Brain Somatic Mutations in MTOR Disrupt Neuronal Ciliogenesis, Leading to Focal Cortical Dyslamination

Neuron. 2018 Jul 11;99(1):83-97.e7. doi: 10.1016/j.neuron.2018.05.039. Epub 2018 Jun 21.

Abstract

Focal malformations of cortical development (FMCDs), including focal cortical dysplasia (FCD) and hemimegalencephaly (HME), are major etiologies of pediatric intractable epilepsies exhibiting cortical dyslamination. Brain somatic mutations in MTOR have recently been identified as a major genetic cause of FMCDs. However, the molecular mechanism by which these mutations lead to cortical dyslamination remains poorly understood. Here, using patient tissue, genome-edited cells, and mouse models with brain somatic mutations in MTOR, we discovered that disruption of neuronal ciliogenesis by the mutations underlies cortical dyslamination in FMCDs. We found that abnormal accumulation of OFD1 at centriolar satellites due to perturbed autophagy was responsible for the defective neuronal ciliogenesis. Additionally, we found that disrupted neuronal ciliogenesis accounted for cortical dyslamination in FMCDs by compromising Wnt signals essential for neuronal polarization. Altogether, this study describes a molecular mechanism by which brain somatic mutations in MTOR contribute to the pathogenesis of cortical dyslamination in FMCDs.

Keywords: MTOR; brain somatic mutation; focal malformations of cortical development; primary cilia.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Animals
  • Autophagy / genetics*
  • Cell Polarity / genetics
  • Centrioles / metabolism
  • Cerebral Cortex / embryology
  • Cerebral Cortex / growth & development
  • Cerebral Cortex / metabolism*
  • Cerebral Cortex / pathology
  • Child
  • Child, Preschool
  • Cilia*
  • Female
  • Gene Editing
  • HEK293 Cells
  • Hemimegalencephaly / embryology
  • Hemimegalencephaly / genetics
  • Hemimegalencephaly / pathology
  • Humans
  • Infant
  • Male
  • Malformations of Cortical Development / embryology
  • Malformations of Cortical Development / genetics*
  • Malformations of Cortical Development / pathology
  • Mice
  • Mutation
  • Neurons / metabolism*
  • Proteins / metabolism
  • TOR Serine-Threonine Kinases / genetics*
  • Tuberous Sclerosis / embryology
  • Tuberous Sclerosis / genetics
  • Tuberous Sclerosis / pathology
  • Wnt Signaling Pathway

Substances

  • OFD1 protein, human
  • OFD1 protein, mouse
  • Proteins
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • mTOR protein, mouse