Related Experiment Video

Updated: Apr 14, 2026

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
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Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Published on: March 9, 2012

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Rheb activation disrupts spine synapse formation through accumulation of syntenin in tuberous sclerosis complex

Hiroko Sugiura1, Shin Yasuda1, Shutaro Katsurabayashi2

  • 1Neural Plasticity Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan.

Nature Communications
|April 17, 2015
PubMed

Insights

Tuberous sclerosis complex (TSC) neurons have higher syntenin levels, disrupting synapse formation. Reducing syntenin in TSC neurons restores normal synapse densities, suggesting Rheb-syntenin signaling as a therapeutic target.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Genetics

Background:

  • Tuberous sclerosis complex (TSC) is caused by mutations in TSC1/TSC2, affecting Rheb GTPase activity.
  • Previous studies showed impaired spine synapse morphogenesis in TSC neurons, independent of mTORC1.
  • Rheb (Ras homolog enriched in brain) is a small GTP-binding protein crucial for cellular signaling.

Purpose of the Study:

  • To investigate the role of Rheb and its interacting proteins in TSC-related synaptic abnormalities.
  • To elucidate the mechanism by which TSC mutations lead to altered synapse formation.
  • To identify potential therapeutic targets for TSC neurological complications.

Main Methods:

  • Co-immunoprecipitation to assess protein-protein interactions.
  • Western blotting to quantify protein levels in wild-type and TSC neurons.
  • Proteasomal degradation assays.
  • Immunofluorescence microscopy to analyze synapse morphology and density.

Main Results:

  • The PDZ protein syntenin preferentially binds to the GDP-bound form of Rheb.
  • Syntenin levels are elevated in TSC neurons due to impaired proteasomal degradation of the Rheb-GDP-syntenin complex.
  • Accumulated syntenin inhibits spine synapse formation by disrupting the syndecan-2/CSK interaction.
  • Syntenin promotes excitatory shaft synapse formation via interaction with ephrinB3.
  • Downregulation of syntenin in TSC neurons normalized both spine and shaft synapse densities.

Conclusions:

  • Rheb-syntenin signaling pathway is implicated in synaptic dysregulation in TSC.
  • Altered Rheb-GDP-syntenin complex formation and subsequent syntenin accumulation contribute to synaptic defects in TSC neurons.
  • Targeting the Rheb-syntenin pathway offers a potential therapeutic strategy for TSC-associated synaptic abnormalities.

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