Ca2+/Calmodulin-dependent protein kinase kinase beta is regulated by multisite phosphorylation

J Biol Chem. 2011 Aug 12;286(32):28066-79. doi: 10.1074/jbc.M111.251504. Epub 2011 Jun 13.

Abstract

Ca(2+)/calmodulin-dependent protein kinase kinase β (CaMKKβ) is a serine/threonine-directed kinase that is activated following increases in intracellular Ca(2+). CaMKKβ activates Ca(2+)/calmodulin-dependent protein kinase I, Ca(2+)/calmodulin-dependent protein kinase IV, and the AMP-dependent protein kinase in a number of physiological pathways, including learning and memory formation, neuronal differentiation, and regulation of energy balance. Here, we report the novel regulation of CaMKKβ activity by multisite phosphorylation. We identify three phosphorylation sites in the N terminus of CaMKKβ, which regulate its Ca(2+)/calmodulin-independent autonomous activity. We then identify the kinases responsible for these phosphorylations as cyclin-dependent kinase 5 (CDK5) and glycogen synthase kinase 3 (GSK3). In addition to regulation of autonomous activity, we find that phosphorylation of CaMKKβ regulates its half-life. We find that cellular levels of CaMKKβ correlate with CDK5 activity and are regulated developmentally in neurons. Finally, we demonstrate that appropriate phosphorylation of CaMKKβ is critical for its role in neurite development. These results reveal a novel regulatory mechanism for CaMKKβ-dependent signaling cascades.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • COS Cells
  • Calcium-Calmodulin-Dependent Protein Kinase Kinase / genetics
  • Calcium-Calmodulin-Dependent Protein Kinase Kinase / metabolism*
  • Chlorocebus aethiops
  • Cyclin-Dependent Kinase 5 / genetics
  • Cyclin-Dependent Kinase 5 / metabolism
  • Glycogen Synthase Kinase 3 / genetics
  • Glycogen Synthase Kinase 3 / metabolism
  • Half-Life
  • Humans
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Neurites / enzymology*
  • Phosphorylation / physiology
  • Protein Structure, Tertiary
  • Rats
  • Signal Transduction / physiology

Substances

  • Nerve Tissue Proteins
  • Cyclin-Dependent Kinase 5
  • CAMKK2 protein, human
  • Calcium-Calmodulin-Dependent Protein Kinase Kinase
  • Camkk2 protein, rat
  • CDK5 protein, human
  • Cdk5 protein, rat
  • Glycogen Synthase Kinase 3