Journal Article

The hereditary spastic paraplegia protein spastin interacts with the ESCRT-III complex-associated endosomal protein CHMP1B

Evan Reid, James Connell, Thomas L. Edwards, Simon Duley, Stephanie E. Brown and Christopher M. Sanderson

in Human Molecular Genetics

Volume 14, issue 1, pages 19-38
Published in print January 2005 | ISSN: 0964-6906
Published online November 2004 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/ddi003
The hereditary spastic paraplegia protein spastin interacts with the ESCRT-III complex-associated endosomal protein CHMP1B

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Pure hereditary spastic paraplegia is characterized by length-dependent degeneration of the distal ends of long axons. Mutations in spastin are the most common cause of the condition. We set out to investigate the function of spastin using a yeast two-hybrid approach to identify interacting proteins. Using full-length spastin as bait, we identified CHMP1B, a protein associated with the ESCRT (endosomal sorting complex required for transport)–III complex, as a binding partner. Several different approaches confirmed the physiological relevance of the interaction in mammalian cells. Epitope-tagged CHMP1B and spastin showed clear cytoplasmic co-localization in Cos-7 and PC12 cells. CHMP1B and spastin interacted specifically in vitro and in vivo in β-lactamase protein fragment complementation assays, and spastin co-immunoprecipitated with CHMP1B. The interaction was mediated by a region of spastin lying between residues 80 and 196 and containing a microtubule interacting and trafficking domain. Expression of epitope-tagged CHMP1B in mammalian cells prevented the development of the abnormal microtubule phenotype associated with expression of ATPase-defective spastin. These data point to a role for spastin in intracellular membrane traffic events and provide further evidence to support the emerging recognition that defects in intracellular membrane traffic are a significant cause of motor neuron pathology.

Journal Article.  12849 words.  Illustrated.

Subjects: Genetics and Genomics

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