Functional consequences of mutations in CDKL5, an X-linked gene involved in infantile spasms and mental retardation

Ilaria Bertani, Laura Rusconi, Fabrizio Bolognese, Greta Forlani, Barbara Conca, Lucia De Monte, Gianfranco Badaracco, Nicoletta Landsberger, Charlotte Kilstrup-Nielsen

Research output: Contribution to journalArticle

Abstract

Mutations in the X-linked cyclin-dependent kinase-like 5 (CDKL5) gene have been identified in patients with Rett syndrome, West syndrome, and X-linked infantile spasms sharing the common features of generally intractable early seizures and mental retardation. Disease-causing mutations are distributed in both the catalytic domain and in the large COOH terminus. In this report, we examine the functional consequences of some Rett mutations of CDKL5 together with some synthetically designed derivatives useful to underline the functional domains of the protein. The mutated CDKL5 derivatives have been subjected to in vitro kinase assays and analyzed for phosphorylation of the TEY (Thr-Glu-Tyr) motif within the activation loop, their subcellular localization, and the capacity of CDKL5 to interact with itself. Whereas wild-type CDKL5 autophosphorylates and mediates the phosphorylation of the methyl-CpG-binding protein 2 (MeCP2) in vitro, Rett-mutated proteins show both impaired and increased catalytic activity suggesting that a tight regulation of CDKL5 is required for correct brain functions. Furthermore, we show that CDKL5 can self-associate and mediate the phosphorylation of its own TEY (Thr-Glu-Tyr) motif. Eventually, we show that the COOH terminus regulates CDKL5 properties; in particular, it negatively influences the catalytic activity and is required for its proper sub-nuclear localization. We propose a model in which CDKL5 phosphorylation is required for its entrance into the nucleus whereas a portion of the COOH-terminal domain is responsible for a stable residency in this cellular compartment probably through protein-protein interactions.

Original languageEnglish
Pages (from-to)32048-32056
Number of pages9
JournalJournal of Biological Chemistry
Volume281
Issue number42
DOIs
Publication statusPublished - Oct 20 2006

ASJC Scopus subject areas

  • Biochemistry

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    Bertani, I., Rusconi, L., Bolognese, F., Forlani, G., Conca, B., De Monte, L., Badaracco, G., Landsberger, N., & Kilstrup-Nielsen, C. (2006). Functional consequences of mutations in CDKL5, an X-linked gene involved in infantile spasms and mental retardation. Journal of Biological Chemistry, 281(42), 32048-32056. https://doi.org/10.1074/jbc.M606325200