Lacrimal gland PKC isoforms are differentially involved in agonist-induced protein secretion

1997 ◽  
Vol 272 (1) ◽  
pp. C263-C269 ◽  
Author(s):  
D. Zoukhri ◽  
R. R. Hodges ◽  
C. Sergheraert ◽  
A. Toker ◽  
D. A. Dartt
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Secretion ◽  
Phorbol Ester ◽  
Lacrimal Gland ◽  
Pkc Delta ◽  
Pkc Epsilon ◽  
Pkc Isoforms ◽  
Pkc Alpha ◽  
Kinase A

In the present study, we have synthesized and N-myristoylated peptides derived from the pseudosubstrate sequences of protein kinase C (PKC)-alpha, -delta, and -epsilon [Myr-PKC-alpha-(15-28), Myr-PKC-delta-(142-153), and Myr-PKC-epsilon-(149-164)], three isoforms present in rat lacrimal gland, and a peptide derived from the sequence of the endogenous inhibitor of protein kinase A [Myr-PKI-(17-25)]. Lacrimal gland acini were preincubated for 60 min with the myristoylated peptides (10(-10) to 3 x 10(-7) M), then protein secretion was stimulated with a phorbol ester, phorbol 12,13-dibutyrate (10(-6) M); vasoactive intestinal peptide (10(-8) M); a cholinergic agonist, carbachol (10(-5) M); or an alpha 1-adrenergic agonist, phenylephrine (10(-4) M), for 20 min. In intact lacrimal gland acini, Myr-PKC-alpha-(15-28) inhibited phorbol 12,13-dibutyrate-induced protein secretion. This effect was not reproduced by the acetylated peptide or by the myristoylated PKI, which inhibited vasoactive intestinal peptide-induced protein secretion, a response mediated by protein kinase A. Carbachol-induced protein secretion was inhibited by all three peptides. In contrast, phenylephrine-induced protein secretion was inhibited only by Myr-PKC-epsilon-(149-164), whereas Myr-PKC-alpha-(15-28) and Myr-PKC-delta-(142-153) had a stimulatory effect. None of these myristoylated peptides affected the calcium increase evoked by cholinergic or alpha 1-adrenergic agonists. We concluded that phorbol ester- and receptor-induced protein secretion involve different PKC isoforms in lacrimal gland.

Phorbol ester-stimulated exocytosis in lacrimal gland: PKC might not be the sole effector

1993 ◽  
Vol 264 (4) ◽  
pp. C1045-C1050 ◽  
Author(s):  
D. Zoukhri ◽  
C. Sergheraert ◽  
B. Rossignol
Keyword(s):  
Phorbol Ester ◽  
Lacrimal Gland ◽  
Inhibitory Effect ◽  
Complete Inhibition ◽  
Pkc Delta ◽  
Kinase C ◽  
Pkc Epsilon ◽  
Diethylaminoethyl Cellulose ◽  
Half Maximal Effective Concentration ◽  
Pkc Alpha

In this work we show that, although both phorbol 12-myristate 13-acetate (PMA) and 4 beta-phorbol 12,13-dibutyrate (PdBu) stimulate the protein discharge in the rat lacrimal gland with the same half-maximal effective concentration (EC50 approximately 2 x 10(-7) M), PdBu is more efficient in eliciting this response compared with PMA. We also show that sphingosine and chelerythrine have no inhibitory effect on the protein discharge stimulated by PMA or PdBu at concentrations up to 2 x 10(-4) and 3 x 10(-5) M, respectively. With staurosporine, a complete inhibition could not be obtained even at 1 microM. However, only with trifluoperazine (TFP) we obtained a complete inhibition of the PMA-induced protein discharge at 10(-4) M TFP. On the other hand, we show that three diacylglycerol-permeant analogues (1-oleoyl-2-acetyl-sn-glycerol, 1,2-dioctanoyl-sn-glycerol, and 1,2-didecanoyl-sn-glycerol) do not stimulate protein discharge. In a previous report from our laboratory (30), we showed that the rat lacrimal gland expresses the alpha-isoform of protein kinase C (PKC). In this study, using specific antibodies directed against the newly identified isoforms of PKC, we show on a diethylaminoethyl-cellulose fraction that, besides PKC-alpha, the rat lacrimal gland expresses PKC-epsilon, as previously suggested by Dartt et al. (11), and PKC-delta. Our results question the direct implication of PKC activity as a sole effector of the phorbol ester-stimulated protein secretion in the rat lacrimal gland.

Do adult rat ventricular myocytes express protein kinase C-alpha?

1997 ◽  
Vol 272 (5) ◽  
pp. H2485-H2491 ◽  
Author(s):  
V. Rybin ◽  
S. F. Steinberg
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Ventricular Myocytes ◽  
Chromatographic Purification ◽  
Adult Rat ◽  
Pkc Delta ◽  
Kinase C ◽  
Pkc Epsilon ◽  
Pkc Isoforms ◽  
Pkc Alpha

Although calcium-insensitive protein kinase C (PKC) isoforms (PKC-epsilon and PKC-delta) are consistently detected in adult ventricular myocytes, the evidence that adult ventricular myocytes also express calcium-sensitive PKC-alpha is inconsistent. The current study used four different anti-PKC-alpha-antibodies to resolve some of the uncertainties regarding the immunodetection of PKC-alpha in adult ventricular myocytes. Three of the antibodies used in this study barely (GIBCO-BRL) or rather faintly (Transduction Laboratories and Seikagaku America) recognize PKC-alpha in crude preparations from adult ventricular myocytes. Although each of these antibodies recognizes a prominent 80-kDa band, which is similar in size to PKC-alpha, this represents nonspecific immunoreactivity and should not be confused with PKC-alpha. This conclusion is based on peptide-blocking experiments (GIBCO-BRL), the absence of the requisite sensitivity to calcium- and phorbol 12-myristate 13-acetate-induced translocation (Seikagaku America and Transduction Laboratories), and/or the failure to copurify with PKC-alpha on DEAE-Sephacel chromatography. Nevertheless, an antibody from Upstate Biotechnology clearly recognizes PKC-alpha and not other unrelated nonspecific immunoreactive species in crude preparations from adult ventricular myocytes. Each of the antisera used in this study could detect PKC-alpha immunoreactivity following chromatographic purification of the samples to enrich for PKC-alpha and remove nonspecific immunoreactive proteins. These results suggest that PKC-alpha is expressed by adult ventricular myocytes and argue that differences in the sensitivity and/or specificity of available antisera contribute to at least some of the confusion regarding PKC-alpha expression in adult ventricular myocytes.

cAMP-positive regulation of angiotensinogen gene expression and protein secretion in rat adipose tissue

2004 ◽  
Vol 286 (3) ◽  
pp. E434-E438 ◽  
Author(s):  
Valérie Serazin ◽  
Marie-Noelle Dieudonné ◽  
Mireille Morot ◽  
Philippe de Mazancourt ◽  
Yves Giudicelli
Keyword(s):  
Adipose Tissue ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Secretion ◽  
Intracellular Camp ◽  
Pathological State ◽  
Mrna Levels ◽  
Adrenergic Stimulation ◽  
Rat Adipose Tissue ◽  
Kinase A

The adipose renin-angiotensin system (RAS) has been assigned to participate in the control of adipose tissue development and in the pathogenesis of obesity-related hypertension. In adipose cells, the biological responses to β-adrenergic stimulation are mediated by an increase in intracellular cAMP. Because cAMP is known to promote adipogenesis and because an association exists between body fat mass, hypertension, and increased sympathetic stimulation, we examined the influence of cAMP on angiotensinogen (ATG) expression and secretion in rat adipose tissue. Exposure of primary cultured differentiated preadipocytes to the cAMP analog 8-bromoadenosine 3′,5′-cyclic monophosphate (8-BrcAMP) or cAMP-stimulating agents (forskolin and IBMX) results in a significant increase in ATG mRNA levels. In adipose tissue fragments, 8-BrcAMP also increases ATG mRNA levels and protein secretion, but not in the presence of the protein kinase A inhibitor H89. The addition of isoproterenol, known to stimulate the synthesis of intracellular cAMP via β-adrenoreceptors, had the same stimulatory effect on ATG expression and secretion. These results indicate that cAMP in vitro upregulates ATG expression and secretion in rat adipose tissue via the protein kinase A-dependent pathway. Further studies are required to determine whether this regulatory pathway is activated in human obesity, where increased sympathetic tone is frequently observed, and to elucidate the importance of adipose ATG to the elevated blood pressure observed in this pathological state.

scholarly journals Does dopamine use several signal pathways to inhibit Na-Pi transport in OK cells?

1998 ◽  
Vol 9 (9) ◽  
pp. 1604-1612
Author(s):  
A D Baines ◽  
R Drangova
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Protein Kinase A ◽  
Tyrosine Kinase Inhibitors ◽  
Phorbol Ester ◽  
Kinase Inhibitors ◽  
Ok Cells ◽  
Kinase C ◽  
Kinase A

In opossum kidney (OK) cells, L-dihydroxyphenylalanine (10 microM) raised dopamine to 10 nM and inhibited Na-inorganic phosphate (Pi) uptake 20% (P = 0.001). Inhibition was completely blocked by carbidopa or SCH23390. Dopamine (1 microM) inhibited uptake 55% (half-maximal inhibition, 0.03 microM). Fenoldopam (0.1 microM, DA1 agonist) inhibited uptake 45 +/- 2%. DA1 antagonists (SKF83566 and SCH23390), but not DA2-antagonist (sulpiride), blocked dopamine inhibition. Quinpirole (DA2 agonist) did not modify Pi uptake. Bisindolylmaleimide (10 microM), a protein kinase C inhibitor, blocked inhibition of Pi uptake by phorbol ester but had no effect on the response to dopamine. Dopamine inhibited Pi uptake in cells that had been exposed to phorbol ester for 18 to 24 h. Dopamine inhibition was not reduced by 1 microM U73,122 but was reduced 20% by 10 microM, which is 10 times the concentration reported to completely inhibit phospholipase C in OK cells. Adenylate cyclase inhibitors SQ 22536 (100 microM) and 2,5-dideoxyadenosine (100 microM) reduced dopamine-stimulated cAMP production, but not dopamine inhibition of Pi uptake. Rp-cAMPS counteracted the inhibition of Pi uptake by Sp-cAMPS but had no effect on the dopamine response. H-89 inhibited dopamine-stimulated protein kinase A activity, but neither H-89 nor H-9 alone or with bisindolylmaleimide altered dopamine inhibition of Pi uptake. Genistein and herbimycin A (tyrosine kinase inhibitors) reduced Pi uptake. However, dopamine, a benzoquinone like several tyrosine kinase inhibitors, did not inhibit tyrosine kinase activity. Thus, dopamine inhibited Pi uptake in this OK cell clone by activating a G protein-linked pathway that operates independently from adenylyl cyclase, protein kinase A, protein kinase C, and protein tyrosine kinase.

Mechanism of inhibition of Raf-1 by protein kinase A

1994 ◽  
Vol 14 (10) ◽  
pp. 6696-6703
Author(s):  
S Häfner ◽  
H S Adler ◽  
H Mischak ◽  
P Janosch ◽  
G Heidecker ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Phorbol Esters ◽  
Kinase Domain ◽  
Amino Terminal ◽  
Mitogenic Signalling ◽  
Pkc Alpha ◽  
Kinase A

The cytoplasmic Raf-1 kinase is essential for mitogenic signalling by growth factors, which couple to tyrosine kinases, and by tumor-promoting phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate, which activate protein kinase C (PKC). Signalling by the Raf-1 kinase can be blocked by activation of the cyclic AMP (cAMP)-dependent protein kinase A (PKA). The molecular mechanism of this inhibition is not precisely known but has been suggested to involve attenuation of Raf-1 binding to Ras. Using purified proteins, we show that in addition to weakening the interaction of Raf-1 with Ras, PKA can inhibit Raf-1 function directly via phosphorylation of the Raf-1 kinase domain. Phosphorylation by PKA interferes with the activation of Raf-1 by either PKC alpha or the tyrosine kinase Lck and even can downregulate the kinase activity of Raf-1 previously activated by PKC alpha or amino-terminal truncation. This type of inhibition can be dissociated from the ability of Raf-1 to associate with Ras, since (i) the isolated Raf-1 kinase domain, which lacks the Ras binding domain, is still susceptible to inhibition by PKA, (ii) phosphorylation of Raf-1 by PKC alpha alleviates the PKA-induced reduction of Ras binding but does not prevent the downregulation of Raf-1 kinase activity by PKA and (iii) cAMP agonists antagonize transformation by v-Raf, which is Ras independent.

A fully automated capillary western system for absolute quantitation of endogenous PKC proteins: An approach to correlate protein quantity with function.

2012 ◽  
Vol 30 (30_suppl) ◽  
pp. 31-31
Author(s):  
Jin-Qiu Chen ◽  
Madeleine Heldman ◽  
Michelle Herrmann ◽  
Noemi Kedei ◽  
Peter Blumberg ◽  
...  
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Relative Abundance ◽  
U937 Cells ◽  
Bryostatin 1 ◽  
Absolute Quantitation ◽  
Pkc Delta ◽  
Pkc Epsilon ◽  
Pkc Isoforms ◽  
Pkc Alpha

31 Background: The human prostate cell line LNCaP and the human myelocytic leukemia cell line U937 differ dramatically in their responses to the two protein kinase C (PKC) targeted ligands phorbol 12-myristate 13-acetate (PMA) and bryostatin 1 and show complex differences in the patterns of transcriptional responses that they induce. Quantitation of relative abundance of individual PKC isoforms in the two cell lines may help to link the downstream effects of the two compounds to these isoforms. Methods: Simple Western is a capillary-based automated Western system recently developed by ProteinSimple. All steps following sample preparation are fully automated in the Simple Western system, including sample loading, size-based protein separation, immunoprobing, washing, detection and data analysis. Simple Western is gel-free and blot-free, uses less amount of samples, and produces highly quantitative, reproducible information that cannot be generated using regular Western assays. Using the Simple Western system, we developed a method for absolute quantitation of endogenous proteins in cell lysates and quantified PKC isoforms in LNCaP and U937 cells. Results: PKC isoforms were measured at levels of picogram or sub-picogram per nanogram cell lysate. PKC delta was identified as the dominant PKC isoforms in both cell lines. In LNCaP cells, PKC delta expression is ~20-fold higher than PKC alpha, ~40-fold higher than PKC epsilon, and at least 20-fold higher than PKC beta. In U937 cells, PKC delta expression is similar to PKC beta, at least 200 fold higher than PKC alpha, and ~50-fold higher than PKC epsilon. Conclusions: The Simple Western system, with its high-quality data quantitation and excellent assay reproducibility, allowed us to detect both the relative abundance of the PKC isoforms and their absolute quantitation in the tested cells. It circumvents the problem that antibodies of different affinities for different proteins yield a misleading impression of relative abundance and it provides an approach to accurately correlate protein quantities with their function.

Propofol-induced Activation of Protein Kinase C Isoforms in Adult Rat Ventricular Myocytes

2006 ◽  
Vol 104 (5) ◽  
pp. 970-977 ◽  
Author(s):  
Peter J. Wickley ◽  
Xueqin Ding ◽  
Paul A. Murray ◽  
Derek S. Damron
Keyword(s):  
Ventricular Myocytes ◽  
Intracellular Location ◽  
Rat Ventricular Myocytes ◽  
Adult Rat ◽  
Pkc Delta ◽  
Pkc Epsilon ◽  
Pkc Zeta ◽  
Pkc Isoforms ◽  
Pkc Alpha ◽  
The Individual

Background Myocardial protection by anesthetics is known to involve activation of protein kinase C (PKC). The authors' objective was to identify the PKC isoforms activated by propofol in rat ventricular myocytes. They also assessed the intracellular location of individual PKC isoforms before and after treatment with propofol. Methods Freshly isolated ventricular myocytes were obtained from adult rat hearts. Immunoblot analysis of cardiomyocyte subcellular fractions was used to assess translocation of individual PKC isoforms before and after exposure to propofol. An enzyme-linked immunosorbent assay kit was used for measuring PKC activity. Immunocytochemistry and confocal microscopy were used to visualize the intracellular location of the individual PKC isoforms. Results Under baseline conditions, PKC-alpha, PKC-delta, and PKC-zeta were associated with both the cytosolic and membrane fractions, whereas PKC-epsilon was exclusively located in the cytosolic fraction. Propofol (10 microM) caused translocation of PKC-alpha, PKC-delta, PKC-epsilon, and PKC-zeta from cytosolic to membrane fraction and increased total PKC activity (211 +/- 17% of baseline; P = 0.003) in a dose-dependent manner. Immunocytochemical localization of the individual PKC isoforms demonstrated that propofol caused translocation of PKC-alpha to the intercalated discs and z-lines; PKC-delta to the perinuclear region; PKC-epsilon to sites associated with the z-lines, intercalated discs, and the sarcolemma; and PKC-zeta to the nucleus. Conclusions These results demonstrate that propofol causes an increase in PKC activity in rat ventricular myocytes. Propofol stimulates translocation of PKC-alpha, PKC-delta, PKC-epsilon, and PKC-zeta to distinct intracellular sites in cardiomyocytes. This may be a fundamentally important cellular mechanism of anesthesia-induced myocardial protection in the setting of ischemia-reperfusion injury.

scholarly journals Mechanism of inhibition of Raf-1 by protein kinase A.

1994 ◽  
Vol 14 (10) ◽  
pp. 6696-6703 ◽  
Author(s):  
S Häfner ◽  
H S Adler ◽  
H Mischak ◽  
P Janosch ◽  
G Heidecker ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Phorbol Esters ◽  
Kinase Domain ◽  
Amino Terminal ◽  
Mitogenic Signalling ◽  
Pkc Alpha ◽  
Kinase A

The cytoplasmic Raf-1 kinase is essential for mitogenic signalling by growth factors, which couple to tyrosine kinases, and by tumor-promoting phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate, which activate protein kinase C (PKC). Signalling by the Raf-1 kinase can be blocked by activation of the cyclic AMP (cAMP)-dependent protein kinase A (PKA). The molecular mechanism of this inhibition is not precisely known but has been suggested to involve attenuation of Raf-1 binding to Ras. Using purified proteins, we show that in addition to weakening the interaction of Raf-1 with Ras, PKA can inhibit Raf-1 function directly via phosphorylation of the Raf-1 kinase domain. Phosphorylation by PKA interferes with the activation of Raf-1 by either PKC alpha or the tyrosine kinase Lck and even can downregulate the kinase activity of Raf-1 previously activated by PKC alpha or amino-terminal truncation. This type of inhibition can be dissociated from the ability of Raf-1 to associate with Ras, since (i) the isolated Raf-1 kinase domain, which lacks the Ras binding domain, is still susceptible to inhibition by PKA, (ii) phosphorylation of Raf-1 by PKC alpha alleviates the PKA-induced reduction of Ras binding but does not prevent the downregulation of Raf-1 kinase activity by PKA and (iii) cAMP agonists antagonize transformation by v-Raf, which is Ras independent.

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