1
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Wisner SR, Chlebowski M, Mandal A, Mai D, Stein C, Petralia RS, Wang YX, Drerup CM. An initial HOPS-mediated fusion event is critical for autophagosome transport initiation from the axon terminal. Autophagy 2024:1-22. [PMID: 38899385 DOI: 10.1080/15548627.2024.2366122] [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: 12/03/2023] [Accepted: 06/05/2024] [Indexed: 06/21/2024] Open
Abstract
In neurons, macroautophagy/autophagy is a frequent and critical process. In the axon, autophagy begins in the axon terminal, where most nascent autophagosomes form. After formation, autophagosomes must initiate transport to exit the axon terminal and move toward the cell body via retrograde transport. During retrograde transport these autophagosomes mature through repetitive fusion events. Complete lysosomal cargo degradation occurs largely in the cell body. The precipitating events to stimulate retrograde autophagosome transport have been debated but their importance is clear: disrupting neuronal autophagy or autophagosome transport is detrimental to neuronal health and function. We have identified the HOPS complex as essential for early autophagosome maturation and consequent initiation of retrograde transport from the axon terminal. In yeast and mammalian cells, HOPS controls fusion between autophagosomes and late endosomes with lysosomes. Using zebrafish strains with loss-of-function mutations in vps18 and vps41, core components of the HOPS complex, we found that disruption of HOPS eliminates autophagosome maturation and disrupts retrograde autophagosome transport initiation from the axon terminal. We confirmed this phenotype was due to loss of HOPS complex formation using an endogenous deletion of the HOPS binding domain in Vps18. Finally, using pharmacological inhibition of lysosomal proteases, we show that initiation of autophagosome retrograde transport requires autophagosome maturation. Together, our data demonstrate that HOPS-mediated fusion events are critical for retrograde autophagosome transport initiation through promoting autophagosome maturation. This reveals critical roles for the HOPS complex in neuronal autophagy which deepens our understanding of the cellular pathology of HOPS-complex linked neurodegenerative diseases.Abbreviations: CORVET: Class C core vacuole/endosome tethering; gRNA: guide RNA; HOPS: homotypic fusion and protein sorting; pLL: posterior lateral line; Vps18: VPS18 core subunit of CORVET and HOPS complexes; Vps41: VPS41 subunit of HOPS complex.
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Affiliation(s)
- Serena R Wisner
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Madison Chlebowski
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA
| | - Amrita Mandal
- National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Don Mai
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA
| | - Chris Stein
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA
| | - Ronald S Petralia
- Advanced Imaging Core, National Institute of Deafness and Other Communication Disorders, NIH, Bethesda, MD, USA
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute of Deafness and Other Communication Disorders, NIH, Bethesda, MD, USA
| | - Catherine M Drerup
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA
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2
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Cen J, Hu N, Shen J, Gao Y, Lu H. Pathological Functions of Lysosomal Ion Channels in the Central Nervous System. Int J Mol Sci 2024; 25:6565. [PMID: 38928271 PMCID: PMC11203704 DOI: 10.3390/ijms25126565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 06/06/2024] [Accepted: 06/10/2024] [Indexed: 06/28/2024] Open
Abstract
Lysosomes are highly dynamic organelles that maintain cellular homeostasis and regulate fundamental cellular processes by integrating multiple metabolic pathways. Lysosomal ion channels such as TRPML1-3, TPC1/2, ClC6/7, CLN7, and TMEM175 mediate the flux of Ca2+, Cl-, Na+, H+, and K+ across lysosomal membranes in response to osmotic stimulus, nutrient-dependent signals, and cellular stresses. These ion channels serve as the crucial transducers of cell signals and are essential for the regulation of lysosomal biogenesis, motility, membrane contact site formation, and lysosomal homeostasis. In terms of pathophysiology, genetic variations in these channel genes have been associated with the development of lysosomal storage diseases, neurodegenerative diseases, inflammation, and cancer. This review aims to discuss the current understanding of the role of these ion channels in the central nervous system and to assess their potential as drug targets.
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Affiliation(s)
| | | | | | - Yongjing Gao
- Institute of Pain Medicine and Special Environmental Medicine, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226019, China; (J.C.); (N.H.); (J.S.)
| | - Huanjun Lu
- Institute of Pain Medicine and Special Environmental Medicine, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226019, China; (J.C.); (N.H.); (J.S.)
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3
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van der Beek J, de Heus C, Sanza P, Liv N, Klumperman J. Loss of the HOPS complex disrupts early-to-late endosome transition, impairs endosomal recycling and induces accumulation of amphisomes. Mol Biol Cell 2024; 35:ar40. [PMID: 38198575 PMCID: PMC10916860 DOI: 10.1091/mbc.e23-08-0328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 12/22/2023] [Accepted: 01/05/2024] [Indexed: 01/12/2024] Open
Abstract
The multisubunit HOPS tethering complex is a well-established regulator of lysosome fusion with late endosomes and autophagosomes. However, the role of the HOPS complex in other stages of endo-lysosomal trafficking is not well understood. To address this, we made HeLa cells knocked out for the HOPS-specific subunits Vps39 or Vps41, or the HOPS-CORVET-core subunits Vps18 or Vps11. In all four knockout cells, we found that endocytosed cargos were trapped in enlarged endosomes that clustered in the perinuclear area. By correlative light-electron microscopy, these endosomes showed a complex ultrastructure and hybrid molecular composition, displaying markers for early (Rab5, PtdIns3P, EEA1) as well as late (Rab7, CD63, LAMP1) endosomes. These "HOPS bodies" were not acidified, contained enzymatically inactive cathepsins and accumulated endocytosed cargo and cation-independent mannose-6-phosphate receptor (CI-MPR). Consequently, CI-MPR was depleted from the TGN, and secretion of lysosomal enzymes to the extracellular space was enhanced. Strikingly, HOPS bodies also contained the autophagy proteins p62 and LC3, defining them as amphisomes. Together, these findings show that depletion of the lysosomal HOPS complex has a profound impact on the functional organization of the entire endosomal system and suggest the existence of a HOPS-independent mechanism for amphisome formation.
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Affiliation(s)
- Jan van der Beek
- Center for Molecular Medicine, University Medical Center Utrecht, Institute of Biomembranes, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - Cecilia de Heus
- Center for Molecular Medicine, University Medical Center Utrecht, Institute of Biomembranes, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - Paolo Sanza
- Center for Molecular Medicine, University Medical Center Utrecht, Institute of Biomembranes, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - Nalan Liv
- Center for Molecular Medicine, University Medical Center Utrecht, Institute of Biomembranes, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - Judith Klumperman
- Center for Molecular Medicine, University Medical Center Utrecht, Institute of Biomembranes, Utrecht University, 3584 CX Utrecht, The Netherlands
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4
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Wang L, Wang T, Wen S, Song R, Zou H, Gu J, Liu X, Bian J, Liu Z, Yuan Y. Puerarin Prevents Cadmium-Induced Neuronal Injury by Alleviating Autophagic Dysfunction in Rat Cerebral Cortical Neurons. Int J Mol Sci 2023; 24:ijms24098328. [PMID: 37176033 PMCID: PMC10179714 DOI: 10.3390/ijms24098328] [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: 02/26/2023] [Revised: 04/23/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023] Open
Abstract
Autophagic dysfunction is one of the main mechanisms of cadmium (Cd)-induced neurotoxicity. Puerarin (Pue) is a natural antioxidant extracted from the medicinal and edible homologous plant Pueraria lobata. Studies have shown that Pue has neuroprotective effects in a variety of brain injuries, including Cd-induced neuronal injury. However, the role of Pue in the regulation of autophagy to alleviate Cd-induced injury in rat cerebral cortical neurons remains unclear. This study aimed to elucidate the protective mechanism of Pue in alleviating Cd-induced injury in rat cerebral cortical neurons by targeting autophagy. Our results showed that Pue alleviated Cd-induced injury in rat cerebral cortical neurons in vitro and in vivo. Pue activates autophagy and alleviates Cd-induced autophagic blockade in rat cerebral cortical neurons. Further studies have shown that Pue alleviates the Cd-induced inhibition of autophagosome-lysosome fusion, as well as the inhibition of lysosomal degradation. The specific mechanism is related to Pue alleviating the inhibition of Cd on the expression levels of the key proteins Rab7, VPS41, and SNAP29, which regulate autophagosome-lysosome fusion, as well as the lysosome-related proteins LAMP2, CTSB, and CTSD. In summary, these results indicate that Pue alleviates Cd-induced autophagic dysfunction in rat cerebral cortical neurons by alleviating autophagosome-lysosome fusion dysfunction and lysosomal degradation dysfunction, thereby alleviating Cd-induced neuronal injury.
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Affiliation(s)
- Li Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Tao Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Shuangquan Wen
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Ruilong Song
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Hui Zou
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Jianhong Gu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Xuezhong Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Jianchun Bian
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Zongping Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Yan Yuan
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
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5
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Glycans in autophagy, endocytosis and lysosomal functions. Glycoconj J 2021; 38:625-647. [PMID: 34390447 PMCID: PMC8497297 DOI: 10.1007/s10719-021-10007-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/14/2021] [Accepted: 06/17/2021] [Indexed: 12/12/2022]
Abstract
Glycans have been shown to function as versatile molecular signals in cells. This prompted us to look at their roles in endocytosis, endolysosomal system and autophagy. We start by introducing the cell biological aspects of these pathways, the concept of the sugar code, and provide an overview on the role of glycans in the targeting of lysosomal proteins and in lysosomal functions. Moreover, we review evidence on the regulation of endocytosis and autophagy by glycans. Finally, we discuss the emerging concept that cytosolic exposure of luminal glycans, and their detection by endogenous lectins, provides a mechanism for the surveillance of the integrity of the endolysosomal compartments, and serves their eventual repair or disposal.
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6
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van der Welle REN, Jobling R, Burns C, Sanza P, van der Beek JA, Fasano A, Chen L, Zwartkruis FJ, Zwakenberg S, Griffin EF, ten Brink C, Veenendaal T, Liv N, van Ravenswaaij‐Arts CMA, Lemmink HH, Pfundt R, Blaser S, Sepulveda C, Lozano AM, Yoon G, Santiago‐Sim T, Asensio CS, Caldwell GA, Caldwell KA, Chitayat D, Klumperman J. Neurodegenerative VPS41 variants inhibit HOPS function and mTORC1-dependent TFEB/TFE3 regulation. EMBO Mol Med 2021; 13:e13258. [PMID: 33851776 PMCID: PMC8103106 DOI: 10.15252/emmm.202013258] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 02/19/2021] [Accepted: 02/22/2021] [Indexed: 11/09/2022] Open
Abstract
Vacuolar protein sorting 41 (VPS41) is as part of the Homotypic fusion and Protein Sorting (HOPS) complex required for lysosomal fusion events and, independent of HOPS, for regulated secretion. Here, we report three patients with compound heterozygous mutations in VPS41 (VPS41S285P and VPS41R662* ; VPS41c.1423-2A>G and VPS41R662* ) displaying neurodegeneration with ataxia and dystonia. Cellular consequences were investigated in patient fibroblasts and VPS41-depleted HeLa cells. All mutants prevented formation of a functional HOPS complex, causing delayed lysosomal delivery of endocytic and autophagic cargo. By contrast, VPS41S285P enabled regulated secretion. Strikingly, loss of VPS41 function caused a cytosolic redistribution of mTORC1, continuous nuclear localization of Transcription Factor E3 (TFE3), enhanced levels of LC3II, and a reduced autophagic response to nutrient starvation. Phosphorylation of mTORC1 substrates S6K1 and 4EBP1 was not affected. In a C. elegans model of Parkinson's disease, co-expression of VPS41S285P /VPS41R662* abolished the neuroprotective function of VPS41 against α-synuclein aggregates. We conclude that the VPS41 variants specifically abrogate HOPS function, which interferes with the TFEB/TFE3 axis of mTORC1 signaling, and cause a neurodegenerative disease.
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Affiliation(s)
- Reini E N van der Welle
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Rebekah Jobling
- Department of PediatricsDivision of Clinical and Metabolic GeneticsThe Hospital for Sick ChildrenUniversity of TorontoTorontoONCanada
| | - Christian Burns
- Department of Biological SciencesDivision of Natural Sciences and MathematicsUniversity of DenverDenverCOUSA
| | - Paolo Sanza
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Jan A van der Beek
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Alfonso Fasano
- Edmond J. Safra Program in Parkinson’s DiseaseMorton and Gloria Shulman Movement Disorders ClinicToronto Western Hospital, UHNTorontoONCanada
- Division of NeurologyUniversity of TorontoTorontoONCanada
- Krembil Brain InstituteTorontoONCanada
- Center for Advancing Neurotechnological Innovation to Application (CRANIA)TorontoONCanada
| | - Lan Chen
- Department of Biological SciencesDivision of Natural Sciences and MathematicsUniversity of DenverDenverCOUSA
| | - Fried J Zwartkruis
- Section Molecular Cancer ResearchCenter for Molecular MedicineUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Susan Zwakenberg
- Section Molecular Cancer ResearchCenter for Molecular MedicineUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Edward F Griffin
- Department of Biological SciencesThe University of AlabamaTuscaloosaALUSA
- Department of NeurologyCenter for Neurodegeneration and Experimental TherapeuticsNathan Shock Center for Basic Research in the Biology of AgingUniversity of Alabama at Birmingham School of MedicineBirminghamALUSA
| | - Corlinda ten Brink
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Tineke Veenendaal
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Nalan Liv
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | | | - Henny H Lemmink
- Department of GeneticsUniversity Medical Center GroningenUniversity of GroningenGroningenThe Netherlands
| | - Rolph Pfundt
- Department of Human GeneticsRadboud University Medical CenterNijmegenThe Netherlands
| | - Susan Blaser
- Department of Diagnostic ImagingHospital for Sick ChildrenTorontoONCanada
| | - Carolina Sepulveda
- Edmond J. Safra Program in Parkinson’s DiseaseMorton and Gloria Shulman Movement Disorders ClinicToronto Western Hospital, UHNTorontoONCanada
- Division of NeurologyUniversity of TorontoTorontoONCanada
| | - Andres M Lozano
- Krembil Brain InstituteTorontoONCanada
- Center for Advancing Neurotechnological Innovation to Application (CRANIA)TorontoONCanada
- Department of NeurosurgeryToronto Western Hospital, UHNTorontoONCanada
- University of TorontoTorontoONCanada
| | - Grace Yoon
- Department of PediatricsDivision of Clinical and Metabolic GeneticsThe Hospital for Sick ChildrenUniversity of TorontoTorontoONCanada
| | | | - Cedric S Asensio
- Department of Biological SciencesDivision of Natural Sciences and MathematicsUniversity of DenverDenverCOUSA
| | - Guy A Caldwell
- Department of Biological SciencesThe University of AlabamaTuscaloosaALUSA
- Department of NeurologyCenter for Neurodegeneration and Experimental TherapeuticsNathan Shock Center for Basic Research in the Biology of AgingUniversity of Alabama at Birmingham School of MedicineBirminghamALUSA
| | - Kim A Caldwell
- Department of Biological SciencesThe University of AlabamaTuscaloosaALUSA
- Department of NeurologyCenter for Neurodegeneration and Experimental TherapeuticsNathan Shock Center for Basic Research in the Biology of AgingUniversity of Alabama at Birmingham School of MedicineBirminghamALUSA
| | - David Chitayat
- Department of PediatricsDivision of Clinical and Metabolic GeneticsThe Hospital for Sick ChildrenUniversity of TorontoTorontoONCanada
- The Prenatal Diagnosis and Medical Genetics ProgramDepartment of Obstetrics and GynecologyUniversity of TorontoTorontoONCanada
| | - Judith Klumperman
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
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7
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Gowrishankar S, Lyons L, Rafiq NM, Roczniak-Ferguson A, De Camilli P, Ferguson SM. Overlapping roles of JIP3 and JIP4 in promoting axonal transport of lysosomes in human iPSC-derived neurons. Mol Biol Cell 2021; 32:1094-1103. [PMID: 33788575 PMCID: PMC8351540 DOI: 10.1091/mbc.e20-06-0382] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The dependence of neurons on microtubule-based motors for the movement of lysosomes over long distances raises questions about adaptations that allow neurons to meet these demands. Recently, JIP3/MAPK8IP3, a neuronally enriched putative adaptor between lysosomes and motors, was identified as a critical regulator of axonal lysosome abundance. In this study, we establish a human induced pluripotent stem cell (iPSC)-derived neuron model for the investigation of axonal lysosome transport and maturation and show that loss of JIP3 results in the accumulation of axonal lysosomes and the Alzheimer’s disease–related amyloid precursor protein (APP)-derived Aβ42 peptide. We furthermore reveal an overlapping role of the homologous JIP4 gene in lysosome axonal transport. These results establish a cellular model for investigating the relationship between lysosome axonal transport and amyloidogenic APP processing and more broadly demonstrate the utility of human iPSC–derived neurons for the investigation of neuronal cell biology and pathology.
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Affiliation(s)
- Swetha Gowrishankar
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair.,Howard Hughes Medical Institute, and
| | - Lila Lyons
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair.,Howard Hughes Medical Institute, and
| | - Nisha Mohd Rafiq
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair.,Howard Hughes Medical Institute, and
| | - Agnes Roczniak-Ferguson
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair
| | - Pietro De Camilli
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair.,Howard Hughes Medical Institute, and.,Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06510
| | - Shawn M Ferguson
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair
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8
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Duan X, Tong C. Autophagy in Drosophila and Zebrafish. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1208:333-356. [PMID: 34260032 DOI: 10.1007/978-981-16-2830-6_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Autophagy is a highly conserved cellular process that delivers cellular contents to the lysosome for degradation. It not only serves as a bulk degradation system for various cytoplasmic components but also functions selectively to clear damaged organelles, aggregated proteins, and invading pathogens (Feng et al., Cell Res 24:24-41, 2014; Galluzzi et al., EMBO J 36:1811-36, 2017; Klionsky et al., Autophagy 12:1-222, 2016). The malfunction of autophagy leads to multiple developmental defects and diseases (Mizushima et al., Nature 451:1069-75, 2008). Drosophila and zebrafish are higher metazoan model systems with sophisticated genetic tools readily available, which make it possible to dissect the autophagic processes and to understand the physiological functions of autophagy (Lorincz et al., Cells 6:22, 2017a; Mathai et al., Cells 6:21, 2017; Zhang and Baehrecke, Trends Cell Biol 25:376-87, 2015). In this chapter, we will discuss recent progress that has been made in the autophagic field by using these animal models. We will focus on the protein machineries required for autophagosome formation and maturation as well as the physiological roles of autophagy in both Drosophila and zebrafish.
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Affiliation(s)
- Xiuying Duan
- MOE Key Laboratory for Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang, China
| | - Chao Tong
- MOE Key Laboratory for Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang, China. .,The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
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9
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Li G, Li PL. Lysosomal TRPML1 Channel: Implications in Cardiovascular and Kidney Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:275-301. [PMID: 35138619 PMCID: PMC9899368 DOI: 10.1007/978-981-16-4254-8_13] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Lysosomal ion channels mediate ion flux from lysosomes and regulate membrane potential across the lysosomal membrane, which are essential for lysosome biogenesis, nutrient sensing, lysosome trafficking, lysosome enzyme activity, and cell membrane repair. As a cation channel, the transient receptor potential mucolipin 1 (TRPML1) channel is mainly expressed on lysosomes and late endosomes. Recently, the normal function of TRPML1 channels has been demonstrated to be important for the maintenance of cardiovascular and renal glomerular homeostasis and thereby involved in the pathogenesis of some cardiovascular and kidney diseases. In arterial myocytes, it has been found that Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP), an intracellular second messenger, can induce Ca2+ release through the lysosomal TRPML1 channel, leading to a global Ca2+ release response from the sarcoplasmic reticulum (SR). In podocytes, it has been demonstrated that lysosomal TRPML1 channels control lysosome trafficking and exosome release, which contribute to the maintenance of podocyte functional integrity. The defect or functional deficiency of lysosomal TRPML1 channels has been shown to critically contribute to the initiation and development of some chronic degeneration or diseases in the cardiovascular system or kidneys. Here we briefly summarize the current evidence demonstrating the regulation of lysosomal TRPML1 channel activity and related signaling mechanisms. We also provide some insights into the canonical and noncanonical roles of TRPML1 channel dysfunction as a potential pathogenic mechanism for certain cardiovascular and kidney diseases and associated therapeutic strategies.
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Affiliation(s)
- Guangbi Li
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Pin-Lan Li
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA.
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10
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Gowrishankar S, Cologna SM, Givogri MI, Bongarzone ER. Deregulation of signalling in genetic conditions affecting the lysosomal metabolism of cholesterol and galactosyl-sphingolipids. Neurobiol Dis 2020; 146:105142. [PMID: 33080336 PMCID: PMC8862610 DOI: 10.1016/j.nbd.2020.105142] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 09/04/2020] [Accepted: 10/14/2020] [Indexed: 12/15/2022] Open
Abstract
The role of lipids in neuroglial function is gaining momentum in part due to a better understanding of how many lipid species contribute to key cellular signalling pathways at the membrane level. The description of lipid rafts as membrane domains composed by defined classes of lipids such as cholesterol and sphingolipids has greatly helped in our understanding of how cellular signalling can be regulated and compartmentalized in neurons and glial cells. Genetic conditions affecting the metabolism of these lipids greatly impact on how some of these signalling pathways work, providing a context to understand the biological function of the lipid. Expectedly, abnormal metabolism of several lipids such as cholesterol and galactosyl-sphingolipids observed in several metabolic conditions involving lysosomal dysfunction are often accompanied by neuronal and myelin dysfunction. This review will discuss the role of lysosomal biology in the context of deficiencies in the metabolism of cholesterol and galactosyl-sphingolipids and their impact on neural function in three genetic disorders: Niemann-Pick type C, Metachromatic leukodystrophy and Krabbe’s disease.
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Affiliation(s)
- S Gowrishankar
- Department of Anatomy and Cell Biology, University of Illinois, Chicago, IL, USA.
| | - S M Cologna
- Department of Chemistry, University of Illinois, Chicago, IL, USA.
| | - M I Givogri
- Department of Anatomy and Cell Biology, University of Illinois, Chicago, IL, USA.
| | - E R Bongarzone
- Department of Anatomy and Cell Biology, University of Illinois, Chicago, IL, USA.
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11
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Lakatos Z, Lőrincz P, Szabó Z, Benkő P, Kenéz LA, Csizmadia T, Juhász G. Sec20 is Required for Autophagic and Endocytic Degradation Independent of Golgi-ER Retrograde Transport. Cells 2019; 8:cells8080768. [PMID: 31344970 PMCID: PMC6721519 DOI: 10.3390/cells8080768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/18/2019] [Accepted: 07/22/2019] [Indexed: 01/07/2023] Open
Abstract
Endocytosis and autophagy are evolutionarily conserved degradative processes in all eukaryotes. Both pathways converge to the lysosome where cargo is degraded. Improper lysosomal degradation is observed in many human pathologies, so its regulatory mechanisms are important to understand. Sec20/BNIP1 (BCL2/adenovirus E1B 19 kDa protein-interacting protein 1) is a BH3 (Bcl-2 homology 3) domain-containing SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein receptors) protein that has been suggested to promote Golgi-ER retrograde transport, mitochondrial fission, apoptosis and mitophagy in yeast and vertebrates. Here, we show that loss of Sec20 in Drosophila fat cells causes the accumulation of autophagic vesicles and prevents proper lysosomal acidification and degradation during bulk, starvation-induced autophagy. Furthermore, Sec20 knockdown leads to the enlargement of late endosomes and accumulation of defective endolysosomes in larval Drosophila nephrocytes. Importantly, the loss of Syx18 (Syntaxin 18), one of the known partners of Sec20, led to similar changes in nephrocytes and fat cells. Interestingly. Sec20 appears to function independent of its role in Golgi-ER retrograde transport in regulating lysosomal degradation, as the loss of its other partner SNAREs Use1 (Unconventional SNARE In The ER 1) and Sec22 or tethering factor Zw10 (Zeste white 10), which function together in the Golgi-ER pathway, does not cause defects in autophagy or endocytosis. Thus, our data identify a potential new transport route specific to lysosome biogenesis and function.
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Affiliation(s)
- Zsolt Lakatos
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Péter Lőrincz
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, H-1117 Budapest, Hungary
- Premium Postdoctoral Research Program, Hungarian Academy of Sciences, H-1117 Budapest, Hungary
| | - Zoltán Szabó
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Péter Benkő
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Lili Anna Kenéz
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Tamás Csizmadia
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Gábor Juhász
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, H-1117 Budapest, Hungary.
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, H-6726 Szeged, Hungary.
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12
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van der Beek J, Jonker C, van der Welle R, Liv N, Klumperman J. CORVET, CHEVI and HOPS – multisubunit tethers of the endo-lysosomal system in health and disease. J Cell Sci 2019; 132:132/10/jcs189134. [DOI: 10.1242/jcs.189134] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
ABSTRACT
Multisubunit tethering complexes (MTCs) are multitasking hubs that form a link between membrane fusion, organelle motility and signaling. CORVET, CHEVI and HOPS are MTCs of the endo-lysosomal system. They regulate the major membrane flows required for endocytosis, lysosome biogenesis, autophagy and phagocytosis. In addition, individual subunits control complex-independent transport of specific cargoes and exert functions beyond tethering, such as attachment to microtubules and SNARE activation. Mutations in CHEVI subunits lead to arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome, while defects in CORVET and, particularly, HOPS are associated with neurodegeneration, pigmentation disorders, liver malfunction and various forms of cancer. Diseases and phenotypes, however, vary per affected subunit and a concise overview of MTC protein function and associated human pathologies is currently lacking. Here, we provide an integrated overview on the cellular functions and pathological defects associated with CORVET, CHEVI or HOPS proteins, both with regard to their complexes and as individual subunits. The combination of these data provides novel insights into how mutations in endo-lysosomal proteins lead to human pathologies.
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Affiliation(s)
- Jan van der Beek
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Institute for Biomembranes, Utrecht University, Utrecht 3584 CX, The Netherlands
| | - Caspar Jonker
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Institute for Biomembranes, Utrecht University, Utrecht 3584 CX, The Netherlands
| | - Reini van der Welle
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Institute for Biomembranes, Utrecht University, Utrecht 3584 CX, The Netherlands
| | - Nalan Liv
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Institute for Biomembranes, Utrecht University, Utrecht 3584 CX, The Netherlands
| | - Judith Klumperman
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Institute for Biomembranes, Utrecht University, Utrecht 3584 CX, The Netherlands
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13
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Lund VK, Madsen KL, Kjaerulff O. Drosophila Rab2 controls endosome-lysosome fusion and LAMP delivery to late endosomes. Autophagy 2018; 14:1520-1542. [PMID: 29940804 PMCID: PMC6135592 DOI: 10.1080/15548627.2018.1458170] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Rab2 is a conserved Rab GTPase with a well-established role in secretory pathway function and phagocytosis. Here we demonstrate that Drosophila Rab2 is recruited to late endosomal membranes, where it controls the fusion of LAMP-containing biosynthetic carriers and lysosomes to late endosomes. In contrast, the lysosomal GTPase Gie/Arl8 is only required for late endosome-lysosome fusion, but not for the delivery of LAMP to the endocytic pathway. We also find that Rab2 is required for the fusion of autophagosomes to the endolysosomal pathway, but not for the biogenesis of lysosome-related organelles. Surprisingly, Rab2 does not rely on HOPS-mediated vesicular fusion for recruitment to late endosomal membranes. Our work suggests that Drosophila Rab2 is a central regulator of the endolysosomal and macroautophagic/autophagic pathways by controlling the major heterotypic fusion processes at the late endosome.
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Affiliation(s)
- Viktor Karlovich Lund
- a Department of Neuroscience, The Faculty of Health Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Kenneth Lindegaard Madsen
- a Department of Neuroscience, The Faculty of Health Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Ole Kjaerulff
- a Department of Neuroscience, The Faculty of Health Sciences , University of Copenhagen , Copenhagen , Denmark
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14
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Majumder R, Sarkar Y, Das S, Ray A, Parui PP. Interfacial pH and polarity detection of amphiphilic self-assemblies using a single Schiff-base molecule. NEW J CHEM 2017. [DOI: 10.1039/c7nj01222e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interfacial pH and polarity for different amphiphilic self-assemblies are estimated at a similar interfacial depth utilizing a unique Schiff-base molecule containing two identical phenol-conjugated-imine moieties.
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Affiliation(s)
- Rini Majumder
- Department of Chemistry
- Jadavpur University
- Kolkata 700032
- India
| | - Yeasmin Sarkar
- Department of Chemistry
- Jadavpur University
- Kolkata 700032
- India
| | - Sanju Das
- Department of Chemistry
- Jadavpur University
- Kolkata 700032
- India
- Department of Chemistry
| | - Ambarish Ray
- Department of Chemistry
- Maulana Azad College
- Kolkata 700013
- India
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15
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Endocytosis of Wingless via a dynamin-independent pathway is necessary for signaling in Drosophila wing discs. Proc Natl Acad Sci U S A 2016; 113:E6993-E7002. [PMID: 27791132 DOI: 10.1073/pnas.1610565113] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Endocytosis of ligand-receptor complexes regulates signal transduction during development. In particular, clathrin and dynamin-dependent endocytosis has been well studied in the context of patterning of the Drosophila wing disc, wherein apically secreted Wingless (Wg) encounters its receptor, DFrizzled2 (DFz2), resulting in a distinctive dorso-ventral pattern of signaling outputs. Here, we directly track the endocytosis of Wg and DFz2 in the wing disc and demonstrate that Wg is endocytosed from the apical surface devoid of DFz2 via a dynamin-independent CLIC/GEEC pathway, regulated by Arf1, Garz, and class I PI3K. Subsequently, Wg containing CLIC/GEEC endosomes fuse with DFz2-containing vesicles derived from the clathrin and dynamin-dependent endocytic pathway, which results in a low pH-dependent transfer of Wg to DFz2 within the merged and acidified endosome to initiate Wg signaling. The employment of two distinct endocytic pathways exemplifies a mechanism wherein cells in tissues leverage multiple endocytic pathways to spatially regulate signaling.
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16
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Abstract
Lysosomes support cellular homeostasis by degrading macromolecules and recycling nutrients. In this issue, Johnson et al. (2016. J. Cell Biol.http://dx.doi.org/10.1083/jcb.201507112) reveal a heterogeneity in lysosomal pH and degradative ability that correlates with lysosome subcellular localization, raising questions about the functional implications and mechanisms underlying these observations.
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Affiliation(s)
- Swetha Gowrishankar
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510 Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510 Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510
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17
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Parchure A, Vyas N, Ferguson C, Parton RG, Mayor S. Oligomerization and endocytosis of Hedgehog is necessary for its efficient exovesicular secretion. Mol Biol Cell 2015; 26:4700-17. [PMID: 26490120 PMCID: PMC4678025 DOI: 10.1091/mbc.e15-09-0671] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 10/14/2015] [Indexed: 12/14/2022] Open
Abstract
Hedgehog (Hh) is a secreted morphogen involved in both short- and long-range signaling necessary for tissue patterning during development. It is unclear how this dually lipidated protein is transported over a long range in the aqueous milieu of interstitial spaces. We previously showed that the long-range signaling of Hh requires its oligomerization. Here we show that Hh is secreted in the form of exovesicles. These are derived by the endocytic delivery of cell surface Hh to multivesicular bodies (MVBs) via an endosomal sorting complex required for transport (ECSRT)-dependent process. Perturbations of ESCRT proteins have a selective effect on long-range Hh signaling in Drosophila wing imaginal discs. Of importance, oligomerization-defective Hh is inefficiently incorporated into exovesicles due to its poor endocytic delivery to MVBs. These results provide evidence that nanoscale organization of Hh regulates the secretion of Hh on ESCRT-derived exovesicles, which in turn act as a vehicle for long-range signaling.
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Affiliation(s)
- Anup Parchure
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Neha Vyas
- Institute for Stem Cell Biology and Regenerative Medicine, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Charles Ferguson
- Institute for Molecular Bioscience and Centre for Microscopy and Microanalysis, University of Queensland, Brisbane St Lucia 4072, Australia
| | - Robert G Parton
- Institute for Molecular Bioscience and Centre for Microscopy and Microanalysis, University of Queensland, Brisbane St Lucia 4072, Australia
| | - Satyajit Mayor
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India Institute for Stem Cell Biology and Regenerative Medicine, Tata Institute of Fundamental Research, Bangalore 560065, India
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18
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Richards SA, Stutzer C, Bosman AM, Maritz-Olivier C. Transmembrane proteins--Mining the cattle tick transcriptome. Ticks Tick Borne Dis 2015; 6:695-710. [PMID: 26096851 DOI: 10.1016/j.ttbdis.2015.06.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/12/2015] [Accepted: 06/08/2015] [Indexed: 11/28/2022]
Abstract
Managing the spread and load of pathogen-transmitting ticks is an important task worldwide. The cattle tick, Rhipicephalus microplus, not only impacts the economy through losses in dairy and meat production, but also raises concerns for human health in regards to the potential of certain transmitted pathogens becoming zoonotic. However, novel strategies to control R. microplus are hindered by lack of understanding tick biology and the discovery of suitable vaccine or acaricide targets. The importance of transmembrane proteins as vaccine targets are well known, as is the case in tick vaccines with Bm86 as antigen. In this study, we describe the localization and functional annotation of 878 putative transmembrane proteins. Thirty proteins could be confirmed in the R. microplus gut using LC-MS/MS analysis and their roles in tick biology are discussed. To the best of our knowledge, 19 targets have not been reported before in any proteomics study in various tick species and the possibility of using the identified proteins as targets for tick control are discussed. Although tissue expression of identified putative proteins through expansive proteomics is necessary, this study demonstrates the possibility of using bioinformatics for the identification of targets for further evaluation in tick control strategies.
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Affiliation(s)
- Sabine A Richards
- Department of Genetics, Faculty of Natural and Agricultural Sciences, University of Pretoria, South Africa
| | - Christian Stutzer
- Department of Genetics, Faculty of Natural and Agricultural Sciences, University of Pretoria, South Africa
| | - Anna-Mari Bosman
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, South Africa
| | - Christine Maritz-Olivier
- Department of Genetics, Faculty of Natural and Agricultural Sciences, University of Pretoria, South Africa.
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19
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Khatter D, Raina VB, Dwivedi D, Sindhwani A, Bahl S, Sharma M. The small GTPase Arl8b regulates assembly of the mammalian HOPS complex on lysosomes. J Cell Sci 2015; 128:1746-61. [PMID: 25908847 PMCID: PMC4432227 DOI: 10.1242/jcs.162651] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 03/18/2015] [Indexed: 01/17/2023] Open
Abstract
The homotypic fusion and protein sorting (HOPS) complex is a multi-subunit complex conserved from yeast to mammals that regulates late endosome and lysosome fusion. However, little is known about how the HOPS complex is recruited to lysosomes in mammalian cells. Here, we report that the small GTPase Arl8b, but not Rab7 (also known as RAB7A), is essential for membrane localization of the human (h)Vps41 subunit of the HOPS complex. Assembly of the core HOPS subunits to Arl8b- and hVps41-positive lysosomes is guided by their subunit-subunit interactions. RNA interference (RNAi)-mediated depletion of hVps41 resulted in the impaired degradation of EGFR that was rescued upon expression of wild-type but not an Arl8b-binding-defective mutant of hVps41, suggesting that Arl8b-dependent lysosomal localization of hVps41 is required for its endocytic function. Furthermore, we have also identified that the Arl8b effector SKIP (also known as PLEKHM2) interacts with and recruits HOPS subunits to Arl8b and kinesin-positive peripheral lysosomes. Accordingly, RNAi-mediated depletion of SKIP impaired lysosomal trafficking and degradation of EGFR. These findings reveal that Arl8b regulates the association of the human HOPS complex with lysosomal membranes, which is crucial for the function of this tethering complex in endocytic degradation.
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Affiliation(s)
- Divya Khatter
- Department of Biological Sciences, Indian Institute of Science Education and Research-Mohali (IISERM), India
| | - Vivek B Raina
- Department of Biological Sciences, Indian Institute of Science Education and Research-Mohali (IISERM), India
| | - Devashish Dwivedi
- Department of Biological Sciences, Indian Institute of Science Education and Research-Mohali (IISERM), India
| | - Aastha Sindhwani
- Department of Biological Sciences, Indian Institute of Science Education and Research-Mohali (IISERM), India
| | - Surbhi Bahl
- Department of Biological Sciences, Indian Institute of Science Education and Research-Mohali (IISERM), India
| | - Mahak Sharma
- Department of Biological Sciences, Indian Institute of Science Education and Research-Mohali (IISERM), India
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20
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The role of TRPMLs in endolysosomal trafficking and function. Cell Calcium 2014; 58:48-56. [PMID: 25465891 DOI: 10.1016/j.ceca.2014.10.008] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/15/2014] [Accepted: 10/17/2014] [Indexed: 12/24/2022]
Abstract
Members of the Transient Receptor Potential-Mucolipin (TRPML) constitute a family of evolutionarily conserved cation channels that function predominantly in endolysosomal vesicles. Whereas loss-of-function mutations in human TRPML1 were first identified as being causative for the lysosomal storage disease, Mucolipidosis type IV, most mammals also express two other TRPML isoforms called TRPML2 and TRPML3. All three mammalian TRPMLs as well as TRPML related genes in other species including Caenorhabditis elegans and Drosophila exhibit overlapping functional and biophysical properties. The functions of TRPML proteins include roles in vesicular trafficking and biogenesis, maintenance of neuronal development, function, and viability, and regulation of intracellular and organellar ionic homeostasis. Biophysically, TRPML channels are non-selective cation channels exhibiting variable permeability to a host of cations including Na(+), Ca(2+), Fe(2+), and Zn(2+), and are activated by a phosphoinositide species, PI(3,5)P2, that is mostly found in endolysosomal membranes. Here, we review the functional and biophysical properties of these enigmatic cation channels, which represent the most ancient and archetypical TRP channels.
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21
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Zlatic SA, Tornieri K, L'hernault SW, Faundez V. Metazoan cell biology of the HOPS tethering complex. CELLULAR LOGISTICS 2014; 1:111-117. [PMID: 21922076 DOI: 10.4161/cl.1.3.17279] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Revised: 07/18/2011] [Accepted: 07/20/2011] [Indexed: 01/09/2023]
Abstract
Membrane fusion with vacuoles, the lysosome equivalent of the yeast Saccharomyces cerevisiae, is among the best understood membrane fusion events. Our precise understanding of this fusion machinery stems from powerful genetics and elegant in vitro reconstitution assays. Central to vacuolar membrane fusion is the multi-subunit tether the HO motypic fusion and Protein Sorting (HOPS) complex, a complex of proteins that organizes other necessary components of the fusion machinery. We lack a similarly detailed molecular understanding of membrane fusion with lysosomes or lysosome-related organelles in metazoans. However, it is likely that fundamental principles of how rabs, SNAREs and HOPS tethers work to fuse membranes with lysosomes and related organelles are conserved between Saccharomyces cerevisiae and metazoans. Here, we discuss emerging differences in the coat-dependent mechanisms that govern HOPS complex subcellular distribution between Saccharomyces cerevisiae and metazoans. These differences reside upstream of the membrane fusion event. We propose that the differences in how coats segregate class C Vps/HOPS tethers to organelles and domains of metazoan cells are adaptations to complex architectures that characterize metazoan cells such as those of neuronal and epithelial tissues.
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Affiliation(s)
- Stephanie A Zlatic
- Graduate Program in Biochemistry, Cell and Developmental Biology; Emory University; Atlanta, GA USA
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22
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Solinger JA, Spang A. Loss of the Sec1/Munc18-family proteins VPS-33.2 and VPS-33.1 bypasses a block in endosome maturation in Caenorhabditis elegans. Mol Biol Cell 2014; 25:3909-25. [PMID: 25273556 PMCID: PMC4244200 DOI: 10.1091/mbc.e13-12-0710] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Evidence is presented for the existence of HOPS and CORVET tethering complexes in metazoans. A role is shown for the SM protein components of tethers in controlling the flux of material through the endosomal system. The end of the life of a transport vesicle requires a complex series of tethering, docking, and fusion events. Tethering complexes play a crucial role in the recognition of membrane entities and bringing them into close opposition, thereby coordinating and controlling cellular trafficking events. Here we provide a comprehensive RNA interference analysis of the CORVET and HOPS tethering complexes in metazoans. Knockdown of CORVET components promoted RAB-7 recruitment to subapical membranes, whereas in HOPS knockdowns, RAB-5 was found also on membrane structures close to the cell center, indicating the RAB conversion might be impaired in the absence of these tethering complexes. Unlike in yeast, metazoans have two VPS33 homologues, which are Sec1/Munc18 (SM)-family proteins involved in the regulation of membrane fusion. We assume that in wild type, each tethering complex contains a specific SM protein but that they may be able to substitute for each other in case of absence of the other. Of importance, knockdown of both SM proteins allowed bypass of the endosome maturation block in sand-1 mutants. We propose a model in which the SM proteins in tethering complexes are required for coordinated flux of material through the endosomal system.
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Affiliation(s)
- Jachen A Solinger
- Growth and Development, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Anne Spang
- Growth and Development, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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23
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Takáts S, Pircs K, Nagy P, Varga Á, Kárpáti M, Hegedűs K, Kramer H, Kovács AL, Sass M, Juhász G. Interaction of the HOPS complex with Syntaxin 17 mediates autophagosome clearance in Drosophila. Mol Biol Cell 2014; 25:1338-54. [PMID: 24554766 PMCID: PMC3982998 DOI: 10.1091/mbc.e13-08-0449] [Citation(s) in RCA: 198] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 02/05/2014] [Accepted: 02/10/2014] [Indexed: 11/25/2022] Open
Abstract
Homotypic fusion and vacuole protein sorting (HOPS) is a tethering complex required for trafficking to the vacuole/lysosome in yeast. Specific interaction of HOPS with certain SNARE (soluble NSF attachment protein receptor) proteins ensures the fusion of appropriate vesicles. HOPS function is less well characterized in metazoans. We show that all six HOPS subunits (Vps11 [vacuolar protein sorting 11]/CG32350, Vps18/Dor, Vps16A, Vps33A/Car, Vps39/CG7146, and Vps41/Lt) are required for fusion of autophagosomes with lysosomes in Drosophila. Loss of these genes results in large-scale accumulation of autophagosomes and blocks autophagic degradation under basal, starvation-induced, and developmental conditions. We find that HOPS colocalizes and interacts with Syntaxin 17 (Syx17), the recently identified autophagosomal SNARE required for fusion in Drosophila and mammals, suggesting their association is critical during tethering and fusion of autophagosomes with lysosomes. HOPS, but not Syx17, is also required for endocytic down-regulation of Notch and Boss in developing eyes and for proper trafficking to lysosomes and eye pigment granules. We also show that the formation of autophagosomes and their fusion with lysosomes is largely unaffected in null mutants of Vps38/UVRAG (UV radiation resistance associated), a suggested binding partner of HOPS in mammals, while endocytic breakdown and lysosome biogenesis is perturbed. Our results establish the role of HOPS and its likely mechanism of action during autophagy in metazoans.
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Affiliation(s)
- Szabolcs Takáts
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary
| | - Karolina Pircs
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary
| | - Péter Nagy
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary
| | - Ágnes Varga
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary
| | - Manuéla Kárpáti
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary
| | - Krisztina Hegedűs
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary
| | - Helmut Kramer
- Department of Neuroscience, Department of Cell Biology, University of Texas Southwestern Medical School, Dallas, TX 75390-9111
| | - Attila L. Kovács
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary
| | - Miklós Sass
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary
| | - Gábor Juhász
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary
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24
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Vacca B, Bazellières E, Nouar R, Harada A, Massey-Harroche D, Le Bivic A. Drebrin E depletion in human intestinal epithelial cells mimics Rab8a loss of function. Hum Mol Genet 2014; 23:2834-46. [PMID: 24399445 DOI: 10.1093/hmg/ddt670] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Intestinal epithelial cells are highly polarized and exhibit a complex architecture with a columnar shape and a specialized apical surface supporting microvilli organized in a brush border. These microvilli are rooted in a dense meshwork of acto-myosin called the terminal web. We have shown recently that Drebrin E, an F-actin-binding protein, is a key protein for the organization of the terminal web and the brush border. Drebrin E is also required for the columnar cell shape of Caco2 cells (human colonic cells). Here, we found that the subcellular localization of several apical markers including dipeptidyl peptidase IV (DPPIV) was strikingly modified in Drebrin E-depleted Caco2 cells. Instead of being mostly present at the apical surface, these proteins are accumulated in an enlarged subapical compartment. Using known intracellular markers, we show by both confocal and electron microscopy that this compartment is related to lysosomes. We also demonstrate that the enrichment of DPPIV in this compartment originates from apical endocytosis and that depletion of Rab8a induces an accumulation of apical proteins in a similar compartment. Consistent with this, the phenotype observed in Drebrin E knock-down Caco2 cells shares some features with a pathology called microvillar inclusion disease (MVID) involving both Myosin Vb and Rab8a. Taken together, these results suggest that Drebrin E redirects the apical recycling pathway in intestinal epithelial cells to the lysosomes, demonstrating that Drebrin E is a key regulator in apical trafficking in Caco2 cells.
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Affiliation(s)
- Barbara Vacca
- Aix-Marseille University, CNRS, UMR7288, Developmental Biology Institute of Marseille (IBDM), Case 907, 13288 Marseille, Cedex 09, France
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Feng X, Huang Y, Lu Y, Xiong J, Wong CO, Yang P, Xia J, Chen D, Du G, Venkatachalam K, Xia X, Zhu MX. Drosophila TRPML forms PI(3,5)P2-activated cation channels in both endolysosomes and plasma membrane. J Biol Chem 2013; 289:4262-72. [PMID: 24375408 DOI: 10.1074/jbc.m113.506501] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transient Receptor Potential mucolipin (TRPML) channels are implicated in endolysosomal trafficking, lysosomal Ca(2+) and Fe(2+) release, lysosomal biogenesis, and autophagy. Mutations in human TRPML1 cause the lysosome storage disease, mucolipidosis type IV (MLIV). Unlike vertebrates, which express three TRPML genes, TRPML1-3, the Drosophila genome encodes a single trpml gene. Although the trpml-deficient flies exhibit cellular defects similar to those in mammalian TRPML1 mutants, the biophysical properties of Drosophila TRPML channel remained uncharacterized. Here, we show that transgenic expression of human TRPML1 in the neurons of Drosophila trpml mutants partially suppressed the pupal lethality phenotype. When expressed in HEK293 cells, Drosophila TRPML was localized in both endolysosomes and plasma membrane and was activated by phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) applied to the cytoplasmic side in whole lysosomes and inside-out patches excised from plasma membrane. The PI(3,5)P2-evoked currents were blocked by phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), but not other phosphoinositides. Using TRPML A487P, which mimics the varitint-waddler (Va) mutant of mouse TRPML3 with constitutive whole-cell currents, we show that TRPML is biphasically regulated by extracytosolic pH, with an optimal pH about 0.6 pH unit higher than that of human TRPML1. In addition to monovalent cations, TRPML exhibits high permeability to Ca(2+), Mn(2+), and Fe(2+), but not Fe(3+). The TRPML currents were inhibited by trivalent cations Fe(3+), La(3+), and Gd(3+). These features resemble more closely to mammalian TRPML1 than TRPML2 and TRPML3, but with some obvious differences. Together, our data support the use of Drosophila for assessing functional significance of TRPML1 in cell physiology.
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Affiliation(s)
- Xinghua Feng
- From the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China, 510150
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Balderhaar HJK, Ungermann C. CORVET and HOPS tethering complexes - coordinators of endosome and lysosome fusion. J Cell Sci 2013; 126:1307-16. [PMID: 23645161 DOI: 10.1242/jcs.107805] [Citation(s) in RCA: 370] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Protein and lipid transport along the endolysosomal system of eukaryotic cells depends on multiple fusion and fission events. Over the past few years, the molecular constituents of both fission and fusion machineries have been identified. Here, we focus on the mechanism of membrane fusion at endosomes, vacuoles and lysosomes, and in particular on the role of the two homologous tethering complexes called CORVET and HOPS. Both complexes are heterohexamers; they share four subunits, interact with Rab GTPases and soluble NSF attachment protein receptors (SNAREs) and can tether membranes. Owing to the presence of specific subunits, CORVET is a Rab5 effector complex, whereas HOPS can bind efficiently to late endosomes and lysosomes through Rab7. Based on the recently described overall structure of the HOPS complex and a number of in vivo and in vitro analyses, important insights into their function have been obtained. Here, we discuss the general function of both complexes in yeast and in metazoan cells in the context of endosomal biogenesis and maturation.
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Affiliation(s)
- Henning J kleine Balderhaar
- University of Osnabrück, Department of Biology/Chemistry, Biochemistry Section, Barbarastrasse 13, 49076 Osnabrück, Germany
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Self-assembly of VPS41 promotes sorting required for biogenesis of the regulated secretory pathway. Dev Cell 2013; 27:425-37. [PMID: 24210660 DOI: 10.1016/j.devcel.2013.10.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 08/06/2013] [Accepted: 10/11/2013] [Indexed: 12/22/2022]
Abstract
The regulated release of polypeptides has a central role in physiology, behavior, and development, but the mechanisms responsible for production of the large dense core vesicles (LDCVs) capable of regulated release have remained poorly understood. Recent work has implicated cytosolic adaptor protein AP-3 in the recruitment of LDCV membrane proteins that confer regulated release. However, AP-3 in mammals has been considered to function in the endolysosomal pathway and in the biosynthetic pathway only in yeast. We now find that the mammalian homolog of yeast VPS41, a member of the homotypic fusion and vacuole protein sorting (HOPS) complex that delivers biosynthetic cargo to the endocytic pathway in yeast, promotes LDCV formation through a common mechanism with AP-3, indicating a conserved role for these proteins in the biosynthetic pathway. VPS41 also self-assembles into a lattice, suggesting that it acts as a coat protein for AP-3 in formation of the regulated secretory pathway.
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Tornieri K, Zlatic SA, Mullin AP, Werner E, Harrison R, L'hernault SW, Faundez V. Vps33b pathogenic mutations preferentially affect VIPAS39/SPE-39-positive endosomes. Hum Mol Genet 2013; 22:5215-28. [PMID: 23918659 DOI: 10.1093/hmg/ddt378] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in Vps33 isoforms cause pigment dilution in mice (Vps33a, buff) and Drosophila (car) and the neurogenic arthrogryposis, renal dysfunction and cholestasis syndrome in humans (ARC1, VPS33B). The later disease is also caused by mutations in VIPAS39, (Vps33b interacting protein, apical-basolateral polarity regulator, SPE-39 homolog; ARC2), a protein that interacts with the HOmotypic fusion and Protein Sorting (HOPS) complex, a tether necessary for endosome-lysosome traffic. These syndromes offer insight into fundamental endosome traffic processes unique to metazoans. However, the molecular and cellular mechanisms underlying these mutant phenotypes remain poorly understood. Here we investigate interactions of wild-type and disease-causing mutations in VIPAS39/SPE-39 and Vps33b by yeast two hybrid, immunoprecipitation and quantitative fluorescent microscopy. We find that although few mutations prevent interaction between VIPAS39/SPE-39 and Vps33b, some mutants fragment VIPAS39/SPE-39-positive endosomes, but all mutants alter the subcellular localization of Vps33b to VIPAS39/SPE-39-positive endosomes. Our data suggest that the ARC syndrome may result through impaired VIPAS39/SPE-39 and Vps33b-dependent endosomal maturation or fusion.
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Pols MS, van Meel E, Oorschot V, ten Brink C, Fukuda M, Swetha MG, Mayor S, Klumperman J. hVps41 and VAMP7 function in direct TGN to late endosome transport of lysosomal membrane proteins. Nat Commun 2013; 4:1361. [PMID: 23322049 DOI: 10.1038/ncomms2360] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 12/05/2012] [Indexed: 12/18/2022] Open
Abstract
Targeted delivery of lysosome-associated membrane proteins is important for lysosome stability and function. Here we identify a pathway for transport of lysosome-associated membrane proteins directly from the trans-Golgi network to late endosomes, which exists in parallel to mannose 6-phosphate receptor and clathrin-dependent transport of lysosomal enzymes to early endosomes. By immunoelectron microscopy we localized endogenous LAMP-1 and -2 as well as LAMP-1-mGFP to non-coated, biosynthetic carriers at the trans-Golgi network and near late endosomes. These LAMP carriers were negative for mannose 6-phosphate receptor, adaptor-protein complex-1, secretory albumin and endocytic markers, but contained the homotypic fusion and protein sorting complex component hVps41 and the soluble N-ethylmaleimide-sensitive factor attachment protein receptors protein VAMP7. Knockdown of hVps41 or VAMP7 resulted in the accumulation of lysosome-associated membrane protein carriers, whereas knockdown of hVps39 or hVps18 did not, indicating that the effect of hVps41 is independent of CORVET/HOPS. Mannose 6-phosphate receptor carriers remained unaffected upon hVps41 or VAMP7 knockdown, implicating that hVps41 and VAMP7 are specifically involved in the fusion of trans-Golgi network-derived lysosome-associated membrane protein carriers with late endosomes.
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Affiliation(s)
- Maaike S Pols
- Department of Cell Biology, University Medical Centre Utrecht, AZU Room H02.313, Heidelberglaan 100, Utrecht 3584 CX, The Netherlands
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Pols MS, ten Brink C, Gosavi P, Oorschot V, Klumperman J. The HOPS proteins hVps41 and hVps39 are required for homotypic and heterotypic late endosome fusion. Traffic 2012; 14:219-32. [PMID: 23167963 DOI: 10.1111/tra.12027] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 11/14/2012] [Accepted: 11/21/2012] [Indexed: 12/11/2022]
Abstract
The homotypic fusion and protein sorting (HOPS) complex is a multisubunit tethering complex that in yeast regulates membrane fusion events with the vacuole, the yeast lysosome. Mammalian homologs of all HOPS components have been found, but little is known about their function. Here, we studied the role of hVps41 and hVps39, two components of the putative human HOPS complex, in the endo-lysosomal pathway of human cells. By expressing hemagglutinin (HA)-tagged constructs, we show by immunoelectron microscopy (immunoEM) that both hVps41 and hVps39 associate with the limiting membrane of late endosomes as well as lysosomes. Small interference RNA (siRNA)-mediated knockdown of hVps41 or hVps39 resulted in an accumulation of late endosomes, a depletion in the number of lysosomes and a block in the degradation of endocytosed cargo. Lysosomal pH and cathepsin B activity remained unaltered in these conditions. By immunoEM we found that hVps41 or hVps39 knockdown impairs homotypic fusion between late endosomes as well as heterotypic fusion between late endosomes and lysosomes. Thus, our data show that both hVps41 and hVps39 are required for late endosomal-lysosomal fusion events and the delivery of endocytic cargo to lysosomes in human cells.
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Affiliation(s)
- Maaike S Pols
- Department of Cell Biology, University Medical Center Utrecht, Heidelberglaan 100, 3584, CX Utrecht, The Netherlands
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Functional analysis of VPS41-mediated neuroprotection in Caenorhabditis elegans and mammalian models of Parkinson's disease. J Neurosci 2012; 32:2142-53. [PMID: 22323726 DOI: 10.1523/jneurosci.2606-11.2012] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Disruption of the lysosomal system has emerged as a key cellular pathway in the neurotoxicity of α-synuclein (α-syn) and the progression of Parkinson's disease (PD). A large-scale RNA interference (RNAi) screen using Caenorhabditis elegans identified VPS-41, a multidomain protein involved in lysosomal protein trafficking, as a modifier of α-syn accumulation and dopaminergic neuron degeneration (Hamamichi et al., 2008). Previous studies have shown a conserved neuroprotective function of human VPS41 (hVPS41) against PD-relevant toxins in mammalian cells and C. elegans neurons (Ruan et al., 2010). Here, we report that both the AP-3 (heterotetrameric adaptor protein complex) interaction domain and clathrin heavy-chain repeat domain are required for protecting C. elegans dopaminergic neurons from α-syn-induced neurodegeneration, as well as to prevent α-syn inclusion formation in an H4 human neuroglioma cell model. Using mutant C. elegans and neuron-specific RNAi, we revealed that hVPS41 requires both a functional AP-3 (heterotetrameric adaptor protein complex) and HOPS (homotypic fusion and vacuole protein sorting)-tethering complex to elicit neuroprotection. Interestingly, two nonsynonymous single-nucleotide polymorphisms found within the AP-3 interacting domain of hVPS41 attenuated the neuroprotective property, suggestive of putative susceptibility factors for PD. Furthermore, we observed a decrease in α-syn protein level when hVPS41 was overexpressed in human neuroglioma cells. Thus, the neuroprotective capacity of hVPS41 may be a consequence of enhanced clearance of misfolded and aggregated proteins, including toxic α-syn species. These data reveal the importance of lysosomal trafficking in maintaining cellular homeostasis in the presence of enhanced α-syn expression and toxicity. Our results support hVPS41 as a potential novel therapeutic target for the treatment of synucleinopathies like PD.
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