Regulation of mammalian Notch signaling and embryonic development by the protein O-glucosyltransferase Rumi
Regulation of mammalian Notch signaling and embryonic development by the protein O-glucosyltransferase Rumi
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DOI：
10.1242/dev.060020
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发表时间：
2011-05-15
期刊：
影响因子：
4.6
通讯作者：
Jafar-Nejad, Hamed
中科院分区：
文献类型：
--
作者：
Fernandez-Valdivia, Rodrigo;Takeuchi, Hideyuki;Jafar-Nejad, Hamed
蛋白质O-葡糖基化是一种保守的翻译后修饰，发生在含有C（1）-X-S-X-P-C（2）共有序列的表皮生长因子样（EGF）重复序列上。果蝇蛋白O-葡糖基转移酶（Poglut）Rumi调节Notch信号传导，但蛋白O-葡糖基化对哺乳动物Notch信号传导和胚胎发育的贡献尚不清楚。在这里，我们表明，小鼠鲁米编码Poglut，和鲁米（-/-）小鼠胚胎死亡前胚胎天9.5后轴截断和严重缺陷的神经管发育，体节发生，心脏发生和血管重塑。小鼠细胞系中的Rumi敲低导致Notch信号传导丧失的细胞和分子表型，而不影响Notch配体结合。生物化学、细胞培养和跨物种转基因实验表明，Rumi水平的降低导致Notch EGF重复序列的O-葡糖基化降低，并且Rumi的酶活性是其在Notch途径中的调节作用的关键。遗传相互作用研究表明，在Jag 1（+/-）（锯齿状1）背景中删除一个Rumi拷贝会导致严重的胆管形态发生缺陷。总之，我们的数据表明，除了O-葡萄糖的EGF重复是必不可少的小鼠胚胎发育和Notch信号，Jag 1诱导的信号是敏感的蛋白质O-葡萄糖基转移酶鲁米的基因剂量。考虑到Rumi（-/-）胚胎与经典Notch信号传导的其他全局调节因子相比显示出更严重的表型，Rumi在哺乳动物发育期间可能具有额外的重要靶点。
Protein O-glucosylation is a conserved post-translational modification that occurs on epidermal growth factor-like (EGF) repeats harboring the C(1)-X-S-X-P-C(2) consensus sequence. The Drosophila protein O-glucosyltransferase (Poglut) Rumi regulates Notch signaling, but the contribution of protein O-glucosylation to mammalian Notch signaling and embryonic development is not known. Here, we show that mouse Rumi encodes a Poglut, and that Rumi(-/-) mouse embryos die before embryonic day 9.5 with posterior axis truncation and severe defects in neural tube development, somitogenesis, cardiogenesis and vascular remodeling. Rumi knockdown in mouse cell lines results in cellular and molecular phenotypes of loss of Notch signaling without affecting Notch ligand binding. Biochemical, cell culture and cross-species transgenic experiments indicate that a decrease in Rumi levels results in reduced O-glucosylation of Notch EGF repeats, and that the enzymatic activity of Rumi is key to its regulatory role in the Notch pathway. Genetic interaction studies show that removing one copy of Rumi in a Jag1(+/-) (jagged 1) background results in severe bile duct morphogenesis defects. Altogether, our data indicate that addition of O-glucose to EGF repeats is essential for mouse embryonic development and Notch signaling, and that Jag1-induced signaling is sensitive to the gene dosage of the protein O-glucosyltransferase Rumi. Given that Rumi(-/-) embryos show more severe phenotypes compared to those displayed by other global regulators of canonical Notch signaling, Rumi is likely to have additional important targets during mammalian development.