Critical role of CDK5 and Polo-like kinase 2 in homeostatic synaptic plasticity during elevated activity

Neuron. 2008 May 22;58(4):571-83. doi: 10.1016/j.neuron.2008.03.021.


Homeostatic plasticity keeps neuronal spiking output within an optimal range in the face of chronically altered levels of network activity. Little is known about the underlying molecular mechanisms, particularly in response to elevated activity. We report that, in hippocampal neurons experiencing heightened activity, the activity-inducible protein kinase Polo-like kinase 2 (Plk2, also known as SNK) was required for synaptic scaling-a principal mechanism underlying homeostatic plasticity. Synaptic scaling also required CDK5, which acted as a "priming" kinase for the phospho-dependent binding of Plk2 to its substrate SPAR, a postsynaptic RapGAP and scaffolding molecule that is degraded following phosphorylation by Plk2. RNAi knockdown of SPAR weakened synapses, and overexpression of a SPAR mutant resistant to Plk2-dependent degradation prevented synaptic scaling. Thus, priming phosphorylation of the Plk2 binding site in SPAR by CDK5, followed by Plk2 recruitment and SPAR phosphorylation-degradation, constitutes a molecular pathway for neuronal homeostatic plasticity during chronically elevated activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Cyclin-Dependent Kinase 5 / physiology*
  • Embryo, Mammalian
  • Excitatory Postsynaptic Potentials
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Hippocampus / cytology
  • Humans
  • Immunoprecipitation
  • Membrane Potentials / physiology
  • Membrane Potentials / radiation effects
  • Nerve Tissue Proteins / metabolism
  • Neuronal Plasticity / physiology*
  • Neurons / cytology*
  • Neurons / physiology*
  • Patch-Clamp Techniques
  • Phosphorylation
  • Protein Kinases / physiology*
  • RNA Interference / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Serine / metabolism
  • Synapses / physiology*
  • Transfection / methods


  • Nerve Tissue Proteins
  • Green Fluorescent Proteins
  • Serine
  • Protein Kinases
  • Cyclin-Dependent Kinase 5
  • Cdk5 protein, rat