The spinal muscular atrophy disease protein SMN is linked to the Rho-kinase pathway via profilin

Hum Mol Genet. 2011 Dec 15;20(24):4865-78. doi: 10.1093/hmg/ddr425. Epub 2011 Sep 14.


Spinal muscular atrophy (SMA), a frequent neurodegenerative disease, is caused by reduced levels of functional survival of motoneuron (SMN) protein. SMN is involved in multiple pathways, including RNA metabolism and splicing as well as motoneuron development and function. Here we provide evidence for a major contribution of the Rho-kinase (ROCK) pathway in SMA pathogenesis. Using an in vivo protein interaction system based on SUMOylation of proteins, we found that SMN is directly interacting with profilin2a. Profilin2a binds to a stretch of proline residues in SMN, which is heavily impaired by a novel SMN2 missense mutation (S230L) derived from a SMA patient. In different SMA models, we identified differential phosphorylation of the ROCK-downstream targets cofilin, myosin-light chain phosphatase and profilin2a. We suggest that hyper-phosphorylation of profilin2a is the molecular link between SMN and the ROCK pathway repressing neurite outgrowth in neuronal cells. Finally, we found a neuron-specific increase in the F-/G-actin ratio that further support the role of actin dynamics in SMA pathogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actins / metabolism
  • Animals
  • Disease Models, Animal
  • Gene Knockdown Techniques
  • Growth Cones / metabolism
  • Growth Cones / pathology
  • Humans
  • Mice
  • Models, Biological
  • Motor Neurons / metabolism
  • Motor Neurons / pathology
  • Muscular Atrophy, Spinal / metabolism*
  • Muscular Atrophy, Spinal / pathology
  • Mutant Proteins / metabolism
  • Mutation, Missense / genetics
  • Neurites / metabolism
  • Phosphorylation
  • Profilins / metabolism*
  • Protein Binding
  • Rats
  • Signal Transduction*
  • Survival of Motor Neuron 1 Protein / genetics
  • Survival of Motor Neuron 1 Protein / metabolism*
  • rho-Associated Kinases / metabolism*


  • Actins
  • Mutant Proteins
  • Profilins
  • Survival of Motor Neuron 1 Protein
  • rho-Associated Kinases