Hereditary spastic paraplegia (HSP), a group of progressive neurodegenerative disorders that impairs the ability to walk, can be caused by mutations in more than 40 different genes. Despite this genetic heterogeneity, the pathologic features – degeneration of long axons in the spinal cord – are relatively uniform, suggesting that dysfunction of a common biochemical pathway might contribute to HSP.
Peter Hedera and colleagues explored whether two proteins implicated in HSP – atlastin-1 and NIPA1 – are part of a common pathway. They report in the January issue of Molecular and Cellular Neuroscience that atlastin-1 and NIPA1 bind to each other and that this interaction helps deliver atlastin-1 to the cell surface. They also show that HSP-causing mutations (in either atlastin-1 or NIPA1) alter the cellular distribution of the complex and reduce growth of axons and dendrites in cultured rat cortical neurons. The findings support the idea that atlastin-1 and NIPA1 are members of a common biochemical pathway that supports axon maintenance, which could provide new therapeutic targets for HSP.