Postnatal neurogenesis generates heterotopias, olfactory micronodules and cortical infiltration following single-cell Tsc1 deletion

Hum Mol Genet. 2012 Feb 15;21(4):799-810. doi: 10.1093/hmg/ddr511. Epub 2011 Nov 7.

Abstract

Neurological symptoms in tuberous sclerosis complex (TSC) and associated brain lesions are thought to arise from abnormal embryonic neurogenesis due to inherited mutations in Tsc1 or Tsc2. Neurogenesis persists postnatally in the human subventricular zone (SVZ) where slow-growing tumors containing Tsc-mutant cells are generated in TSC patients. However, whether Tsc-mutant neurons from the postnatal SVZ contribute to brain lesions and abnormal circuit remodeling in forebrain structures remain unexplored. Here, we report the formation of olfactory lesions following conditional genetic Tsc1 deletion in the postnatal SVZ using transgenic mice or targeted single-cell electroporation. These lesions include migratory heterotopias and olfactory micronodules containing neurons with a hypertrophic dendritic tree. Most significantly, our data identify migrating glial and neuronal precursors that are re-routed and infiltrate forebrain structures (e.g. cortex) and become glia and neurons. These data show that Tsc1-mutant cells from the neonatal and juvenile SVZ generate brain lesions and structural abnormalities, which would not be visible using conventional non-invasive imaging. These findings also raise the hypothesis that micronodules and the persistent infiltration of cells to forebrain structures may contribute to network malfunction leading to progressive neuropsychiatric symptoms in TSC.

Publication types

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

MeSH terms

  • Animals
  • Animals, Newborn
  • Cell Movement
  • Cerebral Cortex / pathology*
  • Dendrites / pathology
  • Electroporation
  • Female
  • Gene Deletion*
  • Male
  • Mice
  • Mice, Transgenic
  • Neurogenesis*
  • Neuroglia / cytology
  • Neurons / cytology
  • Olfactory Bulb / pathology*
  • Periventricular Nodular Heterotopia / pathology*
  • Single-Cell Analysis
  • TOR Serine-Threonine Kinases / metabolism
  • Tuberous Sclerosis / pathology
  • Tuberous Sclerosis Complex 1 Protein
  • Tumor Suppressor Proteins / deficiency*
  • Tumor Suppressor Proteins / genetics

Substances

  • TSC1 protein, human
  • Tsc1 protein, mouse
  • Tuberous Sclerosis Complex 1 Protein
  • Tumor Suppressor Proteins
  • mTOR protein, mouse
  • TOR Serine-Threonine Kinases