Muscarinic regulation of Alzheimer's disease amyloid precursor protein secretion and amyloid beta-protein production in human neuronal NT2N cells.
The Alzheimer amyloid precursor protein (APP) undergoes complex processing resulting in the production of a 4-kDa amyloid peptide (A beta) which has been implicated in the pathogenesis of Alzheimer's disease. Recent studies have shown that cells can secrete carboxyl terminus truncated APP derivatives (APP-S) in response to physiological stimulus. We have used human central nervous system neurons (NT2N) derived from a teratocarcinoma cell line (NT2) to study the signal transduction pathways involved in APP-S secretion and A beta production. Muscarinic receptors (m2 and m3) as well as the heterotrimeric GTP-binding protein Gq and the beta 1 isoform of phospholipase C were present in NT2N neurons. Stimulation of the muscarinic receptor with carbachol resulted in phospholipase C activation as shown by a transient increase in the second messengers 1,2-diacyl-sn-glycerol and inositol 1,4,5-trisphosphate. Carbachol also caused an increase in intracellular Ca2+ levels measured in single NT2N neurons. Under these conditions, carbachol caused a time-dependent 2-fold increase in APP-S secretion into the medium. In contrast, prolonged treatment with carbachol caused a decrease in A beta production into the medium. These results suggest that APP-S secretion and A beta production in NT2N neurons are regulated by the muscarinic/phospholipase C signal transduction pathway. Furthermore, activation of this pathway results in dissociation of APP-S secretion and A beta production.
Wolf
B A
BA
Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104.
Wertkin
A M
AM
Jolly
Y C
YC
Yasuda
R P
RP
Wolfe
B B
BB
Konrad
R J
RJ
Manning
D
D
Ravi
S
S
Williamson
J R
JR
Lee
V M
VM
D000544:Alzheimer Disease / Q000378:metabolism*; D000682:Amyloid / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000096:biosynthesis*; D002217:Carbachol / Q000494:pharmacology; D004789:Enzyme Activation; D006801:Humans; D009474:Neurons / Q000378:metabolism*; D000072002:Prion Proteins; D011328:Prions; D011498:Protein Precursors / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000502:physiology*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism
D000682:Amyloid; D016229:Amyloid beta-Peptides; C512656:PRNP protein, human; D000072002:Prion Proteins; D011328:Prions; D011498:Protein Precursors; D011976:Receptors, Muscarinic; D002217:Carbachol; D010738:Type C Phospholipases