Recruitment of Ca2+ channels by protein kinase C during rapid formation of putative neuropeptide release sites in isolated Aplysia neurons.
Activation of protein kinase C (PKC) in Aplysia bag cell neurons causes the recruitment of voltage-dependent calcium channels. Using imaging techniques on isolated cells, we have now found that an activator of PKC, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), promotes the rapid appearance of new sites of calcium influx associated with a change in the morphology of neurite endings. In untreated cells, calcium influx triggered by action potentials occurs along neurites and in the central region of growth cones, but does not usually occur at the leading edge of lamellipodia. TPA produces extension of the lamellipodium, and action potentials now trigger calcium influx at the distal edge of the newly extended endings. Cotreatment with TPA and a cyclic AMP analog promotes movement of secretory organelles toward the new sites of calcium influx. Our results suggest that these second messenger systems promote the rapid formation of morphological structures that contribute to the potentiation of peptide release.
Knox
R J
RJ
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
Quattrocki
E A
EA
Connor
J A
JA
Kaczmarek
L K
LK
D000200:Action Potentials; D000818:Animals; D001048:Aplysia / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D016501:Neurites / Q000187:drug effects / Q000648:ultrastructure*; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D009479:Neuropeptides / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D015290:Second Messenger Systems; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology
D015220:Calcium Channels; D009479:Neuropeptides; D013873:Thionucleotides; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D000242:Cyclic AMP; D011494:Protein Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium