1
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Gahlot P, Kravic B, Rota G, van den Boom J, Levantovsky S, Schulze N, Maspero E, Polo S, Behrends C, Meyer H. Lysosomal damage sensing and lysophagy initiation by SPG20-ITCH. Mol Cell 2024; 84:1556-1569.e10. [PMID: 38503285 DOI: 10.1016/j.molcel.2024.02.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 01/30/2024] [Accepted: 02/27/2024] [Indexed: 03/21/2024]
Abstract
Cells respond to lysosomal membrane permeabilization by membrane repair or selective macroautophagy of damaged lysosomes, termed lysophagy, but it is not fully understood how this decision is made. Here, we uncover a pathway in human cells that detects lipid bilayer perturbations in the limiting membrane of compromised lysosomes, which fail to be repaired, and then initiates ubiquitin-triggered lysophagy. We find that SPG20 binds the repair factor IST1 on damaged lysosomes and, importantly, integrates that with the detection of damage-associated lipid-packing defects of the lysosomal membrane. Detection occurs via sensory amphipathic helices in SPG20 before rupture of the membrane. If lipid-packing defects are extensive, such as during lipid peroxidation, SPG20 recruits and activates ITCH, which marks the damaged lysosome with lysine-63-linked ubiquitin chains to initiate lysophagy and thus triages the lysosome for destruction. With SPG20 being linked to neurodegeneration, these findings highlight the relevance of a coordinated lysosomal damage response for cellular homeostasis.
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Affiliation(s)
- Pinki Gahlot
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Bojana Kravic
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Giulia Rota
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Johannes van den Boom
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Sophie Levantovsky
- Munich Cluster for Systems Neurology, Medical Faculty, Ludwig-Maximilians-University München, Munich, Germany
| | - Nina Schulze
- Imaging Center Campus Essen, Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Elena Maspero
- IFOM ETS, The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Simona Polo
- IFOM ETS, The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Christian Behrends
- Munich Cluster for Systems Neurology, Medical Faculty, Ludwig-Maximilians-University München, Munich, Germany
| | - Hemmo Meyer
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany.
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2
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Wu R, Pan X, Li W, Zhang Z, Guo Y. Phosphorylation of Thr-225 and Ser-262 on ERD7 Promotes Age-Dependent and Stress-Induced Leaf Senescence through the Regulation of Hydrogen Peroxide Accumulation in Arabidopsis thaliana. Int J Mol Sci 2024; 25:1328. [PMID: 38279327 PMCID: PMC10815956 DOI: 10.3390/ijms25021328] [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: 01/09/2024] [Revised: 01/16/2024] [Accepted: 01/19/2024] [Indexed: 01/28/2024] Open
Abstract
As the final stage of leaf development, leaf senescence is affected by a variety of internal and external signals including age and environmental stresses. Although significant progress has been made in elucidating the mechanisms of age-dependent leaf senescence, it is not clear how stress conditions induce a similar process. Here, we report the roles of a stress-responsive and senescence-induced gene, ERD7 (EARLY RESPONSIVE TO DEHYDRATION 7), in regulating both age-dependent and stress-induced leaf senescence in Arabidopsis. The results showed that the leaves of erd7 mutant exhibited a significant delay in both age-dependent and stress-induced senescence, while transgenic plants overexpressing the gene exhibited an obvious accelerated leaf senescence. Furthermore, based on the results of LC-MS/MS and PRM quantitative analyses, we selected two phosphorylation sites, Thr-225 and Ser-262, which have a higher abundance during senescence, and demonstrated that they play a key role in the function of ERD7 in regulating senescence. Transgenic plants overexpressing the phospho-mimetic mutant of the activation segment residues ERD7T225D and ERD7T262D exhibited a significantly early senescence, while the inactivation segment ERD7T225A and ERD7T262A displayed a delayed senescence. Moreover, we found that ERD7 regulates ROS accumulation by enhancing the expression of AtrbohD and AtrbohF, which is dependent on the critical residues, i.e., Thr-225 and Ser-262. Our findings suggest that ERD7 is a positive regulator of senescence, which might function as a crosstalk hub between age-dependent and stress-induced leaf senescence.
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Affiliation(s)
- Rongrong Wu
- College of Agriculture, Qingdao Agricultural University, Qingdao 266000, China;
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266000, China; (X.P.); (W.L.)
| | - Xiaolu Pan
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266000, China; (X.P.); (W.L.)
| | - Wei Li
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266000, China; (X.P.); (W.L.)
| | - Zenglin Zhang
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266000, China; (X.P.); (W.L.)
| | - Yongfeng Guo
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266000, China; (X.P.); (W.L.)
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3
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Diquigiovanni C, Rizzardi N, Kampmeier A, Liparulo I, Bianco F, De Nicolo B, Cataldi-Stagetti E, Cuna E, Severi G, Seri M, Bertrand M, Haack TB, Marina AD, Braun F, Fato R, Kuechler A, Bergamini C, Bonora E. Mutant SPART causes defects in mitochondrial protein import and bioenergetics reversed by Coenzyme Q. Open Biol 2023; 13:230040. [PMID: 37433330 PMCID: PMC10335854 DOI: 10.1098/rsob.230040] [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: 02/10/2023] [Accepted: 06/20/2023] [Indexed: 07/13/2023] Open
Abstract
Pathogenic variants in SPART cause Troyer syndrome, characterized by lower extremity spasticity and weakness, short stature and cognitive impairment, and a severe mitochondrial impairment. Herein, we report the identification of a role of Spartin in nuclear-encoded mitochondrial proteins. SPART biallelic missense variants were detected in a 5-year-old boy with short stature, developmental delay and muscle weakness with impaired walking distance. Patient-derived fibroblasts showed an altered mitochondrial network, decreased mitochondrial respiration, increased mitochondrial reactive oxygen species and altered Ca2+ versus control cells. We investigated the mitochondrial import of nuclear-encoded proteins in these fibroblasts and in another cell model carrying a SPART loss-of-function mutation. In both cell models the mitochondrial import was impaired, leading to a significant decrease in different proteins, including two key enzymes involved in CoQ10 (CoQ) synthesis, COQ7 and COQ9, with a severe reduction in CoQ content, versus control cells. CoQ supplementation restored cellular ATP levels to the same extent shown by the re-expression of wild-type SPART, suggesting CoQ treatment as a promising therapeutic approach for patients carrying mutations in SPART.
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Affiliation(s)
- Chiara Diquigiovanni
- Department of Medical and Surgical Sciences, University of Bologna, Bologna 40138, Italy
- Center for Applied Biomedical Research (CRBA), University of Bologna, Bologna 40138, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna 40138, Italy
| | - Nicola Rizzardi
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna 40126, Italy
| | - Antje Kampmeier
- Institut für Humangenetik, Universitätsklinikum Essen, Universität Duisburg-Essen, Essen 45122, Germany
| | - Irene Liparulo
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna 40126, Italy
| | - Francesca Bianco
- Department of Medical and Surgical Sciences, University of Bologna, Bologna 40138, Italy
- Department of Veterinary Sciences, University of Bologna, Bologna 40064, Italy
| | - Bianca De Nicolo
- Department of Medical and Surgical Sciences, University of Bologna, Bologna 40138, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna 40138, Italy
| | - Erica Cataldi-Stagetti
- Department of Medical and Surgical Sciences, University of Bologna, Bologna 40138, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna 40138, Italy
| | - Elisabetta Cuna
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna 40126, Italy
| | - Giulia Severi
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna 40138, Italy
| | - Marco Seri
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna 40138, Italy
| | - Miriam Bertrand
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen 72076, Germany
| | - Tobias B. Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen 72076, Germany
- Center for Rare Diseases, University of Tübingen, Tübingen 72076, Germany
| | - Adela Della Marina
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen 45122, Germany
| | - Frederik Braun
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen 45122, Germany
| | - Romana Fato
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna 40126, Italy
| | - Alma Kuechler
- Institut für Humangenetik, Universitätsklinikum Essen, Universität Duisburg-Essen, Essen 45122, Germany
| | - Christian Bergamini
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna 40126, Italy
| | - Elena Bonora
- Department of Medical and Surgical Sciences, University of Bologna, Bologna 40138, Italy
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna 40138, Italy
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Mamun MAA, Cao W, Nakamura S, Maruyama JI. Large-scale identification of genes involved in septal pore plugging in multicellular fungi. Nat Commun 2023; 14:1418. [PMID: 36932089 PMCID: PMC10023807 DOI: 10.1038/s41467-023-36925-y] [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: 01/20/2022] [Accepted: 02/23/2023] [Indexed: 03/19/2023] Open
Abstract
Multicellular filamentous fungi have septal pores that allow cytoplasmic exchange, and thus connectivity, between neighboring cells in the filament. Hyphal wounding and other stress conditions induce septal pore closure to minimize cytoplasmic loss. However, the composition of the septal pore and the mechanisms underlying its function are not well understood. Here, we set out to identify new septal components by determining the subcellular localization of 776 uncharacterized proteins in a multicellular ascomycete, Aspergillus oryzae. The set of 776 uncharacterized proteins was selected on the basis that their genes were present in the genomes of multicellular, septal pore-bearing ascomycetes (three Aspergillus species, in subdivision Pezizomycotina) and absent/divergent in the genomes of septal pore-lacking ascomycetes (yeasts). Upon determining their subcellular localization, 62 proteins were found to localize to the septum or septal pore. Deletion of the encoding genes revealed that 23 proteins are involved in regulating septal pore plugging upon hyphal wounding. Thus, this study determines the subcellular localization of many uncharacterized proteins in A. oryzae and, in particular, identifies a set of proteins involved in septal pore function.
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Affiliation(s)
| | - Wei Cao
- Research Center for Agricultural Information Technology, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki, Japan
| | - Shugo Nakamura
- Department of Information Networking for Innovation and Design, Faculty of Information Networking for Innovation and Design, Toyo University, Tokyo, Japan
| | - Jun-Ichi Maruyama
- Department of Biotechnology, The University of Tokyo, Tokyo, Japan.
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan.
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5
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Cusenza VY, Bonora E, Amodio N, Frazzi R. Spartin: At the crossroad between ubiquitination and metabolism in cancer. Biochim Biophys Acta Rev Cancer 2022; 1877:188813. [PMID: 36195276 DOI: 10.1016/j.bbcan.2022.188813] [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: 08/18/2022] [Revised: 09/28/2022] [Accepted: 09/28/2022] [Indexed: 12/01/2022]
Abstract
SPART is a gene coding for a multifunctional protein called spartin, localized in various organelles of human cells. Mutations in the coding region are responsible for a hereditary form of spastic paraplegia called Troyer syndrome while the epigenetic silencing has been demonstrated for some types of tumors. The main functions of this gene are associated to endosomic trafficking and receptor degradation, microtubule interaction, cytokinesis, fatty acids and oxidative metabolism. Spartin has been shown to be a target regulated by STAT3 and localizes also at the level of the mitochondrial outer membrane, where it forms part of a complex maintaining the integrity of the membrane potential. The most recent evidences report a downregulation of spartin in tumor tissues when compared to adjacent normal samples. This intriguing evidence supports further research aimed at clarifying the role of this protein in cancer development and metabolism.
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Affiliation(s)
- Vincenza Ylenia Cusenza
- Laboratory of Translational Research, Azienda Unità Sanitaria Locale - IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Elena Bonora
- Medical Genetics Unit, Department of Medical and Surgical Sciences, University of Bologna, Italy; IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Nicola Amodio
- Department of Experimental and Clinical Medicine, Magna Graecia University of Catanzaro, Catanzaro, Italy
| | - Raffaele Frazzi
- Laboratory of Translational Research, Azienda Unità Sanitaria Locale - IRCCS di Reggio Emilia, Reggio Emilia, Italy.
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6
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Methylation Heterogeneity and Gene Expression of SPG20 in Solid Tumors. Genes (Basel) 2022; 13:genes13050861. [PMID: 35627246 PMCID: PMC9140344 DOI: 10.3390/genes13050861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/06/2022] [Accepted: 05/10/2022] [Indexed: 12/31/2022] Open
Abstract
Introduction. The downregulation of the Spastic Paraplegia-20 (SPG20) gene is correlated with a rare autosomal recessive disorder called Troyer Syndrome. Only in recent years has SPG20 been studied and partially characterized in cancer. SPG20 has been shown to be hypermethylated in colorectal cancer, gastric cancer, non-Hodgkin’s lymphoma and hepatocellular carcinoma. In this study, we analyze the methylation status and the gene expression of SPG20 in different tumors of various histological origins. Methods. We analyzed the data generated through Infinium Human Methylation 450 BeadChip arrays and RNA-seq approaches extrapolated from The Cancer Genome Atlas (TCGA) database. The statistics were performed with R 4.0.4. Results. We aimed to assess whether the hypermethylation of this target gene was a common characteristic among different tumors and if there was a correlation between the m-values and the gene expression in paired tumor versus solid tissue normal. Overall, our analysis highlighted that SPG20 open sea upstream the TSS is altogether hypermethylated, and the tumor tissues display a higher methylation heterogeneity compared to the solid tissue normal. The gene expression evidences a reproducible, higher gene expression in normal tissues. Conclusion. Our research, based on data mining from TCGA, evidences that colon and liver tumors display a consistent methylation heterogeneity compared to their normal counterparts. This parallels a downregulation of SPG20 gene expression in tumor samples and suggests a role for this multifunctional protein in the control of tumor progression.
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7
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Barajas-Lopez JDD, Tiwari A, Zarza X, Shaw MW, Pascual JS, Punkkinen M, Bakowska JC, Munnik T, Fujii H. EARLY RESPONSE TO DEHYDRATION 7 Remodels Cell Membrane Lipid Composition during Cold Stress in Arabidopsis. PLANT & CELL PHYSIOLOGY 2021; 62:80-91. [PMID: 33165601 DOI: 10.1093/pcp/pcaa139] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 10/24/2020] [Indexed: 05/12/2023]
Abstract
Plants adjust to unfavorable conditions by altering physiological activities, such as gene expression. Although previous studies have identified multiple stress-induced genes, the function of many genes during the stress responses remains unclear. Expression of ERD7 (EARLY RESPONSE TO DEHYDRATION 7) is induced in response to dehydration. Here, we show that ERD7 plays essential roles in both plant stress responses and development. In Arabidopsis, ERD7 protein accumulated under various stress conditions, including exposure to low temperature. A triple mutant of Arabidopsis lacking ERD7 and two closely related homologs had an embryonic lethal phenotype, whereas a mutant lacking the two homologs and one ERD7 allele had relatively round leaves, indicating that the ERD7 gene family has essential roles in development. Moreover, the importance of the ERD7 family in stress responses was evidenced by the susceptibility of the mutant lines to cold stress. ERD7 protein was found to bind to several, but not all, negatively charged phospholipids and was associated with membranes. Lipid components and cold-induced reduction in PIP2 in the mutant line were altered relative to wild type. Furthermore, membranes from the mutant line had reduced fluidity. Taken together, ERD7 and its homologs are important for plant stress responses and development and associated with the modification in membrane lipid composition.
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Affiliation(s)
| | - Arjun Tiwari
- Molecular Plant Biology Unit, Department of Biochemistry, University of Turku, Turku 20014, Finland
| | - Xavier Zarza
- Section Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Science Park 904, Amsterdam, XH 1098, Netherlands
| | - Molly W Shaw
- Department of Hematology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Jes S Pascual
- Molecular Plant Biology Unit, Department of Biochemistry, University of Turku, Turku 20014, Finland
| | - Matleena Punkkinen
- Molecular Plant Biology Unit, Department of Biochemistry, University of Turku, Turku 20014, Finland
| | - Joanna C Bakowska
- Department of Molecular Pharmacology and Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywod, IL 60153, USA
| | - Teun Munnik
- Section Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Science Park 904, Amsterdam, XH 1098, Netherlands
| | - Hiroaki Fujii
- Molecular Plant Biology Unit, Department of Biochemistry, University of Turku, Turku 20014, Finland
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8
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Doner NM, Seay D, Mehling M, Sun S, Gidda SK, Schmitt K, Braus GH, Ischebeck T, Chapman KD, Dyer JM, Mullen RT. Arabidopsis thaliana EARLY RESPONSIVE TO DEHYDRATION 7 Localizes to Lipid Droplets via Its Senescence Domain. FRONTIERS IN PLANT SCIENCE 2021; 12:658961. [PMID: 33936146 PMCID: PMC8079945 DOI: 10.3389/fpls.2021.658961] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/23/2021] [Indexed: 05/09/2023]
Abstract
Lipid droplets (LDs) are neutral-lipid-containing organelles found in all kingdoms of life and are coated with proteins that carry out a vast array of functions. Compared to mammals and yeast, relatively few LD proteins have been identified in plants, particularly those associated with LDs in vegetative (non-seed) cell types. Thus, to better understand the cellular roles of LDs in plants, a more comprehensive inventory and characterization of LD proteins is required. Here, we performed a proteomics analysis of LDs isolated from drought-stressed Arabidopsis leaves and identified EARLY RESPONSIVE TO DEHYDRATION 7 (ERD7) as a putative LD protein. mCherry-tagged ERD7 localized to both LDs and the cytosol when ectopically expressed in plant cells, and the protein's C-terminal senescence domain (SD) was both necessary and sufficient for LD targeting. Phylogenetic analysis revealed that ERD7 belongs to a six-member family in Arabidopsis that, along with homologs in other plant species, is separated into two distinct subfamilies. Notably, the SDs of proteins from each subfamily conferred targeting to either LDs or mitochondria. Further, the SD from the ERD7 homolog in humans, spartin, localized to LDs in plant cells, similar to its localization in mammals; although, in mammalian cells, spartin also conditionally localizes to other subcellular compartments, including mitochondria. Disruption of ERD7 gene expression in Arabidopsis revealed no obvious changes in LD numbers or morphology under normal growth conditions, although this does not preclude a role for ERD7 in stress-induced LD dynamics. Consistent with this possibility, a yeast two-hybrid screen using ERD7 as bait identified numerous proteins involved in stress responses, including some that have been identified in other LD proteomes. Collectively, these observations provide new insight to ERD7 and the SD-containing family of proteins in plants and suggest that ERD7 may be involved in functional aspects of plant stress response that also include localization to the LD surface.
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Affiliation(s)
- Nathan M. Doner
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Damien Seay
- United States Department of Agriculture, US Arid-Land Agricultural Research Center, Agriculture Research Service, Maricopa, AZ, United States
| | - Marina Mehling
- United States Department of Agriculture, US Arid-Land Agricultural Research Center, Agriculture Research Service, Maricopa, AZ, United States
| | - Siqi Sun
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Kerstin Schmitt
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Till Ischebeck
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Kent D. Chapman
- BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, TX, United States
| | - John M. Dyer
- United States Department of Agriculture, US Arid-Land Agricultural Research Center, Agriculture Research Service, Maricopa, AZ, United States
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
- *Correspondence: Robert T. Mullen,
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9
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Joshi DC, Zhang CL, Babujee L, Vevea JD, August BK, Sheng ZH, Chapman ER, Gomez TM, Chiu SY. Inappropriate Intrusion of an Axonal Mitochondrial Anchor into Dendrites Causes Neurodegeneration. Cell Rep 2020; 29:685-696.e5. [PMID: 31618636 PMCID: PMC6884150 DOI: 10.1016/j.celrep.2019.09.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/30/2019] [Accepted: 09/05/2019] [Indexed: 01/21/2023] Open
Abstract
Syntaphilin (SNPH) is a major mitochondrial anchoring protein targeted to axons and excluded from dendrites. In this study, we provide in vivo evidence that this spatial specificity is lost in Shiverer (Shi) mice, a model for progressive multiple sclerosis (MS), resulting in inappropriate intrusion of SNPH into dendrites of cerebellar Purkinje cells with neurodegenerative consequences. Thus, reconstituting dendritic SNPH intrusion in SNPH-KO mice by viral transduction greatly sensitizes Purkinje cells to excitotoxicity when the glutamatergic climbing fibers are stimulated. Finally, we demonstrate in vitro that overexpression of SNPH in dendrites compromises neuronal viability by inducing N-methyl-D-aspartate (NMDA) excitotoxicity, reducing mitochondrial calcium uptake, and interfering with quality control of mitochondria by blocking somal mitophagy. Collectively, we propose that inappropriate immobilization of dendritic mitochondria by SNPH intrusion produces excitotoxicity and suggest that interception of dendritic SNPH intrusion is a therapeutic strategy to combat neurodegeneration.
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Affiliation(s)
- Dinesh C Joshi
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Chuan-Li Zhang
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Lavanya Babujee
- Department of Plant Pathology, College of Agricultural and Life Sciences, University of Wisconsin, Madison, WI, USA
| | - Jason D Vevea
- Howard Hughes Medical Institute and Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Benjamin K August
- Medical School Electron Microscope Facility, University of Wisconsin, Madison, WI, USA
| | - Zu-Hang Sheng
- Synaptic Functions Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Edwin R Chapman
- Howard Hughes Medical Institute and Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Timothy M Gomez
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Shing Yan Chiu
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA.
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10
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Schregle R, Mueller S, Legler DF, Rossy J, Krueger WA, Groettrup M. FAT10 localises in dendritic cell aggresome-like induced structures and contributes to their disassembly. J Cell Sci 2020; 133:jcs240085. [PMID: 32546531 DOI: 10.1242/jcs.240085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 06/04/2020] [Indexed: 08/31/2023] Open
Abstract
Dendritic cell (DC) aggresome-like induced structures (DALIS) are protein aggregates of polyubiquitylated proteins that form transiently during DC maturation. DALIS scatter randomly throughout the cytosol and serve as antigen storage sites synchronising DC maturation and antigen presentation. Maturation of DCs is accompanied by the induction of the ubiquitin-like modifier FAT10 (also known as UBD), which localises to aggresomes, structures that are similar to DALIS. FAT10 is conjugated to substrate proteins and serves as a signal for their rapid and irreversible degradation by the 26S proteasome similar to, yet independently of ubiquitin, thereby contributing to antigen presentation. Here, we have investigated whether FAT10 is involved in the formation and turnover of DALIS, and whether proteins accumulating in DALIS can be modified through conjunction to FAT10 (FAT10ylated). We found that FAT10 localises to DALIS in maturing DCs and that this localisation occurs independently of its conjugation to substrates. Additionally, we investigated the DALIS turnover in FAT10-deficient and -proficient DCs, and observed FAT10-mediated disassembly of DALIS. Thus, we report further evidence that FAT10 is involved in antigen processing, which may provide a functional rationale as to why FAT10 is selectively induced upon DC maturation.
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Affiliation(s)
- Richard Schregle
- Division of Immunology, Department of Biology, University of Konstanz, D-78457 Konstanz, Germany
| | - Stefanie Mueller
- Division of Immunology, Department of Biology, University of Konstanz, D-78457 Konstanz, Germany
| | - Daniel F Legler
- Biotechnology Institute Thurgau at the University of Konstanz, CH-8280 Kreuzlingen, Switzerland
| | - Jérémie Rossy
- Biotechnology Institute Thurgau at the University of Konstanz, CH-8280 Kreuzlingen, Switzerland
| | | | - Marcus Groettrup
- Division of Immunology, Department of Biology, University of Konstanz, D-78457 Konstanz, Germany
- Biotechnology Institute Thurgau at the University of Konstanz, CH-8280 Kreuzlingen, Switzerland
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11
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Darios F, Mochel F, Stevanin G. Lipids in the Physiopathology of Hereditary Spastic Paraplegias. Front Neurosci 2020; 14:74. [PMID: 32180696 PMCID: PMC7059351 DOI: 10.3389/fnins.2020.00074] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 01/20/2020] [Indexed: 12/12/2022] Open
Abstract
Hereditary spastic paraplegias (HSP) are a group of neurodegenerative diseases sharing spasticity in lower limbs as common symptom. There is a large clinical variability in the presentation of patients, partly underlined by the large genetic heterogeneity, with more than 60 genes responsible for HSP. Despite this large heterogeneity, the proteins with known function are supposed to be involved in a limited number of cellular compartments such as shaping of the endoplasmic reticulum or endolysosomal function. Yet, it is difficult to understand why alteration of such different cellular compartments can lead to degeneration of the axons of cortical motor neurons. A common feature that has emerged over the last decade is the alteration of lipid metabolism in this group of pathologies. This was first revealed by the identification of mutations in genes encoding proteins that have or are supposed to have enzymatic activities on lipid substrates. However, it also appears that mutations in genes affecting endoplasmic reticulum, mitochondria, or endolysosome function can lead to changes in lipid distribution or metabolism. The aim of this review is to discuss the role of lipid metabolism alterations in the physiopathology of HSP, to evaluate how such alterations contribute to neurodegenerative phenotypes, and to understand how this knowledge can help develop therapeutic strategy for HSP.
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Affiliation(s)
- Frédéric Darios
- Sorbonne Université, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Institut du Cerveau et de la Moelle Epinière, Paris, France
| | - Fanny Mochel
- Sorbonne Université, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Institut du Cerveau et de la Moelle Epinière, Paris, France.,National Reference Center for Neurometabolic Diseases, Pitié-Salpêtrière University Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Giovanni Stevanin
- Sorbonne Université, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Institut du Cerveau et de la Moelle Epinière, Paris, France.,Equipe de Neurogénétique, Ecole Pratique des Hautes Etudes, PSL Research University, Paris, France
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12
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Liang H, Miao H, Yang H, Gong F, Chen S, Wang L, Zhu H, Pan H. Dwarfism in Troyer syndrome: a family with SPG20 compound heterozygous mutations and a literature review. Ann N Y Acad Sci 2019; 1462:118-127. [PMID: 31535723 DOI: 10.1111/nyas.14229] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/07/2019] [Accepted: 08/14/2019] [Indexed: 01/16/2023]
Abstract
Troyer syndrome is an autosomal recessive disease characterized by spastic paralysis, dysarthria, distal amyotrophy, and short stature. Recently, two siblings (an older brother and a younger sister) were admitted to our hospital for the chief complaints of "short stature and intellectual disability." Through whole exome sequencing of the sister, who is the proband, it was found that her SPG20 gene had compound heterozygous mutations: c.364_365delAT (p.Met122Valfs* 2) and c.892delA (p.Thr298Glnfs* 30). Target testing revealed that the brother had the same genotype as the sister, and the former mutation originated from the father, while the latter mutation originated from the mother. In summary, this is the first report of Troyer syndrome in a family caused by SPG20 compound heterozygous mutations. A novel SPG20 mutation was found, namely c.892delA (p.Thr298Glnfs* 30). In addition, we also summarize these Troyer syndrome patients' heights and their clinical characteristics, and provide a brief review of all known pathogenic mutations of SPG20.
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Affiliation(s)
- Hanting Liang
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Hui Miao
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Hongbo Yang
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Fengying Gong
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Shi Chen
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Linjie Wang
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Huijuan Zhu
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Hui Pan
- Key Laboratory of Endocrinology of National Health Commission, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
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13
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Diquigiovanni C, Bergamini C, Diaz R, Liparulo I, Bianco F, Masin L, Baldassarro VA, Rizzardi N, Tranchina A, Buscherini F, Wischmeijer A, Pippucci T, Scarano E, Cordelli DM, Fato R, Seri M, Paracchini S, Bonora E. A novel mutation in SPART gene causes a severe neurodevelopmental delay due to mitochondrial dysfunction with complex I impairments and altered pyruvate metabolism. FASEB J 2019; 33:11284-11302. [PMID: 31314595 DOI: 10.1096/fj.201802722r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Loss-of-function mutations in the SPART gene cause Troyer syndrome, a recessive form of spastic paraplegia resulting in muscle weakness, short stature, and cognitive defects. SPART encodes for Spartin, a protein linked to endosomal trafficking and mitochondrial membrane potential maintenance. Here, we identified with whole exome sequencing (WES) a novel frameshift mutation in the SPART gene in 2 brothers presenting an uncharacterized developmental delay and short stature. Functional characterization in an SH-SY5Y cell model shows that this mutation is associated with increased neurite outgrowth. These cells also show a marked decrease in mitochondrial complex I (NADH dehydrogenase) activity, coupled to decreased ATP synthesis and defective mitochondrial membrane potential. The cells also presented an increase in reactive oxygen species, extracellular pyruvate, and NADH levels, consistent with impaired complex I activity. In concordance with a severe mitochondrial failure, Spartin loss also led to an altered intracellular Ca2+ homeostasis that was restored after transient expression of wild-type Spartin. Our data provide for the first time a thorough assessment of Spartin loss effects, including impaired complex I activity coupled to increased extracellular pyruvate. In summary, through a WES study we assign a diagnosis of Troyer syndrome to otherwise undiagnosed patients, and by functional characterization we show that the novel mutation in SPART leads to a profound bioenergetic imbalance.-Diquigiovanni, C., Bergamini, C., Diaz, R., Liparulo, I., Bianco, F., Masin, L., Baldassarro, V. A., Rizzardi, N., Tranchina, A., Buscherini, F., Wischmeijer, A., Pippucci, T., Scarano, E., Cordelli, D. M., Fato, R., Seri, M., Paracchini, S., Bonora, E. A novel mutation in SPART gene causes a severe neurodevelopmental delay due to mitochondrial dysfunction with complex I impairments and altered pyruvate metabolism.
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Affiliation(s)
- Chiara Diquigiovanni
- Department of Medical and Surgical Sciences (DIMEC), St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Christian Bergamini
- Department of Pharmacy and Biotechnology (FaBit), University of Bologna, Bologna, Italy
| | - Rebeca Diaz
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom
| | - Irene Liparulo
- Department of Pharmacy and Biotechnology (FaBit), University of Bologna, Bologna, Italy
| | - Francesca Bianco
- Department of Medical and Surgical Sciences (DIMEC), St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Luca Masin
- Department of Pharmacy and Biotechnology (FaBit), University of Bologna, Bologna, Italy
| | | | - Nicola Rizzardi
- Department of Pharmacy and Biotechnology (FaBit), University of Bologna, Bologna, Italy
| | - Antonia Tranchina
- Department of Medical and Surgical Sciences (DIMEC), St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Francesco Buscherini
- Department of Medical and Surgical Sciences (DIMEC), St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Anita Wischmeijer
- Department of Pediatrics, Clinical Genetics Service, Regional Hospital of South Tyrol, Bolzano, Italy
| | - Tommaso Pippucci
- Department of Medical and Surgical Sciences (DIMEC), St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Emanuela Scarano
- Rare Disease Unit, Department of Pediatrics, St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Duccio Maria Cordelli
- Child Neurology and Psychiatry Unit, St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Romana Fato
- Department of Pharmacy and Biotechnology (FaBit), University of Bologna, Bologna, Italy
| | - Marco Seri
- Department of Medical and Surgical Sciences (DIMEC), St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Silvia Paracchini
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom
| | - Elena Bonora
- Department of Medical and Surgical Sciences (DIMEC), St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
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14
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Artemisia amygdalina Upregulates Nrf2 and Protects Neurons Against Oxidative Stress in Alzheimer Disease. Cell Mol Neurobiol 2019; 39:387-399. [DOI: 10.1007/s10571-019-00656-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 01/29/2019] [Indexed: 12/26/2022]
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15
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Ring J, Rockenfeller P, Abraham C, Tadic J, Poglitsch M, Schimmel K, Westermayer J, Schauer S, Achleitner B, Schimpel C, Moitzi B, Rechberger GN, Sigrist SJ, Carmona-Gutierrez D, Kroemer G, Büttner S, Eisenberg T, Madeo F. Mitochondrial energy metabolism is required for lifespan extension by the spastic paraplegia-associated protein spartin. MICROBIAL CELL (GRAZ, AUSTRIA) 2017; 4:411-422. [PMID: 29234670 PMCID: PMC5722644 DOI: 10.15698/mic2017.12.603] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 11/20/2017] [Indexed: 01/11/2023]
Abstract
Hereditary spastic paraplegias, a group of neurodegenerative disorders, can be caused by loss-of-function mutations in the protein spartin. However, the physiological role of spartin remains largely elusive. Here we show that heterologous expression of human or Drosophila spartin extends chronological lifespan of yeast, reducing age-associated ROS production, apoptosis, and necrosis. We demonstrate that spartin localizes to the proximity of mitochondria and physically interacts with proteins related to mitochondrial and respiratory metabolism. Interestingly, Nde1, the mitochondrial external NADH dehydrogenase, and Pda1, the core enzyme of the pyruvate dehydrogenase complex, are required for spartin-mediated cytoprotection. Furthermore, spartin interacts with the glycolysis enhancer phospo-fructo-kinase-2,6 (Pfk26) and is sufficient to complement for PFK26-deficiency at least in early aging. We conclude that mitochondria-related energy metabolism is crucial for spartin's vital function during aging and uncover a network of specific interactors required for this function.
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Affiliation(s)
- Julia Ring
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Patrick Rockenfeller
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, UK
| | - Claudia Abraham
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Jelena Tadic
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Michael Poglitsch
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Katherina Schimmel
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Institute of Molecular and Translational Therapeutic Strategies (IMTTS), IFB-Tx, Hannover Medical School, Hannover, Germany
| | - Julia Westermayer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Simon Schauer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Bettina Achleitner
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Christa Schimpel
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- BioNanoNet Forschungsgesellschaft mbH, Graz, Austria
| | - Barbara Moitzi
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Gerald N. Rechberger
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
| | - Stephan J. Sigrist
- Institute for Biology, Freie Universität Berlin, Berlin, Germany
- NeuroCure, Charité, Berlin, Germany
| | | | - Guido Kroemer
- BioTechMed Graz, Graz, Austria
- Cell Biology and Metabolomics Platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France
- INSERM, U1138, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
- Université Pierre et Marie Curie, Paris, France
- Pôle de Biologie, Hôpital Européen Georges Pompidou, Paris, France
- Karolinska Institute, Department of Women's and Children's Health, Karolinska University Hospital Stockholm, Sweden
| | - Sabrina Büttner
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Tobias Eisenberg
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
| | - Frank Madeo
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
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16
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Novel Homozygous Missense Mutation in SPG20 Gene Results in Troyer Syndrome Associated with Mitochondrial Cytochrome c Oxidase Deficiency. JIMD Rep 2016; 33:55-60. [PMID: 27539578 DOI: 10.1007/8904_2016_580] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 07/14/2016] [Accepted: 07/18/2016] [Indexed: 12/13/2022] Open
Abstract
Troyer syndrome is an autosomal recessive form of hereditary spastic paraplegia (HSP) caused by deleterious mutations in the SPG20 gene. Although the disease is associated with a loss of function mechanism of spartin, the protein encoded by SPG20, the precise pathogenesis is yet to be elucidated. Recent data indicated an important role for spartin in both mitochondrial maintenance and function. Here we report a child presenting with progressive spastic paraparesis, generalized muscle weakness, dysarthria, impaired growth, and severe isolated decrease in muscle cytochrome c oxidase (COX) activity. Whole exome sequencing identified the homozygous c.988A>G variant in SPG20 gene (p.Met330Val) resulting in almost complete loss of spartin in skeletal muscle. Further analyses demonstrated significant tissue specific reduction of COX 4, a nuclear encoded subunit of COX, in muscle suggesting a role for spartin in proper mitochondrial respiratory chain function mediated by COX activity. Our findings need to be verified in other Troyer syndrome patients in order to classify it as a form of HSP caused by mitochondrial dysfunction.
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17
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Oxidative Stress in Caenorhabditis elegans: Protective Effects of Spartin. PLoS One 2015; 10:e0130455. [PMID: 26114733 PMCID: PMC4482654 DOI: 10.1371/journal.pone.0130455] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 05/20/2015] [Indexed: 01/25/2023] Open
Abstract
Troyer syndrome is caused by a mutation in the SPG20 gene, which results in complete loss of expression of the protein spartin. We generated a genetic model of Troyer syndrome in worms to explore the locomotor consequences of a null mutation of the Caenorhabditis elegans SPG20 orthologue, F57B10.9, also known as spg-20. Spg-20 mutants showed decreased length, crawling speed, and thrashing frequency, and had a shorter lifespan than wild-type animals. These results suggest an age-dependent decline in motor function in mutant animals. The drug paraquat was used to induce oxidative stress for 4 days in the animals. We measured survival rate and examined locomotion by measuring crawling speed and thrashing frequency. After 4 days of paraquat exposure, 77% of wild-type animals survived, but only 38% of spg-20 mutant animals survived. Conversely, animals overexpressing spg-20 had a survival rate of 95%. We also tested lifespan after a 1 hour exposure to sodium azide. After a 24 hour recovery period, 87% of wild type animals survived, 57% of spg-20 mutant animals survived, and 82% of animals overexpressing spg-20 survived. In the behavioral assays, spg-20 mutant animals showed a significant decrease in both crawling speed and thrashing frequency compared with wild-type animals. Importantly, the locomotor phenotype for both crawling and thrashing was rescued in animals overexpressing spg-20. The animals overexpressing spg-20 had crawling speeds and thrashing frequencies similar to those of wild-type animals. These data suggest that the protein F57B10.9/SPG-20 might have a protective role against oxidative stress.
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18
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Milewska M, Byrne PC. Different expression levels of spartin cause broad spectrum of cellular consequences in human neuroblastoma cells. Cell Biol Int 2015; 39:1007-15. [PMID: 25821002 DOI: 10.1002/cbin.10472] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/19/2015] [Indexed: 11/11/2022]
Abstract
Hereditary spastic paraplegia describes a diverse group of neurodegenerative conditions characterised by progressive spasticity and weakness of the lower limbs. Mutations in the SPG20 gene encoding spartin cause an autosomal recessive hereditary spastic paraplegia known as Troyer syndrome. To evaluate the cellular consequences of sustained spartin depletion in neuronal cells, we established several clonal SH-SY5Y cell lines with different level of spartin knockdown. Here, we report that cells with modest spartin downregulation show signs of neuronal differentiation such as increased neuritogenesis and cytoskeleton rearrangement. Interestingly, we also indicate that permanent high level spartin depletion results in impaired cell growth and multiple mitochondrial aberrations, which we speculate, arise as a result of chronic oxidative stress. Our studies demonstrate that the scale of spartin downregulation is the major factor that determines the severity of cellular consequences observed and suggest that there is a critical level of spartin expression which must be maintained for proper cellular functions.
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Affiliation(s)
- Malgorzata Milewska
- School of Medicine and Medical Science, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Paula Catherine Byrne
- School of Medicine and Medical Science, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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19
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Zhao J, Hedera P. Strumpellin and Spartin, Hereditary Spastic Paraplegia Proteins, are Binding Partners. J Exp Neurosci 2015; 9:15-25. [PMID: 25987849 PMCID: PMC4426939 DOI: 10.4137/jen.s22969] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 04/06/2015] [Accepted: 04/10/2015] [Indexed: 01/02/2023] Open
Abstract
Hereditary spastic paraplegia (HSP) is one of the most heterogeneous neurodegenerative diseases with more than 50 identified genes causing a relatively stereotypical phenotypic presentation. Recent studies of HSP pathogenesis have suggested the existence of shared biochemical pathways that are crucial for axonal maintenance and degeneration. We explored possible interactions of several proteins associated with this condition. Here we report interactions of endogenous and overexpressed strumpellin with another HSP-associated protein, spartin. This biochemical interaction does not appear to be a part of the Wiskott–Aldrich syndrome protein and Scar homologue (WASH) complex because spartin is not co-immunoprecipitated with WASH1 protein. The spartin–strumpellin association does not require the presence of the microtubule interacting and trafficking domain of spartin. Over-expression of mutant forms of strumpellin with the introduced HSP-causing mutations does not alter the colocalization of these two proteins. Knockdown of strumpellin in cultured cortical rat neurons interferes with development of neuronal branching and results in reduced expression of endogenous spartin. Proteosomal inhibition stabilized the levels of spartin and WASH1 proteins, supporting increased spartin degradation in the absence of strumpellin.
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Affiliation(s)
- Jiali Zhao
- Department of Neurology, Vanderbilt University, Nashville, TN, USA
| | - Peter Hedera
- Department of Neurology, Vanderbilt University, Nashville, TN, USA. ; Center for Molecular Neuroscience, Vanderbilt University, Nashville, TN, USA
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21
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Ghaffari H, Venkataramana M, Jalali Ghassam B, Chandra Nayaka S, Nataraju A, Geetha NP, Prakash HS. Rosmarinic acid mediated neuroprotective effects against H2O2-induced neuronal cell damage in N2A cells. Life Sci 2014; 113:7-13. [PMID: 25058919 DOI: 10.1016/j.lfs.2014.07.010] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 06/10/2014] [Accepted: 07/10/2014] [Indexed: 01/22/2023]
Abstract
AIMS Oxidative stress plays a key role in several ailments including neurodegenerative conditions. The aim of the study was to demonstrate the effect of rosmarinic acid (RA) in preventing oxidative stress related death of neuronal cell lines. MAIN METHODS In the present study, we demonstrated direct neuroprotective effect of RA using H2O2-induced oxidative challenge in N2A mouse neuroblastoma cells. The mechanism of neutralization of H2O2-induced toxicity by RA was evaluated using MTT, lactate dehydrogenase, mitochondrial membrane potential (MMP), intracellular ROS, and comet assays. Up-regulation of brain neuronal markers at molecular level was performed by RT-PCR. KEY FINDINGS Results presented in the paper indicate that H2O2-induced cytotoxicity in N2A cells was suppressed by treatment with RA. Moreover, RA is very effective in attenuating the disruption of lactate dehydrogenase, mitochondrial membrane potential and intracellular ROS. Pretreatment with RA significantly prevents genotoxicity (3.7-fold, p<0.01) and promotes the up-regulation of tyrosine hydroxylase (TH) (4.5-fold, p<0.01), and brain-derived neurotrophic factor (BDNF) genes (5.4-fold, p<0.01) against H2O2-induced cytotoxicity in N2A cells. SIGNIFICANCE Our results revealed that N2A cells are suitable cellular models to evaluate neuroprotective effects of RA, and suggest that RA may potentially serve as an agent for prevention of several human neurodegenerative diseases caused by oxidative stress.
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Affiliation(s)
- Hadi Ghaffari
- Department of Studies in Biotechnology, University of Mysore, Mysore, Karnataka, India
| | - M Venkataramana
- DRDO-BU-Centre for Life Sciences, Bharathiar University Campus, Coimbatore, Tamil Nadu 640046, India
| | | | - S Chandra Nayaka
- Department of Studies in Biotechnology, University of Mysore, Mysore, Karnataka, India
| | - A Nataraju
- Department of Biochemistry, Karnataka State Open University (KSOU), Mysore-06, India
| | - N P Geetha
- Department of Studies in Biotechnology, University of Mysore, Mysore, Karnataka, India
| | - H S Prakash
- Department of Studies in Biotechnology, University of Mysore, Mysore, Karnataka, India.
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22
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Faber C, Zhu ZJ, Castellino S, Wagner DS, Brown RH, Peterson RA, Gates L, Barton J, Bickett M, Hagerty L, Kimbrough C, Sola M, Bailey D, Jordan H, Elangbam CS. Cardiolipin profiles as a potential biomarker of mitochondrial health in diet-induced obese mice subjected to exercise, diet-restriction and ephedrine treatment. J Appl Toxicol 2014; 34:1122-9. [PMID: 25132005 DOI: 10.1002/jat.3030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 04/17/2014] [Accepted: 04/23/2014] [Indexed: 11/08/2022]
Abstract
Cardiolipin (CL) is crucial for mitochondrial energy metabolism and structural integrity. Alterations in CL quantity or CL species have been associated with mitochondrial dysfunction in several pathological conditions and diseases, including mitochondrial dysfunction-related compound attrition and post-market withdrawal of promising drugs. Here we report alterations in the CL profiles in conjunction with morphology of soleus muscle (SM) and brown adipose tissue (BAT) in diet-induced obese (DIO) mice, subjected to ephedrine treatment (EPH: 200 mg kg(-1) day(-1) orally), treadmill exercise (EX: 10 meters per min, 1 h per day), or dietary restriction (DR: 25% less of mean food consumed by the EX group) for 7 days. Mice from the DR and EPH groups had a significant decrease in percent body weight and reduced fat mass compared with DIO controls. Morphologic alterations in the BAT included brown adipocytes with reduced cytoplasmic lipid droplets and increased cytoplasmic eosinophilia in the EX, DR and EPH groups. Increased cytoplasmic eosinophilia in the BAT was ultrastructurally manifested by increased mitochondrial cristae, fenestration of mitochondrial cristae, increased electron density of mitochondrial matrix, and increased complexity of shape and elongation of mitochondria. Mitochondrial ultrastructural alterations in the SM of the EX and DR groups included increased mitochondrial cristae, cup-shaped mitochondria and mitochondrial degeneration. All four CL species (tri-linoleoyl-mono-docosahexaenoyl, tetralinoleoyl, tri-linoleoyl-mono-oleoyl, and di-linoleoyl-di-oleoyl) were increased in the BAT of the DR and EPH groups and in the SM of the EPH and EX groups. In conclusion, cardiolipin profiling supported standard methods for assessing mitochondrial biogenesis and health, and may serve as a potential marker of mitochondrial dysfunction in preclinical toxicity studies.
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Affiliation(s)
- Catherine Faber
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, 47907, USA
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Gamberi T, Massai L, Magherini F, Landini I, Fiaschi T, Scaletti F, Gabbiani C, Bianchi L, Bini L, Nobili S, Perrone G, Mini E, Messori L, Modesti A. Proteomic analysis of A2780/S ovarian cancer cell response to the cytotoxic organogold(III) compound Aubipy(c). J Proteomics 2014; 103:103-20. [PMID: 24705091 DOI: 10.1016/j.jprot.2014.03.032] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 03/17/2014] [Accepted: 03/24/2014] [Indexed: 11/27/2022]
Abstract
UNLABELLED Aubipyc is an organogold(III) compound endowed with encouraging anti-proliferative properties in vitro that is being evaluated pre-clinically as a prospective anticancer agent. A classical proteomic approach is exploited here to elucidate the mechanisms of its biological actions in A2780 human ovarian cancer cells. Based on 2-D gel electrophoresis separation and subsequent mass spectrometry identification, a considerable number of differentially expressed proteins were highlighted in A2780 cancer cells treated with Aubipyc. Bioinformatic analysis of the groups of up-regulated and down-regulated proteins pointed out that Aubipyc primarily perturbs mitochondrial processes and the glycolytic pathway. Notably, some major alterations in the glycolytic pathway were validated through Western blot and metabolic investigations. BIOLOGICAL SIGNIFICANCE This is the first proteomic analysis regarding Aubipyc cytotoxicity in A2780/S ovarian cancer cell line. Aubipyc is a promising gold(III) compound which manifests an appreciable cytotoxicity toward the cell line A2780, being able to overcome resistance to platinum. The proteomic study revealed for Aubipyc different cellular alterations with respect to cisplatin as well as to other gold compound such as auranofin. Remarkably, the bioinformatic analysis of proteomic data pointed out that Aubipyc treatment affected, directly or indirectly, several glycolytic enzymes. These data suggest a new mechanism of action for this gold drug and might have an impact on the use of gold-based drug in cancer treatment.
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Affiliation(s)
- Tania Gamberi
- Department of Clinical and Preclinical Biomedical Sciences, University of Florence, Italy
| | - Lara Massai
- Department of Chemistry, University of Florence, Italy
| | - Francesca Magherini
- Department of Clinical and Preclinical Biomedical Sciences, University of Florence, Italy
| | - Ida Landini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Tania Fiaschi
- Department of Clinical and Preclinical Biomedical Sciences, University of Florence, Italy
| | | | - Chiara Gabbiani
- Department of Chemistry and Industrial Chemistry, University of Pisa, Italy
| | - Laura Bianchi
- Functional Proteomic Section, Department of Life Sciences, University of Siena, Italy
| | - Luca Bini
- Functional Proteomic Section, Department of Life Sciences, University of Siena, Italy
| | - Stefania Nobili
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Gabriele Perrone
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Enrico Mini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Italy
| | - Luigi Messori
- Department of Chemistry, University of Florence, Italy.
| | - Alessandra Modesti
- Department of Clinical and Preclinical Biomedical Sciences, University of Florence, Italy.
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24
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Karlsson AB, Washington J, Dimitrova V, Hooper C, Shekhtman A, Bakowska JC. The role of spartin and its novel ubiquitin binding region in DALIS occurrence. Mol Biol Cell 2014; 25:1355-65. [PMID: 24523286 PMCID: PMC3982999 DOI: 10.1091/mbc.e13-11-0705] [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: 12/12/2022] Open
Abstract
Troyer syndrome is an autosomal recessive hereditary spastic paraplegia (HSP) caused by frameshift mutations in the SPG20 gene that results in a lack of expression of the truncated protein. Spartin is a multifunctional protein, yet only two conserved domains--a microtubule-interacting and trafficking domain and a plant-related senescence domain involved in cytokinesis and mitochondrial physiology, respectively--have been defined. We have shown that overexpressed spartin binds to the Ile44 hydrophobic pocket of ubiquitin, suggesting spartin might contain a ubiquitin-binding domain. In the present study, we demonstrate that spartin contributes to the formation of dendritic aggresome-like induced structures (DALIS) through a unique ubiquitin-binding region (UBR). Using short hairpin RNA, we knocked down spartin in RAW264.7 cells and found that DALIS frequency decreased; conversely, overexpression of spartin increased the percentage of cells containing DALIS. Using nuclear magnetic resonance spectroscopy, we characterized spartin's UBR and defined the UBR's amino acids that are key for ubiquitin binding. We also found that spartin, via the UBR, binds Lys-63-linked ubiquitin chains but does not bind Lys-48-linked ubiquitin chains. Finally, we demonstrate that spartin's role in DALIS formation depends on key residues within its UBR.
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Affiliation(s)
- Amelia B Karlsson
- Department of Molecular Pharmacology and Therapeutics, Loyola University Chicago, Maywood, IL 60153 Department of Chemistry, State University of New York at Albany, Albany, NY 12222 Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104 Department of Oncology, University of Wisconsin-Madison, Madison, WI 53705
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25
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González-Cabo P, Palau F. Mitochondrial pathophysiology in Friedreich's ataxia. J Neurochem 2013; 126 Suppl 1:53-64. [PMID: 23859341 DOI: 10.1111/jnc.12303] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/09/2013] [Accepted: 05/08/2013] [Indexed: 12/01/2022]
Abstract
Neurological examination indicates that Friedreich's ataxia corresponds to a mixed sensory and cerebellar ataxia, which affects the proprioceptive pathways. Neuropathology and pathophysiology of Friedreich's ataxia involves the peripheral sensory nerves, dorsal root ganglia, posterior columns, the spinocerebellar, and corticospinal tracts of the spinal cord, gracile and cuneate nuclei, dorsal nuclei of Clarke, and the dentate nucleus. Involvement of the myocardium and pancreatic islets of Langerhans indicates that it is also a systemic disease. The pathophysiology of the disease is the consequence of frataxin deficiency in the mitochondria and cells. Some of the biological consequences are currently recognized such as the effects on iron-sulfur cluster biogenesis or the oxidative status, but others deserve to be studied in depth. Among physiological aspects of mitochondria that have been associated with neurodegeneration and may be interesting to investigate in Friedreich's ataxia we can include mitochondrial dynamics and movement, communication with other organelles especially the endoplasmic reticulum, calcium homeostasis, apoptosis, and mitochondrial biogenesis and quality control. Changes in the mitochondrial physiology and transport in peripheral and central axons and mitochondrial metabolic functions such as bioenergetics and energy delivery in the synapses are also relevant functions to be considered. Thus, to understand the general pathophysiology of the disease and fundamental pathogenic mechanisms such as dying-back axonopathy, and determine molecular, cellular and tissue therapeutic targets, we need to discover the effect of frataxin depletion on mitochondrial properties and on specific cell susceptibility in the nervous system and other affected organs.
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Affiliation(s)
- Pilar González-Cabo
- Program in Rare and Genetic Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
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26
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Nahm M, Lee MJ, Parkinson W, Lee M, Kim H, Kim YJ, Kim S, Cho YS, Min BM, Bae YC, Broadie K, Lee S. Spartin regulates synaptic growth and neuronal survival by inhibiting BMP-mediated microtubule stabilization. Neuron 2013; 77:680-95. [PMID: 23439121 DOI: 10.1016/j.neuron.2012.12.015] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2012] [Indexed: 01/06/2023]
Abstract
Troyer syndrome is a hereditary spastic paraplegia caused by human spartin (SPG20) gene mutations. We have generated a Drosophila disease model showing that Spartin functions presynaptically with endocytic adaptor Eps15 to regulate synaptic growth and function. Spartin inhibits bone morphogenetic protein (BMP) signaling by promoting endocytic degradation of BMP receptor wishful thinking (Wit). Drosophila fragile X mental retardation protein (dFMRP) and Futsch/MAP1B are downstream effectors of Spartin and BMP signaling in regulating microtubule stability and synaptic growth. Loss of Spartin or elevation of BMP signaling induces age-dependent progressive defects resembling hereditary spastic paraplegias, including motor dysfunction and brain neurodegeneration. Null spartin phenotypes are prevented by administration of the microtubule-destabilizing drug vinblastine. Together, these results demonstrate that Spartin regulates both synaptic development and neuronal survival by controlling microtubule stability via the BMP-dFMRP-Futsch pathway, suggesting that impaired regulation of microtubule stability is a core pathogenic component in Troyer syndrome.
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Affiliation(s)
- Minyeop Nahm
- Department of Cell and Developmental Biology, Dental Research Institute, Seoul National University, Seoul 110-749, Republic of Korea
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27
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Kiebish MA, Yang K, Liu X, Mancuso DJ, Guan S, Zhao Z, Sims HF, Cerqua R, Cade WT, Han X, Gross RW. Dysfunctional cardiac mitochondrial bioenergetic, lipidomic, and signaling in a murine model of Barth syndrome. J Lipid Res 2013; 54:1312-25. [PMID: 23410936 DOI: 10.1194/jlr.m034728] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Barth syndrome is a complex metabolic disorder caused by mutations in the mitochondrial transacylase tafazzin. Recently, an inducible tafazzin shRNA knockdown mouse model was generated to deconvolute the complex bioenergetic phenotype of this disease. To investigate the underlying cause of hemodynamic dysfunction in Barth syndrome, we interrogated the cardiac structural and signaling lipidome of this mouse model as well as its myocardial bioenergetic phenotype. A decrease in the distribution of cardiolipin molecular species and robust increases in monolysocardiolipin and dilysocardiolipin were demonstrated. Additionally, the contents of choline and ethanolamine glycerophospholipid molecular species containing precursors for lipid signaling at the sn-2 position were altered. Lipidomic analyses revealed specific dysregulation of HETEs and prostanoids, as well as oxidized linoleic and docosahexaenoic metabolites. Bioenergetic interrogation uncovered differential substrate utilization as well as decreases in Complex III and V activities. Transgenic expression of cardiolipin synthase or iPLA2γ ablation in tafazzin-deficient mice did not rescue the observed phenotype. These results underscore the complex nature of alterations in cardiolipin metabolism mediated by tafazzin loss of function. Collectively, we identified specific lipidomic, bioenergetic, and signaling alterations in a murine model that parallel those of Barth syndrome thereby providing novel insights into the pathophysiology of this debilitating disease.
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Affiliation(s)
- Michael A Kiebish
- Division of Bioorganic Chemistry and Molecular Pharmacology, Departments of Medicine, Washington University School of Medicine, St. Louis, MO 63110; and
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28
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Çobanoğlu G, Ozansoy M, Başak AN. Are alsin and spartin novel interaction partners? Biochem Biophys Res Commun 2012; 427:1-4. [PMID: 22982304 DOI: 10.1016/j.bbrc.2012.08.103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 08/21/2012] [Indexed: 12/11/2022]
Abstract
Mutations in ALS2 gene/alsin are associated with recessive forms of motor neuron disorders including Juvenile Amyotrophic Lateral Sclerosis (JALS), Infantile-onset Ascending Hereditary Spastic Paraplegia (IAHSP) and Juvenile Primary Lateral Sclerosis (JPLS). In this study, we show that alsin and another MND-linked protein, spartin are related to each other both at mRNA and protein levels in Neuro2a cells. We observed significant alterations in spartin expression in alsin knock-down conditions. We further found that both proteins colocalize in N2a cells and spartin isoform-a precipitates with alsin in the same protein complex. In the light of these results we suggest that alsin and spartin may interact each other physically.
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Affiliation(s)
- Gönenç Çobanoğlu
- Department of Molecular Biology and Genetics, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, Istanbul, Turkey
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29
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Renvoisé B, Stadler J, Singh R, Bakowska JC, Blackstone C. Spg20-/- mice reveal multimodal functions for Troyer syndrome protein spartin in lipid droplet maintenance, cytokinesis and BMP signaling. Hum Mol Genet 2012; 21:3604-18. [PMID: 22619377 DOI: 10.1093/hmg/dds191] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Hereditary spastic paraplegias (HSPs; SPG1-48) are inherited neurological disorders characterized by lower extremity spasticity and weakness. Loss-of-function mutations in the SPG20 gene encoding spartin cause autosomal recessive Troyer syndrome (SPG20), which has additional features of short stature, cognitive deficits and distal amyotrophy. To identify cellular impairments underlying Troyer syndrome, we generated Spg20-/- mice, which exhibit progressive gait defects. Although gross central nervous system pathology appeared largely normal, cerebral cortical neurons cultured from neonatal Spg20-/- mice exhibited increased axon branching, a phenotype suppressed by reintroducing spartin and which required its interaction with the endosomal sorting complex required for transport (ESCRT)-III protein IST1. Analysis of the bone morphogenetic protein (BMP) signaling pathway in Spg20-/- embryonic fibroblasts indicated that Smad1/5 phosphorylation is modestly elevated, possibly due to alterations in BMP receptor trafficking. Cytokinesis was impaired in embryonic fibroblasts cultured from Spg20-/- mice, and binucleated chondrocytes were prominent in epiphyseal growth plates of bones in Spg20-/- mice, perhaps explaining the short stature of patients. Finally, adipose tissue from Spg20-/- female mice exhibited increased lipid droplet (LD) numbers and alterations in perilipin levels, supporting a role for spartin in LD maintenance. Taken together, our results support multimodal functions for spartin that provide important insights into HSP pathogenesis.
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Affiliation(s)
- Benoît Renvoisé
- Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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30
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Court FA, Coleman MP. Mitochondria as a central sensor for axonal degenerative stimuli. Trends Neurosci 2012; 35:364-72. [PMID: 22578891 DOI: 10.1016/j.tins.2012.04.001] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 03/19/2012] [Accepted: 04/02/2012] [Indexed: 12/12/2022]
Abstract
Axonal degeneration is a major contributor to neuronal dysfunction in many neurological conditions and has additional roles in development. It can be triggered by divergent stimuli including mechanical, metabolic, infectious, toxic, hereditary and inflammatory stresses. Axonal mitochondria are an important convergence point as regulators of bioenergetic metabolism, reactive oxygen species (ROS), Ca²⁺ homeostasis and protease activation. The challenges likely to render axonal mitochondria more vulnerable than their cellular counterparts are reviewed, including axonal transport, replenishing nuclear-encoded proteins and maintenance of quality control, fusion and fission in locations remote from the cell body. The potential for mitochondria to act as a decision node in axon loss is considered, highlighting the need to understand the biology of axonal mitochondria and their contributions to degenerative mechanisms for novel therapeutic strategies.
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Affiliation(s)
- Felipe A Court
- Millennium Nucleus for Regenerative Biology, Faculty of Biology, Catholic University of Chile, Santiago 8331150, Chile.
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31
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Finsterer J, Löscher W, Quasthoff S, Wanschitz J, Auer-Grumbach M, Stevanin G. Hereditary spastic paraplegias with autosomal dominant, recessive, X-linked, or maternal trait of inheritance. J Neurol Sci 2012; 318:1-18. [PMID: 22554690 DOI: 10.1016/j.jns.2012.03.025] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 03/25/2012] [Accepted: 03/29/2012] [Indexed: 12/12/2022]
Abstract
Hereditary spastic paraplegia (SPG) is a clinically and genetically heterogeneous group of neurodegenerative disorders that are clinically characterised by progressive spasticity and weakness of the lower-limbs (pure SPG) and, majoritorian, additional more extensive neurological or non-neurological manifestations (complex or complicated SPG). Pure SPG is characterised by progressive spasticity and weakness of the lower-limbs, and occasionally sensory disturbances or bladder dysfunction. Complex SPGs additionally include cognitive impairment, dementia, epilepsy, extrapyramidal disturbances, cerebellar involvement, retinopathy, optic atrophy, deafness, polyneuropathy, or skin lesions in the absence of coexisting disorders. Nineteen SPGs follow an autosomal-dominant (AD-SPG), 27 an autosomal-recessive (AR-SPG), 5 X-linked (XL-SPG), and one a maternal trait of inheritance. SPGs are due to mutations in genes encoding for proteins involved in the maintenance of corticospinal tract neurons. Among the AD-SPGs, 40-45% of patients carry mutations in the SPAST-gene (SPG4) and 10% in the ATL1-gene (SPG3), while the other 9 genes are more rarely involved (NIPA1 (SPG6), KIAA0196 (SPG8), KIF5A (SPG10), RNT2 (SPG12), SPGD1 (SPG13), BSCL2 (SPG17), REEP1 (SPG31), ZFYVE27 (SPG33, debated), and SLC33A1 (SPG42, debated)). Among the AR-SPGs, ~20% of the patients carry mutations in the KIAA1840 (SPG11) gene whereas the 15 other genes are rarely mutated and account for SPGs in single families yet (CYP7B1 (SPG5), SPG7 (SPG7), ZFYVE26 (SPG15), ERLIN2 (SPG18), SPG20 (SPG20), ACP33 (SPG21), KIF1A (SPG30), FA2H (SPG35), NTE (SPG39), GJA12/GJC2 (SPG44), KIAA0415 (SPG48) and 4 genes encoding for the AP4-complex (SPG47)). Among the XL-SPGs, 3 causative genes have been identified (L1CAM (SPG1), PLP1 (SPG2), and SLC16A2 (SPG22)). The diagnosis of SPGs is based on clinical, instrumental and genetic investigations. Treatment is exclusively symptomatic.
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Timmerman V, Clowes VE, Reid E. Overlapping molecular pathological themes link Charcot-Marie-Tooth neuropathies and hereditary spastic paraplegias. Exp Neurol 2012; 246:14-25. [PMID: 22285450 DOI: 10.1016/j.expneurol.2012.01.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 12/29/2011] [Accepted: 01/10/2012] [Indexed: 10/14/2022]
Abstract
In this review we focus on Charcot-Marie-Tooth (CMT) neuropathies and hereditary spastic paraplegias (HSPs). Although these diseases differ in whether they primarily affect the peripheral or central nervous system, both are genetically determined, progressive, long axonopathies that affect motor and sensory pathways. This commonality suggests that there might be similarities in the molecular pathology underlying these conditions, and here we compare the molecular genetics and cellular pathology of the two groups.
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Affiliation(s)
- Vincent Timmerman
- Peripheral Neuropathy Group, Department of Molecular Genetics, VIB, Antwerpen, Belgium.
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Urbanczyk A, Enz R. Spartin recruits PKC-ζ via the PKC-ζ-interacting proteins ZIP1 and ZIP3 to lipid droplets. J Neurochem 2011; 118:737-48. [PMID: 21707618 DOI: 10.1111/j.1471-4159.2011.07367.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Protein kinase C-ζ interacting proteins (ZIP1-3) recruit the enzymatic activity of the atypical protein kinase C isoforms PKC-λ/ι or PKC-ζ to target proteins. In this study, we searched for binding partners of ZIP3 in the CNS and identified spartin, a multifunctional protein that is mutated in spastic paraplegia type 20. In transfected cells, spartin was present on the surface of lipid droplets (LD), whereas ZIP proteins appeared in intracellular speckles. In the presence of spartin, ZIP1 and ZIP3 were translocated to spartin-positive LD. This translocation was mediated by amino acids 196-393 of spartin that interacted with an N-terminal region of ZIP proteins. Furthermore, ZIP proteins interacted simultaneously with spartin and PKC-ζ, resulting in an enrichment of PKC-ζ on spartin/ZIP-labelled LD. Without spartin, neither ZIP proteins nor PKC-ζ were detected on LD. Interestingly, the presence of the spartin/ZIP/PKC-ζ complex increased LD size. This effect was most pronounced upon incorporation of the ZIP3 isoform into the trimer. Finally, we co-localized spartin, ZIP proteins and PKC-ζ in axon terminals of neurons in the mammalian retina. In summary, we describe spartin as new binding partner of the ZIP/PKC-ζ dimer that recruits PKC-ζ to LD and show that the expressed ZIP isoform regulates LD size.
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Affiliation(s)
- Andreas Urbanczyk
- Institut für Biochemie (Emil-Fischer-Zentrum), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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