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Miceli M, Exertier C, Cavaglià M, Gugole E, Boccardo M, Casaluci RR, Ceccarelli N, De Maio A, Vallone B, Deriu MA. ALS2-Related Motor Neuron Diseases: From Symptoms to Molecules. BIOLOGY 2022; 11:77. [PMID: 35053075 PMCID: PMC8773251 DOI: 10.3390/biology11010077] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/22/2021] [Accepted: 12/29/2021] [Indexed: 11/27/2022]
Abstract
Infantile-onset Ascending Hereditary Spastic Paralysis, Juvenile Primary Lateral Sclerosis and Juvenile Amyotrophic Lateral Sclerosis are all motor neuron diseases related to mutations on the ALS2 gene, encoding for a 1657 amino acids protein named Alsin. This ~185 kDa multi-domain protein is ubiquitously expressed in various human tissues, mostly in the brain and the spinal cord. Several investigations have indicated how mutations within Alsin's structured domains may be responsible for the alteration of Alsin's native oligomerization state or Alsin's propensity to interact with protein partners. In this review paper, we propose a description of differences and similarities characterizing the above-mentioned ALS2-related rare neurodegenerative disorders, pointing attention to the effects of ALS2 mutation from molecule to organ and at the system level. Known cases were collected through a literature review and rationalized to deeply elucidate the neurodegenerative clinical outcomes as consequences of ALS2 mutations.
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Affiliation(s)
- Marcello Miceli
- PolitoBIOMedLab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Torino, Italy; (M.M.); (M.C.); (M.B.); (R.R.C.); (N.C.); (A.D.M.)
| | - Cécile Exertier
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Sapienza Università di Roma, 00185 Rome, Italy; (C.E.); (E.G.); (B.V.)
| | - Marco Cavaglià
- PolitoBIOMedLab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Torino, Italy; (M.M.); (M.C.); (M.B.); (R.R.C.); (N.C.); (A.D.M.)
| | - Elena Gugole
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Sapienza Università di Roma, 00185 Rome, Italy; (C.E.); (E.G.); (B.V.)
| | - Marta Boccardo
- PolitoBIOMedLab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Torino, Italy; (M.M.); (M.C.); (M.B.); (R.R.C.); (N.C.); (A.D.M.)
| | - Rossana Rita Casaluci
- PolitoBIOMedLab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Torino, Italy; (M.M.); (M.C.); (M.B.); (R.R.C.); (N.C.); (A.D.M.)
| | - Noemi Ceccarelli
- PolitoBIOMedLab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Torino, Italy; (M.M.); (M.C.); (M.B.); (R.R.C.); (N.C.); (A.D.M.)
| | - Alessandra De Maio
- PolitoBIOMedLab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Torino, Italy; (M.M.); (M.C.); (M.B.); (R.R.C.); (N.C.); (A.D.M.)
| | - Beatrice Vallone
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Sapienza Università di Roma, 00185 Rome, Italy; (C.E.); (E.G.); (B.V.)
| | - Marco A. Deriu
- PolitoBIOMedLab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Torino, Italy; (M.M.); (M.C.); (M.B.); (R.R.C.); (N.C.); (A.D.M.)
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2
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Berdenis van Berlekom A, Notman N, Sneeboer MAM, Snijders GJLJ, Houtepen LC, Nispeling DM, He Y, Dracheva S, Hol EM, Kahn RS, de Witte LD, Boks MP. DNA methylation differences in cortical grey and white matter in schizophrenia. Epigenomics 2021; 13:1157-1169. [PMID: 34323598 PMCID: PMC8386513 DOI: 10.2217/epi-2021-0077] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 07/09/2021] [Indexed: 01/27/2023] Open
Abstract
Aim: Identify grey- and white-matter-specific DNA-methylation differences between schizophrenia (SCZ) patients and controls in postmortem brain cortical tissue. Materials & methods: Grey and white matter were separated from postmortem brain tissue of the superior temporal and medial frontal gyrus from SCZ (n = 10) and control (n = 11) cases. Genome-wide DNA-methylation analysis was performed using the Infinium EPIC Methylation Array (Illumina, CA, USA). Results: Four differentially methylated regions associated with SCZ status and tissue type (grey vs white matter) were identified within or near KLF9, SFXN1, SPRED2 and ALS2CL genes. Gene-expression analysis showed differential expression of KLF9 and SFXN1 in SCZ. Conclusion: Our data show distinct differences in DNA methylation between grey and white matter that are unique to SCZ, providing new leads to unravel the pathogenesis of SCZ.
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Affiliation(s)
- Amber Berdenis van Berlekom
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Department of Translational Neuroscience, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Nina Notman
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Marjolein AM Sneeboer
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Department of Translational Neuroscience, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Gijsje JLJ Snijders
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Lotte C Houtepen
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Danny M Nispeling
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Yujie He
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Department of Translational Neuroscience, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | | | - Stella Dracheva
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Mental Illness Research, Education, & Clinical Center (VISN 2 South), James J Peters VA Medical Center, Bronx, NY, 10468, USA
| | - Elly M Hol
- Department of Translational Neuroscience, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - René S Kahn
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Mental Illness Research, Education, & Clinical Center (VISN 2 South), James J Peters VA Medical Center, Bronx, NY, 10468, USA
| | - Lot D de Witte
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Marco P Boks
- Department of Psychiatry, Brain Center University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
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Kim J, Kim S, Nahm M, Li TN, Lin HC, Kim YD, Lee J, Yao CK, Lee S. ALS2 regulates endosomal trafficking, postsynaptic development, and neuronal survival. J Cell Biol 2021; 220:e202007112. [PMID: 33683284 PMCID: PMC7944400 DOI: 10.1083/jcb.202007112] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 01/07/2021] [Accepted: 02/11/2021] [Indexed: 12/11/2022] Open
Abstract
Mutations in the human ALS2 gene cause recessive juvenile-onset amyotrophic lateral sclerosis and related motor neuron diseases. Although the ALS2 protein has been identified as a guanine-nucleotide exchange factor for the small GTPase Rab5, its physiological roles remain largely unknown. Here, we demonstrate that the Drosophila homologue of ALS2 (dALS2) promotes postsynaptic development by activating the Frizzled nuclear import (FNI) pathway. dALS2 loss causes structural defects in the postsynaptic subsynaptic reticulum (SSR), recapitulating the phenotypes observed in FNI pathway mutants. Consistently, these developmental phenotypes are rescued by postsynaptic expression of the signaling-competent C-terminal fragment of Drosophila Frizzled-2 (dFz2). We further demonstrate that dALS2 directs early to late endosome trafficking and that the dFz2 C terminus is cleaved in late endosomes. Finally, dALS2 loss causes age-dependent progressive defects resembling ALS, including locomotor impairment and brain neurodegeneration, independently of the FNI pathway. These findings establish novel regulatory roles for dALS2 in endosomal trafficking, synaptic development, and neuronal survival.
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Affiliation(s)
- Joohyung Kim
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
| | - Sungdae Kim
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
| | - Minyeop Nahm
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
| | - Tsai-Ning Li
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hsin-Chieh Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yeongjin David Kim
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
| | - Jihye Lee
- Department of Oral Pathology, Department of Life Science in Dentistry, Dental and Life Science Institute, School of Dentistry, Pusan National University, Yangsan, Korea
| | - Chi-Kuang Yao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Neuroscience Program of Academia Sinica, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Seungbok Lee
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
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4
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Daud S, Kakar N, Goebel I, Hashmi AS, Yaqub T, Nürnberg G, Nürnberg P, Morris-Rosendahl DJ, Wasim M, Volk AE, Kubisch C, Ahmad J, Borck G. Identification of two novel ALS2 mutations in infantile-onset ascending hereditary spastic paraplegia. Amyotroph Lateral Scler Frontotemporal Degener 2016; 17:260-5. [PMID: 26751646 DOI: 10.3109/21678421.2015.1125501] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Biallelic mutations of ALS2 cause a clinical spectrum of overlapping autosomal recessive neurodegenerative disorders: infantile-onset ascending hereditary spastic paralysis (IAHSP), juvenile primary lateral sclerosis (JPLS), and juvenile amyotrophic lateral sclerosis (ALS2). We report on eleven individuals affected with IAHSP from two consanguineous Pakistani families. A combination of linkage analysis with homozygosity mapping and targeted sequencing identified two novel ALS2 mutations, a c.194T > C (p.Phe65Ser) missense substitution located in the first RCC-like domain of ALS2/alsin and a c.2998delA (p.Ile1000*) nonsense mutation. This study of extended families including a total of eleven affected individuals suggests that a given ALS2 mutation may lead to a phenotype with remarkable intrafamilial clinical homogeneity.
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Affiliation(s)
- Shakeela Daud
- a Institute of Biochemistry and Biotechnology (IBBt), UVAS , Lahore , Pakistan
| | - Naseebullah Kakar
- b Institute of Human Genetics, University of Ulm , Ulm , Germany .,c International Graduate School in Molecular Medicine Ulm, University of Ulm , Ulm , Germany .,d Department of Biotechnology and Informatics , BUITEMS , Quetta , Pakistan
| | - Ingrid Goebel
- b Institute of Human Genetics, University of Ulm , Ulm , Germany .,e Institute of Human Genetics, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Abu Saeed Hashmi
- a Institute of Biochemistry and Biotechnology (IBBt), UVAS , Lahore , Pakistan
| | - Tahir Yaqub
- a Institute of Biochemistry and Biotechnology (IBBt), UVAS , Lahore , Pakistan .,f Department of Microbiology , UVAS , Lahore , Pakistan
| | - Gudrun Nürnberg
- g Cologne Center for Genomics (CCG), University of Cologne , Cologne , Germany
| | - Peter Nürnberg
- g Cologne Center for Genomics (CCG), University of Cologne , Cologne , Germany .,h Center for Molecular Medicine Cologne (CMMC), University of Cologne , Cologne , Germany .,i Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne , Cologne , Germany
| | - Deborah J Morris-Rosendahl
- j Clinical Genetics and Genomics, Royal Brompton Hospital , London , United Kingdom .,k National Heart and Lung Institute, Imperial College London , London , United Kingdom
| | - Muhammad Wasim
- a Institute of Biochemistry and Biotechnology (IBBt), UVAS , Lahore , Pakistan
| | - Alexander E Volk
- b Institute of Human Genetics, University of Ulm , Ulm , Germany .,e Institute of Human Genetics, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Christian Kubisch
- b Institute of Human Genetics, University of Ulm , Ulm , Germany .,e Institute of Human Genetics, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Jamil Ahmad
- d Department of Biotechnology and Informatics , BUITEMS , Quetta , Pakistan
| | - Guntram Borck
- b Institute of Human Genetics, University of Ulm , Ulm , Germany
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Zhang Y, Liu J, Luan G, Wang X. Inhibition of the small GTPase Cdc42 in regulation of epileptic-seizure in rats. Neuroscience 2015; 289:381-91. [PMID: 25595978 DOI: 10.1016/j.neuroscience.2014.12.059] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 12/16/2014] [Accepted: 12/16/2014] [Indexed: 11/28/2022]
Abstract
Altered expression of neuronal cytoskeletal proteins are known to play an important role in hyper-excitability of neurons in patients and animal models of epilepsy. Our previous work showed that cell division cycle 42 GTP-binding protein (Cdc42), a small GTPase of the Rho-subfamily, is significantly increased in the brain tissue of patients with temporal lobe epilepsy (TLE) and in the brain tissues of the epileptic model of rats. However, whether inhibition of Cdc42 can modify epileptic seizures has not been investigated. In this study, using a pilocarpine-induced epileptic model, we found that pretreatment with ML141, a specific inhibitor of Cdc42, reduces seizure severity. Whole-cell patch-clamp recording on CA1 pyramidal neurons in hippocampal slices from pilocarpine-induced epileptic model demonstrated that ML141 significantly inhibits the frequency of action potentials (APs), increases the amplitude and frequency of miniature inhibitory postsynaptic currents (mIPSCs), and increases the amplitude of evoked inhibitory postsynaptic currents (eIPSCs). However, ML141 did not have an impact on the miniature excitatory postsynaptic currents (mEPSCs). Our results are the first to indicate that Cdc42 plays an important role in the onset and progression of epileptic-seizures by regulating synaptic inhibition.
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Affiliation(s)
- Y Zhang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China
| | - J Liu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China
| | - G Luan
- Center of Epilepsy, Beijing Institute for Brain Disorders, China
| | - X Wang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China.
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Droppelmann CA, Campos-Melo D, Volkening K, Strong MJ. The emerging role of guanine nucleotide exchange factors in ALS and other neurodegenerative diseases. Front Cell Neurosci 2014; 8:282. [PMID: 25309324 PMCID: PMC4159981 DOI: 10.3389/fncel.2014.00282] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 08/25/2014] [Indexed: 12/11/2022] Open
Abstract
Small GTPases participate in a broad range of cellular processes such as proliferation, differentiation, and migration. The exchange of GDP for GTP resulting in the activation of these GTPases is catalyzed by a group of enzymes called guanine nucleotide exchange factors (GEFs), of which two classes: Dbl-related exchange factors and the more recently described dedicator of cytokinesis proteins family exchange factors. Increasingly, deregulation of normal GEF activity or function has been associated with a broad range of disease states, including neurodegeneration and neurodevelopmental disorders. In this review, we examine this evidence with special emphasis on the novel role of Rho guanine nucleotide exchange factor (RGNEF/p190RhoGEF) in the pathogenesis of amyotrophic lateral sclerosis. RGNEF is the first neurodegeneration-linked GEF that regulates not only RhoA GTPase activation but also functions as an RNA binding protein that directly acts with low molecular weight neurofilament mRNA 3' untranslated region to regulate its stability. This dual role for RGNEF, coupled with the increasing understanding of the key role for GEFs in modulating the GTPase function in cell survival suggests a prominent role for GEFs in mediating a critical balance between cytotoxicity and neuroprotection which, when disturbed, contributes to neuronal loss.
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Affiliation(s)
- Cristian A Droppelmann
- Molecular Medicine Group, Robarts Research Institute, Western University London, ON, Canada
| | - Danae Campos-Melo
- Molecular Medicine Group, Robarts Research Institute, Western University London, ON, Canada
| | - Kathryn Volkening
- Molecular Medicine Group, Robarts Research Institute, Western University London, ON, Canada ; Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University London, ON, Canada
| | - Michael J Strong
- Molecular Medicine Group, Robarts Research Institute, Western University London, ON, Canada ; Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University London, ON, Canada
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Salman MS, Marles SL, Booth FA, Del Bigio MR. Early-onset neurodegenerative disease of the cerebellum and motor axons. Pediatr Neurol 2009; 40:365-70. [PMID: 19380073 DOI: 10.1016/j.pediatrneurol.2008.11.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 11/17/2008] [Accepted: 11/25/2008] [Indexed: 12/11/2022]
Abstract
We describe a novel hereditary neurodegenerative disease of infancy affecting an Aboriginal family from northern Manitoba, Canada. The parents are nonconsanguineous, without a family history of neurodegenerative diseases. Four of 10 siblings (three males and one female) presented with neurologic abnormalities including arthrogryposis, seizures, and severe developmental delay shortly after birth. In two children, cerebellar atrophy and mild cerebral atrophy were documented on neuroimaging. Two children, a boy who died at age 40 months and a girl who died at age 22 months, underwent muscle biopsies at 3 weeks and 4 months of age, respectively. The biopsies revealed fiber-size variability in the boy, and grouped atrophy with fiber-type grouping in the girl. Two boys who died at ages 7.5 and 37 months underwent autopsies that indicated severe atrophy of the cerebellar hemispheres (especially the inferior lobules and vermis), hypomyelination of white-matter fascicles in the striatum, severe atrophy of corticospinal tracts in the brainstem and spinal cord, and atrophy of the anterior spinal roots. In the spinal cord, motor neuron cell bodies and the posterior columns were spared. This clinical entity likely represents a novel neurodegenerative disease of the cerebellum and long motor axons.
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Affiliation(s)
- Michael S Salman
- Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Manitoba, Canada
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8
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Jacquier A, Bellouze S, Blanchard S, Bohl D, Haase G. Astrocytic protection of spinal motor neurons but not cortical neurons against loss of Als2/alsin function. Hum Mol Genet 2009; 18:2127-39. [PMID: 19304783 DOI: 10.1093/hmg/ddp136] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Three neurodegenerative diseases affecting upper and/or lower motor neurons have been associated with loss of ALS2/Alsin function: juvenile amyotrophic lateral sclerosis, primary lateral sclerosis and infantile-onset ascending hereditary spastic paralysis. The distinct neuronal vulnerability and the role of glia in these diseases remains, however, unclear. We here demonstrate that alsin-depleted spinal motor neurons can be rescued from defective survival and axon growth by co-cultured astrocytes. The astrocytic rescue is mediated by a soluble protective factor rather than by cellular contact. Cortical neurons are intrinsically as vulnerable to alsin depletion as spinal motor neurons but cannot be rescued by co-cultured astrocytes. To our knowledge, these data provide the first example of non-cell-autonomous glial effects in a recessive form of motor neuron disease and a potential rationale for the higher vulnerability of upper versus lower motor neurons in ALS2/Alsin-linked disorders.
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Affiliation(s)
- A Jacquier
- Laboratory of Motor Neuron Disease Modeling and Therapy, Institut de Biologie du Développement de Marseille Luminy, Université Aix-Marseille, Case 907, Parc scientifique de Luminy, F-13273 Marseille cedex 09, France
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9
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Soares DC, Barlow PN, Porteous DJ, Devon RS. An interrupted beta-propeller and protein disorder: structural bioinformatics insights into the N-terminus of alsin. J Mol Model 2008; 15:113-22. [PMID: 19023603 DOI: 10.1007/s00894-008-0381-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Accepted: 11/05/2008] [Indexed: 12/11/2022]
Abstract
Defects in the human ALS2 gene, which encodes the 1,657-amino-acid residue protein alsin, are linked to several related motor neuron diseases. We created a structural model for the N-terminal 690-residue region of alsin through comparative modelling based on regulator of chromosome condensation 1 (RCC1). We propose that this alsin region contains seven RCC1-like repeats in a seven-bladed beta-propeller structure. The propeller is formed by a double clasp arrangement containing two segments (residues 1-218 and residues 525-690). The 306-residue insert region, predicted to lie within blade 5 and to be largely disordered, is poorly conserved across species. Surface patches of evolutionary conservation probably indicate locations of binding sites. Both disease-causing missense mutations-Cys157Tyr and Gly540Glu-are buried in the propeller and likely to be structurally disruptive. This study aids design of experimental studies by highlighting the importance of construct length, will enhance interpretation of protein-protein interactions, and enable rational site-directed mutagenesis.
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Affiliation(s)
- Dinesh C Soares
- Medical Genetics Section, Molecular Medicine Centre, Institute of Genetics and Molecular Medicine, Western General Hospital, University of Edinburgh, Crewe Road, Edinburgh EH42XU, UK.
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10
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Verschuuren-Bemelmans CC, Winter P, Sival DA, Elting JW, Brouwer OF, Müller U. Novel homozygous ALS2 nonsense mutation (p.Gln715X) in sibs with infantile-onset ascending spastic paralysis: the first cases from northwestern Europe. Eur J Hum Genet 2008; 16:1407-11. [PMID: 18523452 DOI: 10.1038/ejhg.2008.108] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We describe a previously not recognized nonsense mutation in exon 10 of the ALS2 gene in two sibs with infantile-onset ascending spastic paralysis. The mutation predicts chain termination at amino-acid position 715 of the gene product ALSIN (p.Gln715X). The sibs' parents are descendants of a common ancestor who lived in the northern Netherlands during the eighteenth century. This is the first ALS2 mutation detected in northwestern Europeans. The findings emphasize that mutations in ALS2 also need to be considered in patients from northwestern Europe with early-onset spastic paralysis and amyotrophic or primary lateral sclerosis.
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11
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Masutani T, Taguchi K, Kumanogoh H, Nakamura S, Maekawa S. Molecular interaction of neurocalcin alpha with alsin (ALS2). Neurosci Lett 2008; 438:26-8. [PMID: 18482800 DOI: 10.1016/j.neulet.2008.04.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 04/07/2008] [Accepted: 04/14/2008] [Indexed: 12/11/2022]
Abstract
Membrane microdomains (MDs), or lipid rafts, are recently identified dynamic membrane domains on which various signal-transductions are performed. Intracellular Ca(2+)-binding proteins participate in the Ca(2+) signaling through interaction with various proteins. Neurocalcin alpha (NCalpha) is a member of neuronal calcium sensor (NCS) protein family and shows Ca(2+)-dependent binding to the cell membrane through N-terminal myristoyl moiety. Since NCalpha was identified as a Ca(2+)-dependent binding protein to neuronal MDs, its binding proteins may participate in the signal-transduction on the MDs. In an immunoprecipitate using anti-NCalpha antibody, alsin (ALS2), a protein product of one of the responsive genes for amyotrophic lateral sclerosis, was detected through LC-MS/MS. Specific antibody to alsin was produced and immunoprecipitation using this antibody showed co-sedimentation of NCalpha. Some part of alsin bound to brain-derived MD fraction in the presence of Ca(2+) ions and eluted out by the chelation of Ca(2+) ions, as in the case of NCalpha. Immunostaining of cultured neurons showed broad distribution of alsin and NCalpha, and membrane association of these proteins were increased through Ca(2+) loading by maitotoxin. These results suggest that alsin binds cell membrane in a Ca(2+)-dependent manner through NCalpha and regulates membrane dynamics.
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Affiliation(s)
- Toshinori Masutani
- Division of Biology, Graduate School of Science, Kobe-University, Rokkodaicho 1-1, Nada-ku, Kobe 657-8501, Japan
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12
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Martin LJ. Transgenic mice with human mutant genes causing Parkinson's disease and amyotrophic lateral sclerosis provide common insight into mechanisms of motor neuron selective vulnerability to degeneration. Rev Neurosci 2007; 18:115-36. [PMID: 17593875 DOI: 10.1515/revneuro.2007.18.2.115] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A variety of gene mutations can cause familial forms of Parkinson's disease (PD) or amyotrophic lateral sclerosis (ALS). Mutations in the synaptic protein alpha-synuclein (alpha-Syn) cause PD. Mutations in the antioxidant enzyme superoxide dismutase-1 (SOD1) cause ALS. The mechanisms of human mutant a-Syn and SOD1 toxicity to neurons are not known. Transgenic (tg) mice expressing human mutant alpha-Syn or SOD1 develop profound fatal neurologic disease characterized by progressive motor deficits, paralysis, and neurodegeneration. Ala-53-->Thr (A53T)-mutant alpha-Syn and Gly-93-->Ala (G93A)-mutant SOD1 tg mice develop prominent mitochondrial abnormalities. Interestingly, although nigral neurons in A53T mice are relatively preserved, spinal motor neurons (MNs) undergo profound degeneration. In A53T mice, mitochondria degenerate in neurons, and complex IV activity is reduced. Furthermore, mitochondria in neurons develop DNA breaks and have p53 targeted to the outer membrane. Nitrated a-Syn accumulates in degenerating MNs in A53T mice. mSOD1 mouse MNs accumulate mitochondria from the axon terminals and generate higher levels of reactive oxygen/nitrogen species than MNs in control mice. mSOD1 mouse MNs accumulate DNA single-strand breaks prior to double-strand breaks occurring in nuclear and mitochondrial DNA. Nitrated and aggregated cytochrome c oxidase subunit-I and nitrated SOD2 accumulate in mSOD1 mouse spinal cord. Mitochondria in mSOD1 mouse MNs accumulate NADPH diaphorase and inducible NOS (iNOS)-like immunoreactivity, and iNOS gene deletion significantly extends the lifespan of G93A-mSOD1 mice. Mitochondrial changes develop long before symptoms emerge. These experiments reveal that mitochondrial nitrative stress and perturbations in mitochondrial trafficking may be antecedents of neuronal cell death in animal models of PD and ALS.
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Affiliation(s)
- Lee J Martin
- Department of Pathology, Division of Neuropathology, Department of Neuroscience, Johns Hopkins University School ofMedicine, Baltimore, MD 21205-2196, USA.
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Hadano S, Kunita R, Otomo A, Suzuki-Utsunomiya K, Ikeda JE. Molecular and cellular function of ALS2/alsin: Implication of membrane dynamics in neuronal development and degeneration. Neurochem Int 2007; 51:74-84. [PMID: 17566607 DOI: 10.1016/j.neuint.2007.04.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 04/18/2007] [Accepted: 04/19/2007] [Indexed: 12/11/2022]
Abstract
ALS2 is a causative gene for a juvenile autosomal recessive form of motor neuron diseases (MNDs), including amyotrophic lateral sclerosis 2 (ALS2), juvenile primary lateral sclerosis, and infantile-onset ascending hereditary spastic paralysis. These disorders are characterized by ascending degeneration of the upper motor neurons with or without lower motor neuron involvement. Thus far, a total of 12 independent ALS2 mutations, which include a small deletion, non-sense mutation, or missense mutation spreading widely across the entire coding sequence, are reported. They are predicted to result in either premature termination of translation or substitution of an evolutionarily conserved amino acid. Thus, a loss of functions in the ALS2-coded protein accounts for motor dysfunction and/or degeneration in the ALS2-linked MNDs. The ALS2 gene encodes a novel 184kDa protein of 1657 amino acids, ALS2 or alsin, comprising three predicted guanine nucleotide exchange factor (GEF) domains: the N-terminal RCC1-like domain, the central Dbl homology and pleckstrin homology (DH/PH) domains, and the C-terminal vacuolar protein sorting 9 (VPS9) domain. In addition, eight consecutive membrane occupation and recognition nexus (MORN) motifs are noted in the region between DH/PH and VPS9 domains. ALS2 activates Rab5 small GTPase and involves in endosome/membrane trafficking and fusions in the cells, and also promotes neurite outgrowth in neuronal cultures. Further, a neuroprotective role for ALS2 against cytotoxicity; i.e., the mutant Cu/Zn-superoxide dismutase 1 (SOD1)-mediated toxicity, oxidative stress, and excitotoxicity, has recently been implied. This review outlines current understandings of the molecular and cellular functions of ALS2 and its related proteins on safeguarding the integrity of motor neurons, and sheds light on the molecular pathogenesis of MNDs as well as other conditions of neurodegenerative diseases.
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Affiliation(s)
- Shinji Hadano
- Department of Molecular Life Sciences, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan
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Orban P, Devon RS, Hayden MR, Leavitt BR. Chapter 15 Juvenile amyotrophic lateral sclerosis. HANDBOOK OF CLINICAL NEUROLOGY 2007; 82:301-312. [PMID: 18808900 DOI: 10.1016/s0072-9752(07)80018-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Several forms of genetically defined juvenile amy-otrophic lateral sclerosis (ALS) have now been charac-terized and discussion of these conditions will form the basis for this chapter. ALS2 is an autosomal recessive form of ALS with a juvenile onset and very slow progression that mapped to chromosome 2q33. Nine different mutations have been identified in the ALS2 gene that result in premature stop codons, suggesting a loss of function in the gene product, alsin. The alsin protein is thought to function as a guanine-nucleotide exchange factor for GTPases and may play a role in vesicle transport or membrane trafficking processes. ALS4 is an autosomal dominant form of juvenile onset ALS associated with slow progression, severe muscle weakness and pyramidal signs, in the absence of bulbar and sensory abnormalities. Mutations in the SETX gene cause ALS4, and the SETX gene product senataxin may have DNA and RNA helicase activity and play a role in the regulation of RNA and/or DNA in the cell. A third form of juvenile-onset ALS (ALS5) is associated with slowly progressing lower motor neuron signs (weak-ness and atrophy) initially of the hands and feet, with eventual bulbar involvement. Progressive upper motor neuron disease becomes more obvious with time. ALS5 has been linked to a 6 cM region of chromosome 15q15.1-q21.1, but the causative gene mutation for ALS5 has yet to be identified. The high degree of clin-ical and genetic heterogeneity in the various forms of juvenile ALS can make differential diagnosis difficult, other genetic disorders that must be considered include: spinal muscular atrophy, hereditary spastic paraplegia, SBMA, GM2 gangliosidosis and the hereditary motor neuronopathies/motor forms of Charcot-Marie-Tooth disease. Acquired disorders that must also be consid-ered include heavy metal intoxications (especially lead), multifocal motor neuropathy, paraneoplastic syndromes, vitamin deficiencies (B12) and infections (HTLV-II, HIV and poliomyelitis).
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Affiliation(s)
- Paul Orban
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics and British Columbia Research Institute for Women and Children's Health, University of British Columbia, Vancouver, BC, Canada
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15
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Su X, Lodhi IJ, Saltiel AR, Stahl PD. Insulin-stimulated Interaction between Insulin Receptor Substrate 1 and p85α and Activation of Protein Kinase B/Akt Require Rab5. J Biol Chem 2006; 281:27982-90. [PMID: 16880210 DOI: 10.1074/jbc.m602873200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Binding of insulin to the insulin receptor initiates a cascade of protein phosphorylation and effector recruitment events leading to the activation of multiple distinct signaling pathways. Previous studies suggested that the diversity and specificity of insulin signal transduction are accomplished by both subcellular localization of receptor and the selective activation of downstream signaling molecules. The small GTPase Rab5 is a key regulator of endocytosis. Three Rab5 isoforms (Rab5a, -5b, and -5c) have been identified. Here we exploited the RNA interference technique to specifically knock down individual Rab5 isoforms to determine the cellular function of Rab5 in distinct insulin signaling pathways. Small interference RNA against a single Rab5 isoform had no effect on protein kinase B (PKB)/Akt or MAPK activation by insulin in NIH3T3 cells overexpressing human insulin receptor. However, simultaneous knockdown of all three Rab5 isoforms dramatically attenuated PKB/Akt activation by insulin without affecting MAPK activation. This inhibition of PKB/Akt activation was because of the impaired interaction between insulin receptor substrate 1 and the p85alpha subunit of phosphatidylinositol 3-kinase. These results indicate a requirement of Rab5 in presenting p85 to insulin receptor substrate 1. Additional evidence supporting a role for Rab5 was suggested by studies with GAPex-5, a vps9 domain containing exchange factor. Down-regulation of GAPex-5 impaired insulin-stimulated PKB/Akt activation. Collectively, this study indicates the involvement of Rab5 in insulin signaling.
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Affiliation(s)
- Xiong Su
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Jacquier A, Buhler E, Schäfer MKE, Bohl D, Blanchard S, Beclin C, Haase G. Alsin/Rac1 signaling controls survival and growth of spinal motoneurons. Ann Neurol 2006; 60:105-17. [PMID: 16802292 DOI: 10.1002/ana.20886] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE Recessive mutations in alsin, a guanine-nucleotide exchange factor for the GTPases Rab5 and Rac1, cause juvenile amyotrophic lateral sclerosis (ALS2) and related motoneuron disorders. Alsin function in motoneurons remained unclear because alsin knock-out mice do not develop overt signs of motoneuron degeneration. METHODS To generate an alsin loss-of-function model in an ALS-relevant cell type, we developed a new small interfering RNA electroporation technique that allows efficient knock down of alsin in embryonic rat spinal motoneurons. RESULTS After small interfering RNA-mediated alsin knockdown, cultured motoneurons displayed a reduced apparent size of EEA1-labeled early endosomes and an increased intracellular accumulation of transferrin and L1CAM. Alsin knockdown induced cell death in 32 to 48% of motoneurons and significantly inhibited axon growth in the surviving neurons. Both cellular phenotypes were mimicked by expression of a dominant-negative Rac1 mutant and were completely blocked by expression of a constitutively active Rac1 mutant. Expression of dominant-negative or constitutively active forms of Rab5 had no such effects. INTERPRETATION Our data demonstrate that alsin controls the growth and survival of motoneurons in a Rac1-dependant manner. The strategy reported here illustrates how small interfering RNA electroporation can be used to generate cellular models of neurodegenerative disease involving a loss-of-function mechanism.
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Affiliation(s)
- Arnaud Jacquier
- Institut National de la Sante et de la Recherche Médicale, Marseille, France
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Devon RS, Orban PC, Gerrow K, Barbieri MA, Schwab C, Cao LP, Helm JR, Bissada N, Cruz-Aguado R, Davidson TL, Witmer J, Metzler M, Lam CK, Tetzlaff W, Simpson EM, McCaffery JM, El-Husseini AE, Leavitt BR, Hayden MR. Als2-deficient mice exhibit disturbances in endosome trafficking associated with motor behavioral abnormalities. Proc Natl Acad Sci U S A 2006; 103:9595-600. [PMID: 16769894 PMCID: PMC1480452 DOI: 10.1073/pnas.0510197103] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
ALS2 is an autosomal recessive form of spastic paraparesis (motor neuron disease) with juvenile onset and slow progression caused by loss of function of alsin, an activator of Rac1 and Rab5 small GTPases. To establish an animal model of ALS2 and derive insights into the pathogenesis of this illness, we have generated alsin-null mice. Cytosol from brains of Als2(-/-) mice shows marked diminution of Rab5-dependent endosome fusion activity. Furthermore, primary neurons from Als2(-/-) mice show a disturbance in endosomal transport of insulin-like growth factor 1 (IGF1) and BDNF receptors, whereas neuronal viability and endocytosis of transferrin and dextran seem unaltered. There is a significant decrease in the size of cortical motor neurons, and Als2(-/-) mice are mildly hypoactive. Altered trophic receptor trafficking in neurons of Als2(-/-) mice may underlie the histopathological and behavioral changes observed and the pathogenesis of ALS2.
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Affiliation(s)
- R. S. Devon
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - P. C. Orban
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - K. Gerrow
- Department of Psychiatry, Brain Research Centre, University of British Columbia, Vancouver, BC, Canada V6T 2A1
| | - M. A. Barbieri
- Department of Biological Sciences, Florida International University, Miami, FL 33199
| | - C. Schwab
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - L. P. Cao
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - J. R. Helm
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - N. Bissada
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - R. Cruz-Aguado
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - T.-L. Davidson
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - J. Witmer
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - M. Metzler
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - C. K. Lam
- International Collaboration on Repair Discoveries and Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - W. Tetzlaff
- International Collaboration on Repair Discoveries and Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - E. M. Simpson
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - J. M. McCaffery
- **Integrated Imaging Center, Department of Biology, The Johns Hopkins University, Baltimore, MD 21218; and
| | - A. E. El-Husseini
- Department of Psychiatry, Brain Research Centre, University of British Columbia, Vancouver, BC, Canada V6T 2A1
| | - B. R. Leavitt
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
| | - M. R. Hayden
- *Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, and Child & Family Research Institute, 980 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4
- To whom correspondence should be addressed. E-mail:
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Carney DS, Davies BA, Horazdovsky BF. Vps9 domain-containing proteins: activators of Rab5 GTPases from yeast to neurons. Trends Cell Biol 2005; 16:27-35. [PMID: 16330212 DOI: 10.1016/j.tcb.2005.11.001] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 09/26/2005] [Accepted: 11/16/2005] [Indexed: 12/11/2022]
Abstract
Endocytosis of cell surface receptors plays an important role in regulating cell signaling cascades. In some cases, internalization of an activated receptor attenuates the signaling process, while in other cases the clustering of activated receptors on early endosomal structures has been proposed to be essential for fully activating signaling cascades. Regulating the movement of receptors and other signaling proteins through the endocytic pathway, therefore, has a direct impact on cellular homeostasis. The small GTPase Rab5 is a crucial regulatory component of the endocytic pathway. Activation of Rab5 is mediated by GDP-GTP exchange factors (GEFs) that generate the Rab5-GTP complex. A large number of proteins have been identified that contain a specific, highly conserved domain (Vps9) that catalyzes nucleotide exchange on Rab5, linking the regulation of cell signaling cascades with intracellular receptor trafficking through the endocytic pathway.
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Affiliation(s)
- Darren S Carney
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55905, USA
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Hadano S, Benn SC, Kakuta S, Otomo A, Sudo K, Kunita R, Suzuki-Utsunomiya K, Mizumura H, Shefner JM, Cox GA, Iwakura Y, Brown RH, Ikeda JE. Mice deficient in the Rab5 guanine nucleotide exchange factor ALS2/alsin exhibit age-dependent neurological deficits and altered endosome trafficking. Hum Mol Genet 2005; 15:233-50. [PMID: 16321985 DOI: 10.1093/hmg/ddi440] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
ALS2/alsin is a member of guanine nucleotide exchange factors for the small GTPase Rab5 (Rab5GEFs), which act as modulators in endocytic pathway. Loss-of-function mutations in human ALS2 account for a number of juvenile recessive motor neuron diseases (MNDs). However, the normal physiological role of ALS2 in vivo and the molecular mechanisms underlying motor dysfunction are still unknown. To address these issues, we have generated mice homozygous for disruption of the Als2 gene. The Als2-null mice observed through 21 months of age demonstrated no obvious developmental, reproductive or motor abnormalities. However, immunohistochemical and electrophysiological analyses identified an age-dependent, slowly progressive loss of cerebellar Purkinje cells and disturbance of spinal motor neurons associated with astrocytosis and microglial cell activation, indicating a subclinical dysfunction of motor system in Als2-null mice. Further, quantitative epidermal growth factor (EGF)-uptake analysis identified significantly smaller-sized EGF-positive endosomes in Als2-null fibroblasts, suggesting an alteration of endosome/vesicle trafficking in the cells. Collectively, while loss of ALS2 does not produce a severe disease phenotype in mice, these Als2-null animals should provide a useful model with which to understand the interplay between endosomal dynamics and the long-term viability of large neurons such as Purkinje cells and spinal motor neurons.
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Affiliation(s)
- Shinji Hadano
- Department of Molecular Neuroscience, The Institute of Medical Sciences, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan
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Tudor EL, Perkinton MS, Schmidt A, Ackerley S, Brownlees J, Jacobsen NJO, Byers HL, Ward M, Hall A, Leigh PN, Shaw CE, McLoughlin DM, Miller CCJ. ALS2/Alsin regulates Rac-PAK signaling and neurite outgrowth. J Biol Chem 2005; 280:34735-40. [PMID: 16049005 DOI: 10.1074/jbc.m506216200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Rac and its downstream effectors p21-activated kinase (PAK) family kinases regulate actin dynamics within growth cones to control neurite outgrowth during development. The activity of Rac is stimulated by guanine nucleotide exchange factors (GEFs) that promote GDP release and GTP binding. ALS2/Alsin is a recently described GEF that contains a central domain that is predicted to regulate the activities of Rac and/or Rho and Cdc42 activities. Mutations in ALS2 cause some recessive familial forms of amyotrophic lateral sclerosis (ALS) but the function of ALS2 is poorly understood. Here we demonstrate that ALS2 is present within growth cones of neurons, in which it co-localizes with Rac. Furthermore, ALS2 stimulates Rac but not Rho or Cdc42 activities, and this induces a corresponding increase in PAK1 activity. Finally, we demonstrate that ALS2 promotes neurite outgrowth. Defects in these functions may therefore contribute to motor neuron demise in ALS.
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Affiliation(s)
- Elizabeth L Tudor
- Departments of Neuroscience and Neurology, Institute of Psychiatry, Kings College, London SE5 8AF, United Kingdom
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Topp JD, Carney DS, Horazdovsky BF. Biochemical Characterization of Alsin, a Rab5 and Rac1 Guanine Nucleotide Exchange Factor. Methods Enzymol 2005; 403:261-76. [PMID: 16473593 DOI: 10.1016/s0076-6879(05)03022-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Alsin is the gene product mutated in three juvenile-onset neurodegenerative disorders including amyotrophic lateral sclerosis 2 (ALS2). Sequence motif searches within Alsin predict the presence of Vps9, DH, and PH domains, implying that Alsin may function as a guanine nucleotide exchange factor (GEF) for Rab5 and a member of the Rho GTPase family. Procedures are presented in this chapter for the expression, purification, and biochemical characterization of the individual GEF domains of Alsin. A fractionation method is also described for the determination of Alsin's subcellular distribution. The presence of both Rac1 and Rab5 GEF activities makes Alsin a unique dual exchange factor that may couple endocytosis (via Rab5 activation) to cytoskeletal modulation (via Rac1 activation).
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Abstract
ALS2 is a causative gene product for a form of the familial motor neuron diseases. Computational genomic analysis identified ALS2CL, which is a novel protein highly homologous to the C-terminal region of ALS2. Both proteins contain the VPS9 domain, which is a hallmark for all known members of the guanine nucleotide exchange factors for Rab5 (Rab5GEF), and are known to act as novel factors modulating the Rab5-mediated endosome dynamics in the cells. It has also been reported that oligomerization of ALS2 is one of the fundamental features of its biochemical and physiological function involving endosome dynamics. This chapter describes methods, including purification of the recombinant ALS2 and ALS2CL, and Rab5GEF assay, which have been utilized to clarify the molecular function for ALS2 and ALS2CL.
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