Abstract
Mutations of the cyclin-dependent kinase-like 5 (CDKL5) and netrin-G1 (NTNG1) genes cause a severe neurodevelopmental disorder with clinical features that are closely related to Rett syndrome, including intellectual disability, early-onset intractable epilepsy and autism. We report here that CDKL5 is localized at excitatory synapses and contributes to correct dendritic spine structure and synapse activity. To exert this role, CDKL5 binds and phosphorylates the cell adhesion molecule NGL-1. This phosphorylation event ensures a stable association between NGL-1 and PSD95. Accordingly, phospho-mutant NGL-1 is unable to induce synaptic contacts whereas its phospho-mimetic form binds PSD95 more efficiently and partially rescues the CDKL5-specific spine defects. Interestingly, similarly to rodent neurons, iPSC-derived neurons from patients with CDKL5 mutations exhibit aberrant dendritic spines, thus suggesting a common function of CDKL5 in mice and humans.
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Acknowledgements
We gratefully acknowledge T. Bienvenu for providing primary fibroblasts from CDKL5 patients, H. Van Esch and H. Archer for providing DNA samples from patients, S. Freier, A. Walther, A. Grimme, U. Fischer and B. Moser for their excellent technical assistance, and L. Musante for helpful discussions. L. Pecciarini is acknowledged for karyotype analysis of the iPSC lines. This study was supported by the Telethon Foundation, Ministry of Health, IIT-SEED project, EuroRETT network to V.B. and the EU-FP7 project GENCODYS (241995) to V.M.K.
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V.M.K. and N.R. initiated this study. S.R., M.H., N.R, V.M.K. and V.B. contributed to its conceptualization and V.M.K and V.B. directed it throughout; S.R. performed and analysed neuronal experiments. F.U. generated iPSCs and characterized iPSC-derived neurons. M.H. performed and analysed immunoprecipitation assays and Phos-tag assays. M.H. and N.R. performed mutation search. G.S. was involved in mutagenesis experiments. D.B. performed electrophysiological recordings. A.S. performed electroporation experiments. C.M. and A.B. performed 2D gel analysis. E.G. produced the CDKL5-specific antibody. C.V. and C.S. assisted with the preparation of primary neurons. C.K-N. assisted with the in vitro phosphorylation assays. V.M.K., V.B., S.R., M.H. and N.R. interpreted the results. V.B., V.M.K. and S.R. wrote the manuscript.
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Ricciardi, S., Ungaro, F., Hambrock, M. et al. CDKL5 ensures excitatory synapse stability by reinforcing NGL-1–PSD95 interaction in the postsynaptic compartment and is impaired in patient iPSC-derived neurons. Nat Cell Biol 14, 911–923 (2012). https://doi.org/10.1038/ncb2566
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DOI: https://doi.org/10.1038/ncb2566
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