Linked Life Data

8455026

Source:http://linkedlifedata.com/resource/pubmed/id/8455026

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1993-4-19
pubmed:abstractText
The involvement of B-50, protein kinase C (PKC), and PKC-mediated B-50 phosphorylation in the mechanism of Ca(2+)-induced noradrenaline (NA) release was studied in highly purified rat cerebrocortical synaptosomes permeated with streptolysin-O. Under optimal permeation conditions, 12% of the total NA content (8.9 pmol of NA/mg of synaptosomal protein) was released in a largely (> 60%) ATP-dependent manner as a result of an elevation of the free Ca2+ concentration from 10(-8) to 10(-5) M Ca2+. The Ca2+ sensitivity in the micromolar range is identical for [3H]NA and endogenous NA release, indicating that Ca(2+)-induced [3H]NA release originates from vesicular pools in noradrenergic synaptosomes. Ca(2+)-induced NA release was inhibited by either N- or C-terminal-directed anti-B-50 antibodies, confirming a role of B-50 in the process of exocytosis. In addition, both anti-B-50 antibodies inhibited PKC-mediated B-50 phosphorylation with a similar difference in inhibitory potency as observed for NA release. However, in a number of experiments, evidence was obtained challenging a direct role of PKC and PKC-mediated B-50 phosphorylation in Ca(2+)-induced NA release. PKC pseudosubstrate PKC19-36, which inhibited B-50 phosphorylation (IC50 value, 10(-5) M), failed to inhibit Ca(2+)-induced NA release, even when added before the Ca2+ trigger. Similar results were obtained with PKC inhibitor H-7, whereas polymyxin B inhibited B-50 phosphorylation as well as Ca(2+)-induced NA release. Concerning the Ca2+ sensitivity, we demonstrate that PKC-mediated B-50 phosphorylation is initiated at a slightly higher Ca2+ concentration than NA release. Moreover, phorbol ester-induced PKC down-regulation was not paralleled by a decrease in Ca(2+)-induced NA release from streptolysin-O-permeated synaptosomes. Finally, the Ca(2+)- and phorbol ester-induced NA release was found to be additive, suggesting that they stimulate release through different mechanisms. In summary, we show that B-50 is involved in Ca(2+)-induced NA release from streptolysin-O-permeated synaptosomes. Evidence is presented challenging a role of PKC-mediated B-50 phosphorylation in the mechanism of NA exocytosis after Ca2+ influx. An involvement of PKC or PKC-mediated B-50 phosphorylation before the Ca2+ trigger is not ruled out. We suggest that the degree of B-50 phosphorylation, rather than its phosphorylation after PKC activation itself, is important in the molecular cascade after the Ca2+ influx resulting in exocytosis of NA.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-3042
pubmed:author
pubmed:issnType
Print
pubmed:volume
60
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1264-73
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed-meshheading:8455026-Amino Acid Sequence, pubmed-meshheading:8455026-Animals, pubmed-meshheading:8455026-Bacterial Proteins, pubmed-meshheading:8455026-Calcium, pubmed-meshheading:8455026-Cerebral Cortex, pubmed-meshheading:8455026-GAP-43 Protein, pubmed-meshheading:8455026-Immunoglobulin G, pubmed-meshheading:8455026-Male, pubmed-meshheading:8455026-Membrane Glycoproteins, pubmed-meshheading:8455026-Molecular Sequence Data, pubmed-meshheading:8455026-Nerve Tissue Proteins, pubmed-meshheading:8455026-Norepinephrine, pubmed-meshheading:8455026-Phosphorylation, pubmed-meshheading:8455026-Protein Kinase C, pubmed-meshheading:8455026-Rats, pubmed-meshheading:8455026-Rats, Wistar, pubmed-meshheading:8455026-Streptolysins, pubmed-meshheading:8455026-Synaptosomes, pubmed-meshheading:8455026-Tetradecanoylphorbol Acetate
pubmed:year
1993
pubmed:articleTitle
Studies on the role of B-50 (GAP-43) in the mechanism of Ca(2+)-induced noradrenaline release: lack of involvement of protein kinase C after the Ca2+ trigger.
pubmed:affiliation
Division of Molecular Neurobiology, Rudolf Magnus Institute, Utrecht, The Netherlands.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't