Inhibition of PAH transport by parathyroid hormone in OK cells: involvement of protein kinase C pathway

1997 ◽  
Vol 273 (5) ◽  
pp. F674-F679 ◽  
Author(s):  
Junya Nagai ◽  
Ikuko Yano ◽  
Yukiya Hashimoto ◽  
Mikihisa Takano ◽  
Ken-Ichi Inui
Keyword(s):  
Protein Kinase C ◽  
Parathyroid Hormone ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Regulatory Control ◽  
Dependent Manner ◽  
Transcellular Transport ◽  
Ok Cells ◽  
Kinase C ◽  
Kinase A

We have previously shown that the p-aminohippurate (PAH) transport system in OK kidney epithelial cell line is under the regulatory control of protein kinase C. Parathyroid hormone (PTH) could activate protein kinase C, as well as protein kinase A, in OK cells. In the present study, the effect of PTH on PAH transport was studied in OK cells. PTH inhibited the transcellular transport of PAH from the basal to the apical side, as well as the accumulation of PAH in OK cells. Basolateral PAH uptake was inhibited by PTH in a dose- and time-dependent manner. Protein kinase A activators did not affect the transcellular transport or the accumulation of PAH. The PTH-induced inhibition of the accumulation of PAH was blocked by a protein kinase C inhibitor staurosporine. These results suggest that PTH inhibits the PAH transport in OK cells and that the messenger system mediated by protein kinase C, not protein kinase A, plays an important role in the regulation of PAH transport by PTH.

Regulation of expression of type II sodium-phosphate cotransporters by protein kinases A and C

1998 ◽  
Vol 275 (2) ◽  
pp. F270-F277 ◽  
Author(s):  
Eleanor D. Lederer ◽  
Sameet S. Sohi ◽  
Jeanine M. Mathiesen ◽  
Jon B. Klein
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Sodium Phosphate ◽  
Broad Band ◽  
Confocal Imaging ◽  
Type Ii ◽  
Ok Cells ◽  
Kinase C ◽  
Kinase A

The purpose of the present study was to determine the effect of protein kinase A and protein kinase C activation on the membrane expression of NaPi-4, the type II sodium-phosphate cotransporter in OK cells. NaPi-4 expression was measured using polyclonal antisera produced in rabbits against a peptide identical to the carboxy-terminal 12-amino acid sequence of NaPi-4. The antisera identified an apically localized protein by confocal imaging of intact OK cells and a broad band of 110–140 kDa by immunoblot analysis of OK cell membranes. Treatment of OK cells with parathyroid hormone (PTH) decreased the intensity of the 110- to 140-kDa band, which was detectable by 2 h, maximal by 4 h at 62%, and sustained for 24 h. 8-Bromo-cAMP (8-BrcAMP) inhibited NaPi-4 expression for up to 24 h by over 90%. However, phorbol 12-myristate 13-acetate inhibited NaPi-4 expression by less than 10%. PTH-(3–34), a fragment which stimulates only protein kinase C, inhibited phosphate transport but also had no effect on NaPi-4 expression. We conclude that protein kinase A but not protein kinase C inhibits sodium-phosphate uptake in OK cells by downregulation of NaPi-4 expression.

Ca2+-, phorbol ester-, and cAMP-stimulated enzyme secretion from permeabilized rat pancreatic acini

1986 ◽  
Vol 250 (5) ◽  
pp. G698-G708 ◽  
Author(s):  
T. Kimura ◽  
K. Imamura ◽  
L. Eckhardt ◽  
I. Schulz
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Release ◽  
Enzyme Secretion ◽  
Dependent Manner ◽  
Intact Cells ◽  
Pancreatic Acini ◽  
Kinase C ◽  
Kinase A

Enzyme secretion from the exocrine pancreas is stimulated by receptor-activated breakdown of phosphatidylinositol 4,5-bisphosphate and consequent rise of both inositol 1,4,5-trisphosphate (IP3) and diacylglycerol, which leads to Ca2+ release and to activation of protein kinase C, respectively. Another way involves receptor-mediated stimulation of adenylate cyclase and consequent rise of cAMP and activation of protein kinase A. In the present work we have studied direct stimulation, inhibition, and mutual interaction of these pathways on enzyme secretion from isolated rat pancreatic acini that had been permeabilized by treatment with saponin or digitonin. The data were compared with those obtained in isolated intact acini. The data show that with increasing free Ca2+ concentrations greater than 10(-6) M protein release increases in "leaky" but not in "intact" cells and is maximal at approximately 10(-3) M, increasing about twofold compared with that in the absence of Ca2+. In the presence of the acetylcholine analogue carbachol, this effect of Ca2+ is enhanced by about threefold in leaky cells and is also present in intact cells to a similar extent. cAMP and its analogues, dibutyryl cAMP (dbcAMP) and 8-bromo-cAMP stimulate protein release by about twofold in the presence of Ca2+ in leaky cells. In intact acini cAMP has no effect, and cAMP analogues stimulate enzyme secretion by about twofold in some but not all experiments. Similarly, forskolin, an activator of adenylate cyclases and inhibitors of cyclic nucleotide-dependent phosphodiesterases, such as 3-isobutyl-1-methylxanthine (IBMX) and R0 201724, stimulate protein release in permeabilized acini. The Ca2+-binding protein calmodulin has no effect on enzyme secretion, whereas the calmodulin antagonist trifluoperazine dihydrochloride stimulates protein release in leaky but not in intact acini. The activator of protein kinase C, 12-O-tetradecanoylphorbol 13-acetate (TPA) stimulates protein release in a Ca2+-dependent manner and enhances cAMP-induced secretion. The effects of carbachol, TPA, cAMP, and a combination of both TPA and cAMP are inhibited by the polyamine spermine in permeabilized cells. Spermine has no effect on carbachol-induced enzyme secretion in intact cells. The data suggest that enzyme secretion from pancreatic acinar cells is mediated by cAMP protein kinase A and by Ca2+ phospholipid protein kinase C in a Ca2+-dependent way and that interaction occurs between both pathways.

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.

Peptidergic Modulation of an Insect Na+ Current: Role of Protein Kinase A and Protein Kinase C

2001 ◽  
Vol 85 (1) ◽  
pp. 374-383 ◽  
Author(s):  
Dieter Wicher
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Time Constant ◽  
Periplaneta Americana ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Kinase C ◽  
Kinase A

The modulation of voltage-gated Na+ currents in isolated somata of dorsal unpaired median (DUM) neurons of the cockroach Periplaneta americana was investigated using the patch-clamp technique. The neuropeptide Neurohormone D (NHD), which belongs to the family of adipokinetic hormones, reversibly reduced the Na+ current in concentration-dependent manner (1 pM to 10 nM). At 10 nM, NHD caused an attenuation of the maximum of current-voltage ( I-V) relation for peak currents by 23 ± 6%. An analysis of NHD action on current kinetics in terms of the Hodgkin-Huxley formalism revealed that NHD reduces the time constant of inactivation, whereas steady-state activation and inactivation as well as the time constant of activation were not affected. In addition, NHD prolonged the recovery from inactivation. The cAMP analogue 8-bromo-cAMP, forskolin, and the catalytic subunit of protein kinase A mimicked the action of NHD. Furthermore, preincubation of cells with the protein kinase A inhibitor KT 5720 abolished the action of NHD. Thus NHD seems to modify the Na+ current via channel phosphorylation by protein kinase A. Activation of protein kinase C by oleoylacetylglycerol (OAG) also reduced the Na+ current, but it did not occlude the action of NHD. On the other hand, inhibition of protein kinase C by chelerythrine or Gö 6976 did not essentially impair the NHD effects.

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