Calcium ionophore A23187 specifically decreases the secretion of beta-secretase cleaved amyloid precursor protein during apoptosis in primary rat cortical cultures.
Alzheimer's disease (AD) is characterized by the degeneration and loss of neurons, intracellular neurofibrillary tangles and the accumulation of extracellular senile plaques consisting mainly of beta-amyloid (A beta). A beta is generated from the amyloid precursor protein (APP) by sequential beta- and gamma-secretase cleavage. Alternatively, APP may be cleaved within the A beta region by alpha-secretase, preventing A beta formation. Here we investigated APP processing and secretion in primary neurons, using either colchicine or the calcium ionophore A23187 to induce apoptosis. Cell viability was determined by MTT measurements and apoptosis was further confirmed by annexin V and propidium iodide staining. We found that exposure to A23187 significantly decreased the secretion of soluble beta-secretase cleaved APP (beta-sAPP) in a caspase-dependent manner, although the secretion of total soluble APP beta sAPP) did not change. In addition, caspase inhibition restored cell viability to control levels. Exposure to colchicine did not change the amount of either secreted beta-sAPP or total sAPP and caspase inhibition was only partially able to restore cell viability. We conclude that calcium homeostasis is an important apoptotic effector specifically affecting the beta-secretase cleavage of APP.
Karolinska Institutet, NEUROTEC, Division of Geriatric Medicine, KFC NOVUM, Huddinge, Sweden. Kristina.Sennvik@kfcmail.hs.sll.se
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K
Sennvik
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Benedikz
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Fastbom
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Sundström
B
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Winblad
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Ankarcrona
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D017304:Annexin A5 / Q000032:analysis; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000166:cytology* / Q000196:embryology; D003078:Colchicine / Q000494:pharmacology; D017077:Culture Media, Conditioned / Q000032:analysis; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects; D010450:Endopeptidases; D007476:Ionophores / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D000590:Amino Acid Chloromethyl Ketones; D016564:Amyloid beta-Protein Precursor; D017304:Annexin A5; D017077:Culture Media, Conditioned; D015853:Cysteine Proteinase Inhibitors; D007476:Ionophores; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D000001:Calcimycin; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509281:Bace1 protein, rat; D003078:Colchicine; D002118:Calcium