Tsai P S, Werner S, Weiner R I
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco 94143-0556, USA.
Endocrinology. 1995 Sep;136(9):3831-8. doi: 10.1210/endo.136.9.7649090.
Basic fibroblast growth factor (bFGF) plays an important role in development of the central nervous system and is neurotropic for a variety of neurons. In this study, we investigated whether bFGF is neurotropic for GT1 GnRH neuronal cell lines and if these cells express functional FGF receptors (FGFRs). The GT1 cell lines generated by genetically targeted tumorigenesis display highly differentiated properties of GnRH neurons. Addition of 2 and 10 ng/ml bFGF increased neurite outgrowth of GT1-7 cells and resulted in a significant increase of GT1 cell survival in serum-free medium. However, bFGF had no effect on [3H]thymidine incorporation at 24 or 48 h. RNase protection assays using riboprobes specific for murine FGFRs 1-3 showed that GT1 cells express FGFRs 1 and 3 but not 2. Occupancy of FGFRs with 10 ng/ml bFGF stimulated the sustained tyrosine phosphorylation of both the 42- and 44-kilodalton mitogen-activated protein kinases (MAPKs) for up to 6 h as shown by Western blot analysis. In addition, phosphorylation of the MAPKs was associated with enzyme activation as shown by an in-gel MAPK assay. GT1-1 and GT1-7 cells also express messenger RNA for bFGF, although the level of bioactive bFGF synthesized by GT1 cells appears suboptimal because GT1 cells can further respond to exogenously added bFGF. Thus, we have demonstrated that bFGF is a neurotropic factor in GT1 GnRh neuronal cell lines, raising the possibility that bFGF may play a role in the neurobiology of GnRH neurons.
碱性成纤维细胞生长因子（bFGF）在中枢神经系统发育中起重要作用，并且对多种神经元具有神经趋向性。在本研究中，我们调查了bFGF对GT1 GnRH神经元细胞系是否具有神经趋向性，以及这些细胞是否表达功能性成纤维细胞生长因子受体（FGFRs）。通过基因靶向肿瘤发生产生的GT1细胞系表现出GnRH神经元的高度分化特性。添加2和10 ng/ml的bFGF可增加GT1-7细胞的神经突生长，并导致无血清培养基中GT1细胞存活率显著提高。然而，bFGF在24或48小时对[3H]胸苷掺入没有影响。使用针对小鼠FGFRs 1-3的核糖探针进行的核糖核酸酶保护试验表明，GT1细胞表达FGFRs 1和3，但不表达2。如蛋白质印迹分析所示，用10 ng/ml bFGF占据FGFRs可刺激42和44千道尔顿丝裂原活化蛋白激酶（MAPKs）持续酪氨酸磷酸化长达6小时。此外，如凝胶内MAPK测定所示，MAPKs的磷酸化与酶激活相关。GT1-1和GT1-7细胞也表达bFGF的信使核糖核酸，尽管GT1细胞合成的生物活性bFGF水平似乎不理想，因为GT1细胞可对外源添加的bFGF进一步产生反应。因此，我们已经证明bFGF是GT1 GnRh神经元细胞系中的一种神经趋向性因子，这增加了bFGF可能在GnRH神经元神经生物学中发挥作用的可能性。
