title: The amyloid precursor protein potentiates CHOP induction and cell death in response to ER Ca2+ depletion.
abstract: Here we investigated the role of the amyloid precursor protein (APP) in regulation of Ca(2+) store depletion-induced neural cell death. Ca(2+) store depletion from the endoplasmic reticulum (ER) was induced by the SERCA (Sarco/Endoplasmic Reticulum Calcium ATPase) inhibitor thapsigargin which led to a rapid induction of the unfolded protein response (UPR) and a delayed activation of executioner caspases in the cultures. Overexpression of APP potently enhanced cytosolic Ca(2+) levels and cell death after ER Ca(2+) store depletion in comparison to vector-transfected controls. GeneChip and RT-PCR analysis revealed that the expression of classical UPR chaperone genes was not altered by overexpression of APP. Interestingly, the induction of the ER stress-responsive pro-apoptotic transcription factor CHOP was significantly upregulated in APP-overexpressing cells in comparison to vector-transfected controls. Chelation of intracellular Ca(2+) with BAPTA-AM revealed that enhanced CHOP expression after store depletion occurred in a Ca(2+)-dependent manner in APP-overexpressing cells. Prevention of CHOP induction by BAPTA-AM and by RNA interference was also able to abrogate the potentiating effect of APP on thapsigargin-induced apoptosis. Application of the store-operated channel (SOC)-inhibitors SK & F96365 and 2-APB downmodulated APP-triggered potentiation of cytosolic Ca(2+) levels and apoptosis after treatment with thapsigargin. Our data demonstrate that APP significantly modulates Ca(2+) store depletion-induced cell death in a SOC- and CHOP-dependent manner, but independent of the UPR.
authors.affiliation: Department of Neurosurgery, Johann Wolfgang Goethe University Clinics, D-60590 Frankfurt, Germany.
authors.forename: Ekaterini
authors.initials: E
authors.lastname: Copanaki
authors.forename: Tina
authors.initials: T
authors.lastname: Schürmann
authors.forename: Anne
authors.initials: A
authors.lastname: Eckert
authors.forename: Kristina
authors.initials: K
authors.lastname: Leuner
authors.forename: Walter E
authors.initials: WE
authors.lastname: Müller
authors.forename: Jochen H M
authors.initials: JH
authors.lastname: Prehn
authors.forename: Donat
authors.initials: D
authors.lastname: Kögel
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D002021:Buffers; D002118:Calcium / Q000172:deficiency*; D015220:Calcium Channels / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D016716:PC12 Cells; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D019284:Thapsigargin / Q000494:pharmacology; D051742:Transcription Factor CHOP / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D016564:Amyloid beta-Protein Precursor; D002021:Buffers; D015220:Calcium Channels; D002614:Chelating Agents; D012333:RNA, Messenger; D051742:Transcription Factor CHOP; D004533:Egtazic Acid; D019284:Thapsigargin; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium