Differential involvement of protein kinase C alpha and epsilon in the regulated secretion of soluble amyloid precursor protein.
We investigated the differential role of protein kinase C (PKC) isoforms in the regulated proteolytic release of soluble amyloid precursor protein (sAPPalpha) in SH-SY5Y neuroblastoma cells. We used cells stably transfected with cDNAs encoding either PKCalpha or PKCepsilon in the antisense orientation, producing a reduction of the expression of PKCalpha and PKCepsilon, respectively. Reduced expression of PKCalpha and/or PKCepsilon did not modify the response of the kinase to phorbol ester stimulation, demonstrating translocation of the respective isoforms from the cytosolic fraction to specific intracellular compartments with an interesting differential localization of PKCalpha to the plasma membrane and PKCepsilon to Golgi-like structures. Reduced expression of PKCalpha significantly impaired the secretion of sAPPalpha induced by treatment with phorbol esters. Treatment of PKCalpha-deficient cells with carbachol induced a significant release of sAPPalpha. These results suggest that the involvement of PKCalpha in carbachol-induced sAPPalpha release is negligible. The response to carbachol is instead completely blocked in PKCepsilon-deficient cells suggesting the importance of PKCepsilon in coupling cholinergic receptors with APP metabolism.
Lanni
Cristina
C
Department of Experimental and Applied Pharmacology, Centre of Excellence in Applied Biology and School of Pharmacy, University of Pavia, Viale Taramelli 14, 27100 Pavia, Italy.
Mazzucchelli
Michela
M
Porrello
Emanuela
E
Govoni
Stefano
S
Racchi
Marco
M
D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D045744:Cell Line, Tumor / Q000187:drug effects; D018679:Cholinergic Agonists / Q000494:pharmacology; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009447:Neuroblastoma; D010703:Phorbol Esters / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D051744:Protein Kinase C-epsilon
D016564:Amyloid beta-Protein Precursor; D018679:Cholinergic Agonists; D007527:Isoenzymes; D010703:Phorbol Esters; D002217:Carbachol; C496628:PRKCA protein, human; C497255:PRKCE protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051744:Protein Kinase C-epsilon; D020928:Mitogen-Activated Protein Kinases