ERK1/2 is an endogenous negative regulator of the gamma-secretase activity.
As an essential protease in the generation of amyloid beta, gamma-secretase is believed to play an important role in the pathogenesis of Alzheimer's disease. Although a great deal of progress has been made in identifying the components of gamma-secretase complex, the endogenous regulatory mechanism of gamma-secretase is unknown. Here we show that gamma-secretase is endogenously regulated via extracellular signal regulated MAP kinase (ERK) 1/2-dependent mitogen-activated protein kinase (MAPK) pathway. The inhibition of ERK1/2 activity, either by a treatment with a MEK inhibitor or an ERK knockdown transfection, dramatically increased gamma-secretase activity in several different cell types. JNK or p38 kinase inhibitors had little effect, indicating that the effect is specific to ERK1/2-dependent MAPK pathway. Conversely, increased ERK1/2 activity, by adding purified active ERK1/2 or EGF-induced activation of ERK1/2, significantly reduced gamma-secretase activity, demonstrating down-regulation of gamma-secretase activity by ERK1/2. Whereas gamma-secretase expression was not affected by ERK1/2, its activity was enhanced by phosphatase treatment, indicating that ERK1/2 regulates gamma-secretase activity by altering the pattern of phophorylation. Among the components of isolated gamma-secretase complex, only nicastrin was phosphorylated by ERK1/2, and it precipitated with ERK1/2 in a co-immunoprecipitation assay, which suggests binding between ERK1/2 and nicastrin. Our results show that ERK1/2 is an endogenous regulator of gamma-secretase, which raises the possibility that ERK1/2 down-regulates gamma-secretase activity by directly phosphorylating nicastrin.
Kim
Su-Kyoung
SK
Department of Biochemistry and Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
Park
Hyun-Jung
HJ
Hong
Hyun Seok
HS
Baik
Eun Joo
EJ
Jung
Min Whan
MW
Mook-Jung
Inhee
I
D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases; D002460:Cell Line; D010450:Endopeptidases / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D034622:RNA Interference; D051880:Receptors, Notch / Q000378:metabolism; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D016564:Amyloid beta-Protein Precursor; D051880:Receptors, Notch; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human