Kinetic simulation of signal transduction system in hippocampal long-term potentiation with dynamic modeling of protein phosphatase 2A

Shinichi Kikuchi, Kenji Fujimoto, Noriyuki Kitagawa, Taro Fuchikawa, Michiko Abe, Kotaro Oka, Kohtaro Takei, Masaru Tomita

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

We modeled and analyzed a signal transduction system of long-term potentiation (LTP) in hippocampal post-synapse. Bhalla and Iyengar [Science 283(1999) 381] have developed a hippocampal LTP model. In the conventional model, the concentration of protein phosphatase 2A (PP2A) was fixed. However, it was reported that dynamic inactivation of PP2A was essential for LTP [J. Neurochem. 74 (2000) 807]. We introduced a dynamic modeling of PP2A; inactivation (phosphorylation) of PP2A by calcium/calmodulin-dependent protein kinase II (CaMKII) in the presence of calcium/calmodulin, self-activation (autodephosphorylation) of PP2A, and inactivation (dephosphorylation) of CaMKII by PP2A. This model includes complex feedback loops; both CaMKII and PP2A are autoactivated, while they inactivate each other. Moreover, we proposed an analysis strategy for model validation by applying the results of sensitivity analysis. In our system, calcineurin (CaN) played an essential role, rather than the activation of protein kinase C (PKC) as documented in the conventional model. From results of the analysis of our model, we found the following robustness as characteristics of bistability in our model: (1) PP2A reactions against calcium ion (Ca2+) perturbation; (2) PP2A inactivation against PP2A increase; (3) protein phosphatase 1 (PP1) activation against PF2A increase; and (4) PP2A reactions against PP2A initial concentration. These properties facilitated LTP induction in our system. We showed that another mechanism could introduce bistable behavior by adding dynamic reactions of PP2A.

Original languageEnglish
Pages (from-to)1389-1398
Number of pages10
JournalNeural Networks
Volume16
Issue number9
DOIs
Publication statusPublished - 2003 Nov

Keywords

  • E-Cell
  • E-Neuron
  • Hippocampus
  • Kinetic simulation
  • Long-term potentiation
  • Protein phosphatase 2A

ASJC Scopus subject areas

  • Cognitive Neuroscience
  • Artificial Intelligence

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