title: MEK/ERK signaling contributes to the maintenance of human embryonic stem cell self-renewal.
abstract: MEK/ERK signaling plays a crucial role in a diverse set of cellular functions including cell proliferation, differentiation and survival, and recently has been reported to negatively regulate mouse embryonic stem cell (mESC) self-renewal by antagonizing STAT3 activity. However, its role in human ESCs (hESCs) remains unclear. Here we investigated the functions of MEK/ERK in controlling hESC activity. We demonstrated that MEK/ERK kinases were targets of fibroblast growth factor (FGF) pathway in hESCs. Surprisingly, we found that, in contrast to mESCs, high basal MEK/ERK activity was required for maintaining hESCs in an undifferentiated state. Inhibition of MEK/ERK activity by specific MEK inhibitors PD98059 and U0126, or by RNA interference, rapidly caused the loss of self-renewal capacity. We also showed that MEK/ERK signaling cooperated with phosphoinositide 3-kinase (PI3K)/AKT signaling in maintaining hESC pluripotency. However, MEK/ERK signaling had little or no effect on regulating hESC proliferation and survival, in contrast to PI3K/AKT signaling. Taken together, these findings reveal the unique and crucial role of MEK/ERK signaling in the determination of hESC cell fate and expand our understanding of the molecular mechanisms behind the FGF pathway maintenance of hESC pluripotency. Importantly, these data make evident the striking differences in the control of self-renewal between hESCs and mESCs.
authors.affiliation: Key Laboratory of Cell Proliferation and Differentiation of Ministry of Education, College of Life Sciences, Peking University, Beijing, 100871, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Guangwen
authors.initials: G
authors.lastname: Wang
authors.forename: Chengyan
authors.initials: C
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Zhijia
authors.initials: Z
authors.lastname: Tan
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Song
authors.forename: Mingxiao
authors.initials: M
authors.lastname: Ding
authors.forename: Hongkui
authors.initials: H
authors.lastname: Deng
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002470:Cell Survival; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005346:Fibroblast Growth Factors / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051058:Oncogene Protein v-akt / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D005346:Fibroblast Growth Factors; D019869:Phosphatidylinositol 3-Kinases; D051058:Oncogene Protein v-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases