Ishida Maki, Ichihara Masatoshi, Mii Shinji, Jijiwa Mayumi, Asai Naoya, Enomoto Atsushi, Kato Takuya, Majima Ai, Ping Jiang, Murakumo Yoshiki, Takahashi Masahide
Department of Pathology, and Department of Mrfovs; Technology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Cancer Sci. 2007 Jun;98(6):815-21. doi: 10.1111/j.1349-7006.2007.00457.x. Epub 2007 Mar 27.
The Sprouty (SPRY) family of proteins includes important regulators of downstream signaling initiated by receptor tyrosine kinases. In the present study, we investigated the role of SPRY proteins in intracellular signaling via the RET receptor tyrosine kinase activated by glial cell line-derived neurotrophic factor (GDNF). Expression of SPRY1, SPRY2, SPRY3 and SPRY4 in HEK293T cells transfected with RET and GDNF receptor family alpha1 (GFRalpha1) genes significantly reduced sustained ERK activation as well as ELK-1 activation. Because expression of SPRY2 was efficiently induced by GDNF in TGW human neuroblastoma cells expressing RET and GFRalpha1, we further investigated the role of SPRY2 in the growth and differentiation of TGW cells. Expression of wild-type SPRY2 (WT-SPRY2) decreased the growth of TGW cells. In contrast, expression of a dominant negative form of SPRY2 (MT-SPRY2, with a mutated tyrosine residue) enhanced cell proliferation. In addition, expression of WT-SPRY2 reduced GDNF-dependent neurite outgrowth of TGW cells, whereas expression of MT-SPRY2 enhanced it. Taken together, our results suggest that SPRY2 regulates GDNF-dependent proliferation and differentiation of TGW neuroblastoma cells mediated by RET tyrosine kinase.
Sprouty（SPRY）蛋白家族包括受体酪氨酸激酶引发的下游信号传导的重要调节因子。在本研究中，我们研究了SPRY蛋白在由胶质细胞系衍生的神经营养因子（GDNF）激活的RET受体酪氨酸激酶介导的细胞内信号传导中的作用。在转染了RET和GDNF受体家族α1（GFRα1）基因的HEK293T细胞中，SPRY1、SPRY2、SPRY3和SPRY4的表达显著降低了ERK的持续激活以及ELK-1的激活。由于在表达RET和GFRα1的TGW人神经母细胞瘤细胞中，GDNF可有效诱导SPRY2的表达，我们进一步研究了SPRY2在TGW细胞生长和分化中的作用。野生型SPRY2（WT-SPRY2）的表达降低了TGW细胞的生长。相反，SPRY2的显性负性形式（MT-SPRY2，酪氨酸残基发生突变）的表达增强了细胞增殖。此外，WT-SPRY2的表达降低了TGW细胞中GDNF依赖的神经突生长，而MT-SPRY2的表达则增强了这种生长。综上所述，我们的结果表明，SPRY2调节由RET酪氨酸激酶介导的TGW神经母细胞瘤细胞的GDNF依赖的增殖和分化。
