Calcium ionophore A23187 specifically decreases the secretion of β-secretase cleaved amyloid precursor protein during apoptosis in primary rat cortical cultures

• Published in: Journal of neuroscience research Vol. 63; no. 5; pp. 429 - 437
• Main Authors: Sennvik, Kristina, Benedikz, Eirikur, Fastbom, Johan, Sundström, Erik, Winblad, Bengt, Ankarcrona, Maria
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.03.2001
• Subjects: Alzheimer's disease; Amino Acid Chloromethyl Ketones - pharmacology; Amyloid beta-Protein Precursor - metabolism; Amyloid beta-Protein Precursor - secretion; amyloid precursor protein; Amyloid Precursor Protein Secretases; Animals; Annexin A5 - analysis; apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Aspartic Acid Endopeptidases - metabolism; Biological Transport - drug effects; Blotting, Western; Calcimycin - pharmacology; Calcium - physiology; Cells, Cultured - drug effects; Cells, Cultured - secretion; Cerebral Cortex - cytology; Cerebral Cortex - embryology; Colchicine - pharmacology; Culture Media, Conditioned - analysis; Cysteine Proteinase Inhibitors - pharmacology; Cytoskeleton - drug effects; Endopeptidases; Ionophores - pharmacology; Neurons - drug effects; Neurons - enzymology; Neurons - secretion; primary cultures; Rats; Rats, Sprague-Dawley
• ISSN: 0360-4012; 1097-4547
• DOI: 10.1002/1097-4547(20010301)63:5<429::AID-JNR1038>3.0.CO;2-U

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 β‐amyloid (Aβ). Aβ is generated from the amyloid precursor protein (APP) by sequential β‐ and γ‐secretase cleavage. Alternatively, APP may be cleaved within the Aβ region by α‐secretase, preventing Aβ 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 β‐secretase cleaved APP (β‐sAPP) in a caspase‐dependent manner, although the secretion of total soluble APP βsAPP) did not change. In addition, caspase inhibition restored cell viability to control levels. Exposure to colchicine did not change the amount of either secreted β‐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 β‐secretase cleavage of APP. J. Neurosci. Res. 63:429–437, 2001. © 2001 Wiley‐Liss, Inc.