Stasimon Contributes to the Loss of Sensory Synapses and Motor Neuron Death in a Mouse Model of Spinal Muscular Atrophy

Cell Rep. 2019 Dec 17;29(12):3885-3901.e5. doi: 10.1016/j.celrep.2019.11.058.


Reduced expression of the survival motor neuron (SMN) protein causes the neurodegenerative disease spinal muscular atrophy (SMA). Here, we show that adeno-associated virus serotype 9 (AAV9)-mediated delivery of Stasimon-a gene encoding an endoplasmic reticulum (ER)-resident transmembrane protein regulated by SMN-improves motor function in a mouse model of SMA through multiple mechanisms. In proprioceptive neurons, Stasimon overexpression prevents the loss of afferent synapses on motor neurons and enhances sensory-motor neurotransmission. In motor neurons, Stasimon suppresses neurodegeneration by reducing phosphorylation of the tumor suppressor p53. Moreover, Stasimon deficiency converges on SMA-related mechanisms of p53 upregulation to induce phosphorylation of p53 through activation of p38 mitogen-activated protein kinase (MAPK), and pharmacological inhibition of this kinase prevents motor neuron death in SMA mice. These findings identify Stasimon dysfunction induced by SMN deficiency as an upstream driver of distinct cellular cascades that lead to synaptic loss and motor neuron degeneration, revealing a dual contribution of Stasimon to motor circuit pathology in SMA.

Keywords: SMN; Stasimon; Tmem41b; motor neurons; neurodegeneration; p38 MAPK; p53; proprioceptive neurons; spinal muscular atrophy.

Publication types

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

MeSH terms

  • Animals
  • Dependovirus / genetics
  • Membrane Proteins / administration & dosage
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Motor Neurons / metabolism
  • Motor Neurons / pathology*
  • Muscular Atrophy, Spinal / etiology*
  • Muscular Atrophy, Spinal / metabolism
  • Muscular Atrophy, Spinal / pathology
  • Sensory Receptor Cells / metabolism
  • Sensory Receptor Cells / pathology*
  • Survival of Motor Neuron 1 Protein / physiology*
  • Synapses / metabolism
  • Synapses / pathology*
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism*


  • Membrane Proteins
  • Smn1 protein, mouse
  • Survival of Motor Neuron 1 Protein
  • Tmem41b protein, mouse
  • Trp53 protein, mouse
  • Tumor Suppressor Protein p53
  • p38 Mitogen-Activated Protein Kinases