Kakuda Shinako, Haltiwanger Robert S
Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA.
Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA.
Dev Cell. 2017 Jan 23;40(2):193-201. doi: 10.1016/j.devcel.2016.12.013. Epub 2017 Jan 12.
Fringe proteins are β3-N-acetylglucosaminyltransferases that modulate Notch activity by modifying O-fucose residues on epidermal growth factor-like (EGF) repeats of Notch. Mammals have three Fringes: Lunatic, Manic, and Radical. While Lunatic and Manic Fringe inhibit Notch1 activation from Jagged1 and enhance activation from Delta-like 1, Radical Fringe enhances signaling from both. We used a mass spectrometry approach to determine whether the variable effects of Fringes on Notch1 result from generation of unique glycosylation patterns on Notch1. We found that Lunatic and Manic Fringe modified similar sites on Notch1, while Radical Fringe modified a subset. Fringe modifications at EGF8 and EGF12 enhanced Notch1 binding to and activation from Delta-like 1, while modifications at EGF6 and EGF36 (added by Manic and Lunatic but not Radical) inhibited Notch1 activation from Jagged1. Combined, these results suggest that Fringe modifications "mark" different regions in the Notch1 extracellular domain for activation or inhibition.
边缘蛋白是β3-N-乙酰葡糖胺基转移酶，通过修饰Notch的表皮生长因子样（EGF）重复序列上的O-岩藻糖残基来调节Notch活性。哺乳动物有三种边缘蛋白： Lunatic、Manic和Radical。Lunatic和Manic边缘蛋白抑制来自Jagged1的Notch1激活，并增强来自Delta-like 1的激活，而Radical边缘蛋白增强来自两者的信号传导。我们使用质谱方法来确定边缘蛋白对Notch1的不同影响是否源于Notch1上独特糖基化模式的产生。我们发现Lunatic和Manic边缘蛋白修饰Notch1上的相似位点，而Radical边缘蛋白修饰一个子集。EGF8和EGF12处的边缘蛋白修饰增强了Notch1与Delta-like 1的结合及激活，而EGF6和EGF36处的修饰（由Manic和Lunatic添加，但不是Radical）抑制了来自Jagged1的Notch1激活。综合起来，这些结果表明边缘蛋白修饰在Notch1细胞外结构域中“标记”不同区域以进行激活或抑制。
