1
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He S, He XX, Yang HQ, Zhang JW, Chen S. Two new cases with the UBQLN2 gene mutation in Han Chinese. Neurol Sci 2024:10.1007/s10072-024-07674-7. [PMID: 38943019 DOI: 10.1007/s10072-024-07674-7] [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: 05/13/2024] [Accepted: 06/14/2024] [Indexed: 06/30/2024]
Abstract
Variations in the UBQLN2 gene are associated with a group of diseases with X-linked dominant inheritance and clinical phenotypes of amyotrophic lateral sclerosis (ALS) and/or frontal temporal lobe dementia (FTD). Cases with UBQLN2 variations have been rarely reported worldwide. The reported cases exhibit strong clinical heterogeneity. Here, we report two adult-onset cases with UBQLN2 variations in Han Chinese. Whole exome sequencing revealed the hemizygous P506S (c.1516C > T) and the heterozygous P509S variation (c.1525C > T), both of which were located within the hotspot mutation region. The patient with the P506S variation was a 24-year-old male. The clinical feature was spastic paraplegia without lower motor neuron damage. The patient's mother was an asymptomatic heterozygote carrier with skewed X-chromosome inactivation. The patient with the P509S variation was a 63-year-old female. Clinical features included ALS and parkinsonism. 18F-fluorodopa PET-CT revealed presynaptic dopaminergic deficits in bilateral posterior putamen. These cases further highlight the clinical heterogeneity of UBQLN2 cases.
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Affiliation(s)
- Shuang He
- Department of Neurology, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), Zhengzhou, Henan, 450003, China
| | - Xin-Xin He
- Department of Neurology, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), Zhengzhou, Henan, 450003, China
| | - Hong-Qi Yang
- Department of Neurology, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), Zhengzhou, Henan, 450003, China
| | - Jie-Wen Zhang
- Department of Neurology, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), Zhengzhou, Henan, 450003, China.
| | - Shuai Chen
- Department of Neurology, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), Zhengzhou, Henan, 450003, China.
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2
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Dao TP, Rajendran A, Galagedera SKK, Haws W, Castañeda CA. Short disordered termini and proline-rich domain are major regulators of UBQLN1/2/4 phase separation. Biophys J 2024; 123:1449-1457. [PMID: 38041404 PMCID: PMC11163289 DOI: 10.1016/j.bpj.2023.11.3401] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/03/2023] Open
Abstract
Highly homologous ubiquitin-binding shuttle proteins UBQLN1, UBQLN2, and UBQLN4 differ in both their specific protein quality control functions and their propensities to localize to stress-induced condensates, cellular aggregates, and aggresomes. We previously showed that UBQLN2 phase separates in vitro, and that the phase separation propensities of UBQLN2 deletion constructs correlate with their ability to form condensates in cells. Here, we demonstrated that full-length UBQLN1, UBQLN2, and UBQLN4 exhibit distinct phase behaviors in vitro. Strikingly, UBQLN4 phase separates at a much lower saturation concentration than UBQLN1. However, neither UBQLN1 nor UBQLN4 phase separates with a strong temperature dependence, unlike UBQLN2. We determined that the temperature-dependent phase behavior of UBQLN2 stems from its unique proline-rich region, which is absent in the other UBQLNs. We found that the short N-terminal disordered regions of UBQLN1, UBQLN2, and UBQLN4 inhibit UBQLN phase separation via electrostatics interactions. Charge variants of the N-terminal regions exhibit altered phase behaviors. Consistent with the sensitivity of UBQLN phase separation to the composition of the N-terminal regions, epitope tags placed on the N-termini of the UBQLNs tune phase separation. Overall, our in vitro results have important implications for studies of UBQLNs in cells, including the identification of phase separation as a potential mechanism to distinguish the cellular roles of UBQLNs and the need to apply caution when using epitope tags to prevent experimental artifacts.
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Affiliation(s)
- Thuy P Dao
- Departments of Biology and Chemistry, Syracuse University, Syracuse, New York
| | - Anitha Rajendran
- Departments of Biology and Chemistry, Syracuse University, Syracuse, New York
| | | | - William Haws
- Departments of Biology and Chemistry, Syracuse University, Syracuse, New York
| | - Carlos A Castañeda
- Departments of Biology and Chemistry, Syracuse University, Syracuse, New York; Interdisciplinary Neuroscience Program, Syracuse University, Syracuse, New York; BioInspired Institute, Syracuse University, Syracuse, New York.
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3
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Nementzik LR, Thumbadoo KM, Murray HC, Gordon D, Yang S, Blair IP, Turner C, Faull RLM, Curtis MA, McLean C, Nicholson GA, Swanson MEV, Scotter EL. Distribution of ubiquilin 2 and TDP-43 aggregates throughout the CNS in UBQLN2 p.T487I-linked amyotrophic lateral sclerosis and frontotemporal dementia. Brain Pathol 2024; 34:e13230. [PMID: 38115557 PMCID: PMC11007053 DOI: 10.1111/bpa.13230] [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: 09/25/2023] [Accepted: 11/29/2023] [Indexed: 12/21/2023] Open
Abstract
Mutations in the UBQLN2 gene cause amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The neuropathology of such UBQLN2-linked cases of ALS/FTD is characterised by aggregates of the ubiquilin 2 protein in addition to aggregates of the transactive response DNA-binding protein of 43 kDa (TDP-43). ALS and FTD without UBQLN2 mutations are also characterised by TDP-43 aggregates, that may or may not colocalise with wildtype ubiquilin 2. Despite this, the relative contributions of TDP-43 and ubiquilin 2 to disease pathogenesis remain largely under-characterised, as does their relative deposition as aggregates across the central nervous system (CNS). Here we conducted multiplex immunohistochemistry of three UBQLN2 p.T487I-linked ALS/FTD cases, three non-UBQLN2-linked (sporadic) ALS cases, and 8 non-neurodegenerative disease controls, covering 40 CNS regions. We then quantified ubiquilin 2 aggregates, TDP-43 aggregates and aggregates containing both proteins in regions of interest to determine how UBQLN2-linked and non-UBQLN2-linked proteinopathy differ. We find that ubiquilin 2 aggregates that are negative for TDP-43 are predominantly small and punctate and are abundant in the hippocampal formation, spinal cord, all tested regions of neocortex, medulla and substantia nigra in UBQLN2-linked ALS/FTD but not sporadic ALS. Curiously, the striatum harboured small punctate ubiquilin 2 aggregates in all cases examined, while large diffuse striatal ubiquilin 2 aggregates were specific to UBQLN2-linked ALS/FTD. Overall, ubiquilin 2 is mainly deposited in clinically unaffected regions throughout the CNS such that symptomology in UBQLN2-linked cases maps best to the aggregation of TDP-43.
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Affiliation(s)
- Laura R. Nementzik
- School of Biological SciencesUniversity of AucklandAucklandNew Zealand
- Centre for Brain ResearchUniversity of AucklandAucklandNew Zealand
| | - Kyrah M. Thumbadoo
- School of Biological SciencesUniversity of AucklandAucklandNew Zealand
- Centre for Brain ResearchUniversity of AucklandAucklandNew Zealand
| | - Helen C. Murray
- Centre for Brain ResearchUniversity of AucklandAucklandNew Zealand
- Department of Anatomy and Medical ImagingUniversity of AucklandAucklandNew Zealand
| | - David Gordon
- School of Biological SciencesUniversity of AucklandAucklandNew Zealand
- Centre for Brain ResearchUniversity of AucklandAucklandNew Zealand
| | - Shu Yang
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine, Health, and Human SciencesMacquarie UniversityNorth RydeNew South WalesAustralia
| | - Ian P. Blair
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine, Health, and Human SciencesMacquarie UniversityNorth RydeNew South WalesAustralia
| | - Clinton Turner
- Centre for Brain ResearchUniversity of AucklandAucklandNew Zealand
- Department of Anatomy and Medical ImagingUniversity of AucklandAucklandNew Zealand
- Department of Anatomical Pathology, LabPlusAuckland City HospitalAucklandNew Zealand
| | - Richard L. M. Faull
- Centre for Brain ResearchUniversity of AucklandAucklandNew Zealand
- Department of Anatomy and Medical ImagingUniversity of AucklandAucklandNew Zealand
| | - Maurice A. Curtis
- Centre for Brain ResearchUniversity of AucklandAucklandNew Zealand
- Department of Anatomy and Medical ImagingUniversity of AucklandAucklandNew Zealand
| | - Catriona McLean
- Department of Anatomical PathologyAlfred HealthMelbourneVictoriaAustralia
| | - Garth A. Nicholson
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine, Health, and Human SciencesMacquarie UniversityNorth RydeNew South WalesAustralia
- Northcott Neuroscience LaboratoryANZAC Research InstituteSydneyAustralia
- Molecular Medicine LaboratoryConcord Repatriation General HospitalSydneyAustralia
| | - Molly E. V. Swanson
- School of Biological SciencesUniversity of AucklandAucklandNew Zealand
- Centre for Brain ResearchUniversity of AucklandAucklandNew Zealand
| | - Emma L. Scotter
- School of Biological SciencesUniversity of AucklandAucklandNew Zealand
- Centre for Brain ResearchUniversity of AucklandAucklandNew Zealand
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4
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Safren N, Dao TP, Mohan HM, Huang C, Trotter B, Castañeda CA, Paulson H, Barmada S, Sharkey LM. Pathogenic mutations in UBQLN2 exhibit diverse aggregation propensity and neurotoxicity. Sci Rep 2024; 14:6049. [PMID: 38472280 PMCID: PMC10933299 DOI: 10.1038/s41598-024-55582-9] [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: 11/02/2023] [Accepted: 02/26/2024] [Indexed: 03/14/2024] Open
Abstract
The ubiquitin-adaptor protein UBQLN2 promotes degradation of several aggregate-prone proteins implicated in neurodegenerative diseases. Missense UBQLN2 mutations also cause X-linked amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Previously we demonstrated that the liquid-like properties of UBQLN2 molecular assemblies are altered by a specific pathogenic mutation, P506T, and that the propensity of UBQLN2 to aggregate correlated with neurotoxicity. Here, we systematically assess the effects of multiple, spatially distinct ALS/FTD-linked missense mutations on UBQLN2 aggregation propensity, neurotoxicity, phase separation, and autophagic flux. In contrast to what we observed for the P506T mutation, no other tested pathogenic mutant exhibited a clear correlation between aggregation propensity and neurotoxicity. These results emphasize the unique nature of pathogenic UBQLN2 mutations and argue against a generalizable link between aggregation propensity and neurodegeneration in UBQLN2-linked ALS/FTD.
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Affiliation(s)
- Nathaniel Safren
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA.
| | - Thuy P Dao
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY, 13244, USA
| | - Harihar Milaganur Mohan
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Camellia Huang
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Bryce Trotter
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Carlos A Castañeda
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY, 13244, USA
| | - Henry Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Sami Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Lisa M Sharkey
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
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5
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Eck RJ, Stair JG, Kraemer BC, Liachko NF. Simple models to understand complex disease: 10 years of progress from Caenorhabditis elegans models of amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Front Neurosci 2024; 17:1300705. [PMID: 38239833 PMCID: PMC10794587 DOI: 10.3389/fnins.2023.1300705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 11/28/2023] [Indexed: 01/22/2024] Open
Abstract
The nematode Caenorhabditis elegans are a powerful model system to study human disease, with numerous experimental advantages including significant genetic and cellular homology to vertebrate animals, a short lifespan, and tractable behavioral, molecular biology and imaging assays. Beginning with the identification of SOD1 as a genetic cause of amyotrophic lateral sclerosis (ALS), C. elegans have contributed to a deeper understanding of the mechanistic underpinnings of this devastating neurodegenerative disease. More recently this work has expanded to encompass models of other types of ALS and the related disease frontotemporal lobar degeneration (FTLD-TDP), including those characterized by mutation or accumulation of the proteins TDP-43, C9orf72, FUS, HnRNPA2B1, ALS2, DCTN1, CHCHD10, ELP3, TUBA4A, CAV1, UBQLN2, ATXN3, TIA1, KIF5A, VAPB, GRN, and RAB38. In this review we summarize these models and the progress and insights from the last ten years of using C. elegans to study the neurodegenerative diseases ALS and FTLD-TDP.
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Affiliation(s)
- Randall J. Eck
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, United States
| | - Jade G. Stair
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA, United States
| | - Brian C. Kraemer
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, United States
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA, United States
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States
| | - Nicole F. Liachko
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, United States
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA, United States
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6
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Dao TP, Rajendran A, Galagedera SKK, Haws W, Castañeda CA. Short N-terminal disordered regions and the proline-rich domain are major regulators of phase transitions for full-length UBQLN1, UBQLN2 and UBQLN4. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.27.559790. [PMID: 37808720 PMCID: PMC10557701 DOI: 10.1101/2023.09.27.559790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Highly homologous ubiquitin-binding shuttle proteins UBQLN1, UBQLN2 and UBQLN4 differ in both their specific protein quality control functions and their propensities to localize to stress-induced condensates, cellular aggregates and aggresomes. We previously showed that UBQLN2 phase separates in vitro, and that the phase separation propensities of UBQLN2 deletion constructs correlate with their ability to form condensates in cells. Here, we demonstrated that full-length UBQLN1, UBQLN2 and UBQLN4 exhibit distinct phase behaviors in vitro. Strikingly, UBQLN4 phase separates at a much lower saturation concentration than UBQLN1. However, neither UBQLN1 nor UBQLN4 phase separates with a strong temperature dependence, unlike UBQLN2. We determined that the temperature-dependent phase behavior of UBQLN2 stems from its unique proline-rich (Pxx) region, which is absent in the other UBQLNs. We found that the short N-terminal disordered regions of UBQLN1, UBQLN2 and UBQLN4 inhibit UBQLN phase separation via electrostatics interactions. Charge variants of the N-terminal regions exhibit altered phase behaviors. Consistent with the sensitivity of UBQLN phase separation to the composition of the N-terminal regions, epitope tags placed on the N-termini of the UBQLNs tune phase separation. Overall, our in vitro results have important implications for studies of UBQLNs in cells, including the identification of phase separation as a potential mechanism to distinguish the cellular roles of UBQLNs, and the need to apply caution when using epitope tags to prevent experimental artifacts.
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Affiliation(s)
- Thuy P. Dao
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, USA
| | - Anitha Rajendran
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, USA
| | | | - William Haws
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, USA
| | - Carlos A. Castañeda
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, USA
- Interdisciplinary Neuroscience Program, Syracuse University, Syracuse, NY 13244, USA
- BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
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7
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Ma Q, Xin J, Peng Q, Li N, Sun S, Hou H, Ma G, Wang N, Zhang L, Tam KY, Dussmann H, Prehn JHM, Wang H, Ying Z. UBQLN2 and HSP70 participate in Parkin-mediated mitophagy by facilitating outer mitochondrial membrane rupture. EMBO Rep 2023; 24:e55859. [PMID: 37501540 PMCID: PMC10481660 DOI: 10.15252/embr.202255859] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 07/04/2023] [Accepted: 07/11/2023] [Indexed: 07/29/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two aging-related neurodegenerative diseases that share common key features, including aggregation of pathogenic proteins, dysfunction of mitochondria, and impairment of autophagy. Mutations in ubiquilin 2 (UBQLN2), a shuttle protein in the ubiquitin-proteasome system (UPS), can cause ALS/FTD, but the mechanism underlying UBQLN2-mediated pathogenesis is still uncertain. Recent studies indicate that mitophagy, a selective form of autophagy which is crucial for mitochondrial quality control, is tightly associated with neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and ALS. In this study, we show that after Parkin-dependent ubiquitination of damaged mitochondria, UBQLN2 is recruited to poly-ubiquitinated mitochondria through the UBA domain. UBQLN2 cooperates with the chaperone HSP70 to promote UPS-driven degradation of outer mitochondrial membrane (OMM) proteins. The resulting rupture of the OMM triggers the autophagosomal recognition of the inner mitochondrial membrane receptor PHB2. UBQLN2 is required for Parkin-mediated mitophagy and neuronal survival upon mitochondrial damage, and the ALS/FTD pathogenic mutations in UBQLN2 impair mitophagy in primary cultured neurons. Taken together, our findings link dysfunctional mitophagy to UBQLN2-mediated neurodegeneration.
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Affiliation(s)
- Qilian Ma
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
- Department of Physiology & Medical Physics and FUTURE‐NEURO Research CentreRoyal College of Surgeons in IrelandDublinIreland
| | - Jiaqi Xin
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
| | - Qiang Peng
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
| | - Ningning Li
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
| | - Shan Sun
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
- Faculty of Health SciencesUniversity of MacauMacauChina
| | - Hongyu Hou
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
| | - Guoqiang Ma
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
| | - Nana Wang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
| | - Li Zhang
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear MedicineJiangsu Institute of Nuclear MedicineWuxiChina
| | - Kin Yip Tam
- Faculty of Health SciencesUniversity of MacauMacauChina
| | - Heiko Dussmann
- Department of Physiology & Medical Physics and FUTURE‐NEURO Research CentreRoyal College of Surgeons in IrelandDublinIreland
| | - Jochen HM Prehn
- Department of Physiology & Medical Physics and FUTURE‐NEURO Research CentreRoyal College of Surgeons in IrelandDublinIreland
| | - Hongfeng Wang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
| | - Zheng Ying
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
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8
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Letko A, Brülisauer F, Häfliger IM, Corr E, Scholes S, Drögemüller C. Loss-of-function variant in the ovine TMCO6 gene in North Country Cheviot sheep with motor neuron disease. Genomics 2023; 115:110689. [PMID: 37488055 DOI: 10.1016/j.ygeno.2023.110689] [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: 05/03/2023] [Revised: 06/27/2023] [Accepted: 07/21/2023] [Indexed: 07/26/2023]
Abstract
In North Country Cheviot lambs with early-onset progressive ataxia and motor neuron degeneration, whole-genome sequencing identified a homozygous loss-of-function variant in the ovine transmembrane and coiled-coil domains (TMCO6) gene. The familial recessive form of motor neuron disease in sheep is due to a pathogenic 4 bp deletion leading to a 50% protein truncation that is assumed to result in the absence of a functional TMCO6. This uncharacterised protein is proposed to interact with ubiquilin 1 which is associated with Alzheimer's disease, whereas sporadic forms of amyotrophic lateral sclerosis are caused by variants in UBQLN2. Our findings provide a first spontaneous animal model for TMCO6, which could have implications in the studies of other comparative neurodegenerative diseases. In addition, these results will allow the design of a genetic test to prevent the occurrence of this fatal disease in the affected sheep population.
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Affiliation(s)
- Anna Letko
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern 3012, Switzerland.
| | - Franz Brülisauer
- SRUC Veterinary Services, Pentlands Science Park, Bush Estate Loan, Penicuik, Midlothian EH26 0PZ, United Kingdom.
| | - Irene M Häfliger
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern 3012, Switzerland.
| | - Eilidh Corr
- SRUC Veterinary Services, Pentlands Science Park, Bush Estate Loan, Penicuik, Midlothian EH26 0PZ, United Kingdom.
| | - Sandra Scholes
- SRUC Veterinary Services, Pentlands Science Park, Bush Estate Loan, Penicuik, Midlothian EH26 0PZ, United Kingdom
| | - Cord Drögemüller
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern 3012, Switzerland.
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9
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Sandoval-Pistorius SS, Gerson JE, Liggans N, Ryou JH, Oak K, Li X, Negron-Rios KY, Fischer S, Barsh H, Crowley EV, Skinner ME, Sharkey LM, Barmada SJ, Paulson HL. Ubiquilin-2 regulates pathological alpha-synuclein. Sci Rep 2023; 13:293. [PMID: 36609661 PMCID: PMC9823102 DOI: 10.1038/s41598-022-26899-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 12/21/2022] [Indexed: 01/08/2023] Open
Abstract
The key protein implicated in Parkinson's disease and other synucleinopathies is α-synuclein, and a post-translationally modified form of the protein, phosphorylated at serine 129 (pS129), is a principal component in Lewy bodies, a pathological hallmark of PD. While altered proteostasis has been implicated in the etiology of Parkinson's disease, we still have a limited understanding of how α-synuclein is regulated in the nervous system. The protein quality control protein Ubiquilin-2 (UBQLN2) is known to accumulate in synucleinopathies, but whether it directly regulates α-synuclein is unknown. Using cellular and mouse models, we find that UBQLN2 decreases levels of α-synuclein, including the pS129 phosphorylated isoform. Pharmacological inhibition of the proteasome revealed that, while α-synuclein may be cleared by parallel and redundant quality control pathways, UBQLN2 preferentially targets pS129 for proteasomal degradation. Moreover, in brain tissue from human PD and transgenic mice expressing pathogenic α-synuclein (A53T), native UBQLN2 becomes more insoluble. Collectively, our studies support a role for UBQLN2 in directly regulating pathological forms of α-synuclein and indicate that UBQLN2 dysregulation in disease may contribute to α-synuclein-mediated toxicity.
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Affiliation(s)
- Stephanie S. Sandoval-Pistorius
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA ,grid.214458.e0000000086837370Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109 USA
| | - Julia E. Gerson
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Nyjerus Liggans
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Jaimie H. Ryou
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Kulin Oak
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Xingli Li
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Keyshla Y. Negron-Rios
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Svetlana Fischer
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Henry Barsh
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Emily V. Crowley
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Mary E. Skinner
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Lisa M. Sharkey
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Sami J. Barmada
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Henry L. Paulson
- grid.214458.e0000000086837370Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200 USA
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10
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Lin BC, Higgins NR, Phung TH, Monteiro MJ. UBQLN proteins in health and disease with a focus on UBQLN2 in ALS/FTD. FEBS J 2022; 289:6132-6153. [PMID: 34273246 PMCID: PMC8761781 DOI: 10.1111/febs.16129] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/08/2021] [Accepted: 07/16/2021] [Indexed: 01/12/2023]
Abstract
Ubiquilin (UBQLN) proteins are a dynamic and versatile family of proteins found in all eukaryotes that function in the regulation of proteostasis. Besides their canonical function as shuttle factors in delivering misfolded proteins to the proteasome and autophagy systems for degradation, there is emerging evidence that UBQLN proteins play broader roles in proteostasis. New information suggests the proteins function as chaperones in protein folding, protecting proteins prior to membrane insertion, and as guardians for mitochondrial protein import. In this review, we describe the evidence for these different roles, highlighting how different domains of the proteins impart these functions. We also describe how changes in the structure and phase separation properties of UBQLNs may regulate their activity and function. Finally, we discuss the pathogenic mechanisms by which mutations in UBQLN2 cause amyotrophic lateral sclerosis and frontotemporal dementia. We describe the animal model systems made for different UBQLN2 mutations and how lessons learnt from these systems provide fundamental insight into the molecular mechanisms by which UBQLN2 mutations drive disease pathogenesis through disturbances in proteostasis.
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Affiliation(s)
- Brian C. Lin
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA,Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Nicole R. Higgins
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA,Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Trong H. Phung
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Mervyn J. Monteiro
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA,Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA,Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
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11
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Shah PP, Saurabh K, Kurlawala Z, Vega AA, Siskind LJ, Beverly LJ. Towards a molecular understanding of the overlapping and distinct roles of UBQLN1 and UBQLN2 in lung cancer progression and metastasis. Neoplasia 2022; 25:1-8. [PMID: 35063704 PMCID: PMC8864381 DOI: 10.1016/j.neo.2021.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 10/29/2021] [Accepted: 11/17/2021] [Indexed: 11/30/2022]
Abstract
The Ubiquilin family of proteins (UBQLN) consists of five related proteins (UBQLN1-4 and UBQLNL). Herein, we showed that loss of UBQLN1 and/or UBQLN2 induces cellular processes involved in tumor progression and metastasis, including proliferation, clonogenic potential and migration in lung adenocarcinoma cells. Molecular, biochemical and RNAseq analyses in multiple cellular systems, identified overlapping and distinct gene sets and pathways that were altered following loss of UBQLN1 and/or UBQLN2. The present study, provide evidence that UBQLN1 and UBQLN2 perform similar, but distinct molecular functions in a variety of cell types.
The Ubiquilin family of proteins (UBQLN) consists of five related proteins (UBQLN1-4 and UBQLNL) that all contain ubiquitin-like (UBL) and ubiquitin-associated (UBA) domains. UBQLN1 and UBQLN2 are the most closely related and have been the most well-studied, however their biochemical, biological and cellular functions are still not well understood. Previous studies from our lab reported that loss of UBQLN1 or UBQLN2 induces epithelial mesenchymal transition (EMT) in lung adenocarcinoma cells. Herein, we showed that loss of UBQLN1 and/or UBQLN2 induces cellular processes involved in tumor progression and metastasis, including proliferation, clonogenic potential and migration in lung adenocarcinoma cells. In fact, following simultaneous loss of both UBQLN1 and UBQLN2 many of these processes were further enhanced. To understand the molecular mechanisms by which UBQLN1 and UBQLN2 loss could be additive, we performed molecular, biochemical and RNAseq analyses in multiple cellular systems. We identified overlapping and distinct gene sets and pathways that were altered following loss of UBQLN1 and/or UBQLN2. We have also begun to define cell type specific gene regulation of UBQLN1 and UBQLN2, as well as understand how loss of either gene can alter differentiation of normal cells. The data presented here demonstrate that UBQLN1 and UBQLN2 perform similar, but distinct molecular functions in a variety of cell types.
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Affiliation(s)
- Parag P Shah
- James Graham Brown Cancer Center, University of Louisville, 505 S. Hancock Street, CTRB rm 204, Louisville, KY 40202, USA
| | - Kumar Saurabh
- James Graham Brown Cancer Center, University of Louisville, 505 S. Hancock Street, CTRB rm 204, Louisville, KY 40202, USA
| | - Zimple Kurlawala
- James Graham Brown Cancer Center, University of Louisville, 505 S. Hancock Street, CTRB rm 204, Louisville, KY 40202, USA
| | - Alexis A Vega
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
| | - Leah J Siskind
- James Graham Brown Cancer Center, University of Louisville, 505 S. Hancock Street, CTRB rm 204, Louisville, KY 40202, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Levi J Beverly
- James Graham Brown Cancer Center, University of Louisville, 505 S. Hancock Street, CTRB rm 204, Louisville, KY 40202, USA; Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA; Department of Medicine, Division of Hematology and Oncology, University of Louisville School of Medicine, Louisville, KY 40202, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA.
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12
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Juvenile Amyotrophic Lateral Sclerosis: A Review. Genes (Basel) 2021; 12:genes12121935. [PMID: 34946884 PMCID: PMC8701111 DOI: 10.3390/genes12121935] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/24/2021] [Accepted: 11/26/2021] [Indexed: 12/16/2022] Open
Abstract
Juvenile amyotrophic lateral sclerosis (JALS) is a rare group of motor neuron disorders with gene association in 40% of cases. JALS is defined as onset before age 25. We conducted a literature review of JALS and gene mutations associated with JALS. Results of the literature review show that the most common gene mutations associated with JALS are FUS, SETX, and ALS2. In familial cases, the gene mutations are mostly inherited in an autosomal recessive pattern and mutations in SETX are inherited in an autosomal dominant fashion. Disease prognosis varies from rapidly progressive to an indolent course. Distinct clinical features may emerge with specific gene mutations in addition to the clinical finding of combined upper and lower motor neuron degeneration. In conclusion, patients presenting with combined upper and lower motor neuron disorders before age 25 should be carefully examined for genetic mutations. Hereditary patterns and coexisting features may be useful in determining prognosis.
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13
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Gerson JE, Safren N, Fischer S, Patel R, Crowley EV, Welday JP, Windle AK, Barmada S, Paulson HL, Sharkey LM. Ubiquilin-2 differentially regulates polyglutamine disease proteins. Hum Mol Genet 2021; 29:2596-2610. [PMID: 32681165 DOI: 10.1093/hmg/ddaa152] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 07/07/2020] [Accepted: 07/13/2020] [Indexed: 12/12/2022] Open
Abstract
Divergent protein context helps explain why polyglutamine expansion diseases differ clinically and pathologically. This heterogeneity may also extend to how polyglutamine disease proteins are handled by cellular pathways of proteostasis. Studies suggest, for example, that the ubiquitin-proteasome shuttle protein Ubiquilin-2 (UBQLN2) selectively interacts with specific polyglutamine disease proteins. Here we employ cellular models, primary neurons and mouse models to investigate the potential differential regulation by UBQLN2 of two polyglutamine disease proteins, huntingtin (HTT) and ataxin-3 (ATXN3). In cells, overexpressed UBQLN2 selectively lowered levels of full-length pathogenic HTT but not of HTT exon 1 fragment or full-length ATXN3. Consistent with these results, UBQLN2 specifically reduced accumulation of aggregated mutant HTT but not mutant ATXN3 in mouse models of Huntington's disease (HD) and spinocerebellar ataxia type 3 (SCA3), respectively. Normally a cytoplasmic protein, UBQLN2 translocated to the nuclei of neurons in HD mice but not in SCA3 mice. Remarkably, instead of reducing the accumulation of nuclear mutant ATXN3, UBQLN2 induced an accumulation of cytoplasmic ATXN3 aggregates in neurons of SCA3 mice. Together these results reveal a selective action of UBQLN2 toward polyglutamine disease proteins, indicating that polyglutamine expansion alone is insufficient to promote UBQLN2-mediated clearance of this class of disease proteins. Additional factors, including nuclear translocation of UBQLN2, may facilitate its action to clear intranuclear, aggregated disease proteins like HTT.
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Affiliation(s)
- Julia E Gerson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Nathaniel Safren
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Svetlana Fischer
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Ronak Patel
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Emily V Crowley
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Jacqueline P Welday
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Alexandra K Windle
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Sami Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Lisa M Sharkey
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
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14
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Saxton AD, Kraemer BC. Human Ubiquilin 2 and TDP-43 co-pathology drives neurodegeneration in transgenic C. elegans. G3-GENES GENOMES GENETICS 2021; 11:6272515. [PMID: 33963840 DOI: 10.1093/g3journal/jkab158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/01/2021] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a debilitating, fatal neurodegenerative disease that causes rapid muscle wasting. It shares a spectrum of symptoms and pathology with frontotemporal lobar degeneration (FTLD). These diseases are caused by aberrant activity of a set of proteins including TDP-43 and UBIQUILIN-2 (UBQLN2). UBQLN2 encodes an ubiquitin-like adaptor protein involved in the ubiquitin-proteasome protein degradation pathway. Mutations in the PXX domain of UBQLN2 cause familial ALS. UBQLN2 aggregates in skein-like inclusions with other ALS and FTLD associated proteins including TDP-43 and ubiquitin. To facilitate further investigation of UBQLN2-mediated mechanisms of neurodegeneration, we made Caenorhabditis elegans transgenic lines pan-neuronally expressing human UBQLN2 cDNAs carrying either the wild-type UBQLN2 sequence or UBQLN2 with ALS causing mutations. Transgenic animals exhibit motor dysfunction accompanied by neurodegeneration of GABAergic motor neurons. At low levels of UBQLN2 expression, wild-type UBQLN2 causes significant motor impairment and neurodegeneration that is exacerbated by ALS associated mutations in UBQLN2. At higher levels of UBQLN2 expression, both wild-type and ALS mutated versions of UBQLN2 cause severe impairment. Molecular genetic investigation revealed that UBQLN2 dependent locomotor defects do not require the involvement of the endogenous homolog of TDP-43 in C. elegans (tdp-1). However, co-expression of wild-type human TDP-43 exacerbates UBQLN2 deficits. This model of UBQLN2-mediated neurodegeneration may be useful for further mechanistic investigation into the molecular cascades driving neurodegeneration in ALS and ALS-FTLD.
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Affiliation(s)
- Aleen D Saxton
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, Washington, 98108, United States of America
| | - Brian C Kraemer
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, Washington, 98108, United States of America; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98104, USA; Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA; Department of Pathology, University of Washington School of Medicine, Seattle, Washington 98195, USA
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15
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The Role of White Matter Dysfunction and Leukoencephalopathy/Leukodystrophy Genes in the Aetiology of Frontotemporal Dementias: Implications for Novel Approaches to Therapeutics. Int J Mol Sci 2021; 22:ijms22052541. [PMID: 33802612 PMCID: PMC7961524 DOI: 10.3390/ijms22052541] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/22/2021] [Accepted: 03/01/2021] [Indexed: 01/01/2023] Open
Abstract
Frontotemporal dementia (FTD) is a common cause of presenile dementia and is characterized by behavioural and/or language changes and progressive cognitive deficits. Genetics is an important component in the aetiology of FTD, with positive family history of dementia reported for 40% of cases. This review synthesizes current knowledge of the known major FTD genes, including C9orf72 (chromosome 9 open reading frame 72), MAPT (microtubule-associated protein tau) and GRN (granulin), and their impact on neuronal and glial pathology. Further, evidence for white matter dysfunction in the aetiology of FTD and the clinical, neuroimaging and genetic overlap between FTD and leukodystrophy/leukoencephalopathy are discussed. The review highlights the role of common variants and mutations in genes such as CSF1R (colony-stimulating factor 1 receptor), CYP27A1 (cytochrome P450 family 27 subfamily A member 1), TREM2 (triggering receptor expressed on myeloid cells 2) and TMEM106B (transmembrane protein 106B) that play an integral role in microglia and oligodendrocyte function. Finally, pharmacological and non-pharmacological approaches for enhancing remyelination are discussed in terms of future treatments of FTD.
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16
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Gerson JE, Linton H, Xing J, Sutter AB, Kakos FS, Ryou J, Liggans N, Sharkey LM, Safren N, Paulson HL, Ivanova MI. Shared and divergent phase separation and aggregation properties of brain-expressed ubiquilins. Sci Rep 2021; 11:287. [PMID: 33431932 PMCID: PMC7801659 DOI: 10.1038/s41598-020-78775-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 11/25/2020] [Indexed: 01/29/2023] Open
Abstract
The brain-expressed ubiquilins, UBQLNs 1, 2 and 4, are highly homologous proteins that participate in multiple aspects of protein homeostasis and are implicated in neurodegenerative diseases. Studies have established that UBQLN2 forms liquid-like condensates and accumulates in pathogenic aggregates, much like other proteins linked to neurodegenerative diseases. However, the relative condensate and aggregate formation of the three brain-expressed ubiquilins is unknown. Here we report that the three ubiquilins differ in aggregation propensity, revealed by in-vitro experiments, cellular models, and analysis of human brain tissue. UBQLN4 displays heightened aggregation propensity over the other ubiquilins and, like amyloids, UBQLN4 forms ThioflavinT-positive fibrils in vitro. Measuring fluorescence recovery after photobleaching (FRAP) of puncta in cells, we report that all three ubiquilins undergo liquid-liquid phase transition. UBQLN2 and 4 exhibit slower recovery than UBQLN1, suggesting the condensates formed by these brain-expressed ubiquilins have different compositions and undergo distinct internal rearrangements. We conclude that while all brain-expressed ubiquilins exhibit self-association behavior manifesting as condensates, they follow distinct courses of phase-separation and aggregation. We suggest that this variability among ubiquilins along the continuum from liquid-like to solid informs both the normal ubiquitin-linked functions of ubiquilins and their accumulation and potential contribution to toxicity in neurodegenerative diseases.
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Affiliation(s)
- Julia E Gerson
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
| | - Hunter Linton
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Jiazheng Xing
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Alexandra B Sutter
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
- Neuroscience Graduate Program, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Fayth S Kakos
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Jaimie Ryou
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Nyjerus Liggans
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Lisa M Sharkey
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Nathaniel Safren
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
| | - Magdalena I Ivanova
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
- Department of Neurology, Biophysics Program, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
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17
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Shinoda Y, Haga Y, Akagawa K, Fukunaga K. Wildtype σ1 receptor and the receptor agonist improve ALS-associated mutation-induced insolubility and toxicity. J Biol Chem 2020; 295:17573-17587. [PMID: 33453999 PMCID: PMC7762949 DOI: 10.1074/jbc.ra120.015012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 10/10/2020] [Indexed: 12/12/2022] Open
Abstract
Genetic mutations related to ALS, a progressive neurological disease, have been discovered in the gene encoding σ-1 receptor (σ1R). We previously reported that σ1RE102Q elicits toxicity in cells. The σ1R forms oligomeric states that are regulated by ligands. Nevertheless, little is known about the effect of ALS-related mutations on oligomer formation. Here, we transfected NSC-34 cells, a motor neuronal cell line, and HEK293T cells with σ1R-mCherry (mCh), σ1RE102Q-mCh, or nontagged forms to investigate detergent solubility and subcellular distribution using immunocytochemistry and fluorescence recovery after photobleaching. The oligomeric state was determined using crosslinking procedure. σ1Rs were soluble to detergents, whereas the mutants accumulated in the insoluble fraction. Within the soluble fraction, peak distribution of mutants appeared in higher sucrose density fractions. Mutants formed intracellular aggregates that were co-stained with p62, ubiquitin, and phosphorylated pancreatic eukaryotic translation initiation factor-2-α kinase in NSC-34 cells but not in HEK293T cells. The aggregates had significantly lower recovery in fluorescence recovery after photobleaching. Acute treatment with σ1R agonist SA4503 failed to improve recovery, whereas prolonged treatment for 48 h significantly decreased σ1RE102Q-mCh insolubility and inhibited apoptosis. Whereas σ1R-mCh formed monomers and dimers, σ1RE102Q-mCh also formed trimers and tetramers. SA4503 reduced accumulation of the four types in the insoluble fraction and increased monomers in the soluble fraction. The σ1RE102Q insolubility was diminished by σ1R-mCh co-expression. These results suggest that the agonist and WT σ1R modify the detergent insolubility, toxicity, and oligomeric state of σ1RE102Q, which may lead to promising new treatments for σ1R-related ALS.
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Affiliation(s)
- Yasuharu Shinoda
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Yudai Haga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Koichiro Akagawa
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Kohji Fukunaga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
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18
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Aggresome formation and liquid-liquid phase separation independently induce cytoplasmic aggregation of TAR DNA-binding protein 43. Cell Death Dis 2020; 11:909. [PMID: 33097688 PMCID: PMC7585435 DOI: 10.1038/s41419-020-03116-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/06/2020] [Accepted: 10/08/2020] [Indexed: 12/12/2022]
Abstract
Cytoplasmic inclusion of TAR DNA-binding protein 43 (TDP-43) is a pathological hallmark of amyotrophic lateral sclerosis (ALS) and a subtype of frontotemporal lobar degeneration (FTLD). Recent studies have suggested that the formation of cytoplasmic TDP-43 aggregates is dependent on a liquid-liquid phase separation (LLPS) mechanism. However, it is unclear whether TDP-43 pathology is induced through a single intracellular mechanism such as LLPS. To identify intracellular mechanisms responsible for TDP-43 aggregation, we established a TDP-43 aggregation screening system using a cultured neuronal cell line stably expressing EGFP-fused TDP-43 and a mammalian expression library of the inherited ALS/FTLD causative genes, and performed a screening. We found that microtubule-related proteins (MRPs) and RNA-binding proteins (RBPs) co-aggregated with TDP-43. MRPs and RBPs sequestered TDP-43 into the cytoplasmic aggregates through distinct mechanisms, such as microtubules and LLPS, respectively. The MRPs-induced TDP-43 aggregates were co-localized with aggresomal markers and dependent on histone deacetylase 6 (HDAC6), suggesting that aggresome formation induced the co-aggregation. However, the MRPs-induced aggregates were not affected by 1,6-hexanediol, an LLPS inhibitor. On the other hand, the RBPs-induced TDP-43 aggregates were sensitive to 1,6-hexanediol, but not dependent on microtubules or HDAC6. In sporadic ALS patients, approximately half of skein-like TDP-43 inclusions were co-localized with HDAC6, but round and granular type inclusion were not. Moreover, HDAC6-positive and HDAC6-negative inclusions were found in the same ALS patient, suggesting that the two distinct pathways are both involved in TDP-43 pathology. Our findings suggest that at least two distinct pathways (i.e., aggresome formation and LLPS) are involved in inducing the TDP-43 pathologies.
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19
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Halloran M, Ragagnin AMG, Vidal M, Parakh S, Yang S, Heng B, Grima N, Shahheydari H, Soo KY, Blair I, Guillemin GJ, Sundaramoorthy V, Atkin JD. Amyotrophic lateral sclerosis-linked UBQLN2 mutants inhibit endoplasmic reticulum to Golgi transport, leading to Golgi fragmentation and ER stress. Cell Mol Life Sci 2020; 77:3859-3873. [PMID: 31802140 PMCID: PMC11105036 DOI: 10.1007/s00018-019-03394-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 10/28/2019] [Accepted: 11/22/2019] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are fatal neurodegenerative diseases that are related genetically and pathologically. Mutations in the UBQLN2 gene, encoding the ubiquitin-like protein ubiquilin2, are associated with familial ALS/FTD, but the pathophysiological mechanisms remain unclear. Here, we demonstrate that ALS/FTD UBQLN2 mutants P497H and P506T inhibit protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus in neuronal cells. In addition, we observed that Sec31-positive ER exit sites are clustered in UBQLN2T487I patient spinal cord tissues. Both the ER-Golgi intermediate (ERGIC) compartment and the Golgi become disorganised and fragmented. This activates ER stress and inhibits ER-associated degradation. Hence, this study highlights perturbations in secretory protein trafficking and ER homeostasis as pathogenic mechanisms associated with ALS/FTD-associated forms of UBQLN2.
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Affiliation(s)
- Mark Halloran
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Audrey M G Ragagnin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Marta Vidal
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Sonam Parakh
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Shu Yang
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Benjamin Heng
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Natalie Grima
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Hamideh Shahheydari
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Kai-Ying Soo
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Ian Blair
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Gilles J Guillemin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Vinod Sundaramoorthy
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Julie D Atkin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia.
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Melbourne, Australia.
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20
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Zheng T, Yang Y, Castañeda CA. Structure, dynamics and functions of UBQLNs: at the crossroads of protein quality control machinery. Biochem J 2020; 477:3471-3497. [PMID: 32965492 PMCID: PMC7737201 DOI: 10.1042/bcj20190497] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/23/2020] [Accepted: 08/26/2020] [Indexed: 12/12/2022]
Abstract
Cells rely on protein homeostasis to maintain proper biological functions. Dysregulation of protein homeostasis contributes to the pathogenesis of many neurodegenerative diseases and cancers. Ubiquilins (UBQLNs) are versatile proteins that engage with many components of protein quality control (PQC) machinery in cells. Disease-linked mutations of UBQLNs are most commonly associated with amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and other neurodegenerative disorders. UBQLNs play well-established roles in PQC processes, including facilitating degradation of substrates through the ubiquitin-proteasome system (UPS), autophagy, and endoplasmic-reticulum-associated protein degradation (ERAD) pathways. In addition, UBQLNs engage with chaperones to sequester, degrade, or assist repair of misfolded client proteins. Furthermore, UBQLNs regulate DNA damage repair mechanisms, interact with RNA-binding proteins (RBPs), and engage with cytoskeletal elements to regulate cell differentiation and development. Important to the myriad functions of UBQLNs are its multidomain architecture and ability to self-associate. UBQLNs are linked to numerous types of cellular puncta, including stress-induced biomolecular condensates, autophagosomes, aggresomes, and aggregates. In this review, we focus on deciphering how UBQLNs function on a molecular level. We examine the properties of oligomerization-driven interactions among the structured and intrinsically disordered segments of UBQLNs. These interactions, together with the knowledge from studies of disease-linked mutations, provide significant insights to UBQLN structure, dynamics and function.
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Affiliation(s)
- Tongyin Zheng
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, U.S.A
| | - Yiran Yang
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, U.S.A
| | - Carlos A. Castañeda
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, U.S.A
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, U.S.A
- Bioinspired Institute, and the Interdisciplinary Neuroscience Program, Syracuse University, Syracuse, NY 13244, U.S.A
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21
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Häkkinen S, Chu SA, Lee SE. Neuroimaging in genetic frontotemporal dementia and amyotrophic lateral sclerosis. Neurobiol Dis 2020; 145:105063. [PMID: 32890771 DOI: 10.1016/j.nbd.2020.105063] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/30/2020] [Accepted: 08/26/2020] [Indexed: 02/06/2023] Open
Abstract
Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) have a strong clinical, genetic and pathological overlap. This review focuses on the current understanding of structural, functional and molecular neuroimaging signatures of genetic FTD and ALS. We overview quantitative neuroimaging studies on the most common genes associated with FTD (MAPT, GRN), ALS (SOD1), and both (C9orf72), and summarize visual observations of images reported in the rarer genes (CHMP2B, TARDBP, FUS, OPTN, VCP, UBQLN2, SQSTM1, TREM2, CHCHD10, TBK1).
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Affiliation(s)
- Suvi Häkkinen
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
| | - Stephanie A Chu
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
| | - Suzee E Lee
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA.
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22
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Solomon DA, Mitchell JC, Salcher-Konrad MT, Vance CA, Mizielinska S. Review: Modelling the pathology and behaviour of frontotemporal dementia. Neuropathol Appl Neurobiol 2020; 45:58-80. [PMID: 30582188 DOI: 10.1111/nan.12536] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 12/16/2018] [Indexed: 12/11/2022]
Abstract
Frontotemporal dementia (FTD) encompasses a collection of clinically and pathologically diverse neurological disorders. Clinical features of behavioural and language dysfunction are associated with neurodegeneration, predominantly of frontal and temporal cortices. Over the past decade, there have been significant advances in the understanding of the genetic aetiology and neuropathology of FTD which have led to the creation of various disease models to investigate the molecular pathways that contribute to disease pathogenesis. The generation of in vivo models of FTD involves either targeting genes with known disease-causative mutations such as GRN and C9orf72 or genes encoding proteins that form the inclusions that characterize the disease pathologically, such as TDP-43 and FUS. This review provides a comprehensive summary of the different in vivo model systems used to understand pathomechanisms in FTD, with a focus on disease models which reproduce aspects of the wide-ranging behavioural phenotypes seen in people with FTD. We discuss the emerging disease pathways that have emerged from these in vivo models and how this has shaped our understanding of disease mechanisms underpinning FTD. We also discuss the challenges of modelling the complex clinical symptoms shown by people with FTD, the confounding overlap with features of motor neuron disease, and the drive to make models more disease-relevant. In summary, in vivo models can replicate many pathological and behavioural aspects of clinical FTD, but robust and thorough investigations utilizing shared features and variability between disease models will improve the disease-relevance of findings and thus better inform therapeutic development.
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Affiliation(s)
- D A Solomon
- UK Dementia Research Institute, King's College London, London, Camberwell, UK.,Department of Basic & Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, Camberwell, UK
| | - J C Mitchell
- Department of Basic & Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, Camberwell, UK
| | - M-T Salcher-Konrad
- Department of Basic & Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, Camberwell, UK
| | - C A Vance
- Department of Basic & Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, Camberwell, UK
| | - S Mizielinska
- UK Dementia Research Institute, King's College London, London, Camberwell, UK.,Department of Basic & Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, Camberwell, UK
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23
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Neumann M, Mackenzie IRA. Review: Neuropathology of non-tau frontotemporal lobar degeneration. Neuropathol Appl Neurobiol 2020; 45:19-40. [PMID: 30357887 DOI: 10.1111/nan.12526] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 09/29/2018] [Indexed: 12/12/2022]
Abstract
Frontotemporal dementia (FTD) is a heterogeneous clinical syndrome associated with frontotemporal lobar degeneration (FTLD) as a relatively consistent neuropathological hallmark feature. However, the discoveries in the past decade of many of the relevant pathological proteins aggregating in human FTD brains in addition to several new FTD causing gene mutations underlined that FTD is a diverse condition on the neuropathological and genetic basis. This resulted in a novel molecular classification of these conditions based on the predominant protein abnormality and allows most cases of FTD to be placed now into one of three broad molecular subgroups; FTLD with tau, TAR DNA-binding protein 43 or FET protein accumulation (FTLD-tau, FTLD-TDP and FTLD-FET respectively). This review will provide an overview of the molecular neuropathology of non-tau FTLD, insights into disease mechanisms gained from the study of human post mortem tissue as well as discussion of current controversies in the field.
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Affiliation(s)
- M Neumann
- Department of Neuropathology, University Hospital of Tübingen, Tübingen, Germany.,Molecular Neuropathology of Neurodegenerative Diseases, German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - I R A Mackenzie
- Department of Pathology, University of British Columbia and Vancouver General Hospital, Vancouver, BC, Canada
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24
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Sharkey LM, Sandoval-Pistorius SS, Moore SJ, Gerson JE, Komlo R, Fischer S, Negron-Rios KY, Crowley EV, Padron F, Patel R, Murphy GG, Paulson HL. Modeling UBQLN2-mediated neurodegenerative disease in mice: Shared and divergent properties of wild type and mutant UBQLN2 in phase separation, subcellular localization, altered proteostasis pathways, and selective cytotoxicity. Neurobiol Dis 2020; 143:105016. [PMID: 32653673 DOI: 10.1016/j.nbd.2020.105016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/26/2020] [Accepted: 07/07/2020] [Indexed: 12/12/2022] Open
Abstract
The ubiquitin-binding proteasomal shuttle protein UBQLN2 is implicated in common neurodegenerative disorders due to its accumulation in disease-specific aggregates and, when mutated, directly causes familial frontotemporal dementia/amyotrophic lateral sclerosis (FTD/ALS). Like other proteins linked to FTD/ALS, UBQLN2 undergoes phase separation to form condensates. The relationship of UBQLN2 phase separation and accumulation to neurodegeneration, however, remains uncertain. Employing biochemical, neuropathological and behavioral assays, we studied the impact of overexpressing WT or mutant UBQLN2 in the CNS of transgenic mice. Expression of UBQLN2 harboring a pathogenic mutation (P506T) elicited profound and widespread intraneuronal inclusion formation and aggregation without prominent neurodegenerative or behavioral changes. Both WT and mutant UBQLN2 formed ubiquitin- and P62-positive inclusions in neurons, supporting the view that UBQLN2 is intrinsically prone to phase separate, with the size, shape and frequency of inclusions depending on expression level and the presence or absence of a pathogenic mutation. Overexpression of WT or mutant UBQLN2 resulted in a dose-dependent decrease in levels of a key interacting chaperone, HSP70, as well as dose-dependent profound degeneration of the retina. We conclude that, at least in mice, robust aggregation of a pathogenic form of UBQLN2 is insufficient to cause neuronal loss recapitulating that of human FTD/ALS. Our results nevertheless support the view that altering the normal cellular balance of UBQLN2, whether wild type or mutant protein, has deleterious effects on cells of the CNS and retina that likely reflect perturbations in ubiquitin-dependent protein homeostasis.
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Affiliation(s)
- Lisa M Sharkey
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America.
| | - Stephanie S Sandoval-Pistorius
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Shannon J Moore
- Michigan Neuroscience Institute and Department of Physiology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Julia E Gerson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Robert Komlo
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Svetlana Fischer
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Keyshla Y Negron-Rios
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Emily V Crowley
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Francisco Padron
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Ronak Patel
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Geoffrey G Murphy
- Michigan Neuroscience Institute and Department of Physiology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America.
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25
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Vicencio E, Beltrán S, Labrador L, Manque P, Nassif M, Woehlbier U. Implications of Selective Autophagy Dysfunction for ALS Pathology. Cells 2020; 9:cells9020381. [PMID: 32046060 PMCID: PMC7072226 DOI: 10.3390/cells9020381] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disorder that progressively affects motor neurons in the brain and spinal cord. Due to the biological complexity of the disease, its etiology remains unknown. Several cellular mechanisms involved in the neurodegenerative process in ALS have been found, including the loss of RNA and protein homeostasis, as well as mitochondrial dysfunction. Insoluble protein aggregates, damaged mitochondria, and stress granules, which contain RNA and protein components, are recognized and degraded by the autophagy machinery in a process known as selective autophagy. Autophagy is a highly dynamic process whose dysregulation has now been associated with neurodegenerative diseases, including ALS, by numerous studies. In ALS, the autophagy process has been found deregulated in both familial and sporadic cases of the disease. Likewise, mutations in genes coding for proteins involved in the autophagy machinery have been reported in ALS patients, including selective autophagy receptors. In this review, we focus on the role of selective autophagy in ALS pathology.
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Affiliation(s)
- Emiliano Vicencio
- Center for Integrative Biology, Faculty of Science, Universidad Mayor, Camino la Piramide 5750, Huechuraba 8580745, Santiago, Chile; (E.V.); (S.B.); (L.L.); (P.M.)
| | - Sebastián Beltrán
- Center for Integrative Biology, Faculty of Science, Universidad Mayor, Camino la Piramide 5750, Huechuraba 8580745, Santiago, Chile; (E.V.); (S.B.); (L.L.); (P.M.)
| | - Luis Labrador
- Center for Integrative Biology, Faculty of Science, Universidad Mayor, Camino la Piramide 5750, Huechuraba 8580745, Santiago, Chile; (E.V.); (S.B.); (L.L.); (P.M.)
| | - Patricio Manque
- Center for Integrative Biology, Faculty of Science, Universidad Mayor, Camino la Piramide 5750, Huechuraba 8580745, Santiago, Chile; (E.V.); (S.B.); (L.L.); (P.M.)
- Center for Genomics and Bioinformatics, Faculty of Science, Universidad Mayor, Camino la Piramide 5750, Huechuraba 8580745, Santiago, Chile
| | - Melissa Nassif
- Center for Integrative Biology, Faculty of Science, Universidad Mayor, Camino la Piramide 5750, Huechuraba 8580745, Santiago, Chile; (E.V.); (S.B.); (L.L.); (P.M.)
- Escuela de Biotecnología, Facultad de Ciencias, Universidad Mayor, Camino la Piramide 5750, Huechuraba 8580745, Santiago, Chile
- Correspondence: (U.W.); (M.N.)
| | - Ute Woehlbier
- Center for Integrative Biology, Faculty of Science, Universidad Mayor, Camino la Piramide 5750, Huechuraba 8580745, Santiago, Chile; (E.V.); (S.B.); (L.L.); (P.M.)
- Escuela de Biotecnología, Facultad de Ciencias, Universidad Mayor, Camino la Piramide 5750, Huechuraba 8580745, Santiago, Chile
- Correspondence: (U.W.); (M.N.)
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26
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Abstract
Frontotemporal degeneration (FTD) is a heterogeneous spectrum of neurodegenerative disorders characterized by diverse clinical presentations, neuropathological characteristics, and underlying genetic causes. In the last few years, several advances in the knowledge of clinical and biological aspects have been accomplished and three major scenarios have emerged that will represent the core issues in the FTD scene over the next few years. Foremost, the development of cerebrospinal fluid and blood biomarkers as well as neuroimaging techniques will aid the pursuit of new diagnostic and prognostic markers able to identify the ongoing proteinopathy and predict disease progression, which is key in identifying and stratifying patients for enrolment in clinical trials as well as evaluating response to treatment. On the other hand, current research has focused on the first attempts to slow down or revert disease progression, with the identification of disease modulators associated with disease onset and the ongoing development of the first pharmacological treatments for both sporadic and genetic FTD. Future research will certainly improve our knowledge of FTD and possibly open up a new era of disease-modifying therapies for this still-orphan disorder.
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Affiliation(s)
- Barbara Borroni
- Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, 25100, Italy
| | - Alberto Benussi
- Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, 25100, Italy
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27
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Renaud L, Picher-Martel V, Codron P, Julien JP. Key role of UBQLN2 in pathogenesis of amyotrophic lateral sclerosis and frontotemporal dementia. Acta Neuropathol Commun 2019; 7:103. [PMID: 31319884 PMCID: PMC6889556 DOI: 10.1186/s40478-019-0758-7] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 06/22/2019] [Indexed: 12/11/2022] Open
Abstract
Ubiquilin-2 (UBQLN2) is a member of the ubiquilin family, actively implicated in the degradation of misfolded and redundant proteins through the ubiquitin-proteasome system and macroautophagy. UBQLN2 received much attention after the discovery of gene mutations in amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD). The abnormal presence of positive UBQLN2 inclusion in the cytosol of degenerating motor neurons of familial and sporadic forms of ALS patients has been newly related to neurodegeneration. Only recently, data have emerged on its role in liquid-liquid phase separation, in stress granule development and in the formation of secondary amyloid structures. Furthermore, several animal models are available to investigate its involvement in TDP-43 pathology and neuroinflammation in ALS. This review addresses the molecular pathogenetic pathways involving UBQLN2 abnormalities which are converging toward defects in clearance mechanisms. UBQLN2.
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28
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Harman CA, Monteiro MJ. The specificity of ubiquitin binding to ubiquilin-1 is regulated by sequences besides its UBA domain. Biochim Biophys Acta Gen Subj 2019; 1863:1568-1574. [PMID: 31175912 DOI: 10.1016/j.bbagen.2019.06.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/24/2019] [Accepted: 06/03/2019] [Indexed: 12/12/2022]
Abstract
UBQLN proteins regulate proteostasis by facilitating clearance of misfolded proteins through the proteasome and autophagy degradation pathways. Consistent with its proteasomal function, UBQLN proteins contain both UBL and UBA domains, which bind subunits of the proteasome, including the S5a subunit, and ubiquitin chains, respectively. Conclusions regarding the binding properties of UBQLN proteins have been derived principally through studies of its individual domains, not the full-length (FL) proteins. Here we describe the in vitro binding properties of FL-UBQLN1 with the S5a subunit of the proteasome and two different lysine-linked (K48 or K63) ubiquitin chains. We show that in contrast to its isolated UBA domain, which binds almost equally well with both K48 and K63 ubiquitin chains, FL UBQLN1 binds preferentially with K63 chains. Furthermore, we show that deletion of the UBL domain from UBQLN1 abrogates ubiquitin binding. Taken together these results suggest that sequences outside of the UBA domain in UBQLN1 function to regulate the specificity and binding with different ubiquitin moieties. We also show that the UBL domain of UBQLN1 is required for S5a binding and that its binding to UBQLN1, in turn, enhances K48 ubiquitin chain binding to the complex. We discuss the implications of our findings with the known function of UBQLN proteins in protein degradation.
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Affiliation(s)
- Christine A Harman
- Center for Biomedical Engineering and Technology, Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Mervyn J Monteiro
- Center for Biomedical Engineering and Technology, Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States.
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29
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ALS-Linked Mutations Affect UBQLN2 Oligomerization and Phase Separation in a Position- and Amino Acid-Dependent Manner. Structure 2019; 27:937-951.e5. [PMID: 30982635 DOI: 10.1016/j.str.2019.03.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 12/22/2018] [Accepted: 03/15/2019] [Indexed: 12/14/2022]
Abstract
Proteasomal shuttle factor UBQLN2 is recruited to stress granules and undergoes liquid-liquid phase separation (LLPS) into protein-containing droplets. Mutations to UBQLN2 have recently been shown to cause dominant X-linked inheritance of amyotrophic lateral sclerosis (ALS) and ALS/dementia. Interestingly, most of these UBQLN2 mutations reside in its proline-rich (Pxx) region, an important modulator of LLPS. Here, we demonstrated that ALS-linked Pxx mutations differentially affect UBQLN2 LLPS, depending on both amino acid substitution and sequence position. Using size-exclusion chromatography, analytical ultracentrifugation, microscopy, and NMR spectroscopy, we determined that those Pxx mutants that enhanced UBQLN2 oligomerization decreased saturation concentrations needed for LLPS and promoted solid-like and viscoelastic morphological changes to UBQLN2 liquid assemblies. Ubiquitin disassembled all LLPS-induced mutant UBQLN2 aggregates. We postulate that the changes in physical properties caused by ALS-linked Pxx mutations modify UBQLN2 behavior in vivo, possibly contributing to aberrant stress granule morphology and dynamics, leading to formation of inclusions, pathological characteristics of ALS.
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30
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D'Ambrosi N, Cozzolino M, Carrì MT. Neuroinflammation in Amyotrophic Lateral Sclerosis: Role of Redox (dys)Regulation. Antioxid Redox Signal 2018; 29:15-36. [PMID: 28895473 DOI: 10.1089/ars.2017.7271] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
SIGNIFICANCE Amyotrophic lateral sclerosis (ALS) is due to degeneration of upper and lower motor neurons in the anterior horn of the spinal cord and in the motor cortex. Mechanisms leading to motor neuron death are complex and currently the disease is untreatable. Recent Advances: Work in genetic models of ALS indicates that an imbalance in the cross talk that physiologically exists between motor neurons and the surrounding cells is eventually detrimental to motor neurons. In particular, the cascade of events collectively known as neuroinflammation and mainly characterized by a reactive phenotype of astrocytes and microglia, moderate infiltration of peripheral immune cells, and elevated levels of inflammatory mediators has been consistently observed in motor regions of the central nervous system (CNS) in sporadic and familial ALS, constituting a hallmark of the disease. Resident glial cells and infiltrated immune cells are considered among the major producers of reactive species of oxygen and nitrogen in pathological conditions of the CNS, including motor neuron diseases. CRITICAL ISSUES The timing and exact role of oxidative stress-mediated neuroinflammation and damage to motor neurons in ALS are still not fully elucidated. FUTURE DIRECTIONS It is clear that a major challenge in the next future will be to envisage effective strategies to modulate the neuroinflammatory response in the symptomatic stage of disease, to prevent progression of neurodegeneration through the propagation of oxidative damage. Antioxid. Redox Signal. 29, 15-36.
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Affiliation(s)
- Nadia D'Ambrosi
- 1 Department of Biology, University of Rome Tor Vergata , Rome, Italy
| | - Mauro Cozzolino
- 2 Institute of Translational Pharmacology , CNR, Rome, Italy
| | - Maria Teresa Carrì
- 1 Department of Biology, University of Rome Tor Vergata , Rome, Italy .,3 Fondazione Santa Lucia , IRCCS, Rome, Italy
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31
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Teyssou E, Chartier L, Amador MDM, Lam R, Lautrette G, Nicol M, Machat S, Da Barroca S, Moigneu C, Mairey M, Larmonier T, Saker S, Dussert C, Forlani S, Fontaine B, Seilhean D, Bohl D, Boillée S, Meininger V, Couratier P, Salachas F, Stevanin G, Millecamps S. Novel UBQLN2 mutations linked to amyotrophic lateral sclerosis and atypical hereditary spastic paraplegia phenotype through defective HSP70-mediated proteolysis. Neurobiol Aging 2017; 58:239.e11-239.e20. [PMID: 28716533 DOI: 10.1016/j.neurobiolaging.2017.06.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 06/14/2017] [Accepted: 06/20/2017] [Indexed: 11/26/2022]
Abstract
Mutations in UBQLN2 have been associated with rare cases of X-linked juvenile and adult forms of amyotrophic lateral sclerosis (ALS) and ALS linked to frontotemporal dementia (FTD). Here, we report 1 known (c.1489C>T, p.Pro497Ser, P497S) and 3 novel (c.1481C>T, p.Pro494Leu, P494L; c.1498C>T, p.Pro500Ser, P500S; and c.1516C>G, p.Pro506Ala, P506A) missense mutations in the PXX domain of UBQLN2 in familial motor neuron diseases including ALS and spastic paraplegia (SP). A novel missense mutation (c.1462G>A, p.Ala488Thr, A488T) adjacent to this hotspot UBQLN2 domain was identified in a sporadic case of ALS. These mutations are conserved in mammals, are absent from ExAC and gnomAD browsers, and are predicted to be deleterious by SIFT in silico analysis. Patient lymphoblasts carrying a UBQLN2 mutation showed absence of ubiquilin-2 accumulation, disrupted binding with HSP70, and impaired autophagic pathway. Our results confirm the role of PXX repeat in ALS pathogenesis, show that UBQLN2-linked disease can manifest like a SP phenotype, evidence a highly reduced disease penetrance in females carrying UBQLN2 mutations, which is important information for genetic counseling, and underline the pivotal role of ubiquilin-2 in proteolysis regulation pathways.
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Affiliation(s)
- Elisa Teyssou
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Laura Chartier
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Maria-Del-Mar Amador
- Département de Neurologie, Assistance Publique Hôpitaux de Paris (APHP), Centre de ressources et de compétences SLA Ile de France, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Roselina Lam
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Géraldine Lautrette
- Service de Neurologie, Centre de ressources et de compétences SLA, CHU Dupuytren, Limoges, France
| | - Marie Nicol
- Service de Neurologie, Centre de ressources et de compétences SLA, CHU Dupuytren, Limoges, France
| | - Selma Machat
- Service de Neurologie, Centre de ressources et de compétences SLA, CHU Dupuytren, Limoges, France
| | - Sandra Da Barroca
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Carine Moigneu
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Mathilde Mairey
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France; Ecole Pratique des Hautes Etudes, EPHE, Université de recherche Paris Sciences et Lettres, Paris, France
| | | | - Safaa Saker
- Banque d'ADN et de cellules du Généthon, Evry, France
| | - Christelle Dussert
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Sylvie Forlani
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Bertrand Fontaine
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France; Département de Neurologie, Assistance Publique Hôpitaux de Paris (APHP), Centre de ressources et de compétences SLA Ile de France, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Danielle Seilhean
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France; Département de Neuropathologie, APHP, Hôpital Pitié-Salpêtrière, Paris, France
| | - Delphine Bohl
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Séverine Boillée
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Vincent Meininger
- Département de Neurologie, Assistance Publique Hôpitaux de Paris (APHP), Centre de ressources et de compétences SLA Ile de France, Hôpital de la Pitié-Salpêtrière, Paris, France; Hôpital des Peupliers, Ramsay Générale de Santé, Paris, France
| | - Philippe Couratier
- Service de Neurologie, Centre de ressources et de compétences SLA, CHU Dupuytren, Limoges, France
| | - François Salachas
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France; Département de Neurologie, Assistance Publique Hôpitaux de Paris (APHP), Centre de ressources et de compétences SLA Ile de France, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Giovanni Stevanin
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France; Ecole Pratique des Hautes Etudes, EPHE, Université de recherche Paris Sciences et Lettres, Paris, France; Centre de Référence de Neurogénétique, Fédération de Génétique, APHP, Hôpital Pitié-Salpêtrière, Paris, France
| | - Stéphanie Millecamps
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMRS1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France.
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Edens BM, Yan J, Miller N, Deng HX, Siddique T, Ma YC. A novel ALS-associated variant in UBQLN4 regulates motor axon morphogenesis. eLife 2017; 6:e25453. [PMID: 28463112 PMCID: PMC5451210 DOI: 10.7554/elife.25453] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/29/2017] [Indexed: 12/12/2022] Open
Abstract
The etiological underpinnings of amyotrophic lateral sclerosis (ALS) are complex and incompletely understood, although contributions to pathogenesis by regulators of proteolytic pathways have become increasingly apparent. Here, we present a novel variant in UBQLN4 that is associated with ALS and show that its expression compromises motor axon morphogenesis in mouse motor neurons and in zebrafish. We further demonstrate that the ALS-associated UBQLN4 variant impairs proteasomal function, and identify the Wnt signaling pathway effector beta-catenin as a UBQLN4 substrate. Inhibition of beta-catenin function rescues the UBQLN4 variant-induced motor axon phenotypes. These findings provide a strong link between the regulation of axonal morphogenesis and a new ALS-associated gene variant mediated by protein degradation pathways.
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Affiliation(s)
- Brittany M Edens
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H Lurie Children's Hospital of Chicago, Chicago, United States
| | - Jianhua Yan
- The Ken & Ruth Davee Department of Neurology, The Les Turner ALS Research and Patient Center, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Nimrod Miller
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H Lurie Children's Hospital of Chicago, Chicago, United States
| | - Han-Xiang Deng
- The Ken & Ruth Davee Department of Neurology, The Les Turner ALS Research and Patient Center, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Teepu Siddique
- The Ken & Ruth Davee Department of Neurology, The Les Turner ALS Research and Patient Center, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Yongchao C Ma
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H Lurie Children's Hospital of Chicago, Chicago, United States
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Amyotrophic Lateral Sclerosis Pathogenesis Converges on Defects in Protein Homeostasis Associated with TDP-43 Mislocalization and Proteasome-Mediated Degradation Overload. Curr Top Dev Biol 2017; 121:111-171. [DOI: 10.1016/bs.ctdb.2016.07.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Motor neuron disease, TDP-43 pathology, and memory deficits in mice expressing ALS-FTD-linked UBQLN2 mutations. Proc Natl Acad Sci U S A 2016; 113:E7580-E7589. [PMID: 27834214 DOI: 10.1073/pnas.1608432113] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Missense mutations in ubiquilin 2 (UBQLN2) cause ALS with frontotemporal dementia (ALS-FTD). Animal models of ALS are useful for understanding the mechanisms of pathogenesis and for preclinical investigations. However, previous rodent models carrying UBQLN2 mutations failed to manifest any sign of motor neuron disease. Here, we show that lines of mice expressing either the ALS-FTD-linked P497S or P506T UBQLN2 mutations have cognitive deficits, shortened lifespans, and develop motor neuron disease, mimicking the human disease. Neuropathologic analysis of the mice with end-stage disease revealed the accumulation of ubiquitinated inclusions in the brain and spinal cord, astrocytosis, a reduction in the number of hippocampal neurons, and reduced staining of TAR-DNA binding protein 43 in the nucleus, with concomitant formation of ubiquitin+ inclusions in the cytoplasm of spinal motor neurons. Moreover, both lines displayed denervation muscle atrophy and age-dependent loss of motor neurons that correlated with a reduction in the number of large-caliber axons. By contrast, two mouse lines expressing WT UBQLN2 were mostly devoid of clinical and pathological signs of disease. These UBQLN2 mouse models provide valuable tools for identifying the mechanisms underlying ALS-FTD pathogenesis and for investigating therapeutic strategies to halt disease.
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Hjerpe R, Bett JS, Keuss MJ, Solovyova A, McWilliams TG, Johnson C, Sahu I, Varghese J, Wood N, Wightman M, Osborne G, Bates GP, Glickman MH, Trost M, Knebel A, Marchesi F, Kurz T. UBQLN2 Mediates Autophagy-Independent Protein Aggregate Clearance by the Proteasome. Cell 2016; 166:935-949. [PMID: 27477512 PMCID: PMC5003816 DOI: 10.1016/j.cell.2016.07.001] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 04/18/2016] [Accepted: 07/02/2016] [Indexed: 12/14/2022]
Abstract
Clearance of misfolded and aggregated proteins is central to cell survival. Here, we describe a new pathway for maintaining protein homeostasis mediated by the proteasome shuttle factor UBQLN2. The 26S proteasome degrades polyubiquitylated substrates by recognizing them through stoichiometrically bound ubiquitin receptors, but substrates are also delivered by reversibly bound shuttles. We aimed to determine why these parallel delivery mechanisms exist and found that UBQLN2 acts with the HSP70-HSP110 disaggregase machinery to clear protein aggregates via the 26S proteasome. UBQLN2 recognizes client-bound HSP70 and links it to the proteasome to allow for the degradation of aggregated and misfolded proteins. We further show that this process is active in the cell nucleus, where another system for aggregate clearance, autophagy, does not act. Finally, we found that mutations in UBQLN2, which lead to neurodegeneration in humans, are defective in chaperone binding, impair aggregate clearance, and cause cognitive deficits in mice. UBQLN2 clears aggregates independent of autophagy via HSP70 and the proteasome A disease mutation in UBQLN2 prevents its binding to HSP70 Mutant UBQLN2 is defective in clearance of aggregates in vivo UBQLN2 knockin mice develop cognitive impairment and brain pathology
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Affiliation(s)
- Roland Hjerpe
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Davidson Building, Henry Wellcome Lab of Cell Biology, University of Glasgow, G12 8QQ Glasgow, UK; The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - John S Bett
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Davidson Building, Henry Wellcome Lab of Cell Biology, University of Glasgow, G12 8QQ Glasgow, UK; The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland.
| | - Matthew J Keuss
- The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Alexandra Solovyova
- Newcastle University Protein and Proteome Analysis, Devonshire Building, Devonshire Terrace, Newcastle upon Tyne NE1 7RU, UK
| | - Thomas G McWilliams
- The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Clare Johnson
- The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Indrajit Sahu
- Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Joby Varghese
- The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Nicola Wood
- The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Melanie Wightman
- The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Georgina Osborne
- Department of Medical and Molecular Genetics, King's College London, 8th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London SE1 9RT, UK
| | - Gillian P Bates
- Department of Medical and Molecular Genetics, King's College London, 8th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London SE1 9RT, UK
| | - Michael H Glickman
- Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Matthias Trost
- The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Axel Knebel
- The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Francesco Marchesi
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, 464 Bearsden Road, Glasgow G61 1QH, UK
| | - Thimo Kurz
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Davidson Building, Henry Wellcome Lab of Cell Biology, University of Glasgow, G12 8QQ Glasgow, UK; The MRC Protein Phosphorylation and Ubiquitylation Unit, The Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland.
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Mackenzie IRA, Neumann M. Molecular neuropathology of frontotemporal dementia: insights into disease mechanisms from postmortem studies. J Neurochem 2016; 138 Suppl 1:54-70. [PMID: 27306735 DOI: 10.1111/jnc.13588] [Citation(s) in RCA: 218] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 02/12/2016] [Accepted: 02/16/2016] [Indexed: 12/13/2022]
Abstract
Frontotemporal dementia (FTD) is a clinical syndrome with a heterogeneous molecular basis. The past decade has seen the discovery of several new FTD-causing genetic mutations and the identification of many of the relevant pathological proteins. The current neuropathological classification is based on the predominant protein abnormality and allows most cases of FTD to be placed into one of three broad molecular subgroups; frontotemporal lobar degeneration with tau, TDP-43 or FET protein accumulation. This review will describe our current understanding of the molecular basis of FTD, focusing on insights gained from the study of human postmortem tissue, as well as some of the current controversies. Most cases of FTD can be subclassified into one of three broad molecular subgroups based on the predominant protein that accumulates as pathological cellular inclusions. Understanding the associated pathogenic mechanisms and recognizing these FTD molecular subtypes in vivo will likely be crucial for the development and use of targeted therapies. This article is part of the Frontotemporal Dementia special issue.
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Affiliation(s)
- Ian R A Mackenzie
- Department of Pathology, University of British Columbia and Vancouver General Hospital, Vancouver, Canada
| | - Manuela Neumann
- Department of Neuropathology, University of Tübingen and German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
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Edens BM, Miller N, Ma YC. Impaired Autophagy and Defective Mitochondrial Function: Converging Paths on the Road to Motor Neuron Degeneration. Front Cell Neurosci 2016; 10:44. [PMID: 26973461 PMCID: PMC4776126 DOI: 10.3389/fncel.2016.00044] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 02/08/2016] [Indexed: 12/12/2022] Open
Abstract
Selective motor neuron degeneration is a hallmark of amyotrophic lateral sclerosis (ALS). Around 10% of all cases present as familial ALS (FALS), while sporadic ALS (SALS) accounts for the remaining 90%. Diverse genetic mutations leading to FALS have been identified, but the underlying causes of SALS remain largely unknown. Despite the heterogeneous and incompletely understood etiology, different types of ALS exhibit overlapping pathology and common phenotypes, including protein aggregation and mitochondrial deficiencies. Here, we review the current understanding of mechanisms leading to motor neuron degeneration in ALS as they pertain to disrupted cellular clearance pathways, ATP biogenesis, calcium buffering and mitochondrial dynamics. Through focusing on impaired autophagic and mitochondrial functions, we highlight how the convergence of diverse cellular processes and pathways contributes to common pathology in motor neuron degeneration.
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Affiliation(s)
- Brittany M. Edens
- Departments of Pediatrics, Neurology, and Physiology, Northwestern University Feinberg School of MedicineChicago, IL, USA
- Lurie Children’s Hospital of ChicagoChicago, IL, USA
| | - Nimrod Miller
- Departments of Pediatrics, Neurology, and Physiology, Northwestern University Feinberg School of MedicineChicago, IL, USA
- Lurie Children’s Hospital of ChicagoChicago, IL, USA
| | - Yong-Chao Ma
- Departments of Pediatrics, Neurology, and Physiology, Northwestern University Feinberg School of MedicineChicago, IL, USA
- Lurie Children’s Hospital of ChicagoChicago, IL, USA
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Bettencourt C, Forabosco P, Wiethoff S, Heidari M, Johnstone DM, Botía JA, Collingwood JF, Hardy J, Milward EA, Ryten M, Houlden H. Gene co-expression networks shed light into diseases of brain iron accumulation. Neurobiol Dis 2016; 87:59-68. [PMID: 26707700 PMCID: PMC4731015 DOI: 10.1016/j.nbd.2015.12.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 11/18/2015] [Accepted: 12/14/2015] [Indexed: 12/21/2022] Open
Abstract
Aberrant brain iron deposition is observed in both common and rare neurodegenerative disorders, including those categorized as Neurodegeneration with Brain Iron Accumulation (NBIA), which are characterized by focal iron accumulation in the basal ganglia. Two NBIA genes are directly involved in iron metabolism, but whether other NBIA-related genes also regulate iron homeostasis in the human brain, and whether aberrant iron deposition contributes to neurodegenerative processes remains largely unknown. This study aims to expand our understanding of these iron overload diseases and identify relationships between known NBIA genes and their main interacting partners by using a systems biology approach. We used whole-transcriptome gene expression data from human brain samples originating from 101 neuropathologically normal individuals (10 brain regions) to generate weighted gene co-expression networks and cluster the 10 known NBIA genes in an unsupervised manner. We investigated NBIA-enriched networks for relevant cell types and pathways, and whether they are disrupted by iron loading in NBIA diseased tissue and in an in vivo mouse model. We identified two basal ganglia gene co-expression modules significantly enriched for NBIA genes, which resemble neuronal and oligodendrocytic signatures. These NBIA gene networks are enriched for iron-related genes, and implicate synapse and lipid metabolism related pathways. Our data also indicates that these networks are disrupted by excessive brain iron loading. We identified multiple cell types in the origin of NBIA disorders. We also found unforeseen links between NBIA networks and iron-related processes, and demonstrate convergent pathways connecting NBIAs and phenotypically overlapping diseases. Our results are of further relevance for these diseases by providing candidates for new causative genes and possible points for therapeutic intervention.
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Affiliation(s)
- Conceição Bettencourt
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK; Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.
| | - Paola Forabosco
- Istituto di Ricerca Genetica e Biomedica CNR, Cagliari, Italy
| | - Sarah Wiethoff
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK; Center for Neurology and Hertie Institute for Clinical Brain Research, Eberhard-Karls-University, Tübingen, Germany
| | - Moones Heidari
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia; Centre for Bioinformatics, Biomarker Discovery and Information-Based Medicine, The University of Newcastle, Callaghan, NSW, Australia
| | - Daniel M Johnstone
- Bosch Institute and Discipline of Physiology, University of Sydney, NSW, Australia
| | - Juan A Botía
- Department of Medical and Molecular Genetics, King's College London, London, UK
| | | | - John Hardy
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Elizabeth A Milward
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia; Centre for Bioinformatics, Biomarker Discovery and Information-Based Medicine, The University of Newcastle, Callaghan, NSW, Australia
| | - Mina Ryten
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK; Department of Medical and Molecular Genetics, King's College London, London, UK
| | - Henry Houlden
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
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Abstract
Around 10-15% of patients diagnosed with frontotemporal dementia (FTD) have a
positive family history for FTD with an autosomal dominant pattern of
inheritance. Since the identification of mutations in MAPT
(microtubule-associated protein tau gene) in 1998, over 10 other genes have been
associated with FTD spectrum disorders, discussed in this review. Along with
MAPT, mutations in GRN (progranulin) and
C9orf72 (chromosome 9 open reading frame 72) are the most
commonly identified in FTD cohorts. The association of FTD and motor neuron
disease (MND) can be caused by mutations in C9orf72 and other
genes, such as TARDBP (TAR DNA-binding protein),
FUS (fused in sarcoma), UBQLN2 (ubiquilin
2). Multisystem proteinopathy is a complex phenotype that includes FTD, Paget
disease of the bone, inclusion body myopathy and MND, and can be due to
mutations in VCP (valosing containing protein) and other
recently identified genes.
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Affiliation(s)
- Leonel T Takada
- MD, PhD, Cognitive and Behavioral Neurology Unit, Department of Neurology, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil
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Ceballos-Diaz C, Rosario AM, Park HJ, Chakrabarty P, Sacino A, Cruz PE, Siemienski Z, Lara N, Moran C, Ravelo N, Golde TE, McFarland NR. Viral expression of ALS-linked ubiquilin-2 mutants causes inclusion pathology and behavioral deficits in mice. Mol Neurodegener 2015; 10:25. [PMID: 26152284 PMCID: PMC4495639 DOI: 10.1186/s13024-015-0026-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 06/30/2015] [Indexed: 12/14/2022] Open
Abstract
Background UBQLN2 mutations have recently been associated with familial forms of amyotrophic lateral sclerosis (ALS) and ALS-dementia. UBQLN2 encodes for ubiquilin-2, a member of the ubiquitin-like protein family which facilitates delivery of ubiquitinated proteins to the proteasome for degradation. To study the potential role of ubiquilin-2 in ALS, we used recombinant adeno-associated viral (rAAV) vectors to express UBQLN2 and three of the identified ALS-linked mutants (P497H, P497S, and P506T) in primary neuroglial cultures and in developing neonatal mouse brains. Results In primary cultures rAAV2/8-mediated expression of UBQLN2 mutants resulted in inclusion bodies and insoluble aggregates. Intracerebroventricular injection of FVB mice at post-natal day 0 with rAAV2/8 expressing wild type or mutant UBQLN2 resulted in widespread, sustained expression of ubiquilin-2 in brain. In contrast to wild type, mutant UBQLN2 expression induced significant pathology with large neuronal, cytoplasmic inclusions and ubiquilin-2-positive aggregates in surrounding neuropil. Ubiquilin-2 inclusions co-localized with ubiquitin, p62/SQSTM, optineurin, and occasionally TDP-43, but were negative for α-synuclein, neurofilament, tau, and FUS. Mutant UBLQN2 expression also resulted in Thioflavin-S-positive inclusions/aggregates. Mice expressing mutant forms of UBQLN2 variably developed a motor phenotype at 3–4 months, including nonspecific clasping and rotarod deficits. Conclusions These findings demonstrate that UBQLN2 mutants (P497H, P497S, and P506T) induce proteinopathy and cause behavioral deficits, supporting a “toxic” gain-of-function, which may contribute to ALS pathology. These data establish also that our rAAV model can be used to rapidly assess the pathological consequences of various UBQLN2 mutations and provides an agile system to further interrogate the molecular mechanisms of ubiquilins in neurodegeneration.
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Affiliation(s)
- Carolina Ceballos-Diaz
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA
| | - Awilda M Rosario
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA
| | - Hyo-Jin Park
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA.,Department of Neurology, College of Medicine, University of Florida, 1149 S Newell Dr, L3-100, PO Box 100236, Gainesville, FL, 32610, USA
| | - Paramita Chakrabarty
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA
| | - Amanda Sacino
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA
| | - Pedro E Cruz
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA
| | - Zoe Siemienski
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA
| | - Nicolas Lara
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA
| | - Corey Moran
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA
| | - Natalia Ravelo
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA.,Department of Neurology, College of Medicine, University of Florida, 1149 S Newell Dr, L3-100, PO Box 100236, Gainesville, FL, 32610, USA
| | - Todd E Golde
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA
| | - Nikolaus R McFarland
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, University of Florida, 1275 Center Dr, PO Box 100159, Gainesville, FL, 32610, USA. .,Department of Neurology, College of Medicine, University of Florida, 1149 S Newell Dr, L3-100, PO Box 100236, Gainesville, FL, 32610, USA.
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41
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Chang L, Monteiro MJ. Defective Proteasome Delivery of Polyubiquitinated Proteins by Ubiquilin-2 Proteins Containing ALS Mutations. PLoS One 2015; 10:e0130162. [PMID: 26075709 PMCID: PMC4468220 DOI: 10.1371/journal.pone.0130162] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 05/17/2015] [Indexed: 12/14/2022] Open
Abstract
Ubiquilin proteins facilitate delivery of ubiquitinated proteins to the proteasome for degradation. Interest in the proteins has been heightened by the discovery that gene mutations in UBQLN2 cause dominant inheritance of amyotrophic lateral sclerosis (ALS). However, the mechanisms by which the mutations cause ALS are not known. Here we report on the underlying defect of ubiquilin-2 proteins containing ALS-linked mutations in affecting proteasome-mediated degradation. We found that overexpression of ubiquilin-2 proteins containing any one of five different ALS mutations slow degradation of Myc, a prototypic proteasome substrate. Examination of coprecipitating proteins indicated that the mutant proteins are generally capable of binding polyubiquitinated proteins, but defective in binding the proteasome. GST-pulldown studies revealed that many of the mutants bind weaker to the S5a subunit of the proteasome, compared with wild type (WT) ubiquilin-2 protein. The results suggest the mutant proteins are unable to deliver their captured cargo to the proteasome for degradation, which presumably leads to toxicity. Quantification of cell death is consistent with this idea. Measurement of protein turnover further indicated the mutant proteins have longer half-lives than WT ubiquilin-2. Our studies provide novel insight into the mechanism by which ALS-linked mutations in UBQLN2 interfere with protein degradation.
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Affiliation(s)
- Lydia Chang
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Mervyn J. Monteiro
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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42
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Safren N, Chang L, Dziki KM, Monteiro MJ. Signature changes in ubiquilin expression in the R6/2 mouse model of Huntington's disease. Brain Res 2015; 1597:37-46. [PMID: 25511991 PMCID: PMC4340744 DOI: 10.1016/j.brainres.2014.12.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/12/2022]
Abstract
Ubiquilin proteins have been implicated in the cause and the pathology of neurodegenerative diseases. In the R6/2 mouse model of Huntington's disease (HD), ubiquilin levels decline during disease progression. Restoration of their levels by transgenic expression of ubiquilin-1 extends survival. Here we provide a comprehensive assessment of the expression and localization of all four ubiquilin proteins in both normal and R6/2-affected mice brains, using antibodies specific for each protein. Ubiquilin-1, 2 and 4 proteins were detected throughout the brain, with increased expression seen in the hippocampus and cerebellum. Ubiquilin-3 expression was not detected. All three ubiquilins expressed in the brain were found in Htt inclusions. Their expression changed during development and disease. Ubiquilin-1 and ubiquilin-2 protein levels decreased from 6 to 18 weeks of mouse development, independent of disease. Ubiquilin-1 and ubiquilin-4 protein levels also changed during HD disease progression. Ubiquilin-4 proteins that are normally expressed in the brain were lost and instead replaced by a novel 115 kDa higher molecular weight immunoreactive band. Taken together, our results demonstrate that all ubiquilin proteins are involved in HD pathology and that distinct changes in the signature of ubiquilin-4 expression could be useful for monitoring end-stage of HD disease.
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Affiliation(s)
- Nathaniel Safren
- Neuroscience Graduate Program, University of Maryland School of Medicine, Baltimore, MD 21201, United States; Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Lydia Chang
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Kristina M Dziki
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Mervyn J Monteiro
- Neuroscience Graduate Program, University of Maryland School of Medicine, Baltimore, MD 21201, United States; Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, United States; Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, 20 North Pine Street, Baltimore, MD 21201, United States.
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Gilpin KM, Chang L, Monteiro MJ. ALS-linked mutations in ubiquilin-2 or hnRNPA1 reduce interaction between ubiquilin-2 and hnRNPA1. Hum Mol Genet 2015; 24:2565-77. [PMID: 25616961 DOI: 10.1093/hmg/ddv020] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 01/21/2015] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS)-linked mutations in UBQLN2 and some members of the heterogeneous nuclear ribonucleoproteins (hnRNPs) family cause ALS. Most mutations in UBQLN2 are missense mutations that occur in and around a PXX repeat motif located in the central domain of the encoded protein. However, neither the function of the PXX motif nor the mechanism by which mutations in UBQLN2 cause ALS is known. We screened a yeast two-hybrid library using the central domain of ubiquilin-2 hoping to identify proteins whose binding is affected by the UBQLN2 mutations. Three such interactors were identified-hnRNPA1, hnRNPA3 and hnRNPU-all members of the hnRNP family. The interacting region in each of these proteins was their glycine-rich domain, the domain most frequently mutated in hnRNP-related proteins that cause ALS. We focused on hnRNPA1, because a mutation in the protein causes ALS. We confirmed the interaction between wild-type (WT) ubiquilin-2 and hnRNPA1 proteins in vitro and in cells. In contrast, all five ALS mutations in ubiquilin-2 that we examined had reduced binding with WT hnRNPA1. In addition, hnRNPA1 carrying the D262V missense mutation that causes ALS failed to bind WT ubiquilin-2. Overexpression of ubiquilin-2 containing the ALS mutations increased cell death and, for several of the mutants, this correlated with increased translocation of hnRNPA1 to the cytoplasm. Knockdown of ubiquilin-2 led to increased turnover of hnRNPA1, indicating ubiquilin-2 functions to stabilize hnRNPA1. The discovery that ubiquilin-2 interacts with hnRNP proteins and that mutation in either protein disrupts interaction suggests a connection between proteostasis and RNA metabolism.
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Affiliation(s)
- Kathleen M Gilpin
- Neuroscience Graduate Program, Center for Biomedical Engineering and Technology and Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 North Pine Street, Baltimore, MD 21201, USA
| | - Lydia Chang
- Neuroscience Graduate Program, Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 North Pine Street, Baltimore, MD 21201, USA
| | - Mervyn J Monteiro
- Neuroscience Graduate Program, Center for Biomedical Engineering and Technology and Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 North Pine Street, Baltimore, MD 21201, USA
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