Motor neuron degeneration in a mouse model of seipinopathy

Cell Death Dis. 2013 Mar 7;4(3):e535. doi: 10.1038/cddis.2013.64.

Abstract

Heterozygosity for missense mutations (N88S/S90L) in BSCL2 (Berardinelli-Seip congenital lipodystrophy type 2)/Seipin is associated with a broad spectrum of motoneuron diseases. To understand the underlying mechanisms how the mutations lead to motor neuropathy, we generated transgenic mice with neuron-specific expression of wild-type (tgWT) or N88S/S90L mutant (tgMT) human Seipin. Transgenes led to the broad expression of WT or mutant Seipin in the brain and spinal cord. TgMT, but not tgWT, mice exhibited late-onset altered locomotor activities and gait abnormalities that recapitulate symptoms of seipinopathy patients. We found loss of alpha motor neurons in tgMT spinal cord. Mild endoreticular stress was present in both tgMT and tgWT neurons; however, only tgMT mice exhibited protein aggregates and disrupted Golgi apparatus. Furthermore, autophagosomes were significantly increased, along with elevated light chain 3 (LC3)-II level in tgMT spinal cord, consistent with the activation of autophagy pathway in response to mutant Seipin expression and protein aggregation. These results suggest that induction of autophagy pathway is involved in the cellular response to mutant Seipin in seipinopathy and that motoneuron loss is a key pathogenic process underlying the development of locomotor abnormalities.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / metabolism
  • Disease Models, Animal
  • GTP-Binding Protein gamma Subunits / genetics*
  • GTP-Binding Protein gamma Subunits / metabolism
  • Golgi Apparatus / pathology
  • Heterotrimeric GTP-Binding Proteins / genetics*
  • Heterotrimeric GTP-Binding Proteins / metabolism
  • Humans
  • Mice
  • Mice, Transgenic
  • Microtubule-Associated Proteins / metabolism
  • Motor Neuron Disease / genetics*
  • Motor Neuron Disease / metabolism
  • Motor Neuron Disease / pathology
  • Motor Neurons / metabolism*
  • Mutation, Missense
  • Nerve Degeneration
  • Spinal Cord / metabolism

Substances

  • BSCL2 protein, human
  • Bscl2 protein, mouse
  • GTP-Binding Protein gamma Subunits
  • MAP1LC3 protein, mouse
  • Microtubule-Associated Proteins
  • Heterotrimeric GTP-Binding Proteins