Role of protein kinase C in the pigment cell of the lizard (Anolis carolinensis)

1987 ◽  
Vol 112 (2) ◽  
pp. 283-287 ◽  
Author(s):  
A. M. Lucas ◽  
A. J. Thody ◽  
S. Shuster
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Pigment Cell ◽  
Anolis Carolinensis ◽  
Regulatory Subunit ◽  
Dependent Manner ◽  
Kinase C

ABSTRACT The role of protein kinase C in melanosome dispersion was examined using the melanophores of the lizard Anolis carolinensis and an in-vitro rate method of bioassay. The phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA), which directly activates protein kinase C, was able to potentiate the melanophore response to α-MSH in a dose-dependent manner. Similarly, the stimulatory response to forskolin, which activates the adenylate cyclase catalytic subunit, was also potentiated by TPA. The response of the melanophore to cyclic AMP, however, remained unaltered by any dose of TPA. We thus propose that the potentiation of α-MSH potency by TPA is through an interaction of protein kinase C with adenylate cyclase and, more specifically, that this interaction may be at the level of the linkage of the nucleotide regulatory subunit Ns with the catalytic moiety C of adenylate cyclase. J. Endocr. (1987) 112, 283–287

The role of protein kinase C in LHRH-induced LH and FSH release and LHRH self-priming in rat anterior pituitary glands in vitro

1988 ◽  
Vol 116 (2) ◽  
pp. 231-239 ◽  
Author(s):  
M. S. Johnson ◽  
R. Mitchell ◽  
G. Fink
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Esters ◽  
Polymyxin B ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Kinase C ◽  
Pituitary Glands

ABSTRACT We have investigated the role of protein kinase C (PKC) in LHRH-induced LH and FSH secretion and LHRH priming. Hemipituitary glands from pro-oestrous rats were incubated with agents known to affect PKC and with or without LHRH, during which time the secretion of gonadotrophins was measured. Phorbol esters and phospholipase C, activators of PKC, released LH and FSH in a concentration-dependent manner and potentiated the LHRH-induced secretion of gonadotrophins in parallel with their ability to release these hormones alone. Inhibitors of PKC had either no effect on LH release (1-(5-isoquinolinesulphonyl)-2-methylpiperazine hydrochloride) or they augmented LHRH-induced gonadotrophin release (polymyxin B and 8-(N,N-diethylamino) octyl-3,4,5-trimethoxybenzoate). Neither the activators nor the inhibitors of PKC, when present with LHRH, caused any change in LHRH priming, even though the activators alone produced a release of gonadotrophins that showed a temporal pattern similar to that produced by LHRH priming. The profiles of effects on LH and FSH secretion were always qualitatively similar. These results show that PKC may be involved in general regulation of gonadotrophin release but that it is not important in acute responses to LHRH nor in LHRH self-priming. J. Endocr. (1988) 116, 231–239

Activation of protein kinase C attenuates prostaglandin E2 responses in a colonic cell line

1988 ◽  
Vol 255 (1) ◽  
pp. G27-G32 ◽  
Author(s):  
G. Warhurst ◽  
N. B. Higgs ◽  
M. Lees ◽  
A. Tonge ◽  
L. A. Turnberg
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Prostaglandin E2 ◽  
Cell Line ◽  
Cellular Response ◽  
Short Circuit ◽  
Regulatory Subunit ◽  
Epithelial Cell Line ◽  
Kinase C

We examined the possibility that the protein kinase C pathway may interact with the adenosine 3',5'-cyclic monophosphate (cAMP) pathway in intestinal epithelium by studying the influence of phorbol esters on the response to prostaglandin E2 (PGE2) in a colonic epithelial cell line. Pretreatment of T84 cells with 4 beta-phorbol 12,13-dibutyrate (PDB) markedly attenuated the rise in short-circuit current provoked by PGE2, a receptor-mediated cAMP agonist. The EC50 of this effect was 52 nM PDB with a half time of 4-6 min. The responses to nonreceptor-mediated agonists, forskolin and dibutyryl cAMP, were unaffected by phorbol ester. PDB also reduced the ability of PGE2 to stimulate adenylate cyclase activity in these cells. The accumulation of cAMP in response to PGE2 was inhibited by PDB (EC50 38 nM), an effect mimicked by the diacylglycerol analogue 1-oleoyl-2-acetyl-sn-glycerol. In addition, PGE2 stimulation of adenylate cyclase in membranes from PDB-treated cells was reduced by 30-40%. Inhibition was not mediated via the catalytic or regulatory subunit of the adenylate cyclase, implying an action involving desensitization of PGE2 receptors. These results provide evidence of a complex interrelationship between protein kinase C- and cAMP-mediated pathways that might be important in regulating the cellular response to secretagogues.

14-3-3 Isotypes facilitate coupling of protein kinase C-ζ to Raf-1: negative regulation by 14-3-3 phosphorylation

2000 ◽  
Vol 345 (2) ◽  
pp. 297-306 ◽  
Author(s):  
Paulus C. J. VAN DER HOEVEN ◽  
José C. M. VAN DER WAL ◽  
Paula RUURS ◽  
Marc C. M. VAN DIJK ◽  
Wim J. VAN BLITTERSWIJK
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Complex Formation ◽  
Dependent Manner ◽  
Cos Cells ◽  
Kinase C ◽  
Pkc Ζ ◽  
Co Precipitation

14-3-3 Proteins may function as adapters or scaffold in signal-transduction pathways. We found previously that protein kinase C-ζ (PKC-ζ) can phosphorylate and activate Raf-1 in a signalling complex [van Dijk, Hilkmann and van Blitterswijk (1997) Biochem. J. 325, 303-307]. We report now that PKC-ζ-Raf-1 interaction is mediated by 14-3-3 proteins in vitro and in vivo. Co-immunoprecipitation experiments in COS cells revealed that complex formation between PKC-ζ and Raf-1 is mediated strongly by the 14-3-3β and -θ isotypes, but not by 14-3-3ζ. Far-Western blotting revealed that 14-3-3 binds PKC-ζ directly at its regulatory domain, where a S186A mutation in a putative 14-3-3-binding domain strongly reduced the binding and the complex formation with 14-3-3β and Raf-1. Treatment of PKC-ζ with lambda protein phosphatase also reduced its binding to 14-3-3β in vitro. Preincubation of an immobilized Raf-1 construct with 14-3-3β facilitated PKC-ζ binding. Together, the results suggest that 14-3-3 binds both PKC-ζ (at phospho-Ser-186) and Raf-1 in a ternary complex. Complex formation was much stronger with a kinase-inactive PKC-ζ mutant than with wild-type PKC-ζ, supporting the idea that kinase activity leads to complex dissociation. 14-3-3β and -θ were substrates for PKC-ζ, whereas 14-3-3ζ was not. Phosphorylation of 14-3-3β by PKC-ζ negatively regulated their physical association. 14-3-3β with its putative PKC-ζ phosphorylation sites mutated enhanced co-precipitation between PKC-ζ and Raf-1, suggesting that phosphorylation of 14-3-3 by PKC-ζ weakens the complex in vivo. We conclude that 14-3-3 facilitates coupling of PKC-ζ to Raf-1 in an isotype-specific and phosphorylation-dependent manner. We suggest that 14-3-3 is a transient mediator of Raf-1 phosphorylation and activation by PKC-ζ.

Erythropoietin and testicular steroidogenesis: the role of second messengers

1995 ◽  
Vol 132 (1) ◽  
pp. 103-108 ◽  
Author(s):  
Carlo Foresta ◽  
Roberto Mioni ◽  
Paola Bordon ◽  
Francesco Gottardello ◽  
Andrea Nogara ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Leydig Cells ◽  
Second Messengers ◽  
Indirect Evidence ◽  
Calcium Flux ◽  
Dependent Manner ◽  
Kinase C ◽  
Testicular Steroidogenesis

Foresta C, Mioni R, Bordon P, Gottardello F, Nogara A, Rossato M. Erythropoietin and testicular steroidogenesis: the role of second messengers. Eur J Endocrinol 1995;132:103–8. ISSN 0804–4643 It has been demonstrated that erythropoietin (EPO) influences rat and human Leydig cell steroidogenesis, stimulating testosterone production through a direct and specific receptor-mediated mechanism. The aim of this study was to investigate the mechanism by which recombinant human erythropoietin (rHuEPO) exerts its stimulatory effect on rat Leydig cells. Recombinant human EPO did not induce, at any dose tested (10−10 to 10−13 mol/l), an increase in either cAMP or cGMP, suggesting that in Leydig cells the effect of rHuEPO does not involve the adenylate or guanylate–cyclase systems. The role of transmembrane calcium flux in rHuEPO-stimulated steroidogenesis was studied by evaluating the effect of calcium channel blocker, verapamil, and by the 45Ca2+ uptake method. Verapamil did not influence rHuEPO-induced testosterone secretion and rHuEPO did not modify calcium recycling, indicating that calcium transmembrane flux is not involved in the rHuEPO effect. The protein kinase C inhibitor staurosporine (10, 30, 100 and 300 nmol/l) inhibited rHuEPO-stimulated testicular steroidogenesis in a dose-dependent manner. This indirect evidence suggests that the stimulatory effect of rHuEPO on rat Leydig cells may involve protein kinase C activation. Carlo Foresta, Institute of Internal Medicine, Via Ospedale Civile 105, 35128 Padova, Italy

The role of protein kinase C in GH secretion induced by GH-releasing factor and GH-releasing peptides in cultured ovine somatotrophs

1997 ◽  
Vol 154 (2) ◽  
pp. 219-230 ◽  
Author(s):  
D Wu ◽  
I J Clarke ◽  
C Chen
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Dependent Manner ◽  
Adenylyl Cyclase Activity ◽  
Down Regulation ◽  
Gh Secretion ◽  
Calphostin C ◽  
Kinase C ◽  
Pka Pathway

Abstract The involvement of protein kinase C (PKC) in the action of GH-releasing factor (GRF) and synthetic GH-releasing peptides (GHRP-2 and GHRP-6) was investigated in ovine somatotrophs in primary culture. In partially purified sheep somatotrophs, GRF and GHRP-2 caused translocation of PKC activity from the cytosol to the cell membranes and caused GH release in a dose- and time-dependent manner. GHRP-6 did not cause PKC translocation. The PKC inhibitors, calphostin C, staurosporine and chelerythrine, partially reduced GH release in response to GRF and GHRP-2 at doses which selectively inhibit PKC activity. These inhibitors totally abolished GH release caused by phorbol 12-myristate 13-acetate (PMA). Down-regulation of PKC by the treatment of cells with phorbol 12,13-dibutyrate for 16 h caused a significant (P<0·001) reduction in total PKC activity and totally abolished PKC translocation in response to a challenge with GRF, GHRP-2 or PMA. In addition, down-regulation abolished GH release in response to GRF, GHRP-2 or GHRP-6. Treatment of cells with H89, a selective PKA inhibitor, totally blocked GH release caused by either GRF or GHRP-2 and partially reduced PMA-induced GH release. H89 had no effect on PKC translocation caused by GRF, GHRP-2 or PMA and did not affect GH release caused by GHRP-6. These data suggest that GHRP-2 and GRF activate PKC in addition to stimulating adenylyl cyclase activity. Although the cAMP–protein kinase A (PKA) pathway is the major signalling pathway employed by GRF and GHRP-2, the activation of PKC may potentiate signalling via the cAMP–PKA pathway in ovine GH secretion. Importantly, the effect of PMA in increasing the secretion of GH from ovine somatotrophs is effected, in part, by up-regulation of the cAMP–PKA pathway. We conclude that there is cross-talk between the PKC pathway and the cAMP–PKA pathway in ovine somatotrophs during the action of GRF or GHRP. Journal of Endocrinology (1997) 154, 219–230

scholarly journals Regulation of Impaired Protein Kinase C Signaling by Chemokines in Murine Macrophages during Visceral Leishmaniasis

2005 ◽  
Vol 73 (12) ◽  
pp. 8334-8344 ◽  
Author(s):  
Ranadhir Dey ◽  
Arup Sarkar ◽  
Nivedita Majumder ◽  
Suchandra Bhattacharyya (Majumdar) ◽  
Kaushik Roychoudhury ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Leishmania Donovani ◽  
Disease Process ◽  
Kinase C ◽  
Parasitic Burden ◽  
Infected Cells

ABSTRACT The protein kinase C (PKC) family regulates macrophage function involved in host defense against infection. In the case of Leishmania donovani infection, the impairment of PKC-mediated signaling is one of the crucial events for the establishment of parasite into the macrophages. Earlier reports established that C-C chemokines mediated protection against leishmaniasis via the generation of nitric oxide after 48 h. In this study, we investigated the role of MIP-1α and MCP-1 in the regulation of impaired PKC activity in the early hours (6 h) of infection. These chemokines restored Ca2+-dependent PKC activity and inhibited Ca2+-independent atypical PKC activity in L. donovani-infected macrophages under both in vivo and in vitro conditions. Pretreatment of macrophages with chemokines induced superoxide anion generation by activating NADPH oxidase components in infected cells. Chemokine administration in vitro induced the migration of infected macrophages and triggered the production of reactive oxygen species. In vivo treatment with chemokines significantly restricted the parasitic burden in livers as well as in spleens. Collectively, these results indicate a novel regulatory role of C-C chemokines in controlling the intracellular growth and multiplication of L. donovani, thereby demonstrating the antileishmanial properties of C-C chemokines in the disease process.

scholarly journals Phosphorylation of human pleckstrin on Ser-113 and Ser-117 by protein kinase C

1996 ◽  
Vol 314 (3) ◽  
pp. 937-942 ◽  
Author(s):  
Karen L. CRAIG ◽  
Calvin B. HARLEY
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phosphorylation Sites ◽  
Wild Type ◽  
Cos Cells ◽  
Phospholipid Hydrolysis ◽  
Kinase C

During platelet activation, receptor-coupled phospholipid hydrolysis stimulates protein kinase C (PKC) and results in the phosphorylation of several proteins, the most prominent being pleckstrin. Pleckstrin is composed of two repeated domains, now called pleckstrin homology (PH) domains, separated by a spacer region that contains several consensus PKC phosphorylation sites. To determine the role of PKC-dependent phosphorylation in pleckstrin function, we mapped the phosphorylation sites in vivo of wild-type and site-directed mutants of pleckstrin expressed in COS cells. Phosphorylation was found to occur almost exclusively on Ser-113 and Ser-117 within the sequence 108-KFARKS*TRRS*IRL-120. Phosphorylation of these sites was confirmed by phosphorylation of the corresponding wild-type and mutant synthetic peptides in vitro.

Spontaneous maturation in Bufo arenarum oocytes: participation of protein kinase C

Zygote ◽  
1996 ◽  
Vol 4 (04) ◽  
pp. 257-262 ◽  
Author(s):  
L. Zelarayán ◽  
J. Oterino ◽  
M.I. Bühler
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Molecular Mechanisms ◽  
Respiratory Activity ◽  
Follicle Cells ◽  
Dependent Manner ◽  
Germinal Vesicle Breakdown ◽  
Kinase C ◽  
Bufo Arenarum

SummaryAlthough progesterone is the maturation inducer in amphibians, it has been demonstrated that inBufo arenarumoocytes resumed meiosis with no need of exogenous hormonal stimulus if derived of their enveloping, follicle cells. This phenomenon, called spontaneous maturation, is quite rare in amphibians. InB. arenarum, spontaneous maturation took place only in oocytes obtained during the reproductive period (spring-summer). During this period the oocytes also demonstrated a respiratory activity characteristic of mature oocytes. Interestingly, full-grownB. arenarumoocytes always responded to progesterone regardless of the season in which they were obtained and of their respiratory activity. The disposition of oocytes competent or not competent to mature spontaneously provides a useful system for the study of molecular mechanisms involved in the maturation process. The data presented here indicate that the activation of protein kinase C (PKC) induces germinal vesicle breakdown (GVBD) in denuded oocytes unable to mature spontaneously (winter oocytes) and is involved in the in vitro spontaneous maturation ofB. arenarumfull-grown oocytes. The inhibition of PKC by 1-(5-isoquinolynyl-sulphonyl-2-methyl-piperazine (H-7) impeded spontaneous maturation in a dose-dependent manner, thus supporting the participation of the PKC pathway during this process. Interestingly phorbol 12-myristate-13-acetate (PMA)-induced GVBD is inhibited by the incubation of the oocytes in dibutyryl cAMP (dbcAMP), indicating that both pathways, PKC and protein kinase A (PKA), are related at a certain point. However, spontaneous GVBD is less sensitive than PMA-induced GVBD to dbcAMP. This fact would support the suggestion that in spontaneous GVBD mechanisms different from activation of PKC are at work.

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