title: STAT3 is involved in phosphatidic acid-induced Bcl-2 expression in HeLa cells.
abstract: Phosphatidic acid (PA), the product of a PLD-mediated reaction, is a lipid second messenger that participates in various intracellular signaling events and is known to regulate a growing list of signaling proteins. We found that Bcl-2 was upregulated by PA treatment in HeLa cells. However, how PA upregulates Bcl-2 expression has not yet been studied. In this study, we tried to discover the mechanisms of Bcl-2 up-regulation by PA treatment in HeLa cells. Treatment with PA resulted in significantly increased expression of Bcl-2 in HeLa cells. Moreover, PA-induced Bcl-2 expression was blocked by mepacrine, an inhibitor of PLA2, but not by propranolol, an inhibitor of PA phospholyhydrolase (PAP). Treatment of 1,2-dipalmitoryl-sn-glycero-3- phosphate (DPPA) also increased Bcl-2 expression. These results indicate that Bcl-2 expression is mediated by lysophosphatidic acid (LPA), not by arachidonic acid (AA). Thereafter, we used MEK1/2 inhibitor, PD98059 to investigate the relationship between ERK1/2 MAPK and PA-induced Bcl-2 expression. PA-induced Bcl-2 expression was decreased when ERK1/2 was inhibited by PD98059. The transcription factor such as STAT3 which is controlled by ERK1/2 MAPK was increased along with Bcl-2 expression when the cells were treated with PA. Furthermore, STAT3 siRNA treatments inhibited PA-induced Bcl-2 expression, suggesting that STAT3 (Ser727) is involved in PA-induced Bcl-2 expression. Taken together, these findings indicate that PA acts as an important mediator for increasing Bcl-2 expression through STAT3 (Ser727) activation via the ERK1/2 MAPK pathway.
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, Seoul 133-791, Korea.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Choi
authors.forename: Jung Han
authors.initials: JH
authors.lastname: Lee
authors.forename: Shin-Young
authors.initials: SY
authors.lastname: Park
authors.forename: Ju Hwan
authors.initials: JH
authors.lastname: Cho
authors.forename: Joong-Soo
authors.initials: JS
authors.lastname: Han
mesh_terms: D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D010712:Phosphatidic Acids / Q000235:genetics* / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics* / Q000378:metabolism; D011796:Quinacrine / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D050796:STAT3 Transcription Factor / Q000235:genetics* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D010712:Phosphatidic Acids; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D050796:STAT3 Transcription Factor; D011433:Propranolol; D020929:Mitogen-Activated Protein Kinase Kinases; D011796:Quinacrine