Dopamine and Ethanol Cause Translocation of
PKC Associated with
RACK: Cross-talk Between PKA and PKC Signaling PathwaysMolecular Pharmacology Fast Forward
First published on January 17, 2008;
Previously we found that neural responses to ethanol and the
dopamine D2 receptor (D2) agonist NPA involve both epsilon protein
kinase C (
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PKC) and cAMP-dependent protein kinase A (PKA). However,
little is known about the mechanism underlying ethanol- and
D2-mediated activation of
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PKC and the relationship to PKA activation.
In the present study, we used a new
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PKC antibody, 14E6, that
selectively recognizes active
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PKC when not bound to its anchoring
protein
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RACK (receptor for activated C-kinase), and PKC isozyme-selective
inhibitors and activators, to measure PKC translocation and
catalytic activity.
We show here that ethanol and NPA activated
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PKC and also induced translocation of both
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PKC and its anchoring
protein,
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RACK to a new cytosolic site. The selective
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PKC agonist,
pseudo-
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RACK, activated
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PKC but did not cause translocation of
the
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PKC/
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RACK complex to the cytosol.
These data suggest a step-wise
activation and translocation of
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PKC following NPA or ethanol
treatment where
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PKC first translocates and binds to its RACK
and subsequently the
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PKC/
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RACK complex translocates to a new
subcellular site. Direct activation of PKA by Sp-cAMPS, PGE1
or the adenosine A2A receptor is sufficient to cause
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PKC translocation
to the cytosolic compartment in a process that is dependent
on PLC activation and requires PKA activity.
These data demonstrate
a novel cross-talk mechanism between
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PKC and PKA signaling systems.
PKA and PKC signaling have been implicated in alcohol rewarding
properties in the mesolimbic dopamine system.
Cross-talk between
PKA and PKC may underlie some of the behaviors associated with
alcoholism.
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