Spartin Regulates Synaptic Growth and Neuronal Survival by Inhibiting BMP-mediated Microtubule Stabilization

Neuron. 2013 Feb 20;77(4):680-95. doi: 10.1016/j.neuron.2012.12.015.

Abstract

Troyer syndrome is a hereditary spastic paraplegia caused by human spartin (SPG20) gene mutations. We have generated a Drosophila disease model showing that Spartin functions presynaptically with endocytic adaptor Eps15 to regulate synaptic growth and function. Spartin inhibits bone morphogenetic protein (BMP) signaling by promoting endocytic degradation of BMP receptor wishful thinking (Wit). Drosophila fragile X mental retardation protein (dFMRP) and Futsch/MAP1B are downstream effectors of Spartin and BMP signaling in regulating microtubule stability and synaptic growth. Loss of Spartin or elevation of BMP signaling induces age-dependent progressive defects resembling hereditary spastic paraplegias, including motor dysfunction and brain neurodegeneration. Null spartin phenotypes are prevented by administration of the microtubule-destabilizing drug vinblastine. Together, these results demonstrate that Spartin regulates both synaptic development and neuronal survival by controlling microtubule stability via the BMP-dFMRP-Futsch pathway, suggesting that impaired regulation of microtubule stability is a core pathogenic component in Troyer syndrome.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Base Sequence / genetics
  • Bone Morphogenetic Protein Receptors / genetics*
  • Bone Morphogenetic Protein Receptors / metabolism
  • Bone Morphogenetic Proteins / genetics*
  • Cell Survival
  • Drosophila / genetics
  • Humans
  • Microtubule-Associated Proteins / metabolism
  • Microtubules / genetics
  • Microtubules / metabolism*
  • Neurons / cytology
  • Neurons / metabolism*
  • Protein Binding / physiology
  • Signal Transduction / genetics
  • Spastic Paraplegia, Hereditary / genetics
  • Spastic Paraplegia, Hereditary / metabolism*
  • Synapses / metabolism

Substances

  • Bone Morphogenetic Proteins
  • Microtubule-Associated Proteins
  • microtubule-associated protein 1B
  • Bone Morphogenetic Protein Receptors

Supplementary concepts

  • Spastic paraplegia 20, autosomal recessive