Xiong Shiqin, Zhao Qiuhui, Rong Zhili, Huang Guanrong, Huang Yiling, Chen Peila, Zhang Shuping, Liu Li, Chang Zhijie
Tsinghua Institute of Genome Research, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084,China.
J Biol Chem. 2003 Dec 12;278(50):50273-82. doi: 10.1074/jbc.M306936200. Epub 2003 Sep 4.
Growth factor signaling by receptor tyrosine kinases regulates several cell fates, such as proliferation and differentiation. Sef was genetically identified as a negative regulator of fibroblast growth factor (FGF) signaling. Using bioinformatic methods and rapid amplification of cDNA ends-PCR, we isolated both the mouse and the human Sef genes, which encoded the Sef protein and Sef-S isoform that was generated through alternative splicing. We provide evidence that the Sef gene products were located mainly on the cell membrane. Co-immunoprecipitation and immunostaining experiments indicate that hSef interacts with FGFR1 and FGFR2 but not FGFR3. Our results demonstrated that stably expressed hSef strongly inhibits FGF2- or nerve growth factor-induced PC-12 cell differentiation. The intracellular domain of hSef is necessary for the inhibitory effect on FGF2-induced PC-12 cell differentiation. Furthermore, our data suggested Sef exerted the negative effect on FGF2-induced PC-12 cell differentiation through the prevention of Ras-mitogen-activated protein kinase signaling, possibly functioning upstream of the Ras molecule. These findings suggest that Sef may play an important role in the regulation of PC-12 cell differentiation.
受体酪氨酸激酶介导的生长因子信号传导调控多种细胞命运，如增殖和分化。Sef在遗传学上被鉴定为成纤维细胞生长因子（FGF）信号传导的负调节因子。利用生物信息学方法和cDNA末端快速扩增-PCR技术，我们分离出了小鼠和人类的Sef基因，它们编码通过可变剪接产生的Sef蛋白和Sef-S异构体。我们提供的证据表明，Sef基因产物主要定位于细胞膜。免疫共沉淀和免疫染色实验表明，hSef与FGFR1和FGFR2相互作用，但不与FGFR3相互作用。我们的结果表明，稳定表达的hSef强烈抑制FGF2或神经生长因子诱导的PC-12细胞分化。hSef的细胞内结构域对于其对FGF2诱导的PC-12细胞分化的抑制作用是必需的。此外，我们的数据表明，Sef通过阻止Ras-丝裂原活化蛋白激酶信号传导对FGF2诱导的PC-12细胞分化发挥负性作用，可能在Ras分子的上游起作用。这些发现表明，Sef可能在PC-12细胞分化的调控中发挥重要作用。
