Up-regulation of Na(+)-Ca2+ exchange activity by interferon-gamma in cultured rat microglia.
The Na(+)-Ca2+ exchanger (NCX) plays a role in regulating intracellular Ca2+ concentration, but little is known about NCX in microglia. We examined mRNA expression of NCX isoforms in cultured rat microglia and the effect of interferon-gamma (IFN-gamma) on NCX activity. RT-PCR showed that all of the known NCX isoforms, NCX1-3, are expressed in cultured microglia. Ouabain and monensin increased 45Ca2+ uptake and intracellular Ca2+ concentration in microglia, suggesting the presence of NCX activity in the reverse mode. Treatment with IFN-gamma (100 U/mL) caused a biphasic increase in NCX activity. The transient increase in NCX activity by IFN-gamma for 1 h was blocked by the protein kinase C (PKC) inhibitors, staurosporine and GF109203X, and the tyrosine kinase inhibitor, herbimycin A. The delayed increase in NCX activity by IFN-gamma for 24 h was blocked by the protein synthesis inhibitor cycloheximide and actinomycin D. Treatment with IFN-gamma for 24 h increased NCX mRNA and protein levels. The increase in NCX activity and NCX protein by IFN-gamma for 24 h was blocked by staurosporine, GF109203X, herbimycin A and the extracellular signal-regulated kinase inhibitor, PD98059. These findings suggest that NCX is up-regulated by IFN-gamma in a biphasic manner in microglia. Moreover, PKC and tyrosine kinase are involved in the up-regulation of NCX and the extracellular signal-regulated protein kinase is also involved in the delayed increase in NCX activity.
Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka, Japan.
Takayuki
T
Nagano
Yasushi
Y
Kawasaki
Akemichi
A
Baba
Motohiko
M
Takemura
Toshio
T
Matsuda
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015151:Immunoblotting; D007371:Interferon-gamma / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects; D017628:Microglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020033:Protein Isoforms / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D019831:Sodium-Calcium Exchanger / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects*
D004791:Enzyme Inhibitors; D020033:Protein Isoforms; D019831:Sodium-Calcium Exchanger; D007371:Interferon-gamma; D002118:Calcium