Journal article
Quantitative and Functional Analyses of Spastin in the Nervous System: Implications for Hereditary Spastic Paraplegia
The Journal of neuroscience, v 28(9), pp 2147-2157
27 Feb 2008
PMID: 18305248
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
Spastin and P60-katanin are two distinct microtubule-severing proteins. Autosomal dominant mutations in the SPG4 locus corresponding to spastin are the most common cause of hereditary spastic paraplegia (HSP), a neurodegenerative disease that afflicts the adult corticospinal tracts. Here we sought to evaluate whether SPG4-based HSP is best understood as a “loss-of-function” disease. Using various rat tissues, we found that P60-katanin levels are much higher than spastin levels during development. In the adult, P60-katanin levels plunge dramatically but spastin levels decline only slightly. Quantitative data of spastin expression in specific regions of the nervous system failed to reveal any obvious explanation for the selective sensitivity of adult corticospinal tracts to loss of spastin activity. An alternative explanation relates to the fact that the mammalian spastin gene has two start codons, resulting in a 616 amino acid protein called M1 and a slightly shorter protein called M85. We found that M1 is almost absent from developing neurons and most adult neurons but comprises 20–25% of the spastin in the adult spinal cord, the location of the axons that degenerate during HSP. Experimental expression in cultured neurons of a short dysfunctional M1 polypeptide (but not a short dysfunctional M85 peptide) is deleterious to normal axonal growth. In squid axoplasm, the M1 peptide dramatically inhibits fast axonal transport, whereas the M85 peptide does not. These results are consistent with a “gain-of-function” mechanism underlying HSP wherein spastin mutations produce a cytotoxic protein in the case of M1 but not M85.
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Details
- Title
- Quantitative and Functional Analyses of Spastin in the Nervous System: Implications for Hereditary Spastic Paraplegia
- Creators
- Joanna M Solowska - Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129Gerardo Morfini - Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612, andAditi Falnikar - Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129B. Timothy Himes - Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129Scott T Brady - Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612, andDongyang Huang - Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612, andPeter W Baas - Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129
- Publication Details
- The Journal of neuroscience, v 28(9), pp 2147-2157
- Publisher
- Society for Neuroscience
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Neurobiology and Anatomy
- Web of Science ID
- WOS:000253549300016
- Scopus ID
- 2-s2.0-39849101639
- Other Identifier
- 991014878216704721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Neurosciences