Clozapine-induced ERK1 and ERK2 signaling in prefrontal cortex is mediated by the EGF receptor

Avril Pereira, George Fink, Suresh Sundram

Research output: Contribution to journalArticleResearchpeer-review

21 Citations (Scopus)

Abstract

The atypical antipsychotic drug clozapine is effective in treatment-refractory schizophrenia. The intracellular signaling pathways that mediate clozapine action remain unknown. A potential candidate is the mitogenactivated protein kinase extracellular signal-regulated kinase (MAPK-ERK) cascade that links G-protein-coupled receptor and ErbB growth factor signaling systems, thereby regulating synaptic plasticity and connectivity, processes impaired in schizophrenia. Here, we examined how clozapine differentially modulated phosphorylation of the MAPK isoforms, ERK1/ERK2 in primary murine prefrontal cortical neurons compared to the typical antipsychotic drug haloperidol. While clozapine and haloperidol acutely decreased cortical pERK1 activation, only clozapine but not haloperidol stimulated pERK1 and pERK2 with continued drug exposure. This delayed ERK increase however, did not occur via the canonical dopamine D2-Gi/o-PKA or serotonin 5HT 2A-Gq-phospholipase-C-linked signaling pathways. Rather, epidermal growth factor (EGF) receptor signaling mediated clozapine-induced ERK activation, given dose-dependent reduction of pERK1 and pERK2 stimulation with the EGF receptor inhibitor, AG1478. Immunocytochemical studies indicated that clozapine treatment increased EGF receptor (Tyr1068) phosphorylation. In vivo mouse treatment studies supported the in vitro findings with initial blockade, subsequent activation, and normalization of the cortical ERK response over 24 h. Furthermore, in vivo clozapine-induced ERK activation was significantly reduced by AG1478. This is the first report that clozapine action on prefrontal cortical neurons involves the EGF signaling system. Since EGF receptor signaling has not been previously linked to antipsychotic drug action, our findings may implicate the EGF system as a molecular substrate in treatment-resistant schizophrenia.

Original languageEnglish
Pages (from-to)185-198
Number of pages14
JournalJournal of Molecular Neuroscience
Volume39
Issue number1-2
DOIs
Publication statusPublished - 1 Sep 2009
Externally publishedYes

Keywords

  • Antipsychotic drug
  • EGF receptor
  • ERK
  • Prefrontal cortex
  • Schizophrenia
  • Signal transduction

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