hPDLSCs were isolated from healthy human molars according to guidelines approved by the Review Board of Chonbuk National University [19]. by activating MAPK-mediated signaling, while it affects differently osteogenic differentiation according to the origins of stem cells. Introduction Fibroblast growth factor (FGF) plays essential roles in multiple biological processes including cellular proliferation, differentiation, and survival [1], [2]. Approximately 24 members of the FGF family have been identified and their functions differ according to the FGF family and cell type from which they were derived. According to the previous reports [3]C[5], the ability of FGF family to modulate cellular functions depends on the type and origin of cells examined. FGF4 is the first FGF detected during embryonic development. This factor is an autocrine and/or paracrine growth factor required for multiple cellular events during embryogenesis [6]. It was previously found that FGF4 increases proliferation of neural progenitors [7] or bone marrow mesenchymal stem cells (BMMSCs) [8] and sustains the survival of trophoblast stem cells [9]. These findings indicate that FGF4 plays a predominant role in stimulating cell proliferation. However, other studies have shown that exogenous FGF4 addition did not increase proliferation of embryonic stem cells (ESCs) [10], [11]. This suggests that FGF4 may have different roles depending on the developmental stages of stem cells and their origin. It is also still unclear whether FGF4 is an essential growth factor for proliferation of ESCs, even though FGF4 has been shown to control stem cell fate and proliferation of many types of cells. The molecular mechanisms by which FGF4 Eliprodil regulates proliferation and differentiation of ESCs are not entirely defined. Mitogen-activated protein kinases (MAPKs) are major signal mediators in response to various stimuli such as growth factors, cytokines, and stress [12]C[14]. There are three kinds of MAPKs including c-Jun N-terminal protein kinase (JNK), extracellular signal-regulated kinase (ERK), and p38 kinase. These kinases are critical for regulating proliferation and differentiation of stem cells in response to FGFs [15], [16]. It is commonly accepted that FGFs exert their effects by activating receptor tyrosine kinases of the FGF receptor family, which eventually leads to activation of Ras-Raf-MAPK signaling pathways [17]. For example, addition of FGF2 stimulates proliferation of mesenchymal stem cells (MSCs) through activation of JNK-mediated signaling [4]. Exogenous FGF2 and 4 enhanced proliferation of bone marrow MSCs (BMMSCs) by activating PI3K-Akt and ERK1/2 signaling [8], [18]. These previous reports proposed that FGF4 may play its predominant role in stimulating proliferation and differentiation of ESCs via MAPK-mediated signaling pathways. In this study, we examined the effects of exogenous FGF4 on proliferation and osteogenic differentiation of mouse ESCs (mESCs). We also investigated the cellular mechanisms by which FGF4 affects proliferation and osteoblastic differentiation of mESCs. In addition, we investigated the effects of FGF4 on human periodontal ligament stem cells (hPDLSCs) and mouse BMMSCs (mBMMSCs). Our present findings show that exogenous FGF4 addition stimulates proliferation of mESCs as well as hPDLSCs and mBMMSCs via the activation of MAPK-mediated signaling. In contrast, FGF4 exerts different roles on osteogenic differentiation according to the origins of stem cells, where it inhibits osteoblastogenesis of mESCs, but accelerates mineralization of hPDLSCs. Rabbit polyclonal to AKR1C3 Materials and Methods Chemicals and Laboratory Wares The mouse ESC line D3 was obtained from the American Type Culture Collection (Rockwille, MD, USA) and fetal bovine serum (FBS) was purchased from Gibco-BRL (Gaithersburg, MD, USA). MAPK inhibitors including SP600125, PD98059, and SB203580 were purchased from TOCRIS (Bristol, UK) and dissolved in absolute ethanol or DMSO prior to use. All antibodies specific for Eliprodil MAPKs, cell cycle regulatory factors, and cell surface markers were obtained from Santa Cruz Biotechnology Inc. (Santa Cruz, CA, USA). Eliprodil Unless specified otherwise, other chemicals and laboratory wares were.