Activation of Endogenous Protein Kinase C by Halothane in Synaptosomes

1996 ◽  
Vol 84 (3) ◽  
pp. 652-662 ◽  
Author(s):  
Hugh C. Hemmings ◽  
Anna I. B. Adamo
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Synaptic Membranes ◽  
Dependent Protein Kinase ◽  
Kinase C ◽  
Endogenous Protein ◽  
Dependent Protein ◽  
Protein Kinase C Activation ◽  
Synapsin 1

Background Protein kinase C is a signal transducing enzyme that is an important regulator of multiple physiologic processes and a potential molecular target for general anesthetic actions. However, the results of previous studies of the effects of general anesthetics on protein kinase C activation in vitro have been inconsistent. Methods The effects of halothane on endogenous brain protein kinase C activation were analyzed in isolated rat cerebrocortical nerve terminals (synaptosomes) and in synaptic membranes. Protein kinase C activation was monitored by the phosphorylation of MARCKS, a specific endogenous substrate. Results Halothane stimulated basal Ca2+ dependent phosphorylation of MARCKS (Mr = 83,000) in lysed synaptic membranes (2.1-fold; P< 0.01) and in intact synaptosomes (1.4-fold; P< 0.01). The EC50 for stimulation of MARCKS phosphorylation by halothene in synaptic membranes was 1.8 vol%. A selective peptide protein kinase C inhibitor, but not a protein phosphatase inhibitor (okadaic acid) or a peptide inhibitor of Ca2+/calmodulin-dependent protein kinase II, another Ca2+/-dependent signal transducing enzyme, blocked halothane-stimulated MARCKS phosphorylation in synaptic membranes. Halothane did not affect the phosphorylation of synapsin 1, a synaptic vesicle-associated protein substrate for Ca2+/calmodulin-dependent protein kinase II and AMP-dependent protein kinase, in synaptic membranes or intact synaptosomes subjected to KC1-evoked depolarization. However, halothane stimulated synapsin 1 phosphorylation evoked by ionomycin (a Ca2+ ionophore that permeabilizes membranes to Ca2+) in intact synaptosomes. Conclusions Halothane acutely stimulated basal protein kinase C activity in synaptosomes when assayed with endogenous nerve terminal substrates, lipids, and protein kinase C. This effect appeared to be selective for protein kinases C, because two other structurally similar second messenger-regulated protein kinases were not affected. Direct determinations of anesthetic effects on endogenous protein kinase C activation, translocation, and/or down-regulation are necessary to determine the ultimate effect of anesthetics on the protein kinase C signaling pathway in intact cells.

ANP stimulates phospholipase C in cultured RIMCT cells: roles of protein kinases and G protein

1991 ◽  
Vol 260 (4) ◽  
pp. F590-F595 ◽  
Author(s):  
T. Berl ◽  
J. Mansour ◽  
I. Teitelbaum
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinases ◽  
G Protein ◽  
Pertussis Toxin ◽  
Cyclic Nucleotide ◽  
Dependent Protein Kinase ◽  
Kinase C ◽  
Dependent Protein ◽  
Stimulation Of

We examined the possibility that, in addition to stimulation of guanylate cyclase (GC), atrial natriuretic peptide (ANP) also activates phospholipase C (PLC) in cultured rat inner medullary collecting tubule (RIMCT) cells. ANP (10(-12)M) causes marked release of inositol trisphosphate (IP3) at a concentration that does not stimulate GC. Concentrations of ANP that stimulate GC (greater than or equal to 10(-10) M) result in attenuated IP3 release. Similarly, exogenous dibutyryl guanosine 3',5'-cyclic monophosphate (10(-6) M) markedly inhibits the response to 10(-10) M ANP. Inhibition of cyclic nucleotide-dependent protein kinase by H 8, but not inhibition of protein kinase C by H 7, restores the response to 10(-8) and 10(-6) M ANP. Therefore, activation of cyclic nucleotide-dependent protein kinase inhibits ANP-stimulated PLC activity. Activation of protein kinase C by phorbol 12-myristate-13-acetate (PMA) decreases ANP-stimulated IP3 production. Pretreatment with H 7, but not H 8, prevents inhibition by PMA. To explore a potential role for G proteins, we examined the effect of guanine nucleotide analogues on ANP-stimulated IP3 production in saponin-permeabilized cells. ANP-stimulated IP3 production is enhanced by GTP gamma S and is inhibited by GDP beta S. Similarly, preincubation with pertussis toxin prevents ANP-stimulated IP3 release. We conclude that ANP stimulates PLC in RIMCT cells via a pertussis toxin-sensitive G protein. Stimulation of PLC is inhibited on activation of either cyclic nucleotide or Ca2+-phospholipid dependent protein kinases.

scholarly journals Dystrophin is phosphorylated by endogenous protein kinases

1993 ◽  
Vol 293 (1) ◽  
pp. 243-247 ◽  
Author(s):  
M Luise ◽  
C Presotto ◽  
L Senter ◽  
R Betto ◽  
S Ceoldo ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinases ◽  
Cyclic Gmp ◽  
Casein Kinase ◽  
Cytoskeletal Proteins ◽  
Kinase C ◽  
Endogenous Protein ◽  
Dependent Protein

Dystrophin, the protein coded by the gene missing in Duchenne muscular dystrophy, is assumed to be a component of the membrane cytoskeleton of skeletal muscle. Like other cytoskeletal proteins in different cell types, dystrophin bound to sarcolemma membranes was found to be phosphorylated by endogenous protein kinases. The phosphorylation of dystrophin was activated by cyclic AMP, cyclic GMP, calcium and calmodulin, and was inhibited by cyclic AMP-dependent protein kinase peptide inhibitor, mastoparan and heparin. These results suggest that membrane-bound dystrophin is a substrate of endogenous cyclic AMP- and cyclic GMP-dependent protein kinases, calcium/calmodulin-dependent kinase and casein kinase II. The possibility that dystrophin could be phosphorylated by protein kinase C is suggested by the inhibition of phosphorylation by staurosporin. On the other hand dystrophin seems not to be a substrate for protein tyrosine kinases, as shown by the lack of reaction of phosphorylated dystrophin with a monoclonal antiphosphotyrosine antibody. Sequence analysis indicates that dystrophin contains seven potential phosphorylation sites for cyclic AMP- and cyclic GMP-dependent protein kinases (all localized in the central rod domain of the molecule) as well as several sites for protein kinase C and casein kinase II. Interestingly, potential sites of phosphorylation by protein kinase C and casein kinase II are located in the proximity of the actin-binding site. These results suggest, by analogy with what has been demonstrated in the case of other cytoskeletal proteins, that the phosphorylation of dystrophin by endogenous protein kinases may modulate both self assembly and interaction of dystrophin with other cytoskeletal proteins in vivo.

scholarly journals Phosphorylation of sucrose synthase from maize seedlings.

1997 ◽  
Vol 44 (4) ◽  
pp. 809-817 ◽  
Author(s):  
S Lindblom ◽  
P Ek ◽  
G Muszyńska ◽  
B Ek ◽  
J Szczegielniak ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Sucrose Synthase ◽  
Maize Seedlings ◽  
Dependent Protein Kinase ◽  
Kinase C ◽  
Endogenous Protein ◽  
Dependent Protein ◽  
Mammalian Protein

Two isoforms of sucrose synthase (SS1 and SS2) from maize (Zea mays, var. Mona) seedlings co-purified with a calcium and phospholipid dependent protein kinase. The enzymatic preparation obtained gave a positive reaction with the antibody against mammalian protein kinase C. Maize sucrose synthase was phosphorylated by the endogenous protein kinase. Also, mammalian protein kinases (protein kinase C and protein kinase A) were able to phosphorylate the 86 kDa subunit of sucrose synthase. When excised seedlings were fed [32P]orthophosphate, sucrose synthase was also phosphorylated. Microsequencing of in vivo labelled enzyme has shown phosphorylation of Ser-15 in SS2. The present work provides evidence that maize sucrose synthase is the physiological substrate of the endogenous calcium and phospholipid dependent protein kinase(s).

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