Stimulation of beta-amyloid precursor protein trafficking by insulin reduces intraneuronal beta-amyloid and requires mitogen-activated protein kinase signaling.
Alzheimer's Disease (AD) is characterized by cerebral accumulation of beta-amyloid peptides (Abeta), which are proteolytically derived from beta-amyloid precursor protein (betaAPP). betaAPP metabolism is highly regulated via various signal transduction systems, e.g., several serine/threonine kinases and phosphatases. Several growth factors known to act via receptor tyrosine kinases also have been demonstrated to regulate sbetaAPP secretion. Among these receptors, insulin and insulin-like growth factor-1 receptors are highly expressed in brain, especially in hippocampus and cortex. Emerging evidence indicates that insulin has important functions in brain regions involved in learning and memory. Here we present evidence that insulin significantly reduces intracellular accumulation of Abeta and that it does so by accelerating betaAPP/Abeta trafficking from the trans-Golgi network, a major cellular site for Abeta generation, to the plasma membrane. Furthermore, insulin increases the extracellular level of Abeta both by promoting its secretion and by inhibiting its degradation via insulin-degrading enzyme. The action of insulin on betaAPP metabolism is mediated via a receptor tyrosine kinase/mitogen-activated protein (MAP) kinase kinase pathway. The results suggest cell biological and signal transduction mechanisms by which insulin modulates betaAPP and Abeta trafficking in neuronal cultures.
Gasparini
L
L
Laboratory of Molecular and Cellular Neuroscience, Fisher Center for Research on Alzheimer Disease, and Laboratory for Mass Spectrometry, The Rockefeller University, New York, New York 10021, USA.
Gouras
G K
GK
Wang
R
R
Gross
R S
RS
Beal
M F
MF
Greengard
P
P
Xu
H
H
D000544:Alzheimer Disease / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D007339:Insulysin; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D004791:Enzyme Inhibitors; D007328:Insulin; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); D020794:Receptor Protein-Tyrosine Kinases; D007339:Insulysin