Regulation by protein kinase-C of putative P-type Ca channels expressed in Xenopus oocytes from cerebellar mRNA.
Xenopus oocytes injected with rat cerebellar mRNA expressed functional voltage-dependent Ca channels detected as an inward Ba current (IBa). The pharmacological resistance to dihydropyridines and omega-conotoxin together with the blockade obtained with Agelenopsis aperta venom suggest that these channels could be somehow assimilated to P-type Ca channels. The precise nature of the transplanted Ca channels was assessed by hybrid-arrest experiments using a specific oligonucleotide antisense-derivated from the recently cloned alpha 1-subunit of P channels (BI-1 clone). In addition, we demonstrate that exogenous Ca channel activity was enhanced by two different PKC activators (a phorbol ester and a structural analog to diacylglycerol). The general electrophysiological and pharmacological properties of the stimulated Ca channels remain unchanged. This potentiation induced by PKC activators is antagonized by a PKC inhibitor (staurosporine) and by a monoclonal antibody directed against PKC. It is concluded that P-type Ca channels are potentially regulated by PKC phosphorylation and the functional relevance of this intracellular pathway is discussed.
Laboratoire de Neurobiologie Cellulaire, Université de Picardie, Faculté des Sciences, Amiens, France.
F
F
Fournier
P
P
Charnet
E
E
Bourinet
C
C
Vilbert
F
F
Matifat
G
G
Charpentier
P
P
Navarre
G
G
Brûlé
D
D
Marlot
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism*; D003001:Cloning, Molecular; D004594:Electrophysiology; D004789:Enzyme Activation; D009865:Oocytes; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D014981:Xenopus
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D012333:RNA, Messenger; D011493:Protein Kinase C