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Xiao S, MacNair L, McGoldrick P, McKeever PM, McLean JR, Zhang M, Keith J, Zinman L, Rogaeva E, Robertson J. Isoform-specific antibodies reveal distinct subcellular localizations of C9orf72 in amyotrophic lateral sclerosis. Ann Neurol 2015; 78:568-83. [PMID: 26174152 DOI: 10.1002/ana.24469] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 12/26/2022]
Abstract
OBJECTIVE A noncoding hexanucleotide repeat expansion in C9orf72 is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). It has been reported that the repeat expansion causes a downregulation of C9orf72 transcripts, suggesting that haploinsufficiency may contribute to disease pathogenesis. Two protein isoforms are generated from three alternatively spliced transcripts of C9orf72; a long form (C9-L) and a short form (C9-S), and their function(s) are largely unknown owing to lack of specific antibodies. METHODS To investigate C9orf72 protein properties, we developed novel antibodies that recognize either C9-L or C9-S. Multiple techniques, including Western blot, immunohistochemistry, and coimmunoprecipitation, were used to determine the expression levels and subcellular localizations of C9-L and C9-S. RESULTS Investigation of expression of C9-L and C9-S demonstrated distinct biochemical profiles, region-specific changes, and distinct subcellular localizations in ALS tissues. In particular, C9-L antibody exhibited a diffuse cytoplasmic staining in neurons and labeled large speckles in cerebellar Purkinje cells. In contrast, C9-S antibody gave very specific labeling of the nuclear membrane in healthy neurons, with apparent relocalization to the plasma membrane of diseased motor neurons in ALS. Coimmunoprecipitation experiments revealed an interaction of the C9-isoforms with both Importin β1 and Ran-GTPase, components of the nuclear pore complex. INTERPRETATION Using these antibodies, we have shown that C9orf72 may be involved in nucleocytoplasmic shuttling and this may have relevance to pathophysiology of ALS/FTLD. Our antibodies have provided improved detection of C9orf72 protein isoforms, which will help elucidate its physiological function and role in ALS/FTLD.
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Affiliation(s)
- Shangxi Xiao
- Tanz Center for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - Laura MacNair
- Tanz Center for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Philip McGoldrick
- Tanz Center for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - Paul M McKeever
- Tanz Center for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Jesse R McLean
- Tanz Center for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - Ming Zhang
- Tanz Center for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - Julia Keith
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Sunnybrook Health Sciences Center, Toronto, Ontario, Canada
| | - Lorne Zinman
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Sunnybrook Health Sciences Center, Toronto, Ontario, Canada
| | - Ekaterina Rogaeva
- Tanz Center for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - Janice Robertson
- Tanz Center for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
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Ward ME, Taubes A, Chen R, Miller BL, Sephton CF, Gelfand JM, Minami S, Boscardin J, Martens LH, Seeley WW, Yu G, Herz J, Filiano AJ, Arrant AE, Roberson ED, Kraft TW, Farese RV, Green A, Gan L. Early retinal neurodegeneration and impaired Ran-mediated nuclear import of TDP-43 in progranulin-deficient FTLD. ACTA ACUST UNITED AC 2014; 211:1937-45. [PMID: 25155018 PMCID: PMC4172214 DOI: 10.1084/jem.20140214] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ward et al. report retinal thinning in humans with progranulin mutations that precedes dementia onset, and an age-dependent retinal neurodegenerative phenotype in progranulin null mice. Nuclear depletion of TDP-43 precedes retinal neuronal loss and is accompanied by reduced GTPase Ran, with overexpression of Ran restoring nuclear TDP-43 and neuronal survival. Frontotemporal dementia (FTD) is the most common cause of dementia in people under 60 yr of age and is pathologically associated with mislocalization of TAR DNA/RNA binding protein 43 (TDP-43) in approximately half of cases (FLTD-TDP). Mutations in the gene encoding progranulin (GRN), which lead to reduced progranulin levels, are a significant cause of familial FTLD-TDP. Grn-KO mice were developed as an FTLD model, but lack cortical TDP-43 mislocalization and neurodegeneration. Here, we report retinal thinning as an early disease phenotype in humans with GRN mutations that precedes dementia onset and an age-dependent retinal neurodegenerative phenotype in Grn-KO mice. Retinal neuron loss in Grn-KO mice is preceded by nuclear depletion of TDP-43 and accompanied by reduced expression of the small GTPase Ran, which is a master regulator of nuclear import required for nuclear localization of TDP-43. In addition, TDP-43 regulates Ran expression, likely via binding to its 3′-UTR. Augmented expression of Ran in progranulin-deficient neurons restores nuclear TDP-43 levels and improves their survival. Our findings establish retinal neurodegeneration as a new phenotype in progranulin-deficient FTLD, and suggest a pathological loop involving reciprocal loss of Ran and nuclear TDP-43 as an underlying mechanism.
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Affiliation(s)
- Michael E Ward
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158 Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - Alice Taubes
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - Robert Chen
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - Bruce L Miller
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - Chantelle F Sephton
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Jeffrey M Gelfand
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - Sakura Minami
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - John Boscardin
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - Lauren Herl Martens
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - William W Seeley
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - Gang Yu
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Joachim Herz
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Anthony J Filiano
- Departments of Neurology and Neurobiology and Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Andrew E Arrant
- Departments of Neurology and Neurobiology and Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Erik D Roberson
- Departments of Neurology and Neurobiology and Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Timothy W Kraft
- Departments of Neurology and Neurobiology and Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Robert V Farese
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - Ari Green
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
| | - Li Gan
- Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158 Gladstone Institute of Neurological Diseases, Department of Neurology, Department of Medicine, Gladstone Institute of Cardiovascular Disease, University of California, San Franciso, San Francisco, CA 94158
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Hanover JA, Love DC, Prinz WA. Calmodulin-driven nuclear entry: trigger for sex determination and terminal differentiation. J Biol Chem 2009; 284:12593-7. [PMID: 19126540 DOI: 10.1074/jbc.r800076200] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We originally proposed that Ca(2+)-calmodulin mediates a novel nuclear entry pathway distinct from the canonic Ran-dependent pathway (Sweitzer, T. D., and Hanover, J. A. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 14574-14579). Although seemingly redundant, Ca(2+)-calmodulin-driven nuclear entry is now known to facilitate nuclear delivery of architectural transcription factors to chromatin. Intriguingly, defects in calmodulin-driven nuclear import of the transcription factors SRY and SOX9 in Sertoli cells lead to human sex reversal diseases with altered male gonad development. Calmodulin-triggered nuclear entry is an evolutionarily ancient feature of eukaryotes observed from yeast to man. Ca(2+)-calmodulin-triggered nuclear entry of key architectural transcription factors is a potentially key epigenetic regulator of terminal differentiation in response to cell signaling.
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Affiliation(s)
- John A Hanover
- Laboratory of Cell Biochemistry and Biology, NIDDK, NIH, Bethesda, MD 20892, USA.
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Abstract
Proteins and enzymes are now generally thought to be organized within the cell to form clusters in a dynamic and versatile way, and heterologous protein-protein interactions are believed to be involved in virtually all cellular events. Therefore we need appropriate tools to detect and study such interactions. Chromatographic techniques prove to be well suited for this kind of investigation. Real complexes formed between proteins can be studied by classic gel filtration. When enzymes are studied, active enzyme gel chromatography is a useful alternative. A variant of classic gel filtration is gel filtration equilibrium analysis, which is similar to equilibrium dialysis. When the association formed is only dynamic and equilibrates very rapidly, either the Hummel-Dryer method of equilibrium gel filtration or large-zone equilibrium filtration sometimes allows the interactions to be analyzed, both qualitatively and quantitatively. Very often, however, interactions between enzymes and proteins can only be evidenced in vitro in media that mimic the intracellular situation. Immobilized proteins are excellent tools for this type of research. Several examples are indeed known where the immobilization of an enzyme on a solid support does not affect its real properties, but rather changes its environment in such a way that the diffusion becomes limiting. Affinity chromatography using immobilized proteins allows the analysis of heterologous protein-protein interactions, both qualitatively and quantitatively. A useful alternative appears to be affinity electrophoresis. The latter technique, however, is exclusively qualitative. All these techniques are described and illustrated with examples taken from the literature.
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Affiliation(s)
- S Beeckmans
- Laboratory of Protein Chemistry, Vrije Universiteit Brussel, Paardenstraat 65, Sint-Genesius-Rode, B-1640, Belgium.
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