Linoleic Acid Induces Mouse Embryonic Stem Cell Proliferation Via Ca2+/PKC, PI3K/Akt, and MAPKs

Abstract

Aims: This study investigated the effect of linoleic acid (LA) on cell proliferation and the related signaling cascade in mouse embryonic stem (ES) cells. Materials & Methods: To examine effects of LA, mouse ES cells (ES-E14TG2a) were used. Moreover, DNA synthesis, glucose production, protein and mRNA expressions were measured. Results: LA increased DNA synthesis in a concentration- (≥ 10^-9 M) and time- (≥ 24 h) dependent manner, as determined by [³H] thymidine incorporation and increased cell number. LA increased intracellular Ca²⁺ levels via regulation of phospholipase C (PLC) and activated protein kinase C (PKC). LA activated phosphatidylinositol 3-kinase (PI3K)/Akt and p44/42 mitogen-activated protein kinases (MAPKs). U73122 (PLC inhibitor), staurosporine (PKC inhibitor), LY294002 (PI3K inhibitor), and Akt inhibitor blocked the phosphorylation of p44/42 MAPKs. In addition, LA stimulated gluconeogenesis through increase expression of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK). LA-induced increases in the cell cycle regulatory proteins, cyclin D1, cyclin E, cyclin-dependent kinase (CDK) 2, and CDK 4, were blocked by U73122, staurosporine, LY294002, Akt inhibitor, PD98059, and metformin (gluconeogenesis inhibitor). Conclusion: LA stimulated cell proliferation via Ca²⁺, PLC/PKC, PI3K/Akt, and p44/42 MAPKs signaling pathways in mouse ES cells.