PGE2 upregulates the Na+/K+ ATPase in HepG2 cells via EP4 receptors and intracellular calcium

被引:9
作者
Hodeify, Rawad [1 ]
Chakkour, Mohamed [2 ]
Rida, Reem [2 ]
Kreydiyyeh, Sawsan [2 ]
机构
[1] Amer Univ Ras Al Khaimah, Sch Arts & Sci, Dept Biotechnol, Ras Al Khaymah, U Arab Emirates
[2] Amer Univ Beirut, Fac Arts & Sci, Dept Biol, Beirut, Lebanon
关键词
CA2+ MOBILIZATION; LIVER; NA+; K+-ATPASE; HEPATOCYTES; MECHANISMS;
D O I
10.1371/journal.pone.0245400
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The Na+/K+ ATPase is a key regulator of the hepatocytes ionic homeostasis, which when altered may lead to many liver disorders. We demonstrated recently, a significant stimulation of the Na+/K+ ATPase in HepG2 cells treated with the S1P analogue FTY 720P, that was mediated through PGE2. The mechanism by which the prostaglandin exerts its effect was not investigated, and is the focus of this work. The type of receptors involved was determined using pharmacological inhibitors, while western blot analysis, fluorescence imaging of GFP-tagged Na+/K+ ATPase, and time-lapse imaging on live cells were used to detect changes in membrane abundance of the Na+/K+ ATPase. The activity of the ATPase was assayed by measuring the amount of inorganic phosphate liberated in the presence and absence of ouabain. The enhanced activity of the ATPase was not observed when EP4 receptors were blocked but still appeared in presence inhibitors of EP1, EP2 and EP3 receptors. The involvement of EP4 was confirmed by the stimulation observed with EP4 agonist. The stimulatory effect of PGE2 did not appear in presence of Rp-cAMP, an inhibitor of PKA, and was imitated by db-cAMP, a PKA activator. Chelating intracellular calcium with BAPTA-AM abrogated the effect of db-cAMP as well as that of PGE2, but PGE2 treatment in a calcium-free PBS medium did not, suggesting an involvement of intracellular calcium, that was confirmed by the results obtained with 2-APB treatment. Live cell imaging showed movement of GFP-Na+/K+ ATPase-positive vesicles to the membrane and increased abundance of the ATPase at the membrane after PGE2 treatment. It was concluded that PGE2 acts via EP4, PKA, and intracellular calcium.
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页数:11
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