Kainate receptors mediate regulated exocytosis of secretory phospholipase A2 in SH-SY5Y neuroblastoma cells

• Main Authors: Farooqui, Akhlaq A., Than, Aung, Tan, Yan, Ong, Wei-Yi, Chen, Peng
• Other Authors: School of Chemical and Biomedical Engineering
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Science::Biological sciences::Human anatomy and physiology::Neurobiology
• Online Access: https://hdl.handle.net/10356/107467; http://hdl.handle.net/10220/16680
• Institution: Nanyang Technological University

Secretory phospholipase A(2) (sPLA(2)) isoforms are widely expressed in the brain and spinal cord. Group IIA sPLA(2) (sPLA(2)-IIA) has been shown to stimulate exocytosis and release of neurotransmitters in neuroendocrine PC12 cells and neurons, suggesting a role of the enzyme in neuronal signaling and synaptic transmission. However, the mechanisms by which sPLA(2) is itself released, and a possible relation between glutamate receptors and sPLA(2) exocytosis, are unknown. This study was carried out to elucidate the effects of glutamate receptor agonists on exocytosis of sPLA(2)-IIA in transfected SH-SY5Y neuroblastoma cells. sPLA(2)-IIA enzyme was packaged in fusion-competent vesicles and released constitutively or upon stimulation, suggesting regulated secretion. The signal peptide of sPLA(2)-IIA is required for its vesicular localization and exocytosis. External application of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate (KA) induced vesicular exocytosis and release of sPLA(2)-IIA. UBP 302, a GluR5-specific KA receptor antagonist, abolished the effect of KA, confirming the role of KA receptors in mediating sPLA(2)-IIA secretion. Moreover, KA-induced sPLA(2)-IIA secretion is dependent on Ca(2+) and protein kinase C. Together, these findings provide evidence of a link between glutamate receptors and regulated sPLA(2) secretion in neurons that may play an important role in synaptic plasticity, pain transmission and neurodegenerative diseases.