Calmodulin-dependent kinase kinase/calmodulin kinase I activity gates extracellular-regulated kinase-dependent long-term potentiation

John M. Schmitt, Eric S. Guire, Takeo Saneyoshi, Thomas R. Soderling

Research output: Contribution to journalArticlepeer-review

122 Scopus citations

Abstract

Intracellular Ca2+ and protein phosphorylation play pivotal roles in long-term potentiation (LTP), a cellular model of learning and memory. Ca2+ regulates multiple intracellular pathways, including the calmodulin-dependent kinases (CaMKs) and the ERKs (extracellular signal-regulated kinases), both of which are required for LTP. However, the mechanism by which Ca2+ activates ERK during LTP remains unknown. Here, we describe a requirement for the CaMK-kinase (CaMKK) pathway upstream of ERK in LTP induction. Both the pharmacological inhibitor of CaMKK, STO-609, and dominant-negative CaMKI (dnCaMKI), a downstream target of CaMKK, blocked neuronal NMDA receptor-dependent ERK activation. In contrast, an inhibitor of CaMKII and nuclear-localized dnCaMKIV had no effect on ERK activation. NMDA receptor-dependent LTP induction robustly activated CaMKI, the Ca 2+-stimulated Ras activator Ras-GRF1 (Ras-guanyl-nucleotide releasing factor), and ERK. STO-609 blocked the activation of all three enzymes during LTP without affecting basal synaptic transmission, activation of CaMKII, or cAMP-dependent activation of ERK. LTP induction itself was suppressed ∼50% by STO-609 in a manner identical to the ERK inhibitor U0126: either inhibitor occluded the effect of the other, suggesting they are part of the same signaling pathway in LTP induction. STO-609 also suppressed regulatory phosphorylation of two downstream ERK targets during LTP, the general translation factors eIF4E (eukaryotic initiation factor 4) and its binding protein 4E-BP1 (eukaryotic initiation factor 4E-binding protein 1). These data indicate an essential role for CaMKK and CaMKI to link NMDA receptor-mediated Ca2+ elevation with ERK-dependent LTP.

Original languageEnglish (US)
Pages (from-to)1281-1290
Number of pages10
JournalJournal of Neuroscience
Volume25
Issue number5
DOIs
StatePublished - Feb 2 2005

Keywords

  • CaM kinase
  • Calcium
  • ERK
  • LTP
  • Synaptic plasticity
  • eIF4E

ASJC Scopus subject areas

  • Neuroscience(all)

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