Protein kinase C regulates the magnitude and stability of CFTR currents in pancreatic duct cells

1995 ◽  
Vol 268 (4) ◽  
pp. C823-C828 ◽  
Author(s):  
J. P. Winpenny ◽  
H. L. McAlroy ◽  
M. A. Gray ◽  
B. E. Argent
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Pancreatic Duct ◽  
Specific Inhibitor ◽  
Fluid Secretion ◽  
Pancreatic Ducts ◽  
Patch Clamp Technique ◽  
Kinase C ◽  
Duct Cells ◽  
Pancreatic Duct Cells

Activation of protein kinase C (PKC) inhibits adenosine 3',5'-cyclic monophosphate (cAMP)-stimulated fluid secretion in rat pancreatic ducts (N. Ashton, R. L. Evans, and B. E. Argent. J. Physiol. Lond. 452: 99P, 1992). Using the patch-clamp technique, we have investigated whether this inhibition of fluid secretion results from an effect of PKC on cystic fibrosis transmembrane conductance regulator (CFTR) Cl channels. Exposure to 100 nM 4 beta-phorbol 12,13-dibutyrate (PDBu) had no effect on CFTR current density in unstimulated duct cells, but caused a 31% increase in the magnitude of CFTR currents recorded from cells stimulated with cAMP. Furthermore, prolonged (2-4 h) exposure of stimulated duct cells to 100 nM PDBu (a condition that should downregulate PKC) significantly slowed the rate at which CFTR currents run down after establishing a whole cell recording. A similar effect was observed with calphostin C (500 nM), a specific inhibitor of PKC. Thus, although inhibition of ductal fluid secretion by PDBu is unlikely to be explained by an effect on CFTR, modulation of PKC activity can affect both the magnitude and stability of CFTR currents in pancreatic duct cells.

scholarly journals Arginine Vasopressin Potentiates the Stimulatory Action of CRH on Pituitary Corticotropes via a Protein Kinase C–Dependent Reduction of the Background TREK-1 Current

Endocrinology ◽  
2015 ◽  
Vol 156 (10) ◽  
pp. 3661-3672 ◽  
Author(s):  
Andy K. Lee ◽  
Frederick W. Tse ◽  
Amy Tse
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Arginine Vasopressin ◽  
Underlying Mechanism ◽  
Sk Channels ◽  
Acth Secretion ◽  
Patch Clamp Technique ◽  
Stimulatory Action ◽  
Kinase C ◽  
Perforated Patch Clamp

The hypothalamic hormone arginine vasopressin (AVP) potentiates the stimulatory action of CRH on ACTH secretion from pituitary corticotropes, but the underlying mechanism is elusive. Using the perforated patch-clamp technique to monitor membrane potentials in mouse corticotropes, we found that AVP triggered a transient hyperpolarization that was followed by a sustained depolarization. The hyperpolarization was caused by intracellular Ca2+ release that in turn activated the small conductance Ca2+-activated K+ (SK) channels. The depolarization was due to the suppression of background TWIK-related K+ (TREK)-1 channels. Direct activation of protein kinase C (PKC) reduced the TREK-1 current, whereas PKC inhibition attenuated the AVP-mediated reduction of the TREK-1 current, implicating the involvement of PKC. The addition of CRH (which stimulates the protein kinase A pathway) in the presence of AVP, or vice versa, resulted in further suppression of the TREK-1 current. In corticotropes with buffered cytosolic Ca2+ concentration ([Ca2+]i), AVP evoked a sustained depolarization, and the coapplication of AVP and CRH caused a larger depolarization than that evoked by AVP or CRH alone. In cells with minimal perturbation of [Ca2+]i and background TREK-1 channels, CRH evoked a sustained depolarization that was superimposed with action potentials, and the subsequent coapplication of AVP and CRH triggered a transient hyperpolarization that was followed by a larger depolarization. In summary, AVP and CRH have additive effects on the suppression of the TREK-1 current, resulting in a more robust depolarization in corticotropes. We suggest that this mechanism contributes to the potentiating action of AVP on CRH-evoked ACTH secretion.

scholarly journals Essential role of protein kinase C ζ in transducing a motility signal induced by superoxide and a chemotactic peptide, fMLP

2007 ◽  
Vol 176 (7) ◽  
pp. 1049-1060 ◽  
Author(s):  
Kageaki Kuribayashi ◽  
Kiminori Nakamura ◽  
Maki Tanaka ◽  
Tsutomu Sato ◽  
Junji Kato ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Morphological Changes ◽  
Specific Inhibitor ◽  
Squamous Carcinoma ◽  
Inflammatory Cells ◽  
Dominant Negative ◽  
Chemotactic Peptide ◽  
Kinase C ◽  
Pkc Ζ

Under various pathological conditions, including infection, malignancy, and autoimmune diseases, tissues are incessantly exposed to reactive oxygen species produced by infiltrating inflammatory cells. We show augmentation of motility associated with morphological changes of human squamous carcinoma SASH1 cells, human peripheral monocytes (hPMs), and murine macrophage-like cell line J774.1 by superoxide stimulation. We also disclose that motility of hPMs and J774.1 induced by a chemotactic peptide (N-formyl-methionyl-leucyl-phenylalanine [fMLP]) was inhibited by superoxide dismutase or N-acetylcystein, indicating stimulation of motility by superoxide generated by fMLP stimulation. In these cells, protein kinase C (PKC) ζ was activated to phosphorylate RhoGDI-1, which liberated RhoGTPases, leading to their activation. These events were inhibited by dominant-negative PKCζ in SASH1 cells, myristoylated PKCζ peptides in hPMs and J774.1, or a specific inhibitor of RhoGTPase in SASH1, hPMs, and J774.1. These results suggest a new approach for manipulation of inflammation as well as tumor cell invasion by targeting this novel signaling pathway.

The role of protein kinase C-δ in PTH stimulation of IGF-binding protein-5 mRNA in UMR-106–01 cells

2002 ◽  
Vol 282 (3) ◽  
pp. E534-E541 ◽  
Author(s):  
Mary S. Erclik ◽  
Jane Mitchell
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Binding Protein ◽  
Specific Inhibitor ◽  
Dominant Negative Mutant ◽  
Nuclear Fraction ◽  
Mrna Levels ◽  
Kinase C ◽  
Umr 106

We have investigated the role of protein kinase C (PKC) signal transduction pathways in parathyroid hormone (PTH) regulation of insulin-like growth factor-binding protein-5 (IGFBP-5) gene expression in the rat osteoblast-like cell line UMR-106–01. Involvement of the PKC pathway was determined by the findings that bisindolylmaleimide I inhibited 40% of the PTH effect, and 1 μM bovine PTH-(3–34) stimulated a 10-fold induction of IGFBP-5 mRNA. PTH-(1–34) and PTH-(3–34) (100 nM) both stimulated PKC-δ translocation from the membrane to the nuclear fraction. Rottlerin, a PKC-δ-specific inhibitor, and a dominant negative mutant of PKC-δ were both able to significantly inhibit PTH-(1–34) and PTH-(3–34) induction of IGFBP-5 mRNA, suggesting a stimulatory role for PKC-δ in the effects of PTH. Phorbol 12-myristate 13-acetate (PMA) stimulated PKC-α translocation from the cytosol to the membrane and inhibited ∼50% of the PTH-(1–34), forskolin, and 8-bromoadenosine 3′,5′-cyclic monophosphate-stimulated IGFBP-5 mRNA levels, suggesting that PKC-α negatively regulates protein kinase A (PKA)-mediated induction of IGFBP-5 mRNA. These results suggest that the induction of IGFBP-5 by PTH is both PKA and PKC dependent and PKC-δ is the primary mediator of the effects of PTH via the PKC pathway.

Inhibition of voltage-gated K+ current in rat intrapulmonary arterial myocytes by endothelin-1

1998 ◽  
Vol 274 (5) ◽  
pp. L842-L853 ◽  
Author(s):  
Larissa A. Shimoda ◽  
J. T. Sylvester ◽  
James S. K. Sham
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Vascular Reactivity ◽  
Signal Transduction Pathway ◽  
Patch Clamp Technique ◽  
Arterial Smooth Muscle ◽  
Kinase C ◽  
Gf 109203X

Although endothelin (ET)-1 is an important regulator of pulmonary vascular tone, little is known about the mechanisms by which ET-1 causes contraction in this tissue. Using the whole cell patch-clamp technique in rat intrapulmonary arterial smooth muscle cells, we found that ET-1 and the voltage-dependent K+(KV)-channel antagonist 4-aminopyridine, but not the Ca2+-activated K+-channel antagonist charybdotoxin (ChTX), caused membrane depolarization. In the presence of 100 nM ChTX, ET-1 (10−10to 10−7 M) caused a concentration-dependent inhibition of K+ current (56.2 ± 3.8% at 10−7 M) and increased the rate of current inactivation. These effects of ET-1 on K+ current were markedly reduced by inhibitors of protein kinase C (staurosporine and GF 109203X) and phospholipase C (U-73122) or under Ca2+-free conditions and were mimicked by activators of protein kinase C (phorbol 12-myristate 13-actetate and 1,2-dioctanoyl- sn-glycerol). These data suggest that ET-1 modulated pulmonary vascular reactivity by depolarizing pulmonary arterial smooth muscle, due in part to the inhibition of KV current that occurred via activation of the phospholipase C-protein kinase C signal transduction pathway.

Potentiation of Apoptosis by Treatment With the Protein Kinase C-Specific Inhibitor Safingol in Mitomycin C-Treated Gastric Cancer Cells

1995 ◽  
Vol 87 (18) ◽  
pp. 1394-1399 ◽  
Author(s):  
G. K. Schwartz ◽  
A. Haimovitz-Friedman ◽  
S. K. Dhupar ◽  
D. Ehleiter ◽  
P. Maslak ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Cancer Cells ◽  
Mitomycin C ◽  
Specific Inhibitor ◽  
Gastric Cancer Cells ◽  
Kinase C

scholarly journals Multiple non-specific effects of sphingosine on adenylate cyclase and cyclic AMP accumulation in S49 lymphoma cells preclude its use as a specific inhibitor of protein kinase C

1990 ◽  
Vol 268 (2) ◽  
pp. 507-511 ◽  
Author(s):  
J A Johnson ◽  
R B Clark
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Mammalian Cells ◽  
Specific Inhibitor ◽  
Lymphoma Cells ◽  
Specific Effects ◽  
Kinase C ◽  
Cyclic Amp Accumulation

Recent studies with phorbol esters have suggested that protein kinase C (PKC) may play a role in the regulation of adenylate cyclase in mammalian cells. Since D-sphingosine has been reported to specifically inhibit PKC in many cell types, we evaluated its effects on stimulation of cyclic AMP accumulation by adrenaline in S49 lymphoma cells. We found sphingosine to have multiple non-specific effects which could not be explained by an inhibition of PKC. These effects included: (i) inhibition by sphingosine (50 microM) of adrenaline-stimulated cyclic AMP accumulation and sphingosine permeation of the cells which rendered them leaky to ATP; (iii) sphingosine (20 microMs) augmentation of adrenaline-stimulated cyclic AMP accumulation; (iii) inhibition by sphingosine of adrenaline-stimulated adenylate cyclase in isolated membranes by up to 95%; and (iv) sphingosine (20 microM) inhibition of cellular mechanisms for the elimination of cyclic AMP. These results demonstrate the importance of evaluating the non-specific effects of sphingosine before concluding that its actions are the consequences of a specific inhibition of PKC.

Generation of the catalytic fragment of protein kinase C alpha in spastic canine basilar artery

1997 ◽  
Vol 87 (5) ◽  
pp. 752-756 ◽  
Author(s):  
Motohiko Sato ◽  
Eiichi Tani ◽  
Tsuyoshi Matsumoto ◽  
Hirokazu Fujikawa ◽  
Shinobu Imajoh-Ohmi
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Basilar Artery ◽  
Cleavage Site ◽  
Limited Proteolysis ◽  
Specific Inhibitor ◽  
Content Type ◽  
Kinase C ◽  
Canine Basilar Artery ◽  
Catalytic Fragment

✓ In previous studies of topical application of calphostin C, a specific inhibitor of the regulatory domain of protein kinase C (PKC), and calpeptin, a selective inhibitor of calpain, to spastic canine basilar artery (BA) researchers have suggested that the catalytic fragment of PKC (known as PKM) is probably formed by a limited proteolysis of continuously activated µ-calpain, but there has been no direct evidence for PKM formation in vasospasm. The present immunoblot study with anti-PKCα antibody shows a significant decrease in cytosolic 80-kD PKCα and a concomitantly significant increase in membrane PKCα in the spastic canine BA. In addition, an immunoblot study in which cleavage site—directed antibodies were used demonstrated a significant increase in immunoreactive 45-kD PKM. The changes in membrane PKCα and PKM were enhanced with the lapse of time after subarachnoid hemorrhage. The cleavage site—directed antibodies distinguish the proteolyzed from the unproteolyzed forms of PKC for in situ analyses of enzyme regulation mediated by proteolysis. The data indicate that PKCα in spastic canine BA is translocated to the cell membrane, where PKCα is rapidly cleaved into PKM as a result of proteolysis of the isozyme by µ-calpain but not by µ-calpain. The authors hypothesize that µ-calpain is continuously activated in spastic canine BA and produces PKM by limited proteolysis of PKCα.

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