of RAB39B-induced increase of mitochondrial α-synuclein decreased mitochondrial membrane potential and increased mitochondrial superoxide. RAB39B deficiency-induced activation of ER stress pro-apoptotic pathway, mitochondrial dysfunction, and oxidative stress caused apoptotic death of SH-SY5Y dopaminergic cells by activating mitochondrial apoptotic cascade. In contrast to neuroprotective effect of wild-type RAB39B, PD mutant (T168K), (W186X), or (G192R) RAB39B did not prevent tunicamycin- or rotenone-induced increase of neurotoxic α-synuclein and activation of pro-apoptotic pathway. Our results suggest that RAB39B is required for survival and macroautophagy function of dopaminergic neurons and that deletion or PD mutation of RAB39B gene-induced RAB39B deficiency induces apoptotic death of dopaminergic neurons via impairing autophagy function and upregulating α-synuclein.
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Affiliation(s)
- Ching-Chi Chiu
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University College of Medicine, Taoyuan, Taiwan
- Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
- Healthy Aging Research Center, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Yi-Hsin Weng
- Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
- Division of Movement Disorders, Department of Neurology, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Tu-Hsueh Yeh
- Department of Neurology, Taipei Medical University Hospital, Taipei, Taiwan
| | - Juu-Chin Lu
- Department of Physiology and Pharmacology, Chang Gung University College of Medicine, No. 259, Wen-Hwa 1St Road, Kweishan, Taoyuan, 333, Taiwan
| | - Wan-Shia Chen
- Department of Physiology and Pharmacology, Chang Gung University College of Medicine, No. 259, Wen-Hwa 1St Road, Kweishan, Taoyuan, 333, Taiwan
| | - Allen Han-Ren Li
- Department of Anesthesiology, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
| | - Ying-Ling Chen
- Department of Nursing, Chang Gung University of Science and Technology, Taoyuan, Taiwan
| | - Kuo-Chen Wei
- Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
- Department of Neurosurgery, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
| | - Hung-Li Wang
- Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
- Healthy Aging Research Center, Chang Gung University College of Medicine, Taoyuan, Taiwan.
- Division of Movement Disorders, Department of Neurology, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
- Department of Physiology and Pharmacology, Chang Gung University College of Medicine, No. 259, Wen-Hwa 1St Road, Kweishan, Taoyuan, 333, Taiwan.
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Wang Z, Yang D, Jiang Y, Wang Y, Niu M, Wang C, Luo H, Xu H, Li J, Zhang YW, Zhang X. Loss of RAB39B does not alter MPTP-induced Parkinson's disease-like phenotypes in mice. Front Aging Neurosci 2023; 15:1087823. [PMID: 36761179 PMCID: PMC9905435 DOI: 10.3389/fnagi.2023.1087823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/05/2023] [Indexed: 01/26/2023] Open
Abstract
Parkinson's disease (PD) is a common neurodegenerative movement disorder with undetermined etiology. A major pathological hallmark of PD is the progressive degeneration of dopaminergic neurons in the substantia nigra. Loss-of-function mutations in the RAB39B gene, which encodes a neuronal-specific small GTPase RAB39B, have been associated with X-linked intellectual disability and pathologically confirmed early-onset PD in multiple families. However, the role of RAB39B in PD pathogenesis remains elusive. In this study, we treated Rab39b knock-out (KO) mice with MPTP to explore whether RAB39B deficiency could alter MPTP-induced behavioral impairments and dopaminergic neuron degeneration. Surprisingly, we found that MPTP treatment impaired motor activity and led to loss of tyrosine hydroxylase-positive dopaminergic neurons and gliosis in both WT and Rab39b KO mice. However, RAB39B deficiency did not alter MPTP-induced impairments. These results suggest that RAB39B deficiency does not contribute to PD-like phenotypes through compromising dopaminergic neurons in mice; and its role in PD requires further scrutiny.
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Affiliation(s)
- Zijie Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, School of Medicine, Center for Brain Sciences, The First Affiliated Hospital of Xiamen University, Institute of Neuroscience, Xiamen University, Xiamen, China,Department of Neurosurgery, Xiang’an Hospital of Xiamen University, Xiamen, China
| | - Dingting Yang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, School of Medicine, Center for Brain Sciences, The First Affiliated Hospital of Xiamen University, Institute of Neuroscience, Xiamen University, Xiamen, China,Department of Neurosurgery, Xiang’an Hospital of Xiamen University, Xiamen, China
| | - Yiru Jiang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, School of Medicine, Center for Brain Sciences, The First Affiliated Hospital of Xiamen University, Institute of Neuroscience, Xiamen University, Xiamen, China
| | - Yong Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, School of Medicine, Center for Brain Sciences, The First Affiliated Hospital of Xiamen University, Institute of Neuroscience, Xiamen University, Xiamen, China
| | - Mengxi Niu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, School of Medicine, Center for Brain Sciences, The First Affiliated Hospital of Xiamen University, Institute of Neuroscience, Xiamen University, Xiamen, China
| | - Chong Wang
- Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen, China
| | - Hong Luo
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, School of Medicine, Center for Brain Sciences, The First Affiliated Hospital of Xiamen University, Institute of Neuroscience, Xiamen University, Xiamen, China
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, School of Medicine, Center for Brain Sciences, The First Affiliated Hospital of Xiamen University, Institute of Neuroscience, Xiamen University, Xiamen, China
| | - Jingwen Li
- Department of Neurosurgery, Xiang’an Hospital of Xiamen University, Xiamen, China
| | - Yun-wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, School of Medicine, Center for Brain Sciences, The First Affiliated Hospital of Xiamen University, Institute of Neuroscience, Xiamen University, Xiamen, China
| | - Xian Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, School of Medicine, Center for Brain Sciences, The First Affiliated Hospital of Xiamen University, Institute of Neuroscience, Xiamen University, Xiamen, China,*Correspondence: Xian Zhang, ✉
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5
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Neurogenetic disorders across the lifespan: from aberrant development to degeneration. Nat Rev Neurol 2022; 18:117-124. [PMID: 34987232 PMCID: PMC10132523 DOI: 10.1038/s41582-021-00595-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 02/08/2023]
Abstract
Intellectual disability and autism spectrum disorder (ASD) are common, and genetic testing is increasingly performed in individuals with these diagnoses to inform prognosis, refine management and provide information about recurrence risk in the family. For neurogenetic conditions associated with intellectual disability and ASD, data on natural history in adults are scarce; however, as older adults with these disorders are identified, it is becoming clear that some conditions are associated with both neurodevelopmental problems and neurodegeneration. Moreover, emerging evidence indicates that some neurogenetic conditions associated primarily with neurodegeneration also affect neurodevelopment. In this Perspective, we discuss examples of diseases that have developmental and degenerative overlap. We propose that neurogenetic disorders should be studied continually across the lifespan to understand the roles of the affected genes in brain development and maintenance, and to inform strategies for treatment.
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6
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Rab GTPases in Parkinson's disease: a primer. Essays Biochem 2021; 65:961-974. [PMID: 34414419 PMCID: PMC8709891 DOI: 10.1042/ebc20210016] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/05/2021] [Accepted: 08/09/2021] [Indexed: 12/15/2022]
Abstract
Parkinson's disease is a prominent and debilitating movement disorder characterized by the death of vulnerable neurons which share a set of structural and physiological properties. Over the recent years, increasing evidence indicates that Rab GTPases can directly as well as indirectly contribute to the cellular alterations leading to PD. Rab GTPases are master regulators of intracellular membrane trafficking events, and alterations in certain membrane trafficking steps can be particularly disruptive to vulnerable neurons. Here, we describe current knowledge on the direct links between altered Rab protein function and PD pathomechanisms.
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Han J, Fan Y, Wu P, Huang Z, Li X, Zhao L, Ji Y, Zhu M. Parkinson's Disease Dementia: Synergistic Effects of Alpha-Synuclein, Tau, Beta-Amyloid, and Iron. Front Aging Neurosci 2021; 13:743754. [PMID: 34707492 PMCID: PMC8542689 DOI: 10.3389/fnagi.2021.743754] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/21/2021] [Indexed: 12/31/2022] Open
Abstract
Parkinson’s disease dementia (PDD) is a common complication of Parkinson’s disease that seriously affects patients’ health and quality of life. At present, the process and pathological mechanisms of PDD remain controversial, which hinders the development of treatments. An increasing number of clinical studies have shown that alpha-synuclein (α-syn), tau, beta-amyloid (Aβ), and iron are closely associated with PDD severity. Thus, we inferred the vicious cycle that causes oxidative stress (OS), due to the synergistic effects of α-syn, tau, Aβ, and, iron, and which plays a pivotal role in the mechanism underlying PDD. First, iron-mediated reactive oxygen species (ROS) production can lead to neuronal protein accumulation (e.g., α-syn andAβ) and cytotoxicity. In addition, regulation of post-translational modification of α-syn by iron affects the aggregation or oligomer formation of α-syn. Iron promotes tau aggregation and neurofibrillary tangles (NFTs) formation. High levels of iron, α-syn, Aβ, tau, and NFTs can cause severe OS and neuroinflammation, which lead to cell death. Then, the increasing formation of α-syn, Aβ, and NFTs further increase iron levels, which promotes the spread of α-syn and Aβ in the central and peripheral nervous systems. Finally, iron-induced neurotoxicity promotes the activation of glycogen synthase kinase 3β (GSK3β) related pathways in the synaptic terminals, which in turn play an important role in the pathological synergistic effects of α-syn, tau and Aβ. Thus, as the central factor regulating this vicious cycle, GSK3β is a potential target for the prevention and treatment of PDD; this is worthy of future study.
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Affiliation(s)
- Jiajun Han
- Traditional Chinese Medicine Innovation Research Center, Shenzhen Hospital of Integrated Traditional Chinese and Western Medicine, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Yaohua Fan
- Traditional Chinese Medicine Innovation Research Center, Shenzhen Hospital of Integrated Traditional Chinese and Western Medicine, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Peipei Wu
- Traditional Chinese Medicine Innovation Research Center, Shenzhen Hospital of Integrated Traditional Chinese and Western Medicine, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Zifeng Huang
- Traditional Chinese Medicine Innovation Research Center, Shenzhen Hospital of Integrated Traditional Chinese and Western Medicine, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Xinrong Li
- Traditional Chinese Medicine Innovation Research Center, Shenzhen Hospital of Integrated Traditional Chinese and Western Medicine, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Lijun Zhao
- Traditional Chinese Medicine Innovation Research Center, Shenzhen Hospital of Integrated Traditional Chinese and Western Medicine, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Yichun Ji
- Shenzhen Bao'an Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Meiling Zhu
- Traditional Chinese Medicine Innovation Research Center, Shenzhen Hospital of Integrated Traditional Chinese and Western Medicine, Guangzhou University of Chinese Medicine, Shenzhen, China
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Di Lazzaro G, Magrinelli F, Estevez-Fraga C, Valente EM, Pisani A, Bhatia KP. X-Linked Parkinsonism: Phenotypic and Genetic Heterogeneity. Mov Disord 2021; 36:1511-1525. [PMID: 33960519 DOI: 10.1002/mds.28565] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 02/23/2021] [Accepted: 02/26/2021] [Indexed: 02/06/2023] Open
Abstract
X-linked parkinsonism encompasses rare heterogeneous disorders mainly inherited as a recessive trait, therefore being more prevalent in males. Recent developments have revealed a complex underlying panorama, including a spectrum of disorders in which parkinsonism is variably associated with additional neurological and non-neurological signs. In particular, a childhood-onset encephalopathy with epilepsy and/or cognitive disability is the most common feature. Their genetic basis is also heterogeneous, with many causative genes and different mutation types ranging from "classical" coding variants to intronic repeat expansions. In this review, we provide an updated overview of the phenotypic and genetic spectrum of the most relevant X-linked parkinsonian syndromes, namely X-linked dystonia-parkinsonism (XDP, Lubag disease), fragile X-associated tremor/ataxia syndrome (FXTAS), beta-propeller protein-associated neurodegeneration (BPAN, NBIA/PARK-WDR45), Fabry disease, Waisman syndrome, methyl CpG-binding protein 2 (MeCP2) spectrum disorder, phosphoglycerate kinase-1 deficiency syndrome (PGK1) and X-linked parkinsonism and spasticity (XPDS). All clinical and radiological features reported in the literature have been reviewed. Epilepsy occasionally represents the symptom of onset, predating parkinsonism even by a few years; action tremor is another common feature along with akinetic-rigid parkinsonism. A focus on the genetic background and its pathophysiological implications is provided. The pathogenesis of these disorders ranges from well-defined metabolic alterations (PGK1) to non-specific lysosomal dysfunctions (XPDS) and vesicular trafficking alterations (Waisman syndrome). However, in other cases it still remains poorly defined. Recognition of the phenotypic and genetic heterogeneity of X-linked parkinsonism has important implications for diagnosis, management, and genetic counseling. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Giulia Di Lazzaro
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
- Department of Systems Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Francesca Magrinelli
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Carlos Estevez-Fraga
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Enza M Valente
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
- IRCCS Mondino Foundation, Pavia, Italy
| | - Antonio Pisani
- IRCCS Mondino Foundation, Pavia, Italy
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
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Koss DJ, Campesan S, Giorgini F, Outeiro TF. Dysfunction of RAB39B-Mediated Vesicular Trafficking in Lewy Body Diseases. Mov Disord 2021; 36:1744-1758. [PMID: 33939203 DOI: 10.1002/mds.28605] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 03/09/2021] [Accepted: 03/12/2021] [Indexed: 12/16/2022] Open
Abstract
Intracellular vesicular trafficking is essential for neuronal development, function, and homeostasis and serves to process, direct, and sort proteins, lipids, and other cargo throughout the cell. This intricate system of membrane trafficking between different compartments is tightly orchestrated by Ras analog in brain (RAB) GTPases and their effectors. Of the 66 members of the RAB family in humans, many have been implicated in neurodegenerative diseases and impairment of their functions contributes to cellular stress, protein aggregation, and death. Critically, RAB39B loss-of-function mutations are known to be associated with X-linked intellectual disability and with rare early-onset Parkinson's disease. Moreover, recent studies have highlighted altered RAB39B expression in idiopathic cases of several Lewy body diseases (LBDs). This review contextualizes the role of RAB proteins in LBDs and highlights the consequences of RAB39B impairment in terms of endosomal trafficking, neurite outgrowth, synaptic maturation, autophagy, as well as alpha-synuclein homeostasis. Additionally, the potential for therapeutic intervention is examined via a discussion of the recent progress towards the development of specific RAB modulators. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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Affiliation(s)
- David J Koss
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Susanna Campesan
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester, UK
| | - Flaviano Giorgini
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester, UK
| | - Tiago F Outeiro
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany.,Max Planck Institute for Experimental Medicine, Goettingen, Germany.,Scientific employee with a honorary contract at Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Göttingen, Germany
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Erskine D, Koss D, Korolchuk VI, Outeiro TF, Attems J, McKeith I. Lipids, lysosomes and mitochondria: insights into Lewy body formation from rare monogenic disorders. Acta Neuropathol 2021; 141:511-526. [PMID: 33515275 PMCID: PMC7952289 DOI: 10.1007/s00401-021-02266-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 12/12/2022]
Abstract
Accumulation of the protein α-synuclein into insoluble intracellular deposits termed Lewy bodies (LBs) is the characteristic neuropathological feature of LB diseases, such as Parkinson's disease (PD), Parkinson's disease dementia (PDD) and dementia with LB (DLB). α-Synuclein aggregation is thought to be a critical pathogenic event in the aetiology of LB disease, based on genetic analyses, fundamental studies using model systems, and the observation of LB pathology in post-mortem tissue. However, some monogenic disorders not traditionally characterised as synucleinopathies, such as lysosomal storage disorders, iron storage disorders and mitochondrial diseases, appear disproportionately vulnerable to the deposition of LBs, perhaps suggesting the process of LB formation may be a result of processes perturbed as a result of these conditions. The present review discusses biological pathways common to monogenic disorders associated with LB formation, identifying catabolic processes, particularly related to lipid homeostasis, autophagy and mitochondrial function, as processes that could contribute to LB formation. These findings are discussed in the context of known mediators of α-synuclein aggregation, highlighting the potential influence of impairments to these processes in the aetiology of LB formation.
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Affiliation(s)
- Daniel Erskine
- Newcastle University Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK.
- Wellcome Centre for Mitochondrial Research, Newcastle upon Tyne, UK.
| | - David Koss
- Newcastle University Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Viktor I Korolchuk
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Tiago F Outeiro
- Newcastle University Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany
- Max Planck Institute for Experimental Medicine, Goettingen, Germany
- Scientific Employee With an Honorary Contract at Deutsches Zentrum Für Neurodegenerative Erkrankungen (DZNE), Göttingen, Germany
| | - Johannes Attems
- Newcastle University Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Ian McKeith
- Newcastle University Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
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11
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Koss DJ, Bondarevaite O, Adams S, Leite M, Giorgini F, Attems J, Outeiro TF. RAB39B is redistributed in dementia with Lewy bodies and is sequestered within aβ plaques and Lewy bodies. Brain Pathol 2020; 31:120-132. [PMID: 32762091 PMCID: PMC8018064 DOI: 10.1111/bpa.12890] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/22/2020] [Accepted: 07/26/2020] [Indexed: 12/19/2022] Open
Abstract
Loss of function mutations within the vesicular trafficking protein Ras analogy in brain 39B (RAB39B) are associated with rare X‐linked Parkinson’s disease (PD). Physiologically, RAB39B is localized to Golgi vesicles and recycling endosomes and is required for glutamatergic receptor maturation but also for alpha‐Synuclein (aSyn) homeostasis and the inhibition of its aggregation. Despite evidence linking RAB39B to neurodegeneration, the involvement of the protein in idiopathic neurodegenerative diseases remains undetermined. Here, analysis of the spatial distribution and expression of RAB39B was conducted in post‐mortem human brain tissue from cases of dementia with Lewy bodies (DLB, n = 10), Alzheimer’s disease (AD, n = 12) and controls (n = 12). Assessment of cortical RAB39B immunoreactivity using tissue microarrays revealed an overall reduction in the area of RAB39B positive gray matter in DLB cases when compared to controls and AD cases. Strikingly, RAB39B co‐localized with beta‐amyloid (Aβ) plaques in all cases examined and was additionally present in a subpopulation of Lewy bodies (LBs) in DLB. Biochemical measures of total RAB39B levels within the temporal cortex were unchanged between DLB, AD and controls. However, upon subcellular fractionation, a reduction of RAB39B in the cytoplasmic pool was found in DLB cases, alongside an increase of phosphorylated aSyn and Aβ in whole tissue lysates. The reduction of cytoplasmic RAB39B is consistent with an impaired reserve capacity for RAB39B‐associated functions, which in turn may facilitate LB aggregation and synaptic impairment. Collectively, our data support the involvement of RAB39B in the pathogenesis of DLB and the co‐aggregation of RAB39B with Aβ in plaques suggests that age‐associated cerebral Aβ pathology may be contributory to the loss of RAB39B. Thus RAB39B, its associated functional pathways and its entrapment in aggregates may be considered as future targets for therapeutic interventions to impede the overall pathological burden and cellular dysfunction in Lewy body diseases.
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Affiliation(s)
- David J Koss
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK
| | - Odeta Bondarevaite
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK
| | - Sara Adams
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK
| | - Marta Leite
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK
| | - Flaviano Giorgini
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester, LE1 7RH, UK
| | - Johannes Attems
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK
| | - Tiago F Outeiro
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK.,Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany.,Max Planck Institute for Experimental Medicine, Goettingen, Germany
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12
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Tang BL. RAB39B's role in membrane traffic, autophagy, and associated neuropathology. J Cell Physiol 2020; 236:1579-1592. [PMID: 32761840 DOI: 10.1002/jcp.29962] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/19/2020] [Accepted: 07/13/2020] [Indexed: 12/14/2022]
Abstract
Neuropathological disorders are increasingly associated with dysfunctions in neuronal membrane traffic and autophagy, with defects among members of the Rab family of small GTPases implicated. Mutations in the human Xq28 localized gene RAB39B have been associated with X-linked neurodevelopmental defects including macrocephaly, intellectual disability, autism spectrum disorder (ASD), as well as rare cases of early-onset Parkinson's disease (PD). Despite the finding that RAB39B regulates GluA2 trafficking and could thus influence synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit composition, reasons for the wide-ranging neuropathological consequences associated with RAB39B defects have been unclear. Recent studies have now unraveled possible mechanisms underlying the neuropathological roles of this brain-enriched small GTPase. Studies in RAB39B knockout mice showed that RAB39B interacts with components of Class I phosphatidylinositol-3-kinase (PI3K) signaling. In its absence, the PI3K-AKT-mechanistic target of rapamycin signaling pathway in neural progenitor cells (NPCs) is hyperactivated, which promotes NPC proliferation, leading to macrocephaly and ASD. Pertaining to early-onset PD, a complex of C9orf72, Smith-Magenis syndrome chromosome region candidate 8 and WD repeat domain 41 that functions in autophagy has been identified as a guanine nucleotide exchange factor of RAB39B. Here, recent findings that have shed light on our mechanistic understanding of RAB39B's role in neurodevelopmental and neurodegenerative pathologies are reviewed. Caveats and unanswered questions are also discussed, and future perspectives outlined.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore
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13
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Gao Y, Wilson GR, Salce N, Romano A, Mellick GD, Stephenson SEM, Lockhart PJ. Genetic Analysis of RAB39B in an Early-Onset Parkinson's Disease Cohort. Front Neurol 2020; 11:523. [PMID: 32670181 PMCID: PMC7332711 DOI: 10.3389/fneur.2020.00523] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 05/12/2020] [Indexed: 12/12/2022] Open
Abstract
Pathogenic variants in the gene encoding RAB39B, resulting in the loss of protein function, lead to the development of X-linked early-onset parkinsonism. The gene is located within a chromosomal region that is susceptible to genomic rearrangement, and while an increased dosage of RAB39B was previously associated with cognitive impairment, the potential role of dosage alterations in Parkinson's disease (PD) remains to be determined. This study aimed to investigate the contribution of the genetic variation in RAB39B to the development of early-onset PD. We performed gene dosage studies and sequence analysis in a cohort of 176 individuals with early-onset PD (age of onset ≤ 50 years) of unknown genetic etiology. An assessment of the copy number variation over both coding exons and the 3' untranslated region (UTR) of RAB39B did not identify any alterations in gene dosage. An analysis of the UTRs identified two male individuals carrying single, likely benign, nucleotide variants in the 3'UTR (chrX:154489749-A-G and chrX:154489197-T-G). Furthermore, one novel variant of uncertain significance was identified in the 5'UTR, 229 bp upstream of the start codon (chrX:154493802-C-T). In silico analyses predicted that this variant disrupts a highly conserved transcription factor binding site and could impact RAB39B expression. The results of this study do not support a significant role for genetic variation in RAB39B as contributing to early-onset PD but do highlight that additional molecular studies are required to determine the mechanisms regulating RAB39B expression and their association with the disease. Genetic investigations in larger parkinsonism/PD cohorts and longitudinal studies of individuals with cognitive impairment due to an altered dosage of RAB39B will be required to fully delineate the contribution of RAB39B to parkinsonism.
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Affiliation(s)
- Yujing Gao
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Gabrielle R Wilson
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Nicholas Salce
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - Alexandra Romano
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - George D Mellick
- Griffith Institute for Drug Discovery (GRIDD), Griffith University, Nathan, QLD, Australia
| | - Sarah E M Stephenson
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Paul J Lockhart
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
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14
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Gao Y, Wilson GR, Stephenson SEM, Oulad-Abdelghani M, Charlet-Berguerand N, Bozaoglu K, McLean CA, Thomas PQ, Finkelstein DI, Lockhart PJ. Distribution of Parkinson's disease associated RAB39B in mouse brain tissue. Mol Brain 2020; 13:52. [PMID: 32228644 PMCID: PMC7106796 DOI: 10.1186/s13041-020-00584-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/10/2020] [Indexed: 12/22/2022] Open
Abstract
Pathogenic variants in the gene encoding the small GTPase Ras analogue in Brain 39b (RAB39B) are associated with early-onset parkinsonism. In this study we investigated the expression and localization of RAB39B (RNA and protein) in mouse brain tissue to gain a better understanding of its normal physiological function(s) and role in disease. We developed novel resources, including monoclonal antibodies directed against RAB39B and mice with Rab39b knockout, and performed real-time PCR and western blot analysis on whole brain lysates. To determine the spatial localization of Rab39b RNA and protein, we performed in-situ hybridization and immunohistochemistry on fresh frozen and fixed brain tissue. Our results show that RAB39B is localized throughout the cortex, hippocampus and substantia nigra of mice throughout postnatal life. We found high levels of RAB39B within MAP2 positive cortical and hippocampal neurons, and TH positive dopaminergic neurons in the substantia nigra pars compacta. Our studies support and extend current knowledge of the localization of RAB39B. We validate RAB39B as a neuron-enriched protein and demonstrate that it is present throughout the mouse cortex and hippocampus. Further, we observe high levels in the substantia nigra pars compacta, the brain region most affected in Parkinson’s disease pathology. The distribution of Rab39b is consistent with human disease associations with parkinsonism and cognitive impairment. We also describe and validate novel resources, including monoclonal antibodies directed against RAB39B and mice with Rab39b knockout, both of which are valuable tools for future studies of the molecular function of RAB39B.
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Affiliation(s)
- Yujing Gao
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, 50 Flemington Road, Parkville, Victoria, 3052, Australia.,Department of Paediatrics, The University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Gabrielle R Wilson
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, 50 Flemington Road, Parkville, Victoria, 3052, Australia.,Department of Paediatrics, The University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Sarah E M Stephenson
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, 50 Flemington Road, Parkville, Victoria, 3052, Australia.,Department of Paediatrics, The University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Mustapha Oulad-Abdelghani
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, Strasbourg University, 67400, Illkirch, France
| | - Nicolas Charlet-Berguerand
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, Strasbourg University, 67400, Illkirch, France
| | - Kiymet Bozaoglu
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, 50 Flemington Road, Parkville, Victoria, 3052, Australia.,Department of Paediatrics, The University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Catriona A McLean
- Anatomical Pathology, Alfred Hospital, Melbourne, Victoria, 3004, Australia
| | - Paul Q Thomas
- Robinson Research Institute and School of Medicine, University of Adelaide, Adelaide, SA, 5005, Australia
| | - David I Finkelstein
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Paul J Lockhart
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, 50 Flemington Road, Parkville, Victoria, 3052, Australia. .,Department of Paediatrics, The University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia.
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15
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Cunningham LA, Moore DJ. Endosomal sorting pathways in the pathogenesis of Parkinson's disease. PROGRESS IN BRAIN RESEARCH 2020; 252:271-306. [PMID: 32247367 PMCID: PMC7206894 DOI: 10.1016/bs.pbr.2020.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The identification of Parkinson's disease (PD)-associated genes has created a powerful platform to begin to understand and nominate pathophysiological disease mechanisms. Herein, we discuss the genetic and experimental evidence supporting endolysosomal dysfunction as a major pathway implicated in PD. Well-studied familial PD-linked gene products, including LRRK2, VPS35, and α-synuclein, demonstrate how disruption of different aspects of endolysosomal sorting pathways by disease-causing mutations may manifest into PD-like phenotypes in many disease models. Newly-identified PD-linked genes, including auxilin, synaptojanin-1 and Rab39b, as well as putative risk genes for idiopathic PD (endophilinA1, Rab29, GAK), further support endosomal sorting deficits as being central to PD. LRRK2 may represent a nexus by regulating many distinct features of endosomal sorting, potentially via phosphorylation of key endocytosis machinery (i.e., auxilin, synaptojanin-1, endoA1) and Rab GTPases (i.e., Rab29, Rab8A, Rab10) that function within these pathways. In turn, LRRK2 kinase activity is critically regulated by Rab29 at the Golgi complex and retromer-associated VPS35 at endosomes. Taken together, the known functions of PD-associated gene products, the impact of disease-linked mutations, and the emerging functional interactions between these proteins points to endosomal sorting pathways as a key point of convergence in the pathogenesis of PD.
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Affiliation(s)
- Lindsey A Cunningham
- Van Andel Institute Graduate School, Grand Rapids, MI, United States; Center for Neurodegenerative Science, Van Andel Institute, Grand Rapids, MI, United States
| | - Darren J Moore
- Center for Neurodegenerative Science, Van Andel Institute, Grand Rapids, MI, United States.
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