Chemical genetic identification of CDKL5 substrates reveals its role in neuronal microtubule dynamics

  • EMBO J. 2018 Dec 14;37(24):e99763. doi: 10.15252/embj.201899763.
Lucas L Baltussen  1 ,  Priscilla D Negraes  2 ,  Margaux Silvestre  1 ,  Suzanne Claxton  1 ,  Max Moeskops  1 ,  Evangelos Christodoulou  3 ,  Helen R Flynn  4 ,  Ambrosius P Snijders  4 ,  Alysson R Muotri  5  6 ,  Sila K Ultanir  7
Affiliations
  • 1. Kinases and Brain Development Laboratory, The Francis Crick Institute, London, UK.
  • 2. Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA, USA.
  • 3. Structural Biology Science Technology Platform, The Francis Crick Institute, London, UK.
  • 4. Proteomics Science Technology Platform, The Francis Crick Institute, London, UK.
  • 5. Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA, USA [email protected] [email protected].
  • 6. Department of Pediatrics/Cellular & Molecular Medicine, Center for Academic Research and Training in Anthropogeny (CARTA), Kavli Institute for Brain and Mind, School of Medicine, Rady Children's Hospital San Diego, University of California San Diego, La Jolla, CA, USA.
  • 7. Kinases and Brain Development Laboratory, The Francis Crick Institute, London, UK [email protected] [email protected].
PMID: 30266824 DOI: 10.15252/embj.201899763
Abstract

Loss-of-function mutations in CDKL5 kinase cause severe neurodevelopmental delay and early-onset seizures. Identification of CDKL5 substrates is key to understanding its function. Using chemical genetics, we found that CDKL5 phosphorylates three microtubule-associated proteins: MAP1S, EB2 and ARHGEF2, and determined the phosphorylation sites. Substrate phosphorylations are greatly reduced in CDKL5 knockout mice, verifying these as physiological substrates. In CDKL5 knockout mouse neurons, dendritic microtubules have longer EB3-labelled plus-end growth duration and these altered dynamics are rescued by reduction of MAP1S levels through shRNA expression, indicating that CDKL5 regulates microtubule dynamics via phosphorylation of MAP1S. We show that phosphorylation by CDKL5 is required for MAP1S dissociation from microtubules. Additionally, anterograde cargo trafficking is compromised in CDKL5 knockout mouse dendrites. Finally, EB2 phosphorylation is reduced in patient-derived human neurons. Our results reveal a novel activity-dependent molecular pathway in dendritic microtubule regulation and suggest a pathological mechanism which may contribute to CDKL5 deficiency disorder.

Keywords
CDKL5; EB2; MAP1S; chemical genetics; microtubule dynamics.