Mammalian numb proteins promote notch1 receptor ubiquitination and degradation of the notch1 intracellular domain
Mammalian numb proteins promote notch1 receptor ubiquitination and degradation of the notch1 intracellular domain
复制标题
DOI：
10.1074/jbc.m302827200
复制
发表时间：
2003-06-20
影响因子：
4.8
通讯作者：
McGlade, CJ
中科院分区：
文献类型：
--
作者：
McGill, MA;McGlade, CJ
细胞命运决定因子Numb通过拮抗Notch信号通路影响发育决策。然而，这种抑制的潜在分子机制尚不清楚。在这里，我们报道哺乳动物Numb蛋白促进膜结合Notch1受体的泛素化。此外，在激活后，Numb表达导致Notch细胞内结构域的降解，这与Hes1荧光素酶报告基因检测检测到的Hes1启动子的Notch依赖性转录激活的丧失相关。Numb的磷酸化酪氨酸结合（PTB）结构域是Notch1泛素化和Notch1核活性下调所必需的。麻木介导的Notch1泛素化不依赖于PEST区域，而PEST区域先前被证明介导了细胞核中sel10依赖的Notch泛素化，这表明E3泛素连接酶参与其中。与此一致，我们证明了Numb与细胞质中含有HECT结构域的E3连接酶Itch相互作用，并且Numb和Itch协同作用以促进膜系住的Notch1的泛素化。这些结果表明，Numb将泛素化机制的组成部分招募到Notch受体，从而促进Notch1在膜上的泛素化，进而促进细胞内结构域的降解，从而绕过其核易位和Notch1靶基因的下游激活。
The cell fate determinant Numb influences developmental decisions by antagonizing the Notch signaling pathway. However, the underlying molecular mechanism of this inhibition is poorly understood. Here we report that the mammalian Numb protein promotes the ubiquitination of membrane-bound Notch1 receptor. Furthermore, Numb expression resulted in the degradation of the Notch intracellular domain following activation, which correlated with a loss of Notch-dependent transcriptional activation of the Hes1 promoter as measured by a Hes1 luciferase reporter assay. The phospho-tyrosine-binding (PTB) domain of Numb was required for both Notch1 ubiquitination and down-regulation of Notch1 nuclear activity. Numb-mediated ubiquitination of Notch1 was not dependent on the PEST region, which was previously shown to mediate Sel10-dependent ubiquitination of Notch in the nucleus, suggesting a distinct E3 ubiquitin ligase is involved. In agreement we demonstrate that Numb interacts with the cytosolic HECT domain-containing E3 ligase Itch and that Numb and Itch act cooperatively to promote ubiquitination of membrane-tethered Notch1. These results suggest that Numb recruits components of the ubiquitination machinery to the Notch receptor thereby facilitating Notch1 ubiquitination at the membrane, which in turn promotes degradation of the intracellular domain circumventing its nuclear translocation and downstream activation of Notch1 target genes.