151
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Szabó Z, Péter M, Héja L, Kardos J. Dual Role for Astroglial Copper-Assisted Polyamine Metabolism during Intense Network Activity. Biomolecules 2021; 11:604. [PMID: 33921742 PMCID: PMC8073386 DOI: 10.3390/biom11040604] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/09/2021] [Accepted: 04/14/2021] [Indexed: 12/29/2022] Open
Abstract
Astrocytes serve essential roles in human brain function and diseases. Growing evidence indicates that astrocytes are central players of the feedback modulation of excitatory Glu signalling during epileptiform activity via Glu-GABA exchange. The underlying mechanism results in the increase of tonic inhibition by reverse operation of the astroglial GABA transporter, induced by Glu-Na+ symport. GABA, released from astrocytes, is synthesized from the polyamine (PA) putrescine and this process involves copper amino oxidase. Through this pathway, putrescine can be considered as an important source of inhibitory signaling that counterbalances epileptic discharges. Putrescine, however, is also a precursor for spermine that is known to enhance gap junction channel communication and, consequently, supports long-range Ca2+ signaling and contributes to spreading of excitatory activity through the astrocytic syncytium. Recently, we presented the possibility of neuron-glia redox coupling through copper (Cu+/Cu2+) signaling and oxidative putrescine catabolism. In the current work, we explore whether the Cu+/Cu2+ homeostasis is involved in astrocytic control on neuronal excitability by regulating PA catabolism. We provide supporting experimental data underlying this hypothesis. We show that the blockade of copper transporter (CTR1) by AgNO3 (3.6 µM) prevents GABA transporter-mediated tonic inhibitory currents, indicating causal relationship between copper (Cu+/Cu2+) uptake and the catabolism of putrescine to GABA in astrocytes. In addition, we show that MnCl2 (20 μM), an inhibitor of the divalent metal transporter DMT1, also prevents the astrocytic Glu-GABA exchange. Furthermore, we observed that facilitation of copper uptake by added CuCl2 (2 µM) boosts tonic inhibitory currents. These findings corroborate the hypothesis that modulation of neuron-glia coupling by copper uptake drives putrescine → GABA transformation, which leads to subsequent Glu-GABA exchange and tonic inhibition. Findings may in turn highlight the potential role of copper signaling in fine-tuning the activity of the tripartite synapse.
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Affiliation(s)
- Zsolt Szabó
- Functional Pharmacology Research Group, Research Centre for Natural Sciences, Institute of Organic Chemistry, H-1117 Budapest, Hungary; (Z.S.); (M.P.); (J.K.)
| | - Márton Péter
- Functional Pharmacology Research Group, Research Centre for Natural Sciences, Institute of Organic Chemistry, H-1117 Budapest, Hungary; (Z.S.); (M.P.); (J.K.)
- Hevesy György Ph.D. School of Chemistry, ELTE Eötvös Loránd University, H-1117 Budapest, Hungary
| | - László Héja
- Functional Pharmacology Research Group, Research Centre for Natural Sciences, Institute of Organic Chemistry, H-1117 Budapest, Hungary; (Z.S.); (M.P.); (J.K.)
| | - Julianna Kardos
- Functional Pharmacology Research Group, Research Centre for Natural Sciences, Institute of Organic Chemistry, H-1117 Budapest, Hungary; (Z.S.); (M.P.); (J.K.)
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152
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Jiang D, Mo G, Jiang Y, Kang B. Exogenous spermidine affects polyamine metabolism in the mouse hypothalamus. Open Life Sci 2021; 16:39-45. [PMID: 33817296 PMCID: PMC7874596 DOI: 10.1515/biol-2021-0006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 10/06/2020] [Accepted: 11/23/2020] [Indexed: 12/03/2022] Open
Abstract
Spermidine is important for the hypothalamic control of pituitary secretion of hormones involved in neuroendocrine functions in mammals. In this study, the effect of exogenous spermidine on the expression of genes and proteins related to polyamine metabolism and polyamine levels was examined. The results indicated that treatment with spermidine at 0.05 mg/g (BW) significantly increased the levels of Oaz1 mRNA and protein expression and decreased putrescine content in mouse hypothalamus (p < 0.05). The administration with spermidine at 0.10 mg/g significantly increased the levels of Oaz1, Oaz2, and Odc expression in mouse hypothalamus (p < 0.05). Treatment with spermidine at 0.05 mg/g significantly increased the levels of Ssat mRNA expression and reduced the level of Smo mRNA expression in mouse hypothalamus (p < 0.05). Putrescine concentrations in the hypothalamus after the administration of spermidine at 0.10 and 0.15 mg/g were significantly higher than those in the control group (p < 0.05). The concentration of both spermidine and spermine in the hypothalamus after the administration of spermidine at 0.15 mg/g was decreased significantly (p < 0.05). In summary, our results indicate that exogenous spermidine affects polyamine homeostasis in the mouse hypothalamus by modulating the expression of genes and proteins related to polyamine metabolism.
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Affiliation(s)
- Dongmei Jiang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, People's Republic of China
| | - Guilin Mo
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, People's Republic of China
| | - Yilong Jiang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, People's Republic of China
| | - Bo Kang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, People's Republic of China
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153
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López-Marqués RL, Davis JA, Harper JF, Palmgren M. Dynamic membranes: the multiple roles of P4 and P5 ATPases. PLANT PHYSIOLOGY 2021; 185:619-631. [PMID: 33822217 PMCID: PMC8133672 DOI: 10.1093/plphys/kiaa065] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/24/2020] [Indexed: 05/31/2023]
Abstract
The lipid bilayer of biological membranes has a complex composition, including high chemical heterogeneity, the presence of nanodomains of specific lipids, and asymmetry with respect to lipid composition between the two membrane leaflets. In membrane trafficking, membrane vesicles constantly bud off from one membrane compartment and fuse with another, and both budding and fusion events have been proposed to require membrane lipid asymmetry. One mechanism for generating asymmetry in lipid bilayers involves the action of the P4 ATPase family of lipid flippases; these are biological pumps that use ATP as an energy source to flip lipids from one leaflet to the other. The model plant Arabidopsis (Arabidopsis thaliana) contains 12 P4 ATPases (AMINOPHOSPHOLIPID ATPASE1-12; ALA1-12), many of which are functionally redundant. Studies of P4 ATPase mutants have confirmed the essential physiological functions of these pumps and pleiotropic mutant phenotypes have been observed, as expected when genes required for basal cellular functions are disrupted. For instance, phenotypes associated with ala3 (dwarfism, pollen defects, sensitivity to pathogens and cold, and reduced polar cell growth) can be related to membrane trafficking problems. P5 ATPases are evolutionarily related to P4 ATPases, and may be the counterpart of P4 ATPases in the endoplasmic reticulum. The absence of P4 and P5 ATPases from prokaryotes and their ubiquitous presence in eukaryotes make these biological pumps a defining feature of eukaryotic cells. Here, we review recent advances in the field of plant P4 and P5 ATPases.
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Affiliation(s)
- Rosa L López-Marqués
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark
| | - James A Davis
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, USA
| | - Jeffrey F Harper
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, USA
| | - Michael Palmgren
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China
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154
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Zheng K, Li T. Prediction of ATPase cation transporting 13A2 molecule in Petromyzon marinus and pan-cancer analysis into human tumors from an evolutionary perspective. Immunogenetics 2021; 73:277-289. [PMID: 33743014 DOI: 10.1007/s00251-021-01216-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/11/2021] [Indexed: 11/30/2022]
Abstract
The ATPase cation transporting 13A2 protein (ATP13A2), which maintains the homeostasis of mitochondria and lysosomes, plays a significant role in human neurodegenerative diseases and cancer. Through constructing a lamprey proteome database, employing multiple sequence alignment and phylogenetic analysis, 5 ATP13A2 proteins from Petromyzon marinus (Pm-ATP13A2) were identified based on the evolutionary perspective. The motif and domain analysis showed that the ATP13A2 protein was conserved. The multiple phosphorylation sites and transmembrane structures highlighted the characteristics of ATP13A2 as the P-ATPase-V cation transporting protein. Based on the information provided by the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, this study was conducted as a preliminary investigation of the carcinogenic effects of the ATP13A2 gene in a variety of tumors. The ATP13A2 was strongly expressed in most tumors, except in two types of nervous system tumors glioblastoma multiforme (GBM) and brain lower grade glioma (LGG). Moreover, the expression of ATP13A2 was strongly correlated with the prognosis of tumor patients. The high expression of ATP13A2 was obviously related to the poor prognosis of LGG. The poor prognosis of LGG patients may affect the ATP13A2 expression through the immune cells and radiotherapy. Also, cancer-related fibroblast infiltration was observed. All in all, this work offers more insights into the molecular evolution of the ATP13A2 protein and facilitates the understanding of the carcinogenic effects of the ATP13A2 in different tumors. Our discussion also promotes the study into the successful evolution of the vertebrate brain and the mechanism of clinical brain-related diseases.
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Affiliation(s)
- Kaifeng Zheng
- College of Life Sciences, Lamprey Research Center, Liaoning Normal University, Dalian, 116081, China.
| | - Tiesong Li
- College of Life Sciences, Lamprey Research Center, Liaoning Normal University, Dalian, 116081, China.
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155
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ATP13A2 Regulates Cellular α-Synuclein Multimerization, Membrane Association, and Externalization. Int J Mol Sci 2021; 22:ijms22052689. [PMID: 33799982 PMCID: PMC7962109 DOI: 10.3390/ijms22052689] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/25/2021] [Accepted: 03/02/2021] [Indexed: 12/02/2022] Open
Abstract
ATP13A2, a late endo-/lysosomal polyamine transporter, is implicated in a variety of neurodegenerative diseases, including Parkinson’s disease and Kufor–Rakeb syndrome, an early-onset atypical form of parkinsonism. Loss-of-function mutations in ATP13A2 result in lysosomal deficiency as a consequence of impaired lysosomal export of the polyamines spermine/spermidine. Furthermore, accumulating evidence suggests the involvement of ATP13A2 in regulating the fate of α-synuclein, such as cytoplasmic accumulation and external release. However, no consensus has yet been reached on the mechanisms underlying these effects. Here, we aimed to gain more insight into how ATP13A2 is linked to α-synuclein biology in cell models with modified ATP13A2 activity. We found that loss of ATP13A2 impairs lysosomal membrane integrity and induces α-synuclein multimerization at the membrane, which is enhanced in conditions of oxidative stress or exposure to spermine. In contrast, overexpression of ATP13A2 wildtype (WT) had a protective effect on α-synuclein multimerization, which corresponded with reduced αsyn membrane association and stimulation of the ubiquitin-proteasome system. We also found that ATP13A2 promoted the secretion of α-synuclein through nanovesicles. Interestingly, the catalytically inactive ATP13A2 D508N mutant also affected polyubiquitination and externalization of α-synuclein multimers, suggesting a regulatory function independent of the ATPase and transport activity. In conclusion, our study demonstrates the impact of ATP13A2 on α-synuclein multimerization via polyamine transport dependent and independent functions.
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156
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The transport mechanism of P4 ATPase lipid flippases. Biochem J 2021; 477:3769-3790. [PMID: 33045059 DOI: 10.1042/bcj20200249] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/02/2020] [Accepted: 09/16/2020] [Indexed: 12/18/2022]
Abstract
P4 ATPase lipid flippases are ATP-driven transporters that translocate specific lipids from the exoplasmic to the cytosolic leaflet of biological membranes, thus establishing a lipid gradient between the two leaflets that is essential for many cellular processes. While substrate specificity, subcellular and tissue-specific expression, and physiological functions have been assigned to a number of these transporters in several organisms, the mechanism of lipid transport has been a topic of intense debate in the field. The recent publication of a series of structural models based on X-ray crystallography and cryo-EM studies has provided the first glimpse into how P4 ATPases have adapted the transport mechanism used by the cation-pumping family members to accommodate a substrate that is at least an order of magnitude larger than cations.
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157
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Invertebrate Models Untangle the Mechanism of Neurodegeneration in Parkinson's Disease. Cells 2021; 10:cells10020407. [PMID: 33669308 PMCID: PMC7920059 DOI: 10.3390/cells10020407] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/09/2021] [Accepted: 02/13/2021] [Indexed: 12/15/2022] Open
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disease, afflicting ~10 million people worldwide. Although several genes linked to PD are currently identified, PD remains primarily an idiopathic disorder. Neuronal protein α-synuclein is a major player in disease progression of both genetic and idiopathic forms of PD. However, it cannot alone explain underlying pathological processes. Recent studies demonstrate that many other risk factors can accelerate or further worsen brain dysfunction in PD patients. Several PD models, including non-mammalian eukaryotic organisms, have been developed to identify and characterize these factors. This review discusses recent findings in three PD model organisms, i.e., yeast, Drosophila, and Caenorhabditis elegans, that opened new mechanisms and identified novel contributors to this disorder. These non-mammalian models share many conserved molecular pathways and cellular processes with humans. New players affecting PD pathogenesis include previously unknown genes/proteins, novel signaling pathways, and low molecular weight substances. These findings might respond to the urgent need to discover novel drug targets for PD treatment and new biomarkers for early diagnostics of this disease. Since the study of neurodegeneration using simple eukaryotic organisms brought a huge amount of information, we include only the most recent or the most important relevant data.
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158
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Petrovich GD, Corradi GR, Pavan CH, Noli Truant S, Adamo HP. Highly exposed segment of the Spf1p P5A-ATPase near transmembrane M5 detected by limited proteolysis. PLoS One 2021; 16:e0245679. [PMID: 33507968 PMCID: PMC7842927 DOI: 10.1371/journal.pone.0245679] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 01/05/2021] [Indexed: 11/20/2022] Open
Abstract
The yeast Spf1p protein is a primary transporter that belongs to group 5 of the large family of P-ATPases. Loss of Spf1p function produces ER stress with alterations of metal ion and sterol homeostasis and protein folding, glycosylation and membrane insertion. The amino acid sequence of Spf1p shows the characteristic P-ATPase domains A, N, and P and the transmembrane segments M1-M10. In addition, Spf1p exhibits unique structures at its N-terminus (N-T region), including two putative additional transmembrane domains, and a large insertion connecting the P domain with transmembrane segment M5 (D region). Here we used limited proteolysis to examine the structure of Spf1p. A short exposure of Spf1p to trypsin or proteinase K resulted in the cleavage at the N and C terminal regions of the protein and abrogated the formation of the catalytic phosphoenzyme and the ATPase activity. In contrast, limited proteolysis of Spf1p with chymotrypsin generated a large N-terminal fragment containing most of the M4-M5 cytosolic loop, and a minor fragment containing the C-terminal region. If lipids were present during chymotryptic proteolysis, phosphoenzyme formation and ATPase activity were preserved. ATP slowed Spf1p proteolysis without detectable changes of the generated fragments. The analysis of the proteolytic peptides by mass spectrometry and Edman degradation indicated that the preferential chymotryptic site was localized near the cytosolic end of M5. The susceptibility to proteolysis suggests an unexpected exposure of this region of Spf1p that may be an intrinsic feature of P5A-ATPases.
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Affiliation(s)
- Guido D. Petrovich
- Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gerardo R. Corradi
- Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carlos H. Pavan
- Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Sofia Noli Truant
- Facultad de Farmacia y Bioquímica, Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral Prof. Dr. Ricardo A. Margni (IDEHU), UBA-CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Hugo P. Adamo
- Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Universidad de Buenos Aires, Buenos Aires, Argentina
- * E-mail:
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159
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Van Veen S, Martin S, Schuermans M, Vangheluwe P. Polyamine Transport Assay Using Reconstituted Yeast Membranes. Bio Protoc 2021; 11:e3888. [PMID: 33732777 DOI: 10.21769/bioprotoc.3888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 10/20/2020] [Accepted: 11/05/2020] [Indexed: 11/02/2022] Open
Abstract
ATP13A2/PARK9 is a late endo-/lysosomal P5B transport ATPase that is associated with several neurodegenerative disorders. We recently characterized ATP13A2 as a lysosomal polyamine exporter, which sheds light on the molecular identity of the unknown mammalian polyamine transport system. Here, we describe step by step a protocol to measure radiolabeled polyamine transport in reconstituted vesicles from yeast cells overexpressing human ATP13A2. This protocol was developed as part of our recent publication (van Veen et al., 2020 ) and will be useful for characterizing the transport function of other putative polyamine transporters, such as isoforms of the P5B transport ATPases.
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Affiliation(s)
- Sarah Van Veen
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Shaun Martin
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Marleen Schuermans
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Peter Vangheluwe
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
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160
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Ray B, Bhat A, Mahalakshmi AM, Tuladhar S, Bishir M, Mohan SK, Veeraraghavan VP, Chandra R, Essa MM, Chidambaram SB, Sakharkar MK. Mitochondrial and Organellar Crosstalk in Parkinson's Disease. ASN Neuro 2021; 13:17590914211028364. [PMID: 34304614 PMCID: PMC8317254 DOI: 10.1177/17590914211028364] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/04/2021] [Accepted: 06/07/2021] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial dysfunction is a well-established pathological event in Parkinson's disease (PD). Proteins misfolding and its impaired cellular clearance due to altered autophagy/mitophagy/pexophagy contribute to PD progression. It has been shown that mitochondria have contact sites with endoplasmic reticulum (ER), peroxisomes and lysosomes that are involved in regulating various physiological processes. In pathological conditions, the crosstalk at the contact sites initiates alterations in intracellular vesicular transport, calcium homeostasis and causes activation of proteases, protein misfolding and impairment of autophagy. Apart from the well-reported molecular changes like mitochondrial dysfunction, impaired autophagy/mitophagy and oxidative stress in PD, here we have summarized the recent scientific reports to provide the mechanistic insights on the altered communications between ER, peroxisomes, and lysosomes at mitochondrial contact sites. Furthermore, the manuscript elaborates on the contributions of mitochondrial contact sites and organelles dysfunction to the pathogenesis of PD and suggests potential therapeutic targets.
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Affiliation(s)
- Bipul Ray
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Mysuru, India
- Centre for Experimental Pharmacology and Toxicology, Central Animal Facility, JSS Academy of Higher Education & Research, Mysuru, India
| | - Abid Bhat
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Mysuru, India
- Centre for Experimental Pharmacology and Toxicology, Central Animal Facility, JSS Academy of Higher Education & Research, Mysuru, India
| | | | - Sunanda Tuladhar
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Mysuru, India
- Centre for Experimental Pharmacology and Toxicology, Central Animal Facility, JSS Academy of Higher Education & Research, Mysuru, India
| | - Muhammed Bishir
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Mysuru, India
| | - Surapaneni Krishna Mohan
- Department of Biochemistry, Panimalar Medical College Hospital & Research Institute, Varadharajapuram, Poonamallee, Chennai – 600123, India
| | - Vishnu Priya Veeraraghavan
- Department of Biochemistry, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai - 600 077, India
| | - Ramesh Chandra
- Drug Discovery & Development Laboratory, Department of Chemistry, University of Delhi, Delhi, 110007, India
- Dr. B. R. Ambedkar Centre for Biomedical Research, University of Delhi, Delhi, 110007, India
| | - Musthafa Mohamed Essa
- Department of Food Science and Nutrition, CAMS, Sultan Qaboos University, Muscat, Oman
- Aging and Dementia Research Group, Sultan Qaboos University, Muscat, Sultanate of Oman
- Visiting Professor, Biomedical Sciences department, University of Pacific, Sacramento, CA, USA
| | - Saravana Babu Chidambaram
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Mysuru, India
- Centre for Experimental Pharmacology and Toxicology, Central Animal Facility, JSS Academy of Higher Education & Research, Mysuru, India
| | - Meena Kishore Sakharkar
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK- S7N 5A2, Canada
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161
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Hamouda NN, Van den Haute C, Vanhoutte R, Sannerud R, Azfar M, Mayer R, Cortés Calabuig Á, Swinnen JV, Agostinis P, Baekelandt V, Annaert W, Impens F, Verhelst SHL, Eggermont J, Martin S, Vangheluwe P. ATP13A3 is a major component of the enigmatic mammalian polyamine transport system. J Biol Chem 2020; 296:100182. [PMID: 33310703 PMCID: PMC7948421 DOI: 10.1074/jbc.ra120.013908] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 11/27/2020] [Accepted: 12/11/2020] [Indexed: 12/13/2022] Open
Abstract
Polyamines, such as putrescine, spermidine, and spermine, are physiologically important polycations, but the transporters responsible for their uptake in mammalian cells remain poorly characterized. Here, we reveal a new component of the mammalian polyamine transport system using CHO-MG cells, a widely used model to study alternative polyamine uptake routes and characterize polyamine transport inhibitors for therapy. CHO-MG cells present polyamine uptake deficiency and resistance to a toxic polyamine biosynthesis inhibitor methylglyoxal bis-(guanylhydrazone) (MGBG), but the molecular defects responsible for these cellular characteristics remain unknown. By genome sequencing of CHO-MG cells, we identified mutations in an unexplored gene, ATP13A3, and found disturbed mRNA and protein expression. ATP13A3 encodes for an orphan P5B-ATPase (ATP13A3), a P-type transport ATPase that represents a candidate polyamine transporter. Interestingly, ATP13A3 complemented the putrescine transport deficiency and MGBG resistance of CHO-MG cells, whereas its knockdown in WT cells induced a CHO-MG phenotype demonstrated as a decrease in putrescine uptake and MGBG sensitivity. Taken together, our findings identify ATP13A3, which has been previously genetically linked with pulmonary arterial hypertension, as a major component of the mammalian polyamine transport system that confers sensitivity to MGBG.
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Affiliation(s)
- Norin Nabil Hamouda
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Chris Van den Haute
- Laboratory for Neurobiology and Gene Therapy, Department of Neurosciences, KU Leuven, Leuven, Belgium; Leuven Viral Vector Core, KU Leuven, Leuven, Belgium
| | - Roeland Vanhoutte
- Laboratory of Chemical Biology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Ragna Sannerud
- VIB-KU Leuven Laboratory of Membrane Trafficking, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Mujahid Azfar
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Rupert Mayer
- Department for Biomolecular Medicine, VIB Center for Medical Biotechnology, VIB Proteomics Core, Ghent University, Ghent, Belgium
| | | | - Johannes V Swinnen
- Laboratory of Lipid Metabolism and Cancer, Department of Oncology, LKI - Leuven Cancer Institute, KU Leuven, Leuven, Belgium
| | - Patrizia Agostinis
- Laboratory of Cell Death Research & Therapy, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium; Department of Oncology, VIB-KU Leuven Center for Cancer Biology, KU Leuven, Leuven, Belgium
| | - Veerle Baekelandt
- Laboratory for Neurobiology and Gene Therapy, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Wim Annaert
- VIB-KU Leuven Laboratory of Membrane Trafficking, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Francis Impens
- Department for Biomolecular Medicine, VIB Center for Medical Biotechnology, VIB Proteomics Core, Ghent University, Ghent, Belgium
| | - Steven H L Verhelst
- Laboratory of Chemical Biology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium; Chemical Proteomics, Leibniz Institute for Analytical Sciences ISAS, Dortmund, Germany
| | - Jan Eggermont
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Shaun Martin
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Peter Vangheluwe
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
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162
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Minakaki G, Krainc D, Burbulla LF. The Convergence of Alpha-Synuclein, Mitochondrial, and Lysosomal Pathways in Vulnerability of Midbrain Dopaminergic Neurons in Parkinson's Disease. Front Cell Dev Biol 2020; 8:580634. [PMID: 33381501 PMCID: PMC7767856 DOI: 10.3389/fcell.2020.580634] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 11/10/2020] [Indexed: 12/15/2022] Open
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disease, characterized by progressive bradykinesia, rigidity, resting tremor, and gait impairment, as well as a spectrum of non-motor symptoms including autonomic and cognitive dysfunction. The cardinal motor symptoms of PD stem from the loss of substantia nigra (SN) dopaminergic (DAergic) neurons, and it remains unclear why SN DAergic neurons are preferentially lost in PD. However, recent identification of several genetic PD forms suggests that mitochondrial and lysosomal dysfunctions play important roles in the degeneration of midbrain dopamine (DA) neurons. In this review, we discuss the interplay of cell-autonomous mechanisms linked to DAergic neuron vulnerability and alpha-synuclein homeostasis. Emerging studies highlight a deleterious feedback cycle, with oxidative stress, altered DA metabolism, dysfunctional lysosomes, and pathological alpha-synuclein species representing key events in the pathogenesis of PD. We also discuss the interactions of alpha-synuclein with toxic DA metabolites, as well as the biochemical links between intracellular iron, calcium, and alpha-synuclein accumulation. We suggest that targeting multiple pathways, rather than individual processes, will be important for developing disease-modifying therapies. In this context, we focus on current translational efforts specifically targeting lysosomal function, as well as oxidative stress via calcium and iron modulation. These efforts could have therapeutic benefits for the broader population of sporadic PD and related synucleinopathies.
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Affiliation(s)
- Georgia Minakaki
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Dimitri Krainc
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Lena F Burbulla
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
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163
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Lin TK, Lin KJ, Lin KL, Liou CW, Chen SD, Chuang YC, Wang PW, Chuang JH, Wang TJ. When Friendship Turns Sour: Effective Communication Between Mitochondria and Intracellular Organelles in Parkinson's Disease. Front Cell Dev Biol 2020; 8:607392. [PMID: 33330511 PMCID: PMC7733999 DOI: 10.3389/fcell.2020.607392] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 10/30/2020] [Indexed: 12/17/2022] Open
Abstract
Parkinson's disease (PD) is a complex neurodegenerative disease with pathological hallmarks including progressive neuronal loss from the substantia nigra pars compacta and α-synuclein intraneuronal inclusions, known as Lewy bodies. Although the etiology of PD remains elusive, mitochondrial damage has been established to take center stage in the pathogenesis of PD. Mitochondria are critical to cellular energy production, metabolism, homeostasis, and stress responses; the association with PD emphasizes the importance of maintenance of mitochondrial network integrity. To accomplish the pleiotropic functions, mitochondria are dynamic not only within their own network but also in orchestrated coordination with other organelles in the cellular community. Through physical contact sites, signal transduction, and vesicle transport, mitochondria and intracellular organelles achieve the goals of calcium homeostasis, redox homeostasis, protein homeostasis, autophagy, and apoptosis. Herein, we review the finely tuned interactions between mitochondria and surrounding intracellular organelles, with focus on the nucleus, endoplasmic reticulum, Golgi apparatus, peroxisomes, and lysosomes. Participants that may contribute to the pathogenic mechanisms of PD will be highlighted in this review.
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Affiliation(s)
- Tsu-Kung Lin
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Center of Parkinson's Disease, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Kai-Jung Lin
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Kai-Lieh Lin
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Department of Anesthesiology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Chia-Wei Liou
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Center of Parkinson's Disease, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Shang-Der Chen
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Center of Parkinson's Disease, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Yao-Chung Chuang
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Center of Parkinson's Disease, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Pei-Wen Wang
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Department of Metabolism, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Jiin-Haur Chuang
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Department of Pediatric Surgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Tzu-Jou Wang
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Department of Pediatric, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
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164
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ATP13A2-mediated endo-lysosomal polyamine export counters mitochondrial oxidative stress. Proc Natl Acad Sci U S A 2020; 117:31198-31207. [PMID: 33229544 PMCID: PMC7733819 DOI: 10.1073/pnas.1922342117] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mutations in ATP13A2 cause a spectrum of related neurodegenerative disorders. ATP13A2 is a lysosomal exporter of polyamines that contributes to lysosomal health and controls cellular polyamine content. Conversely, loss of ATP13A2 leads to lysosomal dysfunction, a hallmark of neurodegeneration. Here, we show that polyamines transported by ATP13A2 provide cellular protection by lowering reactive oxygen species (ROS), which may relate to the antioxidant properties of polyamines. Consequently, dysfunctional ATP13A2 sensitizes cells to oxidative stress, which impairs mitochondria, and induces toxicity and cell death. ATP13A2-mediated polyamine transport represents a conserved pathway that protects against mitochondrial oxidative stress. The combined protective impact of ATP13A2 on lysosomal health and mitochondrial oxidative stress may explain why ATP13A2 exerts potent neuroprotective effects. Recessive loss-of-function mutations in ATP13A2 (PARK9) are associated with a spectrum of neurodegenerative disorders, including Parkinson’s disease (PD). We recently revealed that the late endo-lysosomal transporter ATP13A2 pumps polyamines like spermine into the cytosol, whereas ATP13A2 dysfunction causes lysosomal polyamine accumulation and rupture. Here, we investigate how ATP13A2 provides protection against mitochondrial toxins such as rotenone, an environmental PD risk factor. Rotenone promoted mitochondrial-generated superoxide (MitoROS), which was exacerbated by ATP13A2 deficiency in SH-SY5Y cells and patient-derived fibroblasts, disturbing mitochondrial functionality and inducing toxicity and cell death. Moreover, ATP13A2 knockdown induced an ATF4-CHOP-dependent stress response following rotenone exposure. MitoROS and ATF4-CHOP were blocked by MitoTEMPO, a mitochondrial antioxidant, suggesting that the impact of ATP13A2 on MitoROS may relate to the antioxidant properties of spermine. Pharmacological inhibition of intracellular polyamine synthesis with α-difluoromethylornithine (DFMO) also increased MitoROS and ATF4 when ATP13A2 was deficient. The polyamine transport activity of ATP13A2 was required for lowering rotenone/DFMO-induced MitoROS, whereas exogenous spermine quenched rotenone-induced MitoROS via ATP13A2. Interestingly, fluorescently labeled spermine uptake in the mitochondria dropped as a consequence of ATP13A2 transport deficiency. Our cellular observations were recapitulated in vivo, in a Caenorhabditis elegans strain deficient in the ATP13A2 ortholog catp-6. These animals exhibited a basal elevated MitoROS level, mitochondrial dysfunction, and enhanced stress response regulated by atfs-1, the C. elegans ortholog of ATF4, causing hypersensitivity to rotenone, which was reversible with MitoTEMPO. Together, our study reveals a conserved cell protective pathway that counters mitochondrial oxidative stress via ATP13A2-mediated lysosomal spermine export.
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165
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Li J, Meng Y, Wu X, Sun Y. Polyamines and related signaling pathways in cancer. Cancer Cell Int 2020; 20:539. [PMID: 33292222 PMCID: PMC7643453 DOI: 10.1186/s12935-020-01545-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 09/08/2020] [Indexed: 02/06/2023] Open
Abstract
Polyamines are aliphatic compounds with more than two amino groups that play various important roles in human cells. In cancer, polyamine metabolism dysfunction often occurs, and regulatory mechanisms of polyamine. This review summarizes the existing research on the metabolism and transport of polyamines to study the association of oncogenes and related signaling pathways with polyamines in tumor cells. Drugs that regulate enzymes have been developed for cancer treatment, and in the future, more attention should be paid to treatment strategies that simultaneously modulate polyamine metabolism and carcinogenic signaling pathways. In addition, the polyamine pathway is a potential target for cancer chemoprevention. As an irreversible suicide inhibitor of the ornithine decarboxylase (a vital enzyme of polyamine synthesis), Difluoro-methylornithine had been shown to have the chemoprevention effect on cancer. Therefore, we summarized and analyzed the chemoprophylaxis effect of the difluoromethylornithine in this systematic review.
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Affiliation(s)
- Jiajing Li
- Department of Otorhinolaryngology-Head and Neck Surgery, China-Japan Union Hospital, Jilin University, Changchun, Jilin Province, China.,Department of Pathophysiology, Prostate Diseases Prevention and Treatment Research Center, College of Basic Medical Science, Jilin University, Changchun, China
| | - Yan Meng
- Department of Pathophysiology, Prostate Diseases Prevention and Treatment Research Center, College of Basic Medical Science, Jilin University, Changchun, China
| | - Xiaolin Wu
- Department of Pathophysiology, Prostate Diseases Prevention and Treatment Research Center, College of Basic Medical Science, Jilin University, Changchun, China
| | - Yuxin Sun
- Department of Otorhinolaryngology-Head and Neck Surgery, China-Japan Union Hospital, Jilin University, Changchun, Jilin Province, China.
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166
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The Emerging Role of the Lysosome in Parkinson's Disease. Cells 2020; 9:cells9112399. [PMID: 33147750 PMCID: PMC7692401 DOI: 10.3390/cells9112399] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 10/22/2020] [Accepted: 10/28/2020] [Indexed: 12/12/2022] Open
Abstract
Lysosomal function has a central role in maintaining neuronal homeostasis, and, accordingly, lysosomal dysfunction has been linked to neurodegeneration and particularly to Parkinson’s disease (PD). Lysosomes are the converging step where the substrates delivered by autophagy and endocytosis are degraded in order to recycle their primary components to rebuild new macromolecules. Genetic studies have revealed the important link between the lysosomal function and PD; several of the autosomal dominant and recessive genes associated with PD as well as several genetic risk factors encode for lysosomal, autophagic, and endosomal proteins. Mutations in these PD-associated genes can cause lysosomal dysfunction, and since α-synuclein degradation is mostly lysosomal-dependent, among other consequences, lysosomal impairment can affect α-synuclein turnover, contributing to increase its intracellular levels and therefore promoting its accumulation and aggregation. Recent studies have also highlighted the bidirectional link between Parkinson’s disease and lysosomal storage diseases (LSD); evidence includes the presence of α-synuclein inclusions in the brain regions of patients with LSD and the identification of several lysosomal genes involved in LSD as genetic risk factors to develop PD.
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167
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Erb ML, Moore DJ. LRRK2 and the Endolysosomal System in Parkinson's Disease. JOURNAL OF PARKINSONS DISEASE 2020; 10:1271-1291. [PMID: 33044192 PMCID: PMC7677880 DOI: 10.3233/jpd-202138] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mutations in leucine-rich repeat kinase 2 (LRRK2) cause autosomal dominant familial Parkinson’s disease (PD), with pathogenic mutations enhancing LRRK2 kinase activity. There is a growing body of evidence indicating that LRRK2 contributes to neuronal damage and pathology both in familial and sporadic PD, making it of particular interest for understanding the molecular pathways that underlie PD. Although LRRK2 has been extensively studied to date, our understanding of the seemingly diverse functions of LRRK2 throughout the cell remains incomplete. In this review, we discuss the functions of LRRK2 within the endolysosomal pathway. Endocytosis, vesicle trafficking pathways, and lysosomal degradation are commonly disrupted in many neurodegenerative diseases, including PD. Additionally, many PD-linked gene products function in these intersecting pathways, suggesting an important role for the endolysosomal system in maintaining protein homeostasis and neuronal health in PD. LRRK2 activity can regulate synaptic vesicle endocytosis, lysosomal function, Golgi network maintenance and sorting, vesicular trafficking and autophagy, with alterations in LRRK2 kinase activity serving to disrupt or regulate these pathways depending on the distinct cell type or model system. LRRK2 is critically regulated by at least two proteins in the endolysosomal pathway, Rab29 and VPS35, which may serve as master regulators of LRRK2 kinase activity. Investigating the function and regulation of LRRK2 in the endolysosomal pathway in diverse PD models, especially in vivo models, will provide critical insight into the cellular and molecular pathophysiological mechanisms driving PD and whether LRRK2 represents a viable drug target for disease-modification in familial and sporadic PD.
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Affiliation(s)
- Madalynn L Erb
- Center for Neurodegenerative Science, Van Andel Institute, Grand Rapids, MI, USA
| | - Darren J Moore
- Center for Neurodegenerative Science, Van Andel Institute, Grand Rapids, MI, USA
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168
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Fischer CA, Besora-Casals L, Rolland SG, Haeussler S, Singh K, Duchen M, Conradt B, Marr C. MitoSegNet: Easy-to-use Deep Learning Segmentation for Analyzing Mitochondrial Morphology. iScience 2020; 23:101601. [PMID: 33083756 PMCID: PMC7554024 DOI: 10.1016/j.isci.2020.101601] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 08/18/2020] [Accepted: 09/17/2020] [Indexed: 12/29/2022] Open
Abstract
While the analysis of mitochondrial morphology has emerged as a key tool in the study of mitochondrial function, efficient quantification of mitochondrial microscopy images presents a challenging task and bottleneck for statistically robust conclusions. Here, we present Mitochondrial Segmentation Network (MitoSegNet), a pretrained deep learning segmentation model that enables researchers to easily exploit the power of deep learning for the quantification of mitochondrial morphology. We tested the performance of MitoSegNet against three feature-based segmentation algorithms and the machine-learning segmentation tool Ilastik. MitoSegNet outperformed all other methods in both pixelwise and morphological segmentation accuracy. We successfully applied MitoSegNet to unseen fluorescence microscopy images of mitoGFP expressing mitochondria in wild-type and catp-6 ATP13A2 mutant C. elegans adults. Additionally, MitoSegNet was capable of accurately segmenting mitochondria in HeLa cells treated with fragmentation inducing reagents. We provide MitoSegNet in a toolbox for Windows and Linux operating systems that combines segmentation with morphological analysis.
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Affiliation(s)
- Christian A. Fischer
- Fakultät für Biologie, Ludwig-Maximilians-Universität Munich, Planegg-Martinsried, Munich, 82152 Bavaria, Germany
- Centre for Integrated Protein Science, Ludwig-Maximilians-University, Planegg-Martinsried, Munich, 82152 Bavaria, Germany
- Institute of Computational Biology, Helmholtz Zentrum München – German Research Center for Environmental Health, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Laura Besora-Casals
- Fakultät für Biologie, Ludwig-Maximilians-Universität Munich, Planegg-Martinsried, Munich, 82152 Bavaria, Germany
| | - Stéphane G. Rolland
- Fakultät für Biologie, Ludwig-Maximilians-Universität Munich, Planegg-Martinsried, Munich, 82152 Bavaria, Germany
| | - Simon Haeussler
- Fakultät für Biologie, Ludwig-Maximilians-Universität Munich, Planegg-Martinsried, Munich, 82152 Bavaria, Germany
| | - Kritarth Singh
- Department of Cell and Developmental Biology, Division of Biosciences, University College London, London WC1E 6AP, UK
| | - Michael Duchen
- Department of Cell and Developmental Biology, Division of Biosciences, University College London, London WC1E 6AP, UK
| | - Barbara Conradt
- Fakultät für Biologie, Ludwig-Maximilians-Universität Munich, Planegg-Martinsried, Munich, 82152 Bavaria, Germany
- Centre for Integrated Protein Science, Ludwig-Maximilians-University, Planegg-Martinsried, Munich, 82152 Bavaria, Germany
- Department of Cell and Developmental Biology, Division of Biosciences, University College London, London WC1E 6AP, UK
| | - Carsten Marr
- Institute of Computational Biology, Helmholtz Zentrum München – German Research Center for Environmental Health, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
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169
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Functional validation of a human GLUD2 variant in a murine model of Parkinson's disease. Cell Death Dis 2020; 11:897. [PMID: 33093440 PMCID: PMC7582183 DOI: 10.1038/s41419-020-03043-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/17/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Parkinson's disease (PD) is a common neurodegenerative disease characterized by Lewy body formation and progressive dopaminergic neuron death in the substantia nigra (SN). Genetic susceptibility is a strong risk factor for PD. Previously, a rare gain-of-function variant of GLUD2 glutamate dehydrogenase (T1492G) was reported to be associated with early onset in male PD patients; however, the function and underlying mechanism of this variant remains elusive. In the present study, we generated adeno-associated virus expressing GLUD2 and its mutant under the control of the glial fibrillary acidic protein promotor and injected the virus into the SN pars compacta of either untreated mice or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice. Our results demonstrate that GLUD2 mutation in MPTP-induced PD mice exacerbates movement deficits and nigral dopaminergic neuron death and reduces glutamate transporters expression and function. Using GC-Q-TOF/MS-based metabolomics, we determined that GLUD2 mutation damages mitochondrial function by decreasing succinate dehydrogenase activity to impede the tricarboxylic acid cycle in the SN of MPTP-induced PD mice. Accordingly, GLUD2 mutant mice had reduced energy metabolism and increased apoptosis, possibly due to downregulation of brain-derived neurotrophic factor/nuclear factor E2-related factor 2 signaling in in vitro and in vivo PD models. Collectively, our findings verify the function of GLUD2 in PD and unravel a mechanism by which a genetic variant in human GLUD2 may contribute to disease onset.
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170
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Novel mutations in ATP13A2 associated with mixed neurological presentations and iron toxicity due to nonsense-mediated decay. Brain Res 2020; 1750:147167. [PMID: 33091395 DOI: 10.1016/j.brainres.2020.147167] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 10/05/2020] [Accepted: 10/14/2020] [Indexed: 02/08/2023]
Abstract
BACKGROUND Kufor-Rakeb Syndrome (KRS) is an autosomal recessive disease characterized by Parkinsonism, pyramidal signs, dementia, and supranuclear gaze palsy. KRS is caused by mutations in ATP13A2producing a transmembrane protein responsible for the regulation of intracellular inorganic cations. OBJECTIVE Two siblings born to a Turkish family of consanguineous marriage had mixed neurological presentations with the presence of hypointense images on T2-weighted MRI and were pre-diagnosed as having autosomal recessive spastic paraparesis or ataxia.We aimed to identify the disease-causing mutation by whole-exome sequencing and elucidate the underlying molecular mechanism of the causative mutation. METHODS Prussian blue staining was conducted for the detection of cellular iron accumulation. Disease-causing mutation inATP13A2was detected by whole-exome sequencing. Expression levels of ATP13A2 mRNA and protein were assessed by qRT-PCR and Western Blot. RESULTS Iron deposits in the patients' fibroblasts were detected by Prussian blue staining. Novel homozygous mutation c.1422_1423del:p.P474fs was detected intheATP13A2. As this mutation caused a premature termination codon (PTC), the expression of mutant ATP13A2 mRNA through qRT-PCR analysis was found to be degraded by nonsense-mediated decay and this prevented the expression of ATP13A2 protein in the patients' fibroblasts. CONCLUSIONS Novel frameshift mutation causing a PTC in ATP13A2 lead to degradation of ATP13A2 mRNA by NMD. Iron accumulation due to the absence of ATP13A2 protein in the patient's fibroblasts and hypointense areas on T2-weighted images may expand the spectrum of KRS to consider it as neurodegeneration with brain iron accumulation disorders.
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171
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Astrocytes Protect Human Dopaminergic Neurons from α-Synuclein Accumulation and Propagation. J Neurosci 2020; 40:8618-8628. [PMID: 33046546 DOI: 10.1523/jneurosci.0954-20.2020] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 08/18/2020] [Accepted: 09/01/2020] [Indexed: 12/31/2022] Open
Abstract
The pathologic hallmark of Parkinson's disease is the accumulation of α-synuclein-containing Lewy bodies/neurites almost exclusively in neurons, and rarely in glial cells. However, emerging evidence suggests that glia such as astrocytes play an important role in the development of α-synuclein pathology. Using induced pluripotent stem-derived dopaminergic neurons and astrocytes from healthy subjects and patients carrying mutations in lysosomal ATP13A2, a monogenic form of synucleinopathy, we found that astrocytes rapidly internalized α-synuclein, and exhibited higher lysosomal degradation rates compared with neurons. Moreover, coculturing astrocytes and neurons led to decreased accumulation of α-synuclein in neurons and consequently diminished interneuronal transfer of α-synuclein. These protective functions of astrocytes were attenuated by ATP13A2 deficiency, suggesting that the loss of ATP13A2 function in astrocytes at least partially contributes to neuronal α-synuclein pathology. Together, our results highlight the importance of lysosomal function in astrocytes in the pathogenesis of synucleinopathies.SIGNIFICANCE STATEMENT While most neurodegenerative disorders are characterized by the accumulation of aggregated mutant proteins exclusively in neurons, the contribution of glial cells in this process remains poorly explored. Here, we demonstrate that astrocytes contribute to the removal of extracellular α-synuclein and that disruption of this pathway caused by mutations in the Parkinson's disease-linked gene ATP13A2 result in α-synuclein accumulation in human dopaminergic neurons. We found that astrocytes also protect neurons from α-synuclein propagation, whereas ATP13A2 deficiency in astrocytes compromises this protective function. These results highlight astrocyte-mediated α-synuclein clearance as a potential therapeutic target in disorders characterized by the accumulation of α-synuclein, including Parkinson's disease.
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172
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McKenna MJ, Sim SI, Ordureau A, Wei L, Harper JW, Shao S, Park E. The endoplasmic reticulum P5A-ATPase is a transmembrane helix dislocase. Science 2020; 369:eabc5809. [PMID: 32973005 PMCID: PMC8053355 DOI: 10.1126/science.abc5809] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 07/28/2020] [Indexed: 01/28/2023]
Abstract
Organelle identity depends on protein composition. How mistargeted proteins are selectively recognized and removed from organelles is incompletely understood. Here, we found that the orphan P5A-adenosine triphosphatase (ATPase) transporter ATP13A1 (Spf1 in yeast) directly interacted with the transmembrane segment (TM) of mitochondrial tail-anchored proteins. P5A-ATPase activity mediated the extraction of mistargeted proteins from the endoplasmic reticulum (ER). Cryo-electron microscopy structures of Saccharomyces cerevisiae Spf1 revealed a large, membrane-accessible substrate-binding pocket that alternately faced the ER lumen and cytosol and an endogenous substrate resembling an α-helical TM. Our results indicate that the P5A-ATPase could dislocate misinserted hydrophobic helices flanked by short basic segments from the ER. TM dislocation by the P5A-ATPase establishes an additional class of P-type ATPase substrates and may correct mistakes in protein targeting or topogenesis.
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Affiliation(s)
- Michael J McKenna
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Sue Im Sim
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Alban Ordureau
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Lianjie Wei
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - J Wade Harper
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Sichen Shao
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA.
| | - Eunyong Park
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
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173
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Madeo F, Hofer SJ, Pendl T, Bauer MA, Eisenberg T, Carmona-Gutierrez D, Kroemer G. Nutritional Aspects of Spermidine. Annu Rev Nutr 2020; 40:135-159. [DOI: 10.1146/annurev-nutr-120419-015419] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Natural polyamines (spermidine and spermine) are small, positively charged molecules that are ubiquitously found within organisms and cells. They exert numerous (intra)cellular functions and have been implicated to protect against several age-related diseases. Although polyamine levels decline in a complex age-dependent, tissue-, and cell type–specific manner, they are maintained in healthy nonagenarians and centenarians. Increased polyamine levels, including through enhanced dietary intake, have been consistently linked to improved health and reduced overall mortality. In preclinical models, dietary supplementation with spermidine prolongs life span and health span. In this review, we highlight salient aspects of nutritional polyamine intake and summarize the current knowledge of organismal and cellular uptake and distribution of dietary (and gastrointestinal) polyamines and their impact on human health. We further summarize clinical and epidemiological studies of dietary polyamines.
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Affiliation(s)
- Frank Madeo
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | - Sebastian J. Hofer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Tobias Pendl
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Maria A. Bauer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Tobias Eisenberg
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
- Central Lab Graz Cell Informatics and Analyses (GRACIA), NAWI Graz, University of Graz, 8010 Graz, Austria
| | | | - Guido Kroemer
- Equipe Labellisée par la Ligue Contre le Cancer, Université de Paris, Sorbonne Université, INSERM U1138, Centre de Recherche des Cordeliers, 75006 Paris, France
- Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, F-94805 Villejuif, France
- Pôle de Biologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, F-75015 Paris, France
- Suzhou Institute for Systems Medicine, Chinese Academy of Medical Sciences, Jiangsu 215163, Suzhou, China
- Department of Women's and Children's Health, Karolinska Institute, Karolinska University, S-17177 Solna, Sweden
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174
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Trinh D, Israwi AR, Arathoon LR, Gleave JA, Nash JE. The multi-faceted role of mitochondria in the pathology of Parkinson's disease. J Neurochem 2020; 156:715-752. [PMID: 33616931 DOI: 10.1111/jnc.15154] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 07/29/2020] [Accepted: 07/31/2020] [Indexed: 12/14/2022]
Abstract
Mitochondria are essential for neuronal function. They produce ATP to meet energy demands, regulate homeostasis of ion levels such as calcium and regulate reactive oxygen species that cause oxidative cellular stress. Mitochondria have also been shown to regulate protein synthesis within themselves, as well as within the nucleus, and also influence synaptic plasticity. These roles are especially important for neurons, which have higher energy demands and greater susceptibility to stress. Dysfunction of mitochondria has been associated with several neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease, Huntington's disease, Glaucoma and Amyotrophic Lateral Sclerosis. The focus of this review is on how and why mitochondrial function is linked to the pathology of Parkinson's disease (PD). Many of the PD-linked genetic mutations which have been identified result in dysfunctional mitochondria, through a wide-spread number of mechanisms. In this review, we describe how susceptible neurons are predisposed to be vulnerable to the toxic events that occur during the neurodegenerative process of PD, and how mitochondria are central to these pathways. We also discuss ways in which proteins linked with familial PD control mitochondrial function, both physiologically and pathologically, along with their implications in genome-wide association studies and risk assessment. Finally, we review potential strategies for disease modification through mitochondrial enhancement. Ultimately, agents capable of both improving and/or restoring mitochondrial function, either alone, or in conjunction with other disease-modifying agents may halt or slow the progression of neurodegeneration in Parkinson's disease.
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Affiliation(s)
- Dennison Trinh
- Department of Biological Sciences, University of Toronto Scarborough, Centre for Neurobiology of Stress, Toronto, ON, Canada
| | - Ahmad R Israwi
- Department of Biological Sciences, University of Toronto Scarborough, Centre for Neurobiology of Stress, Toronto, ON, Canada
| | - Lindsay R Arathoon
- Department of Biological Sciences, University of Toronto Scarborough, Centre for Neurobiology of Stress, Toronto, ON, Canada
| | - Jacqueline A Gleave
- Department of Biological Sciences, University of Toronto Scarborough, Centre for Neurobiology of Stress, Toronto, ON, Canada
| | - Joanne E Nash
- Department of Biological Sciences, University of Toronto Scarborough, Centre for Neurobiology of Stress, Toronto, ON, Canada
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175
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Lyons JA, Timcenko M, Dieudonné T, Lenoir G, Nissen P. P4-ATPases: how an old dog learnt new tricks — structure and mechanism of lipid flippases. Curr Opin Struct Biol 2020; 63:65-73. [DOI: 10.1016/j.sbi.2020.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 03/28/2020] [Accepted: 04/05/2020] [Indexed: 12/11/2022]
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176
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Foulquier F, Legrand D. Biometals and glycosylation in humans: Congenital disorders of glycosylation shed lights into the crucial role of Golgi manganese homeostasis. Biochim Biophys Acta Gen Subj 2020; 1864:129674. [PMID: 32599014 DOI: 10.1016/j.bbagen.2020.129674] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/18/2020] [Accepted: 06/24/2020] [Indexed: 12/24/2022]
Abstract
About half of the eukaryotic proteins bind biometals that participate in their structure and functions in virtually all physiological processes, including glycosylation. After reviewing the biological roles and transport mechanisms of calcium, magnesium, manganese, zinc and cobalt acting as cofactors of the metalloproteins involved in sugar metabolism and/or glycosylation, the paper will outline the pathologies resulting from a dysregulation of these metals homeostasis and more particularly Congenital Disorders of Glycosylation (CDGs) caused by ion transporter defects. Highlighting of CDGs due to defects in SLC39A8 (ZIP8) and TMEM165, two proteins transporting manganese from the extracellular space to cytosol and from cytosol to the Golgi lumen, respectively, has emphasized the importance of manganese homeostasis for glycosylation. Based on our current knowledge of TMEM165 structure and functions, this review will draw a picture of known and putative mechanisms regulating manganese homeostasis in the secretory pathway.
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Affiliation(s)
- François Foulquier
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, Lille F-59000, France
| | - Dominique Legrand
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, Lille F-59000, France.
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177
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Mutated ATP10B increases Parkinson's disease risk by compromising lysosomal glucosylceramide export. Acta Neuropathol 2020; 139:1001-1024. [PMID: 32172343 PMCID: PMC7244618 DOI: 10.1007/s00401-020-02145-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 02/18/2020] [Accepted: 03/02/2020] [Indexed: 02/07/2023]
Abstract
Parkinson’s disease (PD) is a progressive neurodegenerative brain disease presenting with a variety of motor and non-motor symptoms, loss of midbrain dopaminergic neurons in the substantia nigra pars compacta and the occurrence of α-synuclein-positive Lewy bodies in surviving neurons. Here, we performed whole exome sequencing in 52 early-onset PD patients and identified 3 carriers of compound heterozygous mutations in the ATP10B P4-type ATPase gene. Genetic screening of a Belgian PD and dementia with Lewy bodies (DLB) cohort identified 4 additional compound heterozygous mutation carriers (6/617 PD patients, 0.97%; 1/226 DLB patients, 0.44%). We established that ATP10B encodes a late endo-lysosomal lipid flippase that translocates the lipids glucosylceramide (GluCer) and phosphatidylcholine (PC) towards the cytosolic membrane leaflet. The PD associated ATP10B mutants are catalytically inactive and fail to provide cellular protection against the environmental PD risk factors rotenone and manganese. In isolated cortical neurons, loss of ATP10B leads to general lysosomal dysfunction and cell death. Impaired lysosomal functionality and integrity is well known to be implicated in PD pathology and linked to multiple causal PD genes and genetic risk factors. Our results indicate that recessive loss of function mutations in ATP10B increase risk for PD by disturbed lysosomal export of GluCer and PC. Both ATP10B and glucocerebrosidase 1, encoded by the PD risk gene GBA1, reduce lysosomal GluCer levels, emerging lysosomal GluCer accumulation as a potential PD driver.
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178
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Smolders S, Van Broeckhoven C. Genetic perspective on the synergistic connection between vesicular transport, lysosomal and mitochondrial pathways associated with Parkinson's disease pathogenesis. Acta Neuropathol Commun 2020; 8:63. [PMID: 32375870 PMCID: PMC7201634 DOI: 10.1186/s40478-020-00935-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 04/21/2020] [Indexed: 12/13/2022] Open
Abstract
Parkinson's disease (PD) and atypical parkinsonian syndromes (APS) are symptomatically characterized by parkinsonism, with the latter presenting additionally a distinctive range of atypical features. Although the majority of patients with PD and APS appear to be sporadic, genetic causes of several rare monogenic disease variants were identified. The knowledge acquired from these genetic factors indicated that defects in vesicular transport pathways, endo-lysosomal dysfunction, impaired autophagy-lysosomal protein and organelle degradation pathways, α-synuclein aggregation and mitochondrial dysfunction play key roles in PD pathogenesis. Moreover, membrane dynamics are increasingly recognized as a key player in the disease pathogenesis due lipid homeostasis alterations, associated with lysosomal dysfunction, caused by mutations in several PD and APS genes. The importance of lysosomal dysfunction and lipid homeostasis is strengthened by both genetic discoveries and clinical epidemiology of the association between parkinsonism and lysosomal storage disorders (LSDs), caused by the disruption of lysosomal biogenesis or function. A synergistic coordination between vesicular trafficking, lysosomal and mitochondria defects exist whereby mutations in PD and APS genes encoding proteins primarily involved one PD pathway are frequently associated with defects in other PD pathways as a secondary effect. Moreover, accumulating clinical and genetic observations suggest more complex inheritance patters of familial PD exist, including oligogenic and polygenic inheritance of genes in the same or interconnected PD pathways, further strengthening their synergistic connection.Here, we provide a comprehensive overview of PD and APS genes with functions in vesicular transport, lysosomal and mitochondrial pathways, and highlight functional and genetic evidence of the synergistic connection between these PD associated pathways.
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Affiliation(s)
- Stefanie Smolders
- Neurodegenerative Brain Diseases Group, VIB Center for Molecular Neurology, University of Antwerp - CDE, Universiteitsplein 1, 2610, Antwerpen, Belgium
- Biomedical Sciences, University of Antwerp, Antwerpen, Belgium
| | - Christine Van Broeckhoven
- Neurodegenerative Brain Diseases Group, VIB Center for Molecular Neurology, University of Antwerp - CDE, Universiteitsplein 1, 2610, Antwerpen, Belgium.
- Biomedical Sciences, University of Antwerp, Antwerpen, Belgium.
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179
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Oh S, Paknejad N, Hite RK. Gating and selectivity mechanisms for the lysosomal K + channel TMEM175. eLife 2020; 9:e53430. [PMID: 32228865 PMCID: PMC7141809 DOI: 10.7554/elife.53430] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 03/29/2020] [Indexed: 12/23/2022] Open
Abstract
Transmembrane protein 175 (TMEM175) is a K+-selective ion channel expressed in lysosomal membranes, where it establishes a membrane potential essential for lysosomal function and its dysregulation is associated with the development of Parkinson's Disease. TMEM175 is evolutionarily distinct from all known channels, predicting novel ion-selectivity and gating mechanisms. Here we present cryo-EM structures of human TMEM175 in open and closed conformations, enabled by resolutions up to 2.6 Å. Human TMEM175 adopts a homodimeric architecture with a central ion-conduction pore lined by the side chains of the pore-lining helices. Conserved isoleucine residues in the center of the pore serve as the gate in the closed conformation. In the widened channel in the open conformation, these same residues establish a constriction essential for K+ selectivity. These studies reveal the mechanisms of permeation, selectivity and gating and lay the groundwork for understanding the role of TMEM175 in lysosomal function.
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Affiliation(s)
- SeCheol Oh
- Structural Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
| | - Navid Paknejad
- Structural Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
| | - Richard K Hite
- Structural Biology Program, Memorial Sloan Kettering Cancer CenterNew YorkUnited States
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