Tyrosine Phosphorylation-dependent Stimulation of Amyloid Precursor Protein Secretion by the m3 Muscarinic Acetylcholine Receptor (*)
- From the Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- §To whom correspondence should be addressed. Tel.: 617-253-8371; Fax: 617-253-6882.
Abstract
Stimulation of m1 and m3 muscarinic acetylcholine receptors, which are coupled to phosphoinositide hydrolysis and protein kinase C activation, has been shown to increase the release of soluble amyloid precursor protein derivatives (APPs). The effect is mimicked by phorbol esters, which directly activate protein kinase C. Using human embryonic kidney cells expressing individual muscarinic receptor subtypes, we found that stimulation of APPs release by the muscarinic agonist carbachol was only partially reduced by a specific inhibitor of protein kinase C (the bisindolylmaleimide GF 109203X), while the response to phorbol 12-myristate 13-acetate (PMA) was abolished. The increase in APPs release elicited by carbachol and PMA was accompanied by elevated tyrosine phosphorylation of several proteins and reduced by tyrosine kinase inhibitors; GF 109203X significantly reduced the stimulation of tyrosine phosphorylation by carbachol and PMA. Inhibition of protein tyrosine phosphatases by vanadyl hydroperoxide markedly increased cellular tyrosine phosphorylation and enhanced APPs release as effectively as PMA and carbachol. Direct phosphorylation of amyloid precursor protein on tyrosine residues following treatment with carbachol, PMA, or vanadyl hydroperoxide was not observed. The results implicate both tyrosine phosphorylation and protein kinase C-dependent mechanisms in the regulation of APPs release by G protein-coupled receptors, and suggest that carbachol and PMA increase APPs release from human embryonic kidney cells expressing m3 muscarinic receptors via partially divergent pathways that converge at a tyrosine phosphorylation-dependent step.
Footnotes
-
↵* Supported in part by grants from the National Institutes of Health (to R. J. W. and B. E. S.) and the Center for Brain Sciences and Metabolism Charitable Trust. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
-
↵1 The abbreviations used are:
- APP
-
amyloid precursor protein
- APPs
-
soluble APP derivatives
- PKC
-
protein kinase C
- HEK
-
human embryonic kidney
- PI
-
phosphoinositide
- PMA
-
phorbol 12-myristate 13-acetate
- APLP
-
APP-like protein.
-
- Received August 25, 1994.
- Revision received January 30, 1995.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
