Opposite regulation by typical and atypical anti‐psychotics of ERK1/2, CREB and Elk‐1 phosphorylation in mouse dorsal striatum

Abstract

The two mitogen-activated protein kinases (MAPKs), extracellular signal-regulated protein kinase 1 and 2 (ERK1/2), are involved in the control of gene expression via phosphorylation and activation of the transcription factors cyclic AMP response element binding protein (CREB) and Elk-1. Here, we have examined the effect of haloperidol and clozapine, two antipsychotic drugs, and eticlopride, a selective dopamine D 2 receptor antagonist, on the state of phosphorylation of ERK1/2, CREB and Elk-1, in the mouse dorsal striatum. Administration of the typical anti-psychotic haloperidol stimulated the phosphorylation of ERK1/2, CREB and Elk-1. Virtually identical results were obtained using eticlopride. In contrast, the atypical anti-psychotic clozapine reduced ERK1/2, CREB and Elk-1 phosphorylation. This opposite regulation was specifically exerted by haloperidol and clozapine on ERK, CREB, and Elk-1 phosphorylation, as both anti-psychotic drugs increased the phosphorylation of the dopamine-and cyclic AMPregulated phosphoprotein of 32 kDa (DARPP-32) at the cyclic AMP-dependent protein kinase (PKA) site. The activation of CREB and Elk-1 induced by haloperidol appeared to be achieved via different signalling pathways, as inhibition of ERK1/2 activation abolished the stimulation of Elk-1 phosphorylation without affecting CREB phosphorylation. This study shows that haloperidol and clozapine induce distinct patterns of phosphorylation in the dorsal striatum. The results provide a novel biochemical paradigm elucidating the molecular mechanisms underlying the distinct therapeutic actions of typical and atypical anti-psychotic agents. Treatment with anti-psychotic (or neuroleptic) drugs currently represents the most common therapy for schizophrenia. One major limitation in the use of conventional antipsychotic drugs, such as haloperidol, is that their prolonged administration induces extra-pyramidal side-effects by modifying transmission in the basal ganglia, a group of brain structures involved in the control of voluntary movements. The atypical anti-psychotic, clozapine, has a superior therapeutic efficacy and does not produce extra-pyramidal sideeffects. The use of this drug, however, is complicated by the relatively high incidence of agranulocytosis, a condition that requires the immediate suspension of clozapine administration.A common feature of anti-psychotic drugs is their ability to act as dopamine D 2 receptor antagonists. Blockade of dopamine D 2 receptors profoundly affects gene expression in the striatum, the major receiving area of the basal ganglia.Administration of haloperidol produces a rapid increase in the expression of various genes including the immediate early gene c-fos (Dragunow et al. 1990;Miller 1990) Abbreviations used: CREB, cyclic AMP response element binding protein; DARPP-32, dopamine and cyclic AMP-regulated phosphoprotein of 32 kDa; ERK1/2, extracellular signal-regulated protein kinase 1 and 2; MAPKs, mitogen-activated protein kinases; MEK, MAPK/ERK kinase.

Haloperidol Regulates the State of Phosphorylation of Ribosomal Protein S6 via Activation of PKA and Phosphorylation of DARPP-32

“…PKA-mediated phosphorylation at Thr34 converts DARPP-32 into an inhibitor of PP-1, thereby suppressing the dephosphorylation of numerous effector targets acting downstream of the cAMP/PKA cascade (Greengard, 2001). Haloperidol is known to increase DARPP-32 phosphorylation at Thr34 in vivo (Pozzi et al, 2003). Western blot analysis revealed a significant increase in the levels of phospho-Thr34-DARPP-32, determined in our experimental conditions 15 and 60 min after administration of haloperidol (Figure 7a).…”

“…In striatopallidal neurons, blockade of D2Rs increases the state of phosphorylation of several substrates of PKA (Bertran-Gonzalez et al, 2008Håkansson et al, 2006;Li et al, 2004;Pozzi et al, 2003). This effect has been attributed to the removal of the inhibitory tone exerted by D2Rs on adenylyl cyclase, which leads to the accumulation of cAMP and activation of PKA.…”

“…In striatopallidal MSNs, haloperidolinduced activation of cAMP-dependent protein kinase A (PKA) and of the protein phosphatase-1 (PP-1) inhibitor, dopamine-and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32), has been proposed to affect gene transcription by acting on nuclear targets, including the cAMP response element-binding protein and histone H3 Konradi and Heckers, 1995;Li et al, 2004;Pozzi et al, 2003). Much less is known about the ability of antipsychotic drugs and of the PKA/DARPP-32 cascade to affect signaling cascades involved in translational control.…”

Antipsychotic Drugs Inhibit the Human Corticotropin-Releasing-Hormone Gene Promoter Activity in Neuro-2A Cells—an Involvement of Protein Kinases

“…In fact, chlorpromazine and other phenothiazine derivatives are recognized calmodulin antagonists and clozapine has been found to reduce ERK1/2-MAPK (Pozzi et al, 2003;Ratnakar et al, 1995). These kinases may play a role in the mechanism of action of those antipsychotics which inhibit their activity, for example, clozapine, chlorpromazine, but not in the mechanism underlying the action of other drugs which enhance ERK-MAPK or CaMK activity (Ninan et al, 2003;Pozzi et al, 2003;Yang et al, 2004). Moreover, the lack of chlorpromazine and clozapine effect on phospho-Ser-133-CREB level rather excluded their action via this pathway.…”

Pharmacogenetics and pharmacogenomics of schizophrenia: a review of last decade of research

“…335 Already, studies have shown that clozapine and haloperidol induce distinct patterns of phosphorylation of gene expression controlling kinases in the dorsal striatum, indicating a possible explanation for their difference in antipsychotic activity. 339,340 This is an exciting area which will undoubtedly improve our knowledge on determinants of response variability.…”