The amyloid precursor protein protects PC12 cells against endoplasmic reticulum stress-induced apoptosis.
Endoplasmic reticulum (ER) stress is believed to play an important role in neurodegenerative disorders such as Alzheimer's disease. In the present study, we investigated the effect of the human amyloid precursor protein (APP) on the ER stress response in PC12 cells. Tunicamycin, an inhibitor of N-glycosylation, rapidly induced the expression of the ER-resident chaperone Bip/grp78, a known target gene of the unfolded protein response. Prolonged treatment with tunicamycin (>/= 12 h) resulted in the activation of executioner caspases 3 and 7. Interestingly, PC12 cells overexpressing human wild-type APP (APPwt) showed increased resistance to tunicamycin-induced apoptosis compared with empty vector-transfected controls. This neuroprotective effect was significantly diminished in cells expressing the Swedish mutation of APP (KM670/671NL). Similar effects were observed when ER stress was induced with brefeldin A, an inhibitor of ER-to-Golgi protein translocation. Of note, APP-mediated neuroprotection was not associated with altered expression of Bip/grp78 or transcription factor C/EBP homologous protein-10 (CHOP/GADD153), suggesting that APP acted either downstream or independently of ER-to-nucleus signaling. Our data indicate that APP plays an important physiological role in protecting neurons from the consequences of prolonged ER stress, and that APP mutations associated with familial Alzheimer's disease may impair this protective activity.
Kögel
Donat
D
Interdisciplinary Center for Clinical Research (IZKF), Research Group Apoptosis and Cell Death, University Münster Clinics, Münster, Germany. koegel@em.uni-frankfurt.de
Schomburg
Robert
R
Schürmann
Tina
T
Reimertz
Claus
C
König
Hans-Georg
HG
Poppe
Monika
M
Eckert
Anne
A
Müller
Walter E
WE
Prehn
Jochen H M
JH
D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020126:Brefeldin A / Q000494:pharmacology; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D006801:Humans; D009154:Mutation; D016716:PC12 Cells; D017510:Protein Folding; D051381:Rats; D013312:Stress, Physiological / Q000378:metabolism*; D014162:Transfection; D014415:Tunicamycin / Q000494:pharmacology
D016564:Amyloid beta-Protein Precursor; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D014415:Tunicamycin; D020126:Brefeldin A