title: Secreted beta-amyloid precursor protein stimulates mitogen-activated protein kinase and enhances tau phosphorylation.
abstract: Biological effects related to cell growth, as well as a role in the pathogenesis of Alzheimer disease, have been ascribed to the beta-amyloid precursor protein (beta-APP). Little is known, however, about the intracellular cascades that mediate these effects. We report that the secreted form of beta-APP potently stimulates mitogen-activated protein kinases (MAPKs). Brief exposure of PC-12 pheochromocytoma cells to beta-APP secreted by transfected Chinese hamster ovary cells stimulated the 43-kDa form of MAPK by > 10-fold. Induction of a dominant inhibitory form of ras in a PC12-derived cell line prevented the stimulation of MAPK by secreted beta-APP, demonstrating the dependence of the effect upon p21ras. Because the microtubule-associated protein tau is hyperphosphorylated in Alzheimer disease, we sought and found a 2-fold enhancement in tau phosphorylation associated with the beta-APP-induced MAPK stimulation. In the ras dominant inhibitory cell line, beta-APP failed to enhance phosphorylation of tau. The data presented here provide a link between secreted beta-APP and the phosphorylation state of tau.
authors.affiliation: Department of Neurology, Harvard Medical School, Boston, MA.
authors.forename: S M
authors.initials: SM
authors.lastname: Greenberg
authors.forename: E H
authors.initials: EH
authors.lastname: Koo
authors.forename: D J
authors.initials: DJ
authors.lastname: Selkoe
authors.forename: W Q
authors.initials: WQ
authors.lastname: Qiu
authors.forename: K S
authors.initials: KS
authors.lastname: Kosik
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004789:Enzyme Activation; D019950:Mitogen-Activated Protein Kinase 1; D016716:PC12 Cells; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism
chemical_list: D016564:Amyloid beta-Protein Precursor; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D016283:Proto-Oncogene Proteins p21(ras)