Amino-terminal region of the beta-amyloid precursor protein activates mitogen-activated protein kinase.
The secreted form of the beta-amyloid precursor protein (beta-APP) has previously been shown to stimulate mitogen-activated protein (MAP) kinases in PC-12 pheochromocytoma cells. The amino-terminal half of secreted beta-APP contains a region rich in cysteine residues reminiscent of cysteine-rich binding regions in other families of extracellular proteins. We found that reductive alkylation of disulfide linkages eliminated the ability of secreted beta-APP to activate MAP kinase. To confirm the role of the cysteine-rich amino-terminal region, fragments representing the amino- and carboxyl-terminal halves of secreted beta-APP were expressed in bacteria as fusion proteins and purified. Ten-minute treatment with the amino-terminal segment of beta-APP activated MAP kinase approximately 15-fold, while the carboxyl segment had no effect. The amino-terminal fragment, like intact secreted beta-APP, was substantially inactivated by reduction of sulfhydryl groups. These results suggest that the amino-terminal region of beta-APP is responsible for activation of MAP kinase and that it requires structural loops created by disulfide linkages for activity.
Greenberg
S M
SM
Department of Neurology, Harvard Medical School, Brigham and Women's Hospital, Boston, MA 02115, USA.
Qiu
W Q
WQ
Selkoe
D J
DJ
Ben-Itzhak
A
A
Kosik
K S
KS
D000478:Alkylation; D000595:Amino Acid Sequence; D016564:Amyloid beta-Protein Precursor / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D006224:Cricetinae; D004220:Disulfides / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D008934:Mitogens / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D016716:PC12 Cells; D051381:Rats
D016564:Amyloid beta-Protein Precursor; D004220:Disulfides; D008934:Mitogens; D017871:Calcium-Calmodulin-Dependent Protein Kinases