Estrogen-Induced Nongenomic Calcium Signaling Inhibits Lipopolysaccharide-Stimulated Tumor Necrosis Factor [alpha] Production in Macrophages

• Published in: PloS one 2013-12, Vol.8 (12), p.e83072
• Main Authors: Liu, Limin, Zhao, Ying, Xie, Keming, Sun, Xiaodong, Gao, Yuzhen, Wang, Zufeng
• Format: Article
• Language: English
• Subjects: Cancer treatment; Estradiol; G proteins; Macrophages; Membrane proteins; Mitogens; Necrosis; Phenols (Class of compounds); Protein kinases; Tumor necrosis factor; Tumors
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0083072

Estrogen is traditionally thought to exert genomic actions through members of the nuclear receptor family. Here, we investigated the rapid nongenomic effects of 17[beta]-estradiol (E.sub.2) on tumor necrosis factor [alpha] (TNF-[alpha]) production following lipopolysaccharide (LPS) stimulation in mouse bone marrow-derived macrophages (BMMs). We found that LPS induced TNF-[alpha] production in BMMs via phosphorylation of p38 mitogen-activated protein kinase (MAPK). E.sub.2 itself did not affect the MAPK pathway, although it attenuated LPS-induced TNF-[alpha] production through suppression of p38 MAPK activation. Recently, G protein-coupled receptor 30 (GPR30) was suggested to be a membrane estrogen receptor (mER) that can mediate nongenomic estradiol signaling. We found that BMMs expressed both intracellular estrogen receptors (iER) and mER GPR30. The specific GPR30 antagonist G-15 significantly blocked effects of estradiol on LPS-induced TNF-[alpha] production, whereas an iER antagonist did not. Moreover, E.sub.2 induced a rapid rise in intracellular free Ca.sup.2+ that was due to the influx of extracellular Ca.sup.2+ and was not inhibited by an iER antagonist or silencing of iER. Ca.sup.2+ influx was also induced by an impermeable E.sub.2 conjugated to BSA (E.sub.2 -BSA), which has been used to investigate the nongenomic effects of estrogen. Consequently, Ca.sup.2+, a pivotal factor in E.sub.2 -stimulated nongenomic action, was identified as the key mediator. The inhibitory effects of E.sub.2 on LPS-induced TNF-[alpha] production and p38 MAPK phosphorylation were dependent on E.sub.2 -triggered Ca.sup.2+ influx because BAPTA, an intracellular Ca.sup.2+ chelator, prevented these effects. Taken together, these data indicate that E.sub.2 can down-regulate LPS-induced TNF-[alpha] production via blockade of p38 MAPK phosphorylation through the mER-mediated nongenomic Ca.sup.2+ signaling pathway in BMMs.