scholarly journals Rate of calcium entry determines the rapid changes in protein kinase C activity in angiotensin II-stimulated adrenal glomerulosa cells

1994 ◽  
Vol 297 (3) ◽  
pp. 523-528 ◽  
Author(s):  
I Kojima ◽  
N Kawamura ◽  
H Shibata
Keyword(s):  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Protein Kinase ◽  
Specific Substrate ◽  
Ang Ii ◽  
Kinase C ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
Peptide Phosphorylation

The present study was conducted to monitor precisely the activity of protein kinase C (PKC) in adrenal glomerulosa cells stimulated by angiotensin II (ANG II). PKC activity in cells was monitored by measuring phosphorylation of a synthetic KRTLRR peptide, a specific substrate for PKC, immediately after the permeabilization of the cells with digitonin [Heasley and Johnson J. Biol. Chem. (1989) 264, 8646-8652]. Addition of 1 nM ANG II induced a gradual increase in KRTLRR peptide phosphorylation, which reached a peak at 30 min, and phosphorylation was sustained thereafter. When the action of ANG II was terminated by adding [Sar1,Ala8]ANG II, a competitive antagonist, both Ca2+ entry and KRTLRR phosphorylation ceased rapidly, whereas diacylglyercol (DAG) content was not changed significantly within 10 min. Similarly, when blockade of Ca2+ entry was achieved by decreasing extracellular Ca2+ to 1 microM or by adding 1 microM nitrendipine, KRTLRR peptide phosphorylation was decreased within 5 min. In addition, restoration of Ca2+ entry was accompanied by an immediate increase in KRTLRR peptide phosphorylation. Under the same condition, DAG content did not change significantly. We then examined the role of the PKC pathway in ANG II-induced aldosterone production. Ro 31-8220 inhibited ANG II-induced KRTLRR phosphorylation without affecting the activity of calmodulin-dependent protein kinase II. In the presence of Ro 31-8220, ANG II-mediated aldosterone production was decreased to approx. 50%. Likewise, intracellular administration of PKC19-36, a sequence corresponding to residues 19-36 of the regulatory domain of PKC known to inhibit PKC activity, attenuated ANG II-mediated activation of PKC and aldosterone output. These results indicate a critical role of Ca2+ entry in the regulation of PKC activity by ANG II.

scholarly journals Angiotensin II Activates Mitogen-Activated Protein Kinase Via Protein Kinase C and Ras/Raf-1 Kinase in Bovine Adrenal Glomerulosa Cells

Endocrinology ◽  
1998 ◽  
Vol 139 (4) ◽  
pp. 1801-1809 ◽  
Author(s):  
Ying Tian ◽  
Roger D. Smith ◽  
Tamas Balla ◽  
Kevin J. Catt
Keyword(s):  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Protein Kinase ◽  
Time Course ◽  
Mitogen Activated Protein Kinase ◽  
Ang Ii ◽  
Mapk Activation ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
Glomerulosa Cells

Abstract Angiotensin II (Ang II) stimulates growth and mitogenesis in bovine adrenal glomerulosa cells, but little is known about the signaling pathways that mediate these responses. An analysis of the growth-promoting pathways in cultured bovine adrenal glomerulosa cells revealed that Ang II, acting via the AT1 receptor, caused rapid but transient activation of mitogen-activated protein kinase (MAPK), with an ED50 of 10–50 pm. Although neither Ca2+ influx nor Ca2+ release from intracellular stores was sufficient to activate MAPK, Ca2+ appeared to play a permissive role in this response. A major component of Ang II-induced MAPK activation was insensitive to pertussis toxin (PTX), although a minor PTX-sensitive component could not be excluded. Ang II also induced the rapid activation of ras and raf-1 kinase with time-courses that correlated with that of MAPK. Activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate was sufficient to activate both MAPK and raf-1 kinase. However, whereas PKC depletion had no effect on Ang II-induced raf-1 kinase activation, it attenuated Ang II-induced MAPK activation. Ang II also stimulated a mobility shift of raf-1, reflecting hyperphosphorylation of the kinase. However, unlike its activation, raf-1 hyperphosphorylation was dependent on PKC and its time-course correlated not with activation, but rather with deactivation of the kinase. Taken together, these findings indicate that Ang II stimulates multiple pathways to MAPK activation via PKC and ras/raf-1 kinase in bovine adrenal glomerulosa cells.

scholarly journals Role of tyrosine kinase and protein kinase C in the steroidogenic actions of angiotensin II, α-melanocyte-stimulating hormone and corticotropin in the rat adrenal cortex

1995 ◽  
Vol 305 (2) ◽  
pp. 433-438 ◽  
Author(s):  
S Kapas ◽  
A Purbrick ◽  
J P Hinson
Keyword(s):  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Zona Glomerulosa ◽  
Aldosterone Secretion ◽  
Melanocyte Stimulating Hormone ◽  
Kinase C ◽  
Stimulating Hormone

The role of protein kinases in the steroidogenic actions of alpha-melanocyte-stimulating hormone (alpha-MSH), angiotensin II (AngII) and corticotropin (ACTH) in the rat adrenal zona glomerulosa was examined. Ro31-8220, a potent selective inhibitor of protein kinase C (PKC), inhibited both AngII- and alpha-MSH-stimulated aldosterone secretion but had no effect on aldosterone secretion in response to ACTH. The effect of Ro31-8220 on PKC activity was measured in subcellular fractions. Basal PKC activity was higher in cytosol than in membrane or nuclear fractions. Incubation of the zona glomerulosa with either alpha-MSH or AngII resulted in significant increases in PKC activity in the nuclear and cytosolic fractions and decreases in the membrane fraction. These effects were all inhibited by Ro31-8220. ACTH caused a significant increase in nuclear PKC activity only, and this was inhibited by Ro31-8220 without any significant effect on the steroidogenic response to ACTH, suggesting that PKC translocation in response to ACTH may be involved in another aspect of adrenal cellular function. Tyrosine phosphorylation has not previously been considered to be an important component of the response of adrenocortical cells to peptide hormones. Both AngII and alpha-MSH were found to activate tyrosine kinase, but ACTH had no effect, observations that have not been previously reported. Tyrphostin 23, a specific antagonist of tyrosine kinases, inhibited aldosterone secretion in response to AngII and alpha-MSH, but not ACTH. These data confirm the importance of PKC in the adrenocortical response to AngII and alpha-MSH, and, furthermore, indicate that tyrosine kinase may play a critical role in the steroidogenic actions of AngII and alpha-MSH in the rat adrenal zona glomerulosa.

scholarly journals Mechanism of inhibitory action of TMB-8 [8-(NN-diethylamino)octyl-3,4,5-trimethoxybenzoate] on aldosterone secretion in adrenal glomerulosa cells

1985 ◽  
Vol 232 (1) ◽  
pp. 87-92 ◽  
Author(s):  
I Kojima ◽  
K Kojima ◽  
H Rasmussen
Keyword(s):  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Protein Kinase ◽  
Calcium Release ◽  
Calcium Influx ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Aldosterone Secretion ◽  
Kinase C ◽  
Glomerulosa Cells

The mechanism of 8-(NN-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8) action was evaluated in isolated adrenal glomerulosa cells. TMB-8 inhibits both angiotensin II- and K+-stimulated aldosterone secretion in a dose-dependent manner. The ID50 for angiotensin II- and K+-stimulated aldosterone secretion is 46 and 28 microM, respectively. In spite of the fact that 100 microM-TMB-8 inhibits angiotensin II-stimulated aldosterone secretion almost completely, TMB-8 (100 microM) does not inhibit angiotensin II-induced 45Ca2+ efflux from prelabelled cells nor does it affect inositol 1,4,5-trisphosphate-induced calcium release from non-mitochondrial pool(s) in saponin-permeabilized cells. TMB-8 has no inhibitory effect on A23187-induced aldosterone secretion, but 12-O-tetradecanoylphorbol 13-acetate-induced aldosterone secretion is completely abolished. TMB-8 effectively inhibits both angiotensin II- and K+-induced increases in calcium influx but has no effect on A23187-induced calcium influx. TMB-8 inhibits the activity of protein kinase C dose-dependently. These results indicate that TMB-8 inhibits aldosterone secretion without inhibiting mobilization of calcium from an intracellular pool. The inhibitory effect of TMB-8 is due largely to an inhibition of plasma membrane calcium influx, but this drug also inhibits the activity of protein kinase C directly.

Regulation of vascular angiotensin II receptors by EGF

1997 ◽  
Vol 273 (4) ◽  
pp. C1241-C1249 ◽  
Author(s):  
Michael E. Ullian ◽  
John R. Raymond ◽  
Mark C. Willingham ◽  
Richard V. Paul
Keyword(s):  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Growth Factor ◽  
Protein Kinase ◽  
Pertussis Toxin ◽  
Receptor Expression ◽  
Ang Ii ◽  
Receptor Density ◽  
Kinase C ◽  
Surface Receptor

After vascular endothelial injury, angiotensin II (ANG II) plays a role in the resulting hypertrophic response, and expression of epidermal growth factor (EGF) is enhanced. Therefore, we tested the possibility that EGF regulates vascular ANG II action and receptor expression. Incubation of cultured aortic vascular smooth muscle cells (VSMC) with EGF (or basic fibroblast growth factor but not platelet-derived growth factor isoforms) resulted in concentration-dependent (1–50 ng/ml EGF), time-dependent (>8 h), and reversible decreases in ANG II surface receptor density. For example, a 50% reduction was observed after exposure to 50 ng/ml EGF for 24 h. Incubation of cultured VSMC with 50 ng/ml EGF for 24 h resulted in a 77% reduction in ANG II-stimulated inositol phosphate formation. EGF not only prevented but also reversed ANG II receptor upregulation by 100 nM corticosterone. The specific tyrosine kinase inhibitor tyrphostin A48 (50 μM) reduced EGF-stimulated thymidine incorporation and EGF-stimulated phosphorylation of mitogen-activated protein kinase but did not prevent EGF from reducing ANG II receptor density. Neither pertussis toxin (100 ng/ml) nor downregulation of protein kinase C by phorbol myristate acetate (100 nM for 24 h) prevented EGF from reducing ANG II receptor density. In summary, EGF is a potent negative regulator of vascular ANG II surface receptor density and ANG II action by mechanisms that do not appear to include tyrosine phorphorylation, pertussis toxin-sensitive G proteins, or phorbol ester-sensitive protein kinase C. The possibility that EGF shifts the cell culture phenotype to one that exhibits reduced surface ANG II density cannot be eliminated by the present studies.

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