scholarly journals Modulation of 1,25-dihydroxyvitamin D3-dependent Ca2+ uptake in skeletal muscle by protein kinase C

1992 ◽  
Vol 281 (2) ◽  
pp. 349-352 ◽  
Author(s):  
V Massheimer ◽  
A R de Boland
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Short Exposure ◽  
Dihydroxyvitamin D3 ◽  
45Ca Uptake ◽  
1,25 Dihydroxyvitamin D3 ◽  
Kinase C ◽  
Stimulation Of

In vitro studies have shown that short exposure (1-10 min) of vitamin D-deficient chick soleus muscle to 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] causes an acute stimulation of tissue 45Ca uptake through voltage-gated Ca2+ channels, with parallel increases in cyclic AMP levels, adenylate cyclase activity and membrane protein phosphorylation. We further investigated the involvement of protein kinases in the rapid effects of 1,25(OH)2D3 on skeletal muscle. The hormone was found to stimulate the protein kinase C (PKC) activity of muscle membranes. The PKC activator phorbol 12-myristate 13-acetate (PMA, 100 nM) was found to rapidly stimulate muscle 45Ca uptake, mimicking 1,25(OH)2D3. Increases of 68% and 46% were observed at 1 and 15 min of exposure to PMA respectively. The effects of PMA were dose-dependent (50-200 nM) and were specific, since the inactive analogue 4 alpha-phorbol was without effect. Analogously to the effects of the sterol, PMA-enhanced 45Ca uptake was abolished by the Ca2+ channel antagonists nifedipine (30 microM) and verapamil (50 microM). Staurosporine (10 nM), a PKC inhibitor, surprisingly potentiated 1,25(OH)2D3-dependent stimulation of 45Ca uptake. Exposure of skeletal muscle to PMA (100 nM) plus 1,25(OH)2D3 (1 nM) produced a less pronounced effect on 45Ca uptake than either agent alone. PMA also decreased muscle cyclic AMP levels. These results suggest a regulatory link between the two major transmembrane signalling systems in the mechanism of action of 1,25(OH)2D3 in skeletal muscle.

Regulation of oxytocin secretion by the ovine corpus luteum: effect of activators of protein kinase C

1990 ◽  
Vol 124 (2) ◽  
pp. 225-232 ◽  
Author(s):  
J. J. Hirst ◽  
G. E. Rice ◽  
G. Jenkin ◽  
G. D. Thorburn
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Corpus Luteum ◽  
Phospholipase C ◽  
Tissue Slices ◽  
Kinase C ◽  
Luteal Tissue ◽  
Dose Dependent ◽  
Stimulation Of

ABSTRACT The effect of protein kinase C activation and dibutyryl cyclic AMP on oxytocin secretion by ovine luteal tissue slices was investigated. Several putative regulators of luteal oxytocin secretion were also examined. Oxytocin was secreted by luteal tissue slices at a basal rate of 234·4 ± 32·8 pmol/g per h (n = 24) during 60-min incubations.Activators of protein kinase C: phorbol 12,13-dibutyrate (n = 8), phorbol 12-myristate,13-acetate (n = 4) and 1,2-didecanoylglycerol (n = 5), caused a dose-dependent stimulation of oxytocin secretion in the presence of a calcium ionophore (A23187; 0·2 μmol/l). Phospholipase C (PLC; 50–250 units/l) also caused a dose-dependent stimulation of oxytocin secretion by luteal slices. Phospholipase C-stimulated oxytocin secretion was potentiated by the addition of an inhibitor of diacylglycerol kinase (R59 022; n = 4). These data suggest that the activation of protein kinase C has a role in the stimulation of luteal oxytocin secretion. The results are also consistent with the involvement of protein kinase C in PLC-stimulated oxytocin secretion. The cyclic AMP second messenger system does not appear to be involved in the control of oxytocin secretion by the corpus luteum. Journal of Endocrinology (1990) 124, 225–232

On the signal transducing mechanisms involved in the synergistic interaction between interleukin-1 and bradykinin on prostaglandin biosynthesis in human gingival fibroblasts

1992 ◽  
Vol 12 (4) ◽  
pp. 263-271 ◽  
Author(s):  
Ulf H. Lerner ◽  
Gustaf Brunius ◽  
Thomas Modeer
Keyword(s):  
Arachidonic Acid ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Phorbol Esters ◽  
Synergistic Interaction ◽  
Human Gingival Fibroblasts ◽  
Gingival Fibroblasts ◽  
Kinase C ◽  
Stimulation Of

Recombinant human interleukin-1β (IL-1β) and bradykinin (BK) synergistically stimulate prostaglandin E2 (PGE2) formation in human gingival fibroblasts cultured for 24 h. Neither BK or IL-1β per se, nor their combinations, caused any acute stimulation of cellular cyclic AMP accumulation. BK, but not IL-1β, caused a rapid, transient rise of intracellular Ca2+ concentration ([Ca2+]i), as assessed by recordings of fura-2 fluorescence in monolayers of prelabelled gingival fibroblasts. IL-1β did not change the effect of BK on [Ca2+]i. Ionomycin and A 23187, two calcium ionophores, synergistically potentiated the stimulatory effect of IL-1β on PGE2 formation. Three different phorbol esters known to activate protein kinase C also synergistically potentiated the action of IL-1β on PGE2 formation. Exogenously added arachidonic acid significantly enhanced the basal formation of PGE2. In IL-1β treated cells, the enhancement of PGE2 formation seen after addition of arachidonic acid, was synergistically upregulated by IL-1β. These data show that i) the synergistic interaction between IL-1β and BK on PGE2 formation is not due to an effect linked to an upregulation of cyclic AMP or [Ca2+]i; ii) the signal transducing mechanism by which BK interacts with IL-1β, however, may be linked to a BK induced stimulation of [Ca2+]i and/or protein kinase C; iii) the mechanism involved in the action of IL-1β may, at least partly, be due to enhancement of the biosynthesis of prostanoids mediated by an upregulation of cyclooxygenase activity.

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