Possible mechanisms underlying the biphasic regulatory effects of arachidonic acid on Ca2+ signaling in HEK293 cells
Possible mechanisms underlying the biphasic regulatory effects of arachidonic acid on Ca2+ signaling in HEK293 cells
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花生四烯酸对 HEK293 细胞 Ca2 信号传导双相调节作用的可能机制
DOI：
10.1016/j.cellsig.2012.03.016
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发表时间：
2012-08-01
影响因子：
4.8
通讯作者：
Luo, Dali
中科院分区：
文献类型：
--
作者：
Chen, Lihong;Meng, Qingli;Luo, Dali
Arachidonic acid (AA), an endogenous lipid signal molecule released from membrane upon cell activation, modulates intracellular Ca2+ ([Ca2+](i)) signaling positively and negatively. However, the mechanisms underlying the biphasic effects of AA are rather obscure. Using probes for measurements of [Ca2+](i) and fluidity of plasma membrane (PM)/endoplasmic reticulum (ER), immunostaining, immunoblotting and shRNA interference approaches, we found that AA at low concentration, 3 mu m reduced the PM fluidity by activating PKC alpha and PKC beta II translocation to PM and also the ER fluidity directly. In accordance, 3 mu M AA did not impact the basal [Ca2+](i) but significantly suppressed the thapsigargin-induced Ca2+ release and Ca2+ influx. Inhibition of PKC with Go6983 or knockdown of PKC alpha or PKC beta using shRNA significantly attenuated the inhibitory effects of 3 mu M AA on PM fluidity and agonist-induced Ca2+ signal. However, AA at high concentration, 30 mu M, caused robust release and entry of Ca2+ accompanied by a facilitated PM fluidity but decreased ER fluidity and dramatic PKC beta I and PKC beta II redistribution in the ER. Compared with ursodeoxycholate acid, a membrane stabilizing agent that only inhibited the 30 mu M AA-induced Ca2+ influx by 45%, Gd3+ at concentration of 10 mu m could completely abolish both release and entry of Ca2+ induced by AA, suggesting that the potentiated PM fluidity is not the only reason for AA eliciting Ca2+ signal. Therefore, the study herein demonstrates that a lowered PM fluidity by PKC activation and a direct ER stabilization contribute significantly for AA downregulation of [Ca2+](i) response, while Gd3+-sensitive 'pores' in PM/ER play an important role in AA-induced Ca2+ signal in HEK293 cells. (C) 2012 Elsevier Inc. All rights reserved.
