Muscarine enhances soluble amyloid precursor protein secretion in human neuroblastoma SH-SY5Y by a pathway dependent on protein kinase C(alpha), src-tyrosine kinase and extracellular signal-regulated kinase but not phospholipase C.
The signalling pathways by which muscarine and epidermal growth factor (EGF) regulate the secretion of the alpha-secretase cleavage product (sAPPalpha) of the amyloid precursor protein (APP) were examined in the human neuroblastoma SH-SY5Y. Using specific inhibitors it was found that over 80% of sAPPalpha secretion, enhanced by muscarine, occurred via the extracellular signal-regulated kinase (ERK1/2) member of the mitogen-activated protein kinase (MAPK) family and was dependent on protein kinase Calpha (PKCalpha) and a member of the Src family of non-receptor tyrosine kinases (Src-TK). In contrast the stimulation of sAPPalpha secretion by EGF was not affected by inhibitors of PKC nor Src-TK but was dependent on ERK1/2. In addition muscarine-enhanced sAPPalpha secretion and ERK1/2 activation were inhibited 60 and 80%, respectively, by micromolar concentrations of the phosphatidylinositol 3 kinase (PI-3K) inhibitor wortmannin. In comparison wortmannin decreased EGF stimulation of sAPPalpha secretion and ERK 1/2 activation by approximately 40%. Unexpectedly, U73122, an inhibitor of phosphoinositide-specific phospholipase C, did not inhibit muscarine enhancement of sAPPalpha secretion. These data are discussed in relation to a pathway for the enhancement of sAPPalpha secretion by muscarine which involves the activation of a Src-TK by G-protein beta/gamma-subunits leading to activation of PKCalpha, and ERK1/2 by a mechanism not involving phospholipase C.
Academic Unit of Cardiovascular Medicine, University of Leeds, Leeds, UK.
Rosa-Maria
RM
Canet-Aviles
Mark
M
Anderton
Nigel M
NM
Hooper
Anthony J
AJ
Turner
Peter F T
PF
Vaughan
D000544:Alzheimer Disease / Q000201:enzymology* / Q000503:physiopathology; D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis* / Q000187:drug effects / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000187:drug effects / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D009116:Muscarine / Q000494:pharmacology*; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009447:Neuroblastoma; D009474:Neurons / Q000187:drug effects / Q000201:enzymology*; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism; D051571:Protein Kinase C-alpha; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D019061:src-Family Kinases / Q000187:drug effects / Q000378:metabolism
D016564:Amyloid beta-Protein Precursor; D007527:Isoenzymes; D018721:Muscarinic Agonists; D009116:Muscarine; D019061:src-Family Kinases; C496628:PRKCA protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases