PKC and bipolar disorder


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(Updated 8/25/04)

[For more information on the relationship between mood stabilizers and protein kinase C (PKC), please click here.]

Hahn CG, Friedman E.
Abnormalities in protein kinase C signaling and the pathophysiology of bipolar disorder.
Bipolar Disord 1999 Dec;1(2):81-6
"Protein kinase C (PKC) is a group of calcium and phospholipid-dependent enzymes, which plays a pivotal role in cell signaling systems. Recently accumulated evidence indicates that alterations in PKC activity play a significant role in the pathophysiology of bipolar disorder. A number of laboratories investigated the effect of mood stabilizers on the regulation of PKC activity in bipolar patients, in animals, and in cultured cells. Following chronic lithium treatment, PKC activation was significantly reduced in rat brains, as measured by the translocation of cytoplasmic PKC to the membrane compartment, or by quantitative binding of the PKC ligand, PDBu. The effect of the therapeutic concentration of lithium in attenuating PKC-dependent intracellular parameters was also demonstrated in cultured cells. More importantly, alterations in platelet PKC was shown in bipolar patients during the manic state of the illness. In comparison to patients with major depressive disorder, schizophrenia, or healthy controls, PKC activity was significantly increased in manic patients, suggesting that changes in PKC may be an illness-specific marker. Interestingly, enhanced PKC activity during mania was suppressed following mood-stabilizer treatment as manic symptoms improved. In parallel to the findings in platelets, postmortem studies demonstrate that membrane-associated PKC and stimulation-induced translocation of cytosolic enzyme to the membrane were also increased in frontal cortex of bipolar patients. Other studies suggest alterations in other signal transduction mechanisms in bipolar disorder. These include alterations in G protein activation, phosphatidylinositol (PI) signaling, cyclic AMP formation, and intracellular calcium homeostasis. The alterations of PKC activity in bipolar disorder may be related to changes in these other intracellular signaling mechanisms. Alternatively, the changes of PKC activity may be the core pathology of the illness. More studies are required to further characterize the association of PKC changes with bipolar disorder, using a proper neuronal model." [Abstract]

Wang HY, Friedman E.
Enhanced protein kinase C activity and translocation in bipolar affective disorder brains.
Biol Psychiatry 1996 Oct 1;40(7):568-75
"Protein kinase C (PKC) activity and its redistribution were determined in the frontal cortices of postmortem brains of bipolar affective disorder subjects and age-, sex-, and postmortem time-matched controls. Membrane and cytosolic PKC activity was determined by histone phosphorylation using [32P]-adenosine triphosphate as substrate. Specific PKC isozyme levels were assessed by Western blot analysis using antipeptide antibodies. Brain membrane-associated PKC activity was higher in bipolar vs. control tissue. An examination of the specific PKC isozymes in cortical homogenates revealed that cytosolic alpha- and membrane-associated gamma- and zeta PKC isozymes were elevated in cortices of bipolar affective disorder subjects, whereas cytosolic epsilon PKC was found to be reduced. In control brain slices, incubation with 1 mumol/L phorbol 12-myristate 13-acetate (PMA) caused an increase in membrane PKC activity, whereas cytosolic enzyme activity was decreased. This redistribution of the enzyme by PMA was markedly potentiated in brain slices of bipolar subjects. The results suggest that PKC-mediated phosphorylation is increased in brains of subjects with bipolar affective illness." [Abstract]

Wang H, Friedman E.
Increased association of brain protein kinase C with the receptor for activated C kinase-1 (RACK1) in bipolar affective disorder.
Biol Psychiatry 2001 Sep 1;50(5):364-70
"BACKGROUND: Membrane protein kinase C (PKC) activity is increased in frontal cortex of subjects with bipolar affective disorder, and lithium was demonstrated to inhibit PKC translocation to membranes. Protein kinase C is anchored to the membrane via the receptor for activated C kinase-1 (RACK1), suggesting that interactions between these proteins may be altered in bipolar disease. METHODS: The levels of RACK1 coimmunoprecipitating with PKC isozymes were compared in homogenates of frontal cortex slices from postmortem bipolar subjects and matched control subjects. RESULTS: Receptor for activated C kinase-1 was located exclusively in membranes and, in control brains, the levels of RACK1 that coimmunoprecipitated with most PKC isozymes were increased by stimulation with the PKC activator, phorbol 12-myristate, 13-acetate (PMA). The association of RACK1 with membrane gammaPKC and zetaPKC was increased under basal conditions in bipolar relative to control brains. Stimulation with PMA increased the amount of RACK1 that coimmunoprecipitated with the alpha, beta, gamma, delta, and varepsilonPKC isozymes, but not zetaPKC, in bipolar tissues over that elicited in control tissues. CONCLUSIONS: These data suggest that the increased association of RACK1 with PKC isozymes may be responsible for the increases in membrane PKC and in its activation that were previously observed in frontal cortex of bipolar affective disorder brains." [Abstract]

Escriba PV, Garcia-Sevilla JA.
Parallel modulation of receptor for activated C kinase 1 and protein kinase C-alpha and beta isoforms in brains of morphine-treated rats.
Br J Pharmacol 1999 May;127(2):343-8
"1. Receptor for activated C kinase 1 (RACK1) is an intracellular receptor for protein kinase C (PKC) that regulates the cellular enzyme localization. Because opiate drugs modulate the levels of brain PKC (Ventayol et al., 1997), the aim of this study was to assess in parallel the effects of morphine on RACK1 and PKC-alpha and beta isozymes densities in rat brain frontal cortex by immunoblot assays. 2. Acute morphine (30 mg kg(-1), i.p., 2 h) induced significant increases in the densities of RACK1 (33%), PKC-alpha (35%) and PKC-beta (23%). In contrast, chronic morphine (10-100 mg kg(-1), i.p., 5 days) induced a decrease in RACK1 levels (22%), paralleled by decreases in the levels of PKC-alpha (16%) and PKC-beta (16%). 3. Spontaneous (48 h) and naloxone (2 mg kg(-1), i.p., 2 h)-precipitated morphine withdrawal after chronic morphine induced marked up-regulations in the levels of RACK1 (38-41%), PKC-alpha (51-52%) and PKC-beta (48-62%). 4. In the same brains and for all combined treatments, there were significant positive correlations between the density of RACK1 and those of PKC-alpha (r=0.85, n = 35) and PKC-beta (r=0.75, n=32). 5. These data indicate that RACK1 is involved in the short- and long-term effects of morphine and in opiate withdrawal, and that RACK1 modulation by morphine or its withdrawal is parallel to those of PKC-alpha and beta isozymes. Since RACK1 facilitates the PKC substrate accessibility, driving its cellular localization, the coordinate regulation of the PKC/RACK system by morphine could be a relevant molecular mechanism in opiate addiction." [Abstract]

Vawter MP, Freed WJ, Kleinman JE.
Neuropathology of bipolar disorder.
Biol Psychiatry 2000 Sep 15;48(6):486-504
"The literature on the neuropathology of bipolar disorder (BD) is reviewed. Postmortem findings in the areas of pathomorphology, signal transduction, neuropeptides, neurotransmitters, cell adhesion molecules, and synaptic proteins are considered. Decreased glial numbers and density in both BD and major depressive disorder (MDD) have been reported, whereas cortical neuron counts were not different in BD (in Brodmann's areas [BAs] 9 and 24). In contrast, MDD patients showed reductions in neuronal size and density (BA 9, BA 47). There are a number of findings of alterations in neuropeptides and monoamines in BD brains. Norepinephrine turnover was increased in several cortical regions and thalamus, whereas the serotonin metabolite, 5-hydroxyindoleacetic acid, and the serotonin transporter were reduced in the cortex. Several reports further implicated both cyclic adenosine monophosphate and phosphatidylinositol (PI) cascade abnormalities. G protein concentrations and activity increases were found in the occipital, prefrontal, and temporal cortices in BD. In the PI signal cascade, alterations in PKC activity were found in the prefrontal cortex. In the occipital cortex, PI hydrolysis was decreased. Two isoforms of the neural cell adhesion molecules were increased in the hippocampus of BD, whereas the synaptic protein marker, synaptophysin, was not changed. The findings of glial reduction, excess signal activity, neuropeptide abnormalities, and monoamine alterations suggest distinct imbalances in neurochemical regulation. Possible alterations in pathways involving ascending projections from the brain stem are considered. Larger numbers of BD brains are needed to further refine the conceptual models that have been proposed, and to develop coherent models of the pathophysiology of BD." [Abstract]

Suzuki K, Kusumi I, Akimoto T, Sasaki Y, Koyama T.
Altered 5-HT-Induced Calcium Response in the Presence of Staurosporine in Blood Platelets from Bipolar Disorder Patients.
Neuropsychopharmacology. 2003 Jun;28(6):1210-4.
"We have reported that the platelet intracellular calcium (Ca) mobilization after stimulation by serotonin (5-HT) is specifically enhanced in bipolar disorder among various psychiatric disorders, compared with that in normal control. To explore the mechanisms of enhanced Ca response to 5-HT in the platelets, we first examined the relation between the 5HT-elicited Ca mobilization and 5-HT(2A) receptor density using the platelets from 13 normal subjects. From this study, we found no significant correlation between two measures. Then, we investigated the effects of staurosporine, a protein kinase C (PKC) inhibitor, on Ca response to 5-HT in platelets from patients with major depressive disorder (unipolar), bipolar disorder, and normal controls. While 5-HT-induced Ca mobilization, in the presence of 100 nM staurosporine, was significantly attenuated in normal controls and patients with major depressive disorder, the inhibitory effect of staurosporine was not observed in bipolar disorder. These results suggest that the failure in inhibiting the platelet intracellular Ca response to 5-HT in bipolar disorder may be related to increased activity of PKC rather than increased 5-HT(2A) receptor number. Moreover, the trend of the Ca response towards staurosporine may become a specific biological marker for unipolar-bipolar dichotomy." [Abstract] [Full Text]

Friedman E, Hoau-Yan-Wang, Levinson D, Connell TA, Singh H.
Altered platelet protein kinase C activity in bipolar affective disorder, manic episode.
Biol Psychiatry 1993 Apr 1;33(7):520-5 [Abstract]

Wang HY, Markowitz P, Levinson D, Undie AS, Friedman E.
Increased membrane-associated protein kinase C activity and translocation in blood platelets from bipolar affective disorder patients.
J Psychiatr Res 1999 Mar-Apr;33(2):171-9
"BACKGROUND: recent investigations have suggested that the phosphoinositide (PI) signal transduction system may be involved in the pathophysiology of bipolar affective disorders. Earlier studies in our laboratory have implicated altered PKC-mediated phosphorylation in bipolar affective disorder and in the clinical action of lithium. In the present study, we compared PKC activity and its translocation in platelets from subjects with bipolar affective disorder and three other groups. METHODS: subjects included 44 with bipolar disorder (acute manic episode), 25 with acute major depression, 23 with schizophrenia in acute exacerbation and 43 controls free of personal or family history of an Axis I disorder. Blood platelet membrane and cytosol PKC activity was measured before and after in vitro stimulation with serotonin (5-HT), thrombin and the direct PKC activator, PMA. In addition, we examined 5-HT-, thrombin- and PMA-elicited translocations of PKC isozymes from cytosol to the membrane in platelets of control subjects. RESULTS: in the basal state, manic subjects demonstrated higher membrane PKC activity than depressive and control subjects. The ratio of membrane to cytosol PKC activity was significantly higher in manic (1.10), as compared to control (0.84), depressed (0.93) or schizophrenic (0.93) subjects. Stimulation of platelets with 5-HT in vitro, resulted in greater membrane to cytosol ratio in the manic subjects compared to the three other groups. The responsiveness of platelets to PMA and thrombin was greater for manic subjects than for depressed and schizophrenic subjects, but not greater than the controls. In this measure both the schizophrenic and depressive groups were less active than controls. The results also demonstrate that platelets contain alpha-, beta-, delta- and zeta-PKC isozymes. While alpha- and beta-PKC isoforms were translocated from cytosol to membrane in response to serotonin, PMA and thrombin, serotonin also elicited the redistribution of delta-PKC and thrombin also activated zeta-PKC. CONCLUSION: the results demonstrate that a heightened PKC-mediated signal transduction is associated with acute mania and suggest a decreased transduction in patients with unipolar depression or schizophrenia." [Abstract]

Young LT, Wang JF, Woods CM, Robb JC.
Platelet protein kinase C alpha levels in drug-free and lithium-treated subjects with bipolar disorder.
Neuropsychobiology 1999;40(2):63-6
"Recent studies suggest that protein kinase C (PKC), particularly the alpha isoform, plays an important role in the action of lithium. There is, however, little evidence from patients with bipolar disorder (BD) to support this effect. The present investigation carried out comparative studies of PKC levels in platelets obtained from BD subjects including those with and without lithium treatment. All subjects met DSM-IV criteria for BD type I confirmed by structured interview (SCID-IV). Levels of PKC-alpha isoform in platelets from controls and from BD subjects were measured with immunoblotting analysis. No significant differences were found between controls, drug-free or lithium-treated BD subjects on membrane or cytosolic levels of PKC-alpha or in the membrane-to-cytosol ratio of this protein. The present study suggests that levels of PKC-alpha do not change in the peripheral tissues of BD subjects with or without lithium treatment." [Abstract]

Pandey GN, Dwivedi Y, SridharaRao J, Ren X, Janicak PG, Sharma R.
Protein kinase C and phospholipase C activity and expression of their specific isozymes is decreased and expression of MARCKS is increased in platelets of bipolar but not in unipolar patients.
Neuropsychopharmacology 2002 Feb;26(2):216-28
"Phospholipase C (PLC) and protein kinase C (PKC) are important components of the phosphoinositide (PI) signaling system. To examine if the abnormalities observed in the PI signaling system of patients with affective disorders, reported in previous studies, are related to abnormalities in one or more of its components, we studied PKC, PI-PLC activity, the expression of their specific isozymes, and expression of myristoylated alanine-rich C-kinase substrate (MARCKS) in platelets obtained from 15 drug-free hospitalized patients with bipolar disorder and 15 with major depressive disorder (unipolar) and from 15 nonhospitalized normal control subjects. We observed a significant decrease in PI-PLC and PKC activity and the expression of selective PKC alpha, betaI, betaII, and PLC delta(1) isozymes in membrane and cytosol fraction of platelets from bipolar but not unipolar patients. On the other hand, the level of MARCKS was significantly increased in membrane and cytosol fraction of platelets from patients with bipolar but not unipolar disorders. These results suggest that alterations in PKC, PLC, and MARCKS may be involved in the pathophysiology of bipolar illness." [Abstract]

Manji HK, Chen G.
PKC, MAP kinases and the bcl-2 family of proteins as long-term targets for mood stabilizers.
Mol Psychiatry 2002;7 Suppl 1:S46-56
"The complexity of the unique biology of bipolar disorder--which includes the predisposition to episodic, and often progressive, mood disturbance--and the dynamic nature of compensatory processes in the brain, coupled with limitations in experimental design, have hindered our ability to identify the underlying pathophysiology of this fascinating neuropsychiatric disorder. Although we have yet to identify the specific abnormal genes in mood disorders, recent studies have implicated critical signal transduction pathways as being integral to the pathophysiology and treatment of bipolar disorder. In particular, a converging body of preclinical data has shown that chronic lithium and valproate, at therapeutically relevant concentrations, regulate the protein kinase C signaling cascade. This has led to the investigation of the antimanic efficacy of tamoxifen (at doses sufficient to inhibit protein kinase C), with very encouraging preliminary results. A growing body of data also suggests that impairments of neuroplasticity and cellular resilience may also underlie the pathophysiology of bipolar disorder. It is thus noteworthy that mood stabilizers, such as lithium and valproate, indirectly regulate a number of factors involved in cell survival pathways--including cAMP response element binding protein, brain derived neurotrophic factor, bcl-2 and mitogen-activated protein kinases--and may thus bring about some of their delayed long-term beneficial effects via under-appreciated neurotrophic effects. The development of novel treatments, which more directly target molecules involved in critical central nervous system cell survival and cell death pathways, has the potential to enhance neuroplasticity and cellular resilience, thereby modulating the long-term course and trajectory of these devastating illnesses." [Abstract]

Chen G, Masana MI, Manji HK.
Lithium regulates PKC-mediated intracellular cross-talk and gene expression in the CNS in vivo.
Bipolar Disord 2000 Sep;2(3 Pt 2):217-36
"It has become increasingly appreciated that the long-term treatment of complex neuropsychiatric disorders like bipolar disorder (BD) involves the strategic regulation of signaling pathways and gene expression in critical neuronal circuits. Accumulating evidence from our laboratories and others has identified the family of protein kinase C (PKC) isozymes as a shared target in the brain for the long-term action of both lithium and valproate (VPA) in the treatment of BD. In rats chronically treated with lithium at therapeutic levels, there is a reduction in the levels of frontal cortical and hippocampal membrane-associated PKC alpha and PKC epsilon. Using in vivO microdialysis, we have investigated the effects of chronic lithium on the intracellular cross-talk between PKC and the cyclic AMP (cAMP) generating system in vivo. We have found that activation of PKC produces an increase in dialysate cAMP levels in both prefrontal cortex and hippocampus, effects which are attenuated by chronic lithium administration. Lithium also regulates the activity of another major signaling pathway the c-Jun N-terminal kinase pathway--in a PKC-dependent manner. Both Li and VPA, at therapeutically relevant concentrations, increase the DNA binding of activator protein 1 (AP-1) family of transcription factors in cultured cells in vitro, and in rat brain ex vivo. Furthermore, both agents increase the expression of an AP-1 driven reporter gene, as well as the expression of several endogenous genes known to be regulated by AP-1. Together, these results suggest that the PKC signaling pathway and PKC-mediated gene expression may be important mediators of lithium's long-term therapeutic effects in a disorder as complex as BD." [Abstract]

Chen, G, Manji, HK, Hawver, DB, Wright, CB, Potter, WZ
Chronic sodium valproate selectively decreases protein kinase C alpha and epsilon in vitro
J Neurochem 1994 63: 2361-2364
"Valproic acid (VPA) is a fatty acid antiepileptic with demonstrated antimanic properties, but the molecular mechanism or mechanisms underlying its therapeutic efficacy remain to be elucidated. In view of the increasing evidence demonstrating effects of the first-line antimanic drug, lithium, on protein kinase C (PKC), we investigated the effects of VPA on various aspects of this enzyme. Chronic exposure (6-7 days) of rat C6 glioma cells to "therapeutic" concentrations (0.6 mM) of VPA resulted in decreased PKC activity in both membrane and cytosolic fractions and increased the cytosol/membrane ratio of PKC activity. Western blot analysis revealed isozyme-selective decreases in the levels of PKC alpha and epsilon (but not delta or zeta) in both the membrane and cytosolic fractions after chronic VPA exposure; VPA added to reaction mixtures did not alter PKC activity or 3H-phorbol ester binding. Together, these data suggest that chronic VPA indirectly lowers the levels of specific isozymes of PKC in C6 cells. Given the pivotal role of PKC in regulating neuronal signal transduction and modulating intracellular cross-talk between neurotransmitter systems, the specific decreases in PKC alpha and epsilon may play a role in the antimanic effects of VPA." [Abstract]

Manji HK, Etcheberrigaray R, Chen G, Olds JL.
Lithium decreases membrane-associated protein kinase C in hippocampus: selectivity for the alpha isozyme.
J Neurochem 1993 Dec;61(6):2303-10
"We investigated the effects of lithium on alterations in the amount and distribution of protein kinase C (PKC) in discrete areas of rat brain by using [3H]phorbol 12,13-dibutyrate quantitative autoradiography as well as western blotting. Chronic administration of lithium resulted in a significant decrease in membrane-associated PKC in several hippocampal structures, most notably the subiculum and the CA1 region. In contrast, only modest changes in [3H]phorbol 12,13-dibutyrate binding were observed in the various other cortical and subcortical structures examined. Immunoblotting using monoclonal anti-PKC antibodies revealed an isozyme-specific 30% decrease in hippocampal membrane-associated PKC alpha, in the absence of any changes in the labeling of either the beta (I/II) or gamma isozymes. These changes were observed only after chronic (4 week) treatment with lithium, and not after acute (5 days) treatment, suggesting potential clinical relevance. Given the critical role of PKC in regulating neuronal signal transduction, lithium's effects on PKC in the limbic system represent an attractive molecular mechanism for its efficacy in treating both poles of manic-depressive illness. In addition, the decreased hippocampal membrane-associated PKC observed in the present study offers a possible explanation for lithium-induced memory impairment." [Abstract]

Soares JC, Chen G, Dippold CS, Wells KF, Frank E, Kupfer DJ, Manji HK, Mallinger AG.
Concurrent measures of protein kinase C and phosphoinositides in lithium-treated bipolar patients and healthy individuals: a preliminary study.
Psychiatry Res 2000 Aug 21;95(2):109-18
"This study examined the hypothesis that lithium inhibits the PI signaling pathway in humans during in vivo administration by concurrently measuring PKC isozymes and platelet membrane phosphoinositides in lithium-treated patients and healthy individuals. The platelet membrane and cytosolic levels of PKC alpha, beta I, beta II, delta, and epsilon were measured using Western blotting. The relative platelet membrane contents of phosphatidylinositol (PI), phosphatidylinositol-4-phosphate (PIP), and phosphatidylinositol-4,5-bisphosphate (PIP(2)) were measured with two-dimensional thin-layer chromatography. Nine euthymic lithium-treated bipolar subjects and 11 healthy control subjects were studied. Compared to control subjects, lithium-treated bipolar patients had significantly lower levels of cytosolic PKC alpha isozyme (t-test=-3.24, d.f.=17, P=0.01) and PIP(2) platelet membrane levels (t-test=-2.51, d.f.=18, P=0.02), and a trend toward reduced levels of cytosolic PKC beta II isozyme (t=-2.17, d.f.=17, P=0.05). There was no significant correlation between PIP(2) and any of the PKC isozymes. These preliminary findings suggest that chronic lithium treatment may decrease the levels of both cytosolic PKC alpha isozyme and membrane PIP(2) in platelets of bipolar disorder patients." [Abstract]

Seung Kim HF, Weeber EJ, Sweatt JD, Stoll AL, Marangell LB.
Inhibitory effects of omega-3 fatty acids on protein kinase C activity in vitro.
Mol Psychiatry 2001 Mar;6(2):246-8
"Preliminary clinical data indicate that omega-3 fatty acids may be effective mood stabilizers for patients with bipolar disorder. Both lithium and valproic acid are known to inhibit protein kinase C (PKC) activity after subchronic administration in cell culture and in vivo. The current study was undertaken to determine the effects of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on protein kinase C phosphotransferase activity in vitro. Various concentrations of DHA, EPA, and arachidonic acid (AA) were incubated with the catalytic domain of protein kinase C beta from rat brain. Protein kinase C activity was measured by quantifying incorporation of (32)P-PO(4) into a synthetic peptide substrate. Both DHA and EPA, as well as the combination of DHA and EPA, inhibited PKC activity at concentrations as low as 10 micromol l(-1). In contrast, arachidonic acid had no effect on PKC activity. Thus, PKC represents a potential site of action of omega-3 fatty acids in their effects on the treatment of bipolar disorder." [Abstract]

Morishita S, Aoki S, Watanabe S.
Different effect of desipramine on protein kinase C in platelets between bipolar and major depressive disorders.
Psychiatry Clin Neurosci 1999 Feb;53(1):11-5
"Protein kinase C (PKC) activity was investigated in platelets from affective disorder subjects and healthy volunteers. The PKC activity of platelets incubated with desipramine was determined in vitro. The PKC activity of the major depressive disorder subjects and healthy volunteers was inhibited by desipramine, whereas that of the bipolar disorder subjects showed both inhibition and activation. In addition, the base PKC activity incubation with antidepressants of the major depressive disorder patients was significantly higher than of the bipolar disorder patients. These preliminary results suggest that the function of PKC may, at least in part, be associated with the mechanism of affective disorder." [Abstract]

Gould TD, Manji HK.
Signaling networks in the pathophysiology and treatment of mood disorders.
J Psychosom Res. 2002 Aug;53(2):687-97.
"Over the past decade, the focus of research into the pathophysiology of mood disorders (bipolar disorder and unipolar depression in particular) has shifted from an interest in the biogenic amines to an emphasis on second messenger systems within cells. Second messenger systems rely on cell membrane receptors to relay information from the extracellular environment to the interior of the cell. Within the cell, this information is processed and altered, eventually to the point where gene and protein expression patterns are changed. There is a preponderance of evidence implicating second messenger systems and their primary contact with the extracellular environment, G proteins, in the pathophysiology of mood disorders. After an introduction to G proteins and second messenger pathways, this review focuses on the evidence implicating G proteins and two second messenger systems-the adenylate cyclase (cyclic adenosine monophosphate, cAMP) and phosphoinositide (protein kinase C, PKC) intracellular signaling cascades-in the pathophysiology and treatment of bipolar disorder and unipolar depression. Emerging evidence implicates changes in cellular resiliency, neuroplasticity and additional cellular pathways in the pathophysiology of mood disorders. The systems discussed within this review have been implicated in neuroplastic processes and in modulation of many other cellular pathways, making them likely candidates for mediators of these findings." [Abstract]

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Recent Bipolar Disorder & PKC Research

1) Ha CM, Park D, Han JK, Jang JI, Park JY, Hwang EM, Seok H, Chang S
Calcyon forms a novel ternary complex with dopamine D1 receptor through PSD-95 and plays a role in dopamine receptor internalization.
J Biol Chem. 2012 Jul 26;
Calcyon, once known for interacting directly with the dopamine D1 receptor (D1DR), is implicated in various neuropsychiatric disorders including schizophrenia, bipolar disorder and ADHD. Although its direct interaction with D1DR has been shown to be misinterpreted, it still plays important roles in the D1DR signaling. Here, we found that calcyon interacts with the PSD-95 and subsequently forms a ternary complex with D1DR through PSD-95. Calcyon is phosphorylated on Ser169 by the PKC activator PMA or by the D1DR agonist SKF81297, and its phosphorylation increases its association with PSD-95 and recruitment to the cell surface. Interestingly, the internalization of D1DR at the cell surface was enhanced by PMA and SKF81297 in the presence of calcyon, but not in the presence of its S169A phospho-deficient mutant, suggesting that the phosphorylation of caclyon and the internalization of the surface D1DR are tightly correlated. Our results suggest that calcyon regulates D1DR trafficking by forming a ternary complex with D1DR through PSD-95 and thus, possibly linking a glutamatergic and dopamine receptor signalings. This also raises the possibility that a novel ternary complex could represent a potential therapeutic target for the modulation of related neuropsychiatric disorders. [PubMed Citation] [Order full text from Infotrieve]

2) Kovtun O, Tomlinson ID, Sakrikar DS, Chang JC, Blakely RD, Rosenthal SJ
Visualization of the cocaine-sensitive dopamine transporter with ligand-conjugated quantum dots.
ACS Chem Neurosci. 2011 Jul 20;2(7):370-8.
The presynaptic dopamine (DA) transporter is responsible for DA inactivation following release and is a major target for the psychostimulants cocaine and amphetamine. Dysfunction and/or polymorphisms in human DAT (SLC6A3) have been associated with schizophrenia, bipolar disorder, Parkinson's disease, and attention-deficit hyperactivity disorder (ADHD). Despite the clinical importance of DAT, many uncertainties remain regarding the transporter's regulation, in part due to the poor spatiotemporal resolution of conventional methodologies and the relative lack of efficient DAT-specific fluorescent probes. We developed a quantum dot-based labeling approach that uses a DAT-specific, biotinylated ligand, 2-?-carbomethoxy-3-?-(4-fluorophenyl)tropane (IDT444), that can be bound by streptavidin-conjugated quantum dots. Flow cytometry and confocal microscopy were used to detect DAT in stably and transiently transfected mammalian cells. IDT444 is useful for quantum-dot-based fluorescent assays to monitor DAT expression, function, and plasma membrane trafficking in living cells as evidenced by the visualization of acute, protein-kinase-C (PKC)-dependent DAT internalization. [PubMed Citation] [Order full text from Infotrieve]

3) Koenigsberg HW, Yuan P, Diaz GA, Guerreri S, Dorantes C, Mayson S, Zamfirescu C, New AS, Goodman M, Manji HK, Siever LJ
Platelet protein kinase C and brain-derived neurotrophic factor levels in borderline personality disorder patients.
Psychiatry Res. 2012 May 25;
Borderline personality disorder (BPD) is a prevalent and difficult to treat psychiatric condition characterized by abrupt mood swings, intense anger and depression, unstable interpersonal relationships, impulsive self-destructive behavior and a suicide rate of approximately 10%. Possible underlying molecular dysregulations in BPD have not been well explored. Protein kinase C (PKC) and brain-derived neurotrophic factor (BDNF) have both been implicated in affective disorders, but their role in BPD has not been examined. Platelets were isolated from blood obtained from 24 medication-free BPD patients and 18 healthy control subjects. PKC-?, phosphorylated-PKC-? (p-PKC?), PKC-?II, and BDNF were measured in platelet homogenates by immunoblotting. In the males, platelet BDNF and PKC-? levels were lower in patients than controls. p-PKC-? and PKC-?II were lower at trend levels. In the entire sample, platelet p-PKC? and PKC-? activity were lower, at a trend level, in patients compared to controls. This is the first report to our knowledge of PKC and BDNF activity in BPD and calls for replication. These findings are consistent with altered PKC and BDNF activity in a range of neuropsychiatric conditions including bipolar disorder, depression and suicide. [PubMed Citation] [Order full text from Infotrieve]

4) Steckert AV, Valvassori SS, Mina F, Lopes-Borges J, Varela RB, Kapczinski F, Dal-Pizzol F, Quevedo J
Protein kinase C and oxidative stress in an animal model of mania.
Curr Neurovasc Res. 2012 Feb;9(1):47-57.
The present study aims to investigate the effects of protein kinase C using the inhibitor Tamoxifen (TMX) on oxidative stress in a rat animal model of mania induced by d-amphetamine (d-AMPH). In the reversal model, d-AMPH or saline (Sal) were administered to rats for 14 days, and between days 8-14, rats were treated with TMX or Sal. In the prevention model, rats were pretreated with TMX or Sal, and between days 8-14, d-AMPH or Sal were administrated. In both experiments locomotor activity and risk-taking behavior were assessed by open-field test and oxidative stress was measured in prefrontal, amygdala, hippocampus and striatum. The results showed that TMX reversed and prevented d- AMPH-induced behavioral effects. In addition, the d-AMPH administration induced oxidative damage in both structures tested in two models. The TMX was able to reverse and prevent this impairment, however in a way dependent of cerebral area and technique evaluated. These findings reinforce the hypothesis that PKC play an important role in the pathophysiology of BD and the need for the study of inhibitors of PKC as a possible target for treatment the BD. [PubMed Citation] [Order full text from Infotrieve]

5) Kandaswamy R, McQuillin A, Curtis D, Gurling H
Tests of linkage and allelic association between markers in the 1p36 PRKCZ (protein kinase C zeta) gene region and bipolar affective disorder.
Am J Med Genet B Neuropsychiatr Genet. 2012 Mar;159B(2):201-9.
Three linkage studies of families with multiple cases of bipolar disorder and/or unipolar affective disorder have confirmed the involvement of the chromosome 1p36 region in the etiology of affective disorders with LOD scores of 2.7, 3.6, and 3.97. We investigated the protein kinase C zeta gene (PRKCZ) as a susceptibility locus for bipolar disorder because it is highly brain expressed and is localized close to the marker D1S243 which was linked to affective disorder in a single large UCL bipolar disorder family with a LOD of 3.1. PRKCZ encodes an unusual type of protein kinase which affects axonal differentiation through Wnt-signaling. We genotyped four microsatellite markers and nine single nucleotide polymorphism (SNP) markers within or near the PRKCZ gene in the UCL case-control sample of 600 bipolar disorder patients and up to 605 supernormal controls. Markers D1S243 and rs3128396 were significantly associated with bipolar disorder (empirical P = 0.037 and P = 0.040, respectively). We also included data from eight SNPs which were genotyped as part of our GWA study on bipolar disorder for association analysis. Tests of haplotypic association found that a haplotype block comprising markers rs3128296, rs2503706, and rs3128309 was associated with bipolar disorder (empirical P = 0.004). A previous linkage study had shown greater evidence for linkage within female cases compared to males. Therefore, to assess if the association was sex-specific, we performed a female-only allelic-association analysis, which resulted in SNPs rs3128296 and rs3128309 becoming associated with bipolar disorder (P = 0.004 and P = 0.016, respectively). PRKCZ may play a role in susceptibility to bipolar affective disorder. [PubMed Citation] [Order full text from Infotrieve]

6) Armani F, Andersen ML, Andreatini R, Frussa-Filho R, Tufik S, Galduróz JC
Successful combined therapy with tamoxifen and lithium in a paradoxical sleep deprivation-induced mania model.
CNS Neurosci Ther. 2012 Feb;18(2):119-25.
[PubMed Citation] [Order full text from Infotrieve]

7) Abrial E, Lucas G, Scarna H, Haddjeri N, Lambás-Seńas L
A role for the PKC signaling system in the pathophysiology and treatment of mood disorders: involvement of a functional imbalance?
Mol Neurobiol. 2011 Dec;44(3):407-19.
Mood disorders, such as bipolar and major depressive disorders, are frequent, severe, and often disabling neuropsychiatric diseases affecting millions of individuals worldwide. Available mood stabilizers and antidepressants remain unsatisfactory because of their delayed and partial therapeutic efficacy. Therefore, the development of targeted therapies, working more rapidly and being fully effective, is urgently needed. In this context, the protein kinase C (PKC) signaling system, which regulates multiple neuronal processes implicated in mood regulation, can constitute a novel therapeutic target. This paper reviews the currently available knowledge regarding the role of the PKC signaling pathway in the pathophysiology of mood disorders and the therapeutic potential of PKC modulators. Current antidepressants and mood stabilizers have been shown to modulate the PKC pathway, and the inhibition of this intracellular signaling cascade results in antimanic-like properties in animal models. Disrupted PKC activity has been found both in postmortem brains and platelet from patients with mood disorders. Finally, the PKC inhibitor tamoxifen has recently demonstrated potent antimanic properties in several clinical trials. Overall, emerging data from preclinical and clinical research suggest an imbalance of the PKC signaling system in mood disorders. Thus, PKC may be a critical molecular target for the development of innovative therapeutics. [PubMed Citation] [Order full text from Infotrieve]

8) Li X, Law JW, Lee AY
Semaphorin 5A and plexin-B3 regulate human glioma cell motility and morphology through Rac1 and the actin cytoskeleton.
Oncogene. 2012 Feb 2;31(5):595-610.
Semaphorins are implicated in glioma progression, although little is known about the underlying mechanisms. We have reported plexin-B3 expression in human gliomas, which upon stimulation by Sema5A causes significant inhibition of cell migration and invasion. The concomitant inactivation of Rac1 is of mechanistic importance because forced expression of constitutively active Rac1 abolishes these inhibitory effects. Furthermore, Sema5A induces prominent cell collapse and ramification of processes reminiscent of astrocytic morphology, which temporally associate with extensive disassembly of actin stress fibers and disruption of focal adhesions, followed by accumulation of actin patches in protrusions. Mechanistically, Sema5A induces transient protein kinase C (PKC) phosphorylation of fascin-1, which can reduce its actin-binding/bundling activities and temporally parallels its translocation from cell body to extending processes. PKC inhibition or fascin-1 knockdown is sufficient to abrogate Sema5A-induced morphological differentiation, whereas the process is hastened by forced expression of fascin-1. Intriguingly, Sema5A induces re-expression of glial fibrillary acidic protein (GFAP), which when silenced restricts differentiation of glioma cells to bipolar instead of multipolar morphology. Therefore, we hypothesize complementary functions of fascin-1 and GFAP in the early and late phases of Sema5A-induced astrocytic differentiation of gliomas, respectively. In summary, Sema5A and plexin-B3 impede motility but promote differentiation of human gliomas. These effects are plausibly compromised in high-grade human astrocytomas in which Sema5A expression is markedly reduced, hence leading to infiltrative and anaplastic characteristics. This is evident by increased invasiveness of glioma cells when endogenous Sema5A is silenced. Therefore, Sema5A and plexin-B3 represent potential novel targets in counteracting glioma progression. [PubMed Citation] [Order full text from Infotrieve]

9) Xuqian W, Kanghua L, Weihong Y, Xi Y, Rongping D, Qin H, Fangtian D, Chunhua Zhao R
Intraocular Transplantation of Human Adipose-Derived Mesenchymal Stem Cells in a Rabbit Model of Experimental Retinal Holes.
Ophthalmic Res. 2011 Apr 5;46(4):199-207.
Aims: To investigate whether human adipose-derived mesenchymal stem cell (hAD-MSC) transplantation would ameliorate the healing process of a rabbit model of retinal holes. Methods: Retinal holes were made in the left eyes of 20 New Zealand white rabbits and randomly filled by hAD-MSCs (transplantation group) or phosphate-buffered saline (control group), respectively. Frequency-domain optical coherence tomography (OCT) scan was performed on days 2, 4, 12, 20 and 32 postoperatively, and immunofluorescence was performed on days 12 and 32 to further identify the cell types of the injured area. Results: Frequency-domain OCT scan showed that the mean center thickness of the reconstructed tissue reached a normal level on day 12 in the transplantation group, while in the control group, the mean center thickness was normal on day 32. Furthermore, compared to the control group where only anti-glial fibrillary acidic protein-labeled glial-like cells were detected, donor-derived opsin-positive photoreceptor-like cells and protein kinase C-positive bipolar-like cells were sporadically found in the transplantation group. Conclusions: Transplanted hAD-MSCs could engraft in the retinal hole of a rabbit model, and clearly accelerated the healing process and ameliorated injury recovery. [PubMed Citation] [Order full text from Infotrieve]

10) Peng L, Li B, Du T, Wang F, Hertz L
Does conventional anti-bipolar and antidepressant drug therapy reduce NMDA-mediated neuronal excitation by downregulating astrocytic GluK2 function?
Pharmacol Biochem Behav. 2012 Feb;100(4):712-25.
Chronic treatment with anti-bipolar drugs (lithium, carbamazepine, and valproic acid) down-regulates mRNA and protein expression of kainate receptor GluK2 in mouse brain and cultured astrocytes. It also abolishes glutamate-mediated, Ca(2+)-dependent ERK(1/2) phosphorylation in the astrocytes. Chronic treatment with the SSRI fluoxetine enhances astrocytic GluK2 expression, but increases mRNA editing, abolishing glutamate-mediated ERK(1/2) phosphorylation and [Ca(2+)](i) increase, which are shown to be GluK2-mediated. Neither drug group affects Glu4/Glu5 expression necessary for GluK2's ionotropic effect. Consistent with a metabotropic effect, the PKC inhibitor GF 109203X and the IP(3) inhibitor xestospongin C abolish glutamate stimulation in cultured astrocytes. In CA1/CA3 pyramidal cells in hippocampal slices, activation of extrasynaptic GluK2 receptors, presumably including astrocytic, metabotropic GluK2 receptors, causes long-lasting inhibition of slow neuronal afterhyperpolarization mediated by Ca(2+)-dependent K(+) flux. This may be secondary to the induced astrocytic [Ca(2+)](i) increase, causing release of 'gliotransmitter' glutamate. Neuronal NMDA receptors respond to astrocytic glutamate release with enhancement of excitatory glutamatergic activity. Since reduction of NMDA receptor activity is known to have antidepressant effect in bipolar depression and major depression, these observations suggest that the inactivation of astrocytic GluK2 activity by antidepressant/anti-bipolar therapy ameliorates depression by inhibiting astrocytic glutamate release. A resultant strengthening of neuronal afterhyperpolarization may cause reduced NMDA-mediated activity. [PubMed Citation] [Order full text from Infotrieve]

11) Moretti M, Valvassori SS, Steckert AV, Rochi N, Benedet J, Scaini G, Kapczinski F, Streck EL, Zugno AI, Quevedo J
Tamoxifen effects on respiratory chain complexes and creatine kinase activities in an animal model of mania.
Pharmacol Biochem Behav. 2011 Apr;98(2):304-10.
The present study aimed to investigate the effects of tamoxifen (TMX) on locomotor behavior and on the activities of mitochondrial respiratory chain complexes and creatine kinase (CK) in the brain of rats subjected to an animal model of mania induced by d-amphetamine (D-AMPH)-reversion and prevention protocols. The D-AMPH administration increased locomotor activity in saline-treated rats under prevention and reversion treatment; furthermore, there was evident reduction in the locomotion in the D-amphetamine group treated with TMX. D-AMPH significantly decreased the activity of mitochondrial respiratory chain complexes in saline-treated rats in prefrontal cortex, hippocampus, striatum and amygdala in both prevention and reversion treatment. Depending on the cerebral area and evaluated complex, TMX was able to prevent and reverse this impairment. A decrease in CK activity was also verified in the brain of rats when D-AMPH was administrated in both experiments; the administration of TMX reversed but not prevented the decrease in CK activity induced by D-AMPH. The present study demonstrated that TMX reversed and prevented the alterations in behavioral and energy metabolism induced by D-AMPH (alterations were also observed in bipolar disorder), reinforcing the need for more studies about inhibitors of PKC as possible targets for new medications in the treatment of bipolar disorder. [PubMed Citation] [Order full text from Infotrieve]

12) Galeotti N, Ghelardini C
Antidepressant phenotype by inhibiting the phospholipase Cβ(1)--protein kinase Cγ pathway in the forced swim test.
Neuropharmacology. 2011 May;60(6):937-43.
Although great advances have recently been made in the study of signal transduction, the pathogenesis of affective disorders is still unknown. There is mounting evidence suggesting that elevated phosphoinositide-protein kinase C (PI-PKC) signal transduction pathway may be a pathophysiological feature of bipolar and major depressive disorders. The aim of the present study was to further investigated the phospholipase C-protein kinase C (PLC-PKC) cascade by evaluating the effect produced by an acute blockade of this intracellular pathway at PLC and PKC level. Adult male mice were administered with pharmacological inhibitors of PLC or PKC and then subjected to the forced swim test (FST), an animal model which emulates the behavioural despair paradigm of depression. In this study we also tested the hypothesis that it might be possible to selectively modulate depressive behaviour by inhibiting the expression of specific PLC and PKC isoforms by means of specific antisense oligonucleotides (aODNs). Administration of the PLC inhibitors neomycin and U73122 as well as of the PKC inhibitors calphostin C and chelerytrine dose-dependently reduced the immobility time in the FST producing an antidepressant-like behaviour. Selective knockdown of the PLC?(1) and PKC? isoforms also induced an antidepressant phenotype. Conversely, the inhibition of the expression of PLC?(3) was unable to modify the immobility time values. The PLC and PKC modulators used, at the highest effective doses, altered neither locomotor activity nor motor coordination. We demonstrate that selective blockade of PLC?(1)-PKC? signalling pathway produces an antidepressant-like phenotype in mice. [PubMed Citation] [Order full text from Infotrieve]

13) Perlis RH, Huang J, Purcell S, Fava M, Rush AJ, Sullivan PF, Hamilton SP, McMahon FJ, Schulze TG, Schulze T, Potash JB, Zandi PP, Willour VL, Penninx BW, Boomsma DI, Vogelzangs N, Middeldorp CM, Rietschel M, Nöthen M, Cichon S, Gurling H, Bass N, McQuillin A, Hamshere M, Craddock N, Sklar P, Smoller JW
Genome-wide association study of suicide attempts in mood disorder patients.
Am J Psychiatry. 2010 Dec;167(12):1499-507.
[PubMed Citation] [Order full text from Infotrieve]

14) O'Brien BJ, Hirano AA, Buttermore ED, Bhat MA, Peles E
Localization of the paranodal protein Caspr in the mammalian retina.
Mol Vis. 2010;16:1854-63.
[PubMed Citation] [Order full text from Infotrieve]

15) Amrollahi Z, Rezaei F, Salehi B, Modabbernia AH, Maroufi A, Esfandiari GR, Naderi M, Ghebleh F, Ahmadi-Abhari SA, Sadeghi M, Tabrizi M, Akhondzadeh S
Double-blind, randomized, placebo-controlled 6-week study on the efficacy and safety of the tamoxifen adjunctive to lithium in acute bipolar mania.
J Affect Disord. 2011 Mar;129(1-3):327-31.
[PubMed Citation] [Order full text from Infotrieve]

16) Machado-Vieira R, Salvadore G, DiazGranados N, Ibrahim L, Latov D, Wheeler-Castillo C, Baumann J, Henter ID, Zarate CA
New therapeutic targets for mood disorders.
ScientificWorldJournal. 2010;10:713-26.
Existing pharmacological treatments for bipolar disorder (BPD) and major depressive disorder (MDD) are often insufficient for many patients. Here we describe a number of targets/compounds that clinical and preclinical studies suggest could result in putative novel treatments for mood disorders. These include: (1) glycogen synthase kinase-3 (GSK-3) and protein kinase C (PKC), (2) the purinergic system, (3) histone deacetylases (HDACs), (4) the melatonergic system, (5) the tachykinin neuropeptides system, (6) the glutamatergic system, and (7) oxidative stress and bioenergetics. The paper reviews data on new compounds that have shown antimanic or antidepressant effects in subjects with mood disorders, or similar effects in preclinical animal models. Overall, an improved understanding of the neurobiological underpinnings of mood disorders is critical in order to develop targeted treatments that are more effective, act more rapidly, and are better tolerated than currently available therapies. [PubMed Citation] [Order full text from Infotrieve]

17) Ali SM, Ahmad A, Shahabuddin S, Ahmad MU, Sheikh S, Ahmad I
Endoxifen is a new potent inhibitor of PKC: a potential therapeutic agent for bipolar disorder.
Bioorg Med Chem Lett. 2010 Apr 15;20(8):2665-7.
Protein kinase C (PKC) plays a major role in regulation of both pre and postsynaptic neurotransmission. Excessive activation of PKC results in symptoms related to bipolar disorder. Tamoxifen, a widely used breast cancer drug is known to inhibit PKC and demonstrate antimanic properties in human. We describe herein the synthesis of endoxifen, a tamoxifen active metabolite and compared its PKC inhibitory activity with that of tamoxifen. Endoxifen exhibited fourfold higher potency compared to tamoxifen. [PubMed Citation] [Order full text from Infotrieve]

18) Pavan C, Vindigni V, Michelotto L, Rimessi A, Abatangelo G, Cortivo R, Pinton P, Zavan B
Weight gain related to treatment with atypical antipsychotics is due to activation of PKC-β.
Pharmacogenomics J. 2010 Oct;10(5):408-17.
Atypical antipsychotics (APDs) are currently used in clinical practice for a variety of mental disorders such as schizophrenia, bipolar disorder and severe behavioral disturbances. A well-known disadvantage of using these compounds is a propensity for weight gain, resulting frequently in obesity. The mechanisms underlying pharmacologically induced weight gain are still controversial. The objective of this study was to evaluate in vitro the effects of different APDs on adipogenic events in cultured human pre-adipocytes and in rat muscle-derived stem cells (MDSCs), aiming to identify a common intracellular event contributable to these drugs. Culture behavior was evaluated in terms of cell proliferation, lipid accumulation, gene expression and morphological features. Results indicate that APDs influence adipogenic events through changes in the differentiation and proliferation of pre-adipocytes and MDSCs that are brought on by protein kinase C-? (PKC-?) activation. These data identify a signaling route that could be a potential target of pharmacological approaches for preventing the weight gain associated with APD treatment. [PubMed Citation] [Order full text from Infotrieve]

19) Barbier E, Wang JB
Anti-depressant and anxiolytic like behaviors in PKCI/HINT1 knockout mice associated with elevated plasma corticosterone level.
BMC Neurosci. 2009;10:132.
[PubMed Citation] [Order full text from Infotrieve]

20) Herrick S, Evers DM, Lee JY, Udagawa N, Pak DT
Postsynaptic PDLIM5/Enigma Homolog binds SPAR and causes dendritic spine shrinkage.
Mol Cell Neurosci. 2010 Feb;43(2):188-200.
Dendritic spine morphology is thought to play important roles in synaptic development and plasticity, and morphological derangements in spines are correlated with several neurological disorders. Here, we identified an interaction between Spine-Associated RapGAP (SPAR), a postsynaptic protein that reorganizes actin cytoskeleton and drives dendritic spine head growth, and PDLIM5/Enigma Homolog (ENH), a PDZ-LIM (postsynaptic density-95/Discs large/zona occludens 1-Lin11/Isl-1/Mec3) family member. PDLIM5 has been implicated in susceptibility to bipolar disorder, major depression, and schizophrenia, but its function in neurological disease is poorly understood. We show that PDLIM5 is present in the postsynaptic density, where it promotes decreased dendritic spine head size and longer, filopodia-like morphology. Conversely, RNA interference against PDLIM5 or loss of PDLIM5 interaction with SPAR caused increased spine head diameter. Furthermore, PKC activation promoted delivery of PDLIM5 into dendritic spines and increased its spine colocalization with SPAR. These data reveal new postsynaptic functions for PDLIM5 in shrinkage of dendritic spines that may be relevant to its association with psychiatric illness. [PubMed Citation] [Order full text from Infotrieve]