MINIREVIEW
Protein kinaseCe:functionin neurons
Yasuhito Shirai, Naoko Adachi and Naoaki Saito
Biosignal Research Center, Kobe University, Japan
Expression of PKC- in the brain
Northern- and immunoblot analyses of the brain have
revealed the predominant presence of protein kinase
Ce (PKCe) mRNA and protein, respectively [1,2]; the
subtype has been cloned from rat brain [3]. Immuno-
histochemistry of PKCe reveals the most abundant
expression of the enzyme in the hippocampus, olfac-
tory tubercle and Calleja’s islands, with moderate
expression in the cerebral cortex, anterior olfactory
nuclei, accumbens nucleus, lateral septal nuclei and
caudate putamen (Table 1). The distribution of PKCe
in the brain is consistent with results of in situ hybrid-
ization [4]. Interestingly, the immunoreactivity of the
protein is evident in the nerve fibers, and precise obser-
vation using electron microscopy reveals its presy-
naptic localization [4,5]. These findings suggest the
involvement of PKCe in neurite outgrowth and presyn-
aptic functions such as neurotransmitter release.
As little is known about the role of PKCe in brain
development, we measured changes in the amount of
PKCe proteinin the rat brain from birth to day 28.
Substantial amounts of PKCe were already detected at
birth but substantial increases were detected in the
forebrain between days 5 and 7, and in the hindbrain
between days 7 and 14 (Fig. 1). This remarkable
increase suggests the importance of PKCe for neural
network construction because its timing is coincident
with synapse formation in the brain.
Neurite outgrowth
Overexpression of PKCe promotes nerve growth
factor-induced neurite outgrowth, whereas its down-
regulation inhibits this [6]. Interestingly, the phenome-
non is independent of its catalytic activity because
expression of the regulatory domain alone (eRD)
induces neurite outgrowth [7]. Larsson et al. [8] dem-
onstrated that the actin binding site between the C1A
and C1B is important for morphological change of
neurons. They also reported that the PKCe-induced
neurite outgrowth is blocked by active Ras homolog
Keywords
alcohol; ischemia; LTP; neurite outgrowth;
pain
Correspondence
Y. Shirai, Laboratory of Molecular
Pharmacology, Biosignal Research Center,
Kobe 657-8501, Japan
Fax: +81 78803 5971
Tel: +81 78803 5962
E-mail: shirai@kobe-u.ac.jp
(Received 26 December 2007, revised 26
May 2008, accepted 16 June 2008)
doi:10.1111/j.1742-4658.2008.06556.x
Protein kinase Ce is expressed at higher levels in the brain compared to
other tissues such as the heart and kidney, suggesting that it plays an
important role in the nervous system. Several neural functions of PKCe,
including neurotransmitter release and ion channel regulation, have been
identified using PKCe knockout mice. In this review, we focus on the
involvement of proteinkinase Ce in neurite outgrowth, presynaptic regula-
tion, alcohol actions, ischemic preconditioning and pain.
Abbreviations
ERK, extracellular signal-regulated kinase; GABA
A
, c-aminobutyrate type A; KO, knockout; LTP, long-term potentiation; NMDA, N-methyl-
D-aspartate; PIP
2
, phosphatidylinositol 4,5-bis phosphate; PKCe, proteinkinase Ce; RhoA, Ras homolog gene family, member A; ROCK,
Rho-associated coiled-coil-containing protein kinase.
3988 FEBS Journal 275 (2008) 3988–3994 ª 2008 The Authors Journal compilation ª 2008 FEBS
gene family, member A (RhoA) and led by inhibition
of the RhoA effector Rho-associated coiled-coil-
containing proteinkinase (ROCK), indicating that
attenuation of the RhoA-ROCK pathway is involved
in the process [9]. Additionally, activation of Cdc42 is
implicated in PKCe-induced neurite outgrowth [10].
How PKCe regulates RhoA and Cdc42 is still
unknown. We have recently shown that PKCe binds
to phosphatidylinositol 4,5-bis phosphate (PIP
2
) and
that the PIP
2
binding is necessary for PKCe-induced
neurite induction and its membrane localization [11].
The PIP
2
binding of PKCe may influence the function
of actin binding proteins, leading to actin rearrange-
ment and neurite induction. In addition, the binding of
PKCe to PIP
2
may contribute towards inhibition of
the RhoA-ROCK pathway. For example, the binding
of PKCe to PIP
2
may reduce the level of free PIP
2
that
can activate RhoA by regulating the open state of the
RhoA ⁄ RhoGDI complex [12]. Alternatively, PKCe
may attenuate RhoA via RhoGAP, which is reported
to bind to PKCe and induce neurite outgrowth [13].
Interestingly, the binding of full length PKCe to Rho-
GAP and PIP
2
is dependent on 12-O-tetradecanoyl-
phorbol 13-acetate, but eRD can bind to PIP
2
without
12-O-tetradecanoylphorbol-13-acetate [11,13]. These
results suggest that the open conformation is impor-
tant for the binding of PKCe to RhoGAP and PIP
2
.
Actin binding to PKCe may regulate the neurite cyto-
sckelecton as well as induce the open conformation of
PKCe, permitting its interaction with RhoGAP and ⁄ or
PIP
2
. Taken together, these studies suggest a model for
the involvement of PKCe in neurite function. Hor-
mones and neurotransmitters, including nerve growth
factor, activate PKC, resulting in a conformational
change that accompanies translocation to the plasma
membrane. Activated PKCe on the plasma membrane
interacts with actin, RhoGAP and PIP
2
, resulting in
neurite outgrowth by inhibiting the RhoA-ROCK
pathway, activation of Cdc42 and cytoskeletal rear-
rangement (Fig. 2). Although the C1B and V3 regions
of PKCe play a functionin the induction of neurite
outgrowth, the mechanism by which this occurs has
yet to be determined [11,14].
Presynaptic functions
Long-term potentiation (LTP) is at least one com-
ponent in the complex mechanism of learning and
Table 1. Relative densities of PKCe immunoreactivity in the rat
brain. 0, no immunoreactivity; 1, faint immunoreactivity; 2, lower
immunoreactivity; 3 moderate immunoreactivity; 4, moderately
dense immunoreactivity; 5, most dense immunoreactivity. Modified
from Table 1 of [4].
Region Region
Olfactory bulb Thalamus
Olfactory nerve layer 0 Reticular nucleus 1
External plexiform layer 3 Dorsal nuclei 1
Internal granular layer 2 Ventroposterior nucleus 1
Glomerular layer 2 Lateral geniculate nuclei 1
Mitral cell layer 1 Medial geniculate nuclei 2
Anterior olfactory nuclei 3 Cerebellar cortex
Amygdara 2 Molecular layer 2
Caudate-putamen 3 Purkinje cell layer 0
Globus pallidus 2 Granular layer 1
Accumbens nucleus 3 Substantia nigra
Olfactory tubercle 4 Pars compacta 1
Callrja’s island 4 Pars reticulate 2
Septal area Mammilary nuclei 2
Laternal septal nucleus 3 Suprior colicullus 1
Medial septal nucleus 1 Inferior colicullus 1
Diagonal band 1 Pontine nuclei 1
Septo-hippocampal
nucleus
4 Locus coeruleus 1
Habnulla Mesencephalic trigeminal
nucleus
2
Medial 0 Inferior olive 2
Lateral 0 Vestbular nuclei 0
Neocortex Cochlear nucleus 0
Layer I 3 Solitary nucleus 0
Layer II 3 Gracile nucleus 0
Layer III 1 Cuneate nucleus 0
Layer IV 2 Spinal cord
Layer V 2 Substantia gelatinosa 2
Layer VI 2 Vental horn 1
Hippocampus White matter
CA1 4 Optic nerve 0
CA2 4 Anterior commissure 0
CA3 5 Corpus callosum 0
Dentate gyrus Pyramidal tract 2
Hilus 4 Facial nerve 1
Granular layer 2 Cochlear nerve 1
Molecular layer 3 Cerebral peduncle 1
Spinal trigeminal tract 1
Medial longitudinal
fasciculus
1
Inferior cerebellar peduncle 1
P1 P3 P5 P7 P14 P28
F H H HFHF H H
PKC
Actin
FFF
Fig. 1. The ontogeny of PKCe in the rat brain as assessed by
immunoblot analysis. The brain was dissected from rats of various
ages and cut at the level of the caudal end of the inferior colliculus.
The rostal half (F) and the caudal half (H) were homogenized and
the homogenates (50 lg of protein) were subjected to SDS ⁄ PAGE,
followed by a western blot for PKCe.
Y. Shirai et al. Function of PKCe in neurons
FEBS Journal 275 (2008) 3988–3994 ª 2008 The Authors Journal compilation ª 2008 FEBS 3989
memory. There is general agreement that calmodulin-
dependent kinase II plays an essential role in this phe-
nomenon. PKC is also thought to be necessary, but
not sufficient, to induce LTP based on the findings
that phorbol esters mimic LTP and PKC inhibitors
prevent it [15].
The mechanisms underlying LTP have been most
extensively studied in the hippocampus, although LTP
occurs in a number of brain regions. There are two
types of LTP in the hippocampus [15]; one is LTP in
the pathway from the Schaffer collaterals to CA1 (SC-
CA1) and the other is the pathway from the mossy
fibers to CA3 (MF-CA3). The former is calcium-
dependent and involves N -methyl-d-aspartate
(NMDA) receptor phosphorylation by PKCc in the
postsynaptic neurons [16]. The latter appears to be
mediated by presynaptic events. PKCe is present at the
terminals of neurons and is localized at the presynaps-
es of the mossy fibers, consistent with a role for PKCe
in LTP at MF-CA3 [3,4]. Indeed, PKCe at the nerve
terminal is involved in phorbol ester-induced enhance-
ment of glutamate exocytosis [17] and in phorbol
ester-induced synaptic potentiation [19]. Thus, PKCe
at the nerve terminal would be expected to contribute
to the MF-CA3 LTP by increasing presynaptic neuro-
transmitter release. Generally, sustained activation of
PKC is needed for the presynaptic regulation of neural
plasticity [4]. The importance of the actin binding site
in both the sustained activation of PKCe and
enhanced exocytosis has been reported [18]. However,
how PKCe is activated presynaptically during LTP is
not fully understood. One attractive mechanism is that
of the ‘retrograde messenger’. Arachidonic acid pro-
duced at a postsynaptic site could diffuse to the
presynaptic terminal to activate PKCe. Indeed, arachi-
donic acid is released from cultured neurons by activa-
tion of NMDA receptors [19] and subtype-specifically
activates PKCe [20].
Presynaptic PKCe is also important for synaptic
maturation. It is well known that co-culture of purified
neurons with astrocytes facilitates synaptogenesis and
synapse maturation. Hama et al. [21] reported that
contact of neurons with astrocytes enhances the excit-
atory postsynaptic potential and induces excitatory
synapses, and that facilitated excitory synaptogenesis is
blocked by inhibitors of PKC [19]. Of the several PKC
subtypes present in the presynaptic neurons, Hama
et al. [19] propose that PKCe plays a key role in the
phenomenon because arachidonic acid production by
phospholipase A
2
is necessary for PKC activation and
synaptogenesis [19]. These results strongly suggest that
PKCe is involved in presynaptic modulation and regu-
lation, although there is no consensus on the involve-
ment of PKCe in LTP.
Actions of alcohol
PKCe is thought to mediate several actions of ethanol.
For example, ethanol stimulates the translocation of
PKCe in NG108-15 cells [22] and chronic ethanol
Activation
Conformational change
Membrane localization
PKC
RhoGAP
PIP
2
F-actin
RhoA/
ROCK
inhibition
Cdc42
Actin
binding
Protein
Neurite outgrowth
?
Fig. 2. Proposed model for neurite induc-
tion by PKCe. Activation of PKCe results in
an open conformation and translocation to
the plasma membrane. The PKCe on the
plasma membrane interacts with actin,
RhoGAP and PIP
2
via the actin binding site
C1 and V3 regions, resulting in neurite
outgrowth by inhibiting the RhoA-ROCK
pathway, activation of Cdc42, and
cytoskeletal rearrangement.
Function of PKCe inneurons Y. Shirai et al.
3990 FEBS Journal 275 (2008) 3988–3994 ª 2008 The Authors Journal compilation ª 2008 FEBS
exposure increases the amount of PKCe in NG108-15
and PC cells [23,24]. More directly, PKCe null mice
show a higher sensitivity than their wild-type litter-
mates to the acute behavioral effects of ethonal, and
demonstrate a marked reduction in ethanol self-admin-
istration [25]. The involvement of PKCe in the actions
of alcohol was confirmed in PKCe transgenic mice
[26]. Conditional expression of PKCe in the basal fore-
brain, amygdala and cerebellum of PKCe null mice
rescues the hypersensitivity and restores ethanol
consumption. Also, doxycycline-induced reduction of
PKCe expression results in a knockout (KO) mice-like
phenotype [26]. As the conditional transgenic mice do
not express PKC e in the hippocampus, these effects of
PKCe on the response to ethanol are unlikely to be
the result of responses in the hippocampus.
The hypersensitivity to and avoidance of ethanol in
PKCe KO mice appears to be mediated by the c-ami-
nobutyrate type A (GABA
A
) receptor. This is based
on studies demonstrating that KO mice showed a
greater increase in locomotor activity than wild-type
mice in response to pentobarbital and diazepam, which
are allosteric activators of the GABA
A
receptor
[25,26]. GABA
A
receptors are ligand-gated Cl
–
chan-
nels that are considered to be an important target of
ethanol. GABA
A
receptors are pentameric proteins
complexes comprising eight different classes. Most
GABA
A
receptors are compossed of two a, two b and
one c
2
subunit. Recently, it has shown that PKCe
directly phosphorylates S327 in the large intracellular
loop of the c
2
subunit and that mutation of this site
enhanced the ethanol-induced GABA-stimulated cur-
rent [27]. These results confirm that PKCe regulates
the sensitivity of GABA
A
receptors to ethanol via
direct phosphorylation.
Finally, chronic ethanol exposure up-regulates
N-type calcium channels. Because this up-regulation
can be inhibited by a selective inhibitor of PKCe [28],
ethanol induces N-type calcium channel expression in
a PKCe-dependent manner. These results suggest that
inhibition of PKCe might comprise a viable treatment
for alcoholism.
Ischemic preconditioning
Subleathal and mild ischemic insult, or ‘precondition-
ing’, promotes tolerance against more severe subse-
quent ischemic insults in organs such as the heart and
brain. This phenomenon involves many factors, includ-
ing PKC [29–31]. Involvement of PKCe in the precon-
ditioning has been well established in cardiac cells
using PKCe-specific peptide activators and inhibitors
[29,31] and has been confirmed using PKCe KO mice
[32]. Unlike wild-type and heterozygous mice, precon-
ditioning in PKCe KO mice does not reduce infarct
size caused by ischemia reperfusion, implicating the
involvement of PKCe in preconditioning. These results
were obtained from a non-neural system but PKCe
acts in a similar way in neurons.
Indeed, the role of PKCe in neural preconditioning
has been investigated using hippocampal slices [33,34]
and primary cultured neurons [35,36] as well as PKCe-
specific peptide activators and inhibitors. According to
these studies, NMDA and adenosine receptor-mediated
neural preconditioning require PKCe activation.
Although the mechanism of PKCe-mediated neural
preconditioning is not fully understood, inhibition of
extracellular signal-regulated kinase (ERK) attenuated
the adenosine receptor-mediated neural precondition-
ing, implicating the involvement of ERK in precondi-
tioning [34]. These findings suggest that PKCe may
have a protective role in stroke. Recently, Shimomura
et al. [37] demonstrated that the levels of PKCe are
markedly lower in the core of focal cerebral ischemia
and that this loss was prevented by hypothermia,
which is known to be neuroprotective [37]. How
hypotheramia alters levels of PKCe is currently
unknown.
Pain
PKCe also localizes and functions in peripheral
neurons such as nociceptive neurons. The nociceptive
sensory neurons express the capsaicin receptor TRPV1,
which is a nonselective cation channel activated not
only by capsaicin, but also by heat (> 43 °C).
TRPV1 is essential for the sensation of thermal and
inflammatory pain [38] and pro-inflammatory signals,
including ATP and bradykinin, enhance TRPV1 activ-
ity in a PKC-dependent manner [39,40]. Among the
PKC subtypes, PKCe has been reported to be predom-
inantly and specifically involved in nociceptor sensiti-
zation [39,40]. Indeed, PKCe directly phosphorylates
Ser502 and Ser800 of TRPV1 [41]. It has also been
shown that desensitization of TRPV1 is regulated by
PKCe-mediated phosphorylation at Ser800 [42]. Fur-
thermore, phosphorylation by PKCe appears to con-
tribute to the proteinase-activated receptor 2-mediated
potentiation of TRPV1 [43]. These findings suggest
that PKCe may be a therapeutic target for regulating
TRPV1 and pain.
Other functions
PKCe also modulates the Na
+
channel in hippocam-
pal neurons [44]. Acetylcholine binding to muscarinic
Y. Shirai et al. Function of PKCe in neurons
FEBS Journal 275 (2008) 3988–3994 ª 2008 The Authors Journal compilation ª 2008 FEBS 3991
receptors activates G-proteins, phospholipase C and
PKCe, resulting in a reduction of the peak of the Na
+
current in hippocampal neurons. This reduction is not
observed in PKCe KO mice, implicating PKCe in the
regulation of Na
+
channels. Such modulation of Na
+
channels by PKCe is likely to affect integration of
depolarizing inputs in dendrites and the threshold and
frequency of firing of action. In addition, PKCe is
involved in phorbol ester-induced secretion of b-amy-
loid precursor protein and the reduction of b-amyloid
(Ab) peptides [45]. Neural overexpression of PKCe
decreased Ab levels via endothelin-coverting enzyme
[46], suggesting that PKCe is one of the regulators of
a-secretase and Ab production.
PKCe in the non-neural system is sometimes related
to the neuronal system. For example, astrocytes have
traditionally been considered as passive bystanders in
the formation and operation of the neural network,
but accumulating evidence argues against such a
model, and instead supports a model in which astro-
cytes play a critical role in the creation and control of
synapses. Interestingly, differentiation of astrocytes, in
part, is regulated by PKCe. Sterinhart et al. [47] dem-
onstrated that 4b-phorbol 12-myristate 13-acetate and
PKCe overexpression induces the differentiation of
multipotential neural precursor cells to astrocytes, and
that this induction is inhibited by a kinase negative
mutant of PKCe [47]. They also demonstrated the
involvement of Notch in this processes.
Perspective
As described above, PKCe plays several important
roles in neurons. However, its precise function and
mechanism of action inneurons is yet to be fully
understood compared to the other functions deter-
mined for this enzyme [48]. One of the reasons is that
several PKC isoforms exist in the same neuron [3,4]
and different PKC subtypes can have opposing func-
tions. For example, PKCc is also involved in GABA
A
receptor regulation in response to ethanol but, in
contrast to PKCe, PKCc plays an inhibitory role in
ethanol-induced enhancement of GABA
A
receptor-
mediated inhibitory postsynaptic currents in CA1 [49].
Ethanol enhanced inhibitory postsynaptic currents in
wild-type mice, but not in PKCc null mice. By con-
trast, these currents are potentiated in PKCe KO mice.
In addition, unlike the protective effect of PKCe on
reperfusion injury, PKCd exacerbates injury [30].
The PKCe KO mice have been an invaluable model
for discriminating between the effects of ePKC and
other PKCs. Notably, the importance of PKCe in the
ethanol sensitivity and in Na
+
channel regulation have
been clearly demonstrated using KO mice. By contrast,
the involvement of PKCe in the LTP or its protective
effect on stoke have not been validated using PKCe
KO mice. It is possible that such experiments are
ongoing or that the KO mice might be somehow
different from wild-type mice due to compensation by
other PKC subtype(s). Because PKCe obviously has
important functions in neurons, more specific inhibi-
tors and activators would be useful to define the pre-
cise and subtype-specific functions of PKCe. With
respect to delivery to the brain, development of a
chemical inhibitor of PKCe that crosses the blood–
brain barrier is necessary because the PKCe inhibitors
used so far are peptides that cannot be employed effec-
tively for in vivo neural studies. These PKCe-specific
inhibitors or activators are expected to be utilized as a
drug for stroke, Alzheimer’s disease and pain because
the functions of the enzyme have been reported as
descibed above.
References
1 Ono Y, Fujii T, Ogita K, Kikkawa U, Igarashi K &
Nishizuka Y (1988) The structure, expression, and
properties of additional members of the protein kinase
C family. J Biol Chem 263, 6927–6932.
2 Westel WC, Khan WA, Merchenthaler I, Rivera H,
Halpern AE, Phung HM, Negro-Vilar A & Hannun
YA (1992) Tissue and cellular distribution of the
extended family of proteinkinase C isoenzymes. J Cell
Biol 117, 121–133.
3 Koide H, Ogita K, Kikkawa U & Nishizuka Y (1992)
Isolation and characterization of the e subspecies of
protein kinase C from rat brain. Proc Natl Acad Sci
USA 89, 1149–1153.
4 Saito N, Itouji A, Totani Y, Osawa I, Koide H,
Fujisawa N, Ogita K & Tanaka C (1993) Cellular and
intracellular localization of e-subspecies of protein
kinase C in the rat brain; presynaptic localization of
the e-subspecies. Brain Res 607, 241–248.
5 Tanaka C & Nishizuka Y (1994) The proteinkinase C
family for neural signaling. Annu Rev Neurosci 17, 551–
567.
6 Hundle B, McMahon T, Dagar J & Messing RO (1995)
Overexpression of e-protein kinase C enhances nerve
growth factor-induced phosphorylation of mitogen-acti-
vated protein kinases and neurite outgrowth. J Biol
Chem 270, 30134–30140.
7 Zeidman R, Lofgren B, Pahlman S & Larsson C (1999)
PKCe, via its regulatory domain and independently of
its catalytic domain, induces neurite-like processes in
neuroblastoma cells. J Cell Biol 145, 713–726.
8 Zeidman R, Troller U, Raghunath A, Pahlman S &
Larsson C (2002) Proteinkinase Ce actin-binding site is
Function of PKCe inneurons Y. Shirai et al.
3992 FEBS Journal 275 (2008) 3988–3994 ª 2008 The Authors Journal compilation ª 2008 FEBS
important for neurite outgrowth during neuronal differ-
entiation. Mol Biol Cell 13, 12–24.
9 Lingm M, Troller U, Zeidman R, Lundberg C & Lars-
son C (2004) Induction of neurites by the regulatory
domains of PKCd and e is counteracted by PKC cata-
lytic activity and by the RhoA pathway. Exp Cell Res
292, 135–150.
10 Troller U & Larsson C (2006) Cdc42 is involved in
PKCe- and d-induced neurite outgrowth and stress fibre
dismantling. Biochem Biophys Res Commun 349, 91–98.
11 Shirai Y, Murakami T, Kuramasu M, Iijima L & Saito
N (2007) A novel PIP
2
binding of ePKC and its contri-
bution to the nerutite induction ability. J Neurochem
102, 1635–1644.
12 Faure J, Vignais PV & Dagher MC (1999) Phosphoino-
sitide-dependent activation involves partial opening of
the RhoA ⁄ Rho-GDI complex. Eur J Biochem 262,
879–889.
13 Troller U & Larsson C (2004) A possible role for
p190RhoGAP in PKCe-induced morphological effects.
Cellular Sigmal 16, 245–252.
14 Lingm M, Troller U, Zeidman R, Stensman H, Schultz
A & Larssonm C (2005) Identification of conserved
amino acids N-terminal of the PKC eC1b domain
crucial for proteinkinase Ce-mediated induction of
neurite outgrowth. J Cell Biol 280, 17910–17919.
15 Hussain RJ & Carpenter DO (2005) A comparison of
the roles of proteinkinase C in long-term potentiation
in rat hippocampal areas CA1 and CA3. Cell Mol
Neurobiol 25, 649–661.
16 Saito N & Shirai Y (2002) Proteinkinase Cc (PKCc):
function of neuron specific isotype. J Biochem 132,
683–687.
17 Saitoh N, Hori T & Takahashi T (2001) Activation of
the epsilon isoform of proteinkinase C in the mamma-
lian nerve terminal. Proc Natl Acad Sci USA 98, 14017–
14021.
18 Prekeris R, Mayhew MW, Cooper JB & Terrian DM
(1996) Identification and localization of an actin-bind-
ing motif that is unique to the epsilon isoform of
protein kinase C and paraticipates in the regulation
of synapitic function. J Cell Biol 132, 77–90.
19 Dumus A, Sebben M & Haynes L (1988) NMDA recep-
tors activate the arachidnic acid cascade system in stria-
tal neurons. Nature 336, 68–70.
20 Kasahara K & Kikkawa U (1995) Distinct effects of
saturated fatty acids on proteinkinase C subspecies.
J Biochem 117, 648–653.
21 Hama H, Hara Chikako, Kazuhiko Yamaguchi & Miy-
awaki A (2004) PKC signaling mediates global enhance-
ment of excitatory synaptogenesis inneurons triggers by
local contact with astrocytes. Neuron 41, 405–415.
22 Gordon AS, Yao L, Wu Z, Coe IR & Diamond I
(1997) Ethanol alters the subcellular localization of
d- and e-protein kinase C in NG108-15 cells. Mol Phar-
macol 52, 554–559.
23 Messing RO, Petersen PJ & Henrich CJ (1991) Chronic
ethanol exposure increases level of proteinkinase Cd
and e and proteinkinase mediated phosphorylation in
cultured neural cells. J Biol Chem 266, 23428–23432.
24 Coe IR, Yao L, Diamond I & Gordon AS (1996) The
role of proteinkinase C in cellular tolerance to ethanol.
J Biol Chem 271, 29468–29472.
25 Hodge CW, Mehmert KK, Kelly SP, McMahon T,
Haywood A, Olive MF, Wang D, Sanchez-Perez AM &
Messig RO (1999) Suppersensitivity to allosteric
GABA
A
receptor modulators and alcohol in mice lack-
ing PKCe. Nat Neurosci 2, 997–1002.
26 Choi DS, Jahan DW, Dadgar J, Chang WS & Messing
RO (2002) Conditional rescue of proteinkinase C e
regulates ethanol preference and hypnotic sensitivity
in adult mice. J Neurosci 22, 9905–9911.
27 Qi ZH, Song M, Wallace MJ, Wang D, Newton PM,
MaMahon T, Chou WH, Zhang C, Shokat KM &
Messing RO (2007) Proteinkinase C epsilon regulates
GABA
A
receptor sensitivity to ethanol and bendodiaze-
pines through phosphorylation of c2 subunits. J Biol
Chem 282, 33052–33063.
28 Mcmahon T, Andersen R, Metten P, Crabbe JC &
Messing RO (2000) Proteinkinase Ce mediates up-regu-
lation of N-type calcium channels by ethanol. Mol
Pharmacol 57, 53–58.
29 Armstrong SC (2004) Proteinkinase activation and
myocardial ischemia ⁄ reperfusion injury. Cardiov Res 61,
427–436.
30 Chou WH & Messing RO (2005) Proteinkinase C
isozymes in stroke. TCM 15, 47–51.
31 Murriel CL & Mochly-Rosen D (2003) Opposing roles
of d and ePKC in cardiac ischemia and reperfusion: tar-
geting the apoptotic machinery. Arc Biochem Biophys
420, 246–254.
32 Saurin AT, Pennington DJ, Raat NJH, Latchman DS,
Owen MJ & Marber M (2002) Targeted disruption of
the proteinkinase C epsilon gene abolishes the infarct
size reduction that follows ischemic preconditioning of
isolated buffer-perfusion mouse hearts. Cardiov Res 55,
672–680.
33 Raval AP, Dave KR, Mochly-Rosen D, Sick TJ &
Perez-Pinzon MA (2003) ePKC is required for the
induction of tolerance by ischemic and NMDA-medi-
ated preconditioning in the organotypic hippocampal
slice. J Neuroscience 23, 384–391.
34 Lange-Asschenfeldt C, Raval AP, Dave KR, Mochly-
Rosen D, Sick TJ & Perez-Pinzon MA (2004) Epsilon
protein kinase C mediated ischemic tolerance requires
activation of the extracellular regulated kinase pathway
in the orgonotypic hippocampal slice. J Cereb Blood
Flow Metab 24, 636–645.
Y. Shirai et al. Function of PKCe in neurons
FEBS Journal 275 (2008) 3988–3994 ª 2008 The Authors Journal compilation ª 2008 FEBS 3993
35 Wang J, Bright R, Mochly-Rosen D & Giffard RG
(2004) Cell-specific role for e- and bI-protein kinase C
isozymes in protecting cortical neurons and astrocytes
from ischemia-like injury. Neuropharmacology 47,
136–145.
36 Di-Capua N, Sperling O & Zoref-Shani E (2003) Pro-
tein kinase C-e is involved in the adenosine-activated
signal transduction pathway conferring protection
against ischemia-reperfusion injury in primary rat neu-
ronal cultures. J Neurochem 84, 409–412.
37 Shimomura T, Zhao H & Steinberg GK (2007) ePKC
may contribute to the protective effect of hypothermia in
a rat focal cerebral ischemia model. Stroke 38, 375–380.
38 Davis J, Gray J, Gunthorpe MJ, Hatcher JP, Davey
PT, Overend P, Harries MH, Latcham J, Clapham C,
Atkinson K et al. (2000) Vanilloid receptor-1 is essential
for inflammatory thermal hyperalgesia. Nature 405 ,
183–187.
39 Premkumar LS & Ahern GP (2000) Induction of vanil-
loid receptor channel activity by proteinkinase C. Nat-
ure 408, 985–990.
40 Tominaga M, Wada M & Masu M (2001) Poteintiation
of capsaicin receptor activity by metanotropic ATP
receptor as a possible mechanism for ATP-evoked pain
and hyperalgesia. Proc Natl Acad Sci USA 98, 6951–
6956.
41 Numazaki M, Tominaga T, Toyooka H & Tominaga
M (2002) Direct phosphorylation of capsaicin receptor
VR1 by proteinkinase Ce and identification of two
target serine residues. J Biol Chem 277, 13375–13378.
42 Mandadi S, Tominaga T, Numazaki M, Murayama N,
Saito N, Armati PJ, Roufogails B & Tominaga M
(2006) Increased sensitivity of desensitized TRPV1 by
PMA occurs through PKCe-mediated phosphorylation
at S800. Pain 123, 106–116.
43 Dai Y, Moriyama T, Higashi T, Togashi K, Kobayashi
K, Yamanaka H, Tominaga M & Noguchi K (2004)
Proteinase-activated receptor2-mediated potentiation of
transient receptor potential vanilloid subfamily 1 activ-
ity reveals a mechanism for proteinase-induced inflam-
matory pain. J Neurosci 24, 4298–4299.
44 Chen Y, Cantrell AR, Messinbg RO, Sceuer T & Cat-
terall WA (2005) Specific modulation of Na
+
channels
in hippocampal neurons by proteinkinase Ce. J Neuro-
sci 25, 507–513.
45 Zhu G, Wang D, Lin YH, McMahon T, Koo EH &
Messing RO (2001) Proteinkinase C e suppresses Ab
production and promotes activation of a-secretase.
Biochem Bioohys Res Commun 285, 997–1006.
46 Choi DS, Wang D, Yu GQ, Zhu G, Kharazia VN,
Paredes JP, Chang WS, Deitchman JK, Mucke L &
Messing RO (2006) PKCe increases endothelin convert-
inbg enzyme activity and reuduces amyloid plaque
pathology in transgenic mice. Proc Natl Acad Sci USA
103, 8215–8220.
47 Steinhart R, Kazimirsky G, Okhrimenko H, Ben-Hur T
& Broudei C (2007) PKCe induces astrocytes differenti-
ation of multipotential neural precursor cells. Glia 55,
224–232.
48 Akita Y (2002) Proteinkinase Ce (PKC-e): its unique
structure and function. J Biochem 132, 847–852.
49 Proctor WR, Poelchen W, Bowers BJ, Wehner JM,
Messiing RO & Dunwiddie TV (2003) Ethanol differen-
tially enhances hippocampal GABA
A
receptor mediated
responses inproteinkinase Cc (PKCc ) ans PKCe null
mice. J Pharmacol Exp Ther 305, 264–270.
Function of PKCe inneurons Y. Shirai et al.
3994 FEBS Journal 275 (2008) 3988–3994 ª 2008 The Authors Journal compilation ª 2008 FEBS
. PIP
2
binding of PKCe may in uence the function
of actin binding proteins, leading to actin rearrange-
ment and neurite induction. In addition, the binding. phosphatidylinositol 4,5-bis phosphate; PKCe, protein kinase Ce; RhoA, Ras homolog gene family, member A; ROCK,
Rho-associated coiled-coil-containing protein kinase.
3988