Differential activation of subtype purinergic receptors modulates Ca2+ mobilization and COX-2 in human microglia

✍ Scribed by Hyun B. Choi; Seok H. Hong; Jae K. Ryu; Seung U. Kim; James G. McLarnon

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 289 KB
• Volume: 43
• Category: Article
• ISSN: 0894-1491
• DOI: 10.1002/glia.10239

✦ Synopsis

We have studied modulation of purinergic receptors (P(2Y) and P(2X) subtypes) on changes in intracellular Ca(2+) Ca(2+) and expression and production of COX-2 in human microglia. Measurements using Ca(2+)-sensitive spectrofluorometry showed adenosine triphosphate (ATP) to cause rapid transient increases in Ca(2+). Application of ATP plus the P(2X) antagonist, pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), or treatment with adenosine diphosphate-beta-S (ADP-beta-S), a selective P(2Y) agonist, led to a considerable prolongation in Ca(2+) responses compared with ATP. The prolonged time courses were consistent with sustained activation of store-operated channels (SOC) since SKF96365, an inhibitor of SOC, blocked this component of the response. RT-PCR data showed that microglia expressed no COX-2 either constitutively or following treatment of cells with ATP (100 microM for 8 h). However, treatment using ATP plus PPADS or with ADP-beta-S led to marked expression of COX-2. The enhanced COX-2 with ATP plus PPADS treatment was absent in the presence of SKF96365 or using Ca(2+)-free solution. Immunocytochemistry, using a specific anti-COX-2 antibody, also revealed a pattern of purinergic modulation whereby lack of P(2X) activation enhanced the production of COX-2 protein. These results suggest that modulation of subtypes of purinergic receptors regulates COX-2 in human microglia with a link involving SOC-mediated influx of Ca(2+).