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Nat Commun. 2015 Apr 16;6:6842. doi: 10.1038/ncomms7842.

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

Author information

1
Neural Plasticity Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan.
2
Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka 814-0180, Japan.
3
Center of Basic Technology Research, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan.
4
Department of Pathology and Oncology, Juntendo University, School of Medicine, Tokyo 113-8421, Japan.

Abstract

Rheb is a small GTP-binding protein and its GTPase activity is activated by the complex of Tsc1 and Tsc2 whose mutations cause tuberous sclerosis complex (TSC). We previously reported that cultured TSC neurons showed impaired spine synapse morphogenesis in an mTORC1-independent manner. Here we show that the PDZ protein syntenin preferentially binds to the GDP-bound form of Rheb. The levels of syntenin are significantly higher in TSC neurons than in wild-type neurons because the Rheb-GDP-syntenin complex is prone to proteasomal degradation. Accumulated syntenin in TSC neurons disrupts spine synapse formation through inhibition of the association between syndecan-2 and calcium/calmodulin-dependent serine protein kinase. Instead, syntenin enhances excitatory shaft synapse formation on dendrites by interacting with ephrinB3. Downregulation of syntenin in TSC neurons restores both spine and shaft synapse densities. These findings suggest that Rheb-syntenin signalling may be a novel therapeutic target for abnormalities in spine and shaft synapses in TSC neurons.

PMID:
25880340
DOI:
10.1038/ncomms7842
[Indexed for MEDLINE]
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