Mechanisms of insect limb development

昆虫肢体发育机制

• 批准号: 15207018
• 负责人: HAYASHI Shigeo
• 金额: $ 12.9万
• 依托单位: RIKEN
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15207018/
• 关键词: Signaling; Drosophila; imaginal disc; Notch; Nedd4; Deltex; endocytosis; ubiqitination; 付属肢; エンドサイトーシス; ユビキチン; 成虫原基; gfp; 気管; 翅; 細胞移動; Signaling; Drosophila; imaginal disc; Notch; Nedd4; Deltex; endocytosis; ubiqitination; 付属肢; エンドサイトーシス; ユビキチン; 成虫原基; gfp; 気管; 翅; 細胞移動

Ligand-induced proteolytic cleavage and internalization of the plasma membrane receptor Notch leads to its activation. Ligand-independent, steady state internalization of Notch, however, does not lead to activation. The mechanism by which downstream effectors discriminate these bipartite modes of Notch internalization is not understood. Nedd4 is a HECT domain-containing E3 ubiquitin ligase that targets transmembrane receptors containing the PPSY motif for endocytosis. Deltex is a positive regulator of Notch signaling and encodes a putative ubiquitin ligase of the ring finger type. We show that Notch is ubiquitinated, and destabilized by Nedd4 in a manner requiring the PPSY motif in the Notch intracellular domain. Loss of Nedd4 function dominantly suppresses the Notch and Deltex mutant phenotypes and its hyper activation attenuates Notch activity. In tissue culture cells, dominant-negative form of Nedd4 blocks steady-state Notch internalization and activates Notch signaling independently of ligand binding, and this effect was further potentiated by Deltex. Nedd4 destines Deltex to degradation in a Notch-dependent manner. Nedd4 antagonizes Notch signaling by promoting internalization of Notch and degradation of Notch and Deltex. Those functions of Nedd4 may be important for the protection of unstimulated cells from sporadic activation of Notch signaling.

配体诱导的蛋白水解裂解和质膜受体缺口的内在化导致其激活。但是，Notch的配体无关，稳态内在化并不导致激活。尚不清楚下游效应歧视这些两部分模式的机制。 NEDD4是一种含有域的E3泛素连接酶，靶向含有内吞作用的PPSY基序的跨膜受体。 Deltex是Notch信号传导的正调节剂，并编码环手指类型的推定的泛素连接酶。我们表明，Notch是泛素化的，并以NEDD4的方式破坏了NEDD4的稳定，需要在Notch细胞内结构域中进​​行PPSY基序。 NEDD4功能的丧失主要抑制了缺口和Deltex突变体表型，其超活化会减弱缺口活性。在组织培养细胞中，NEDD4的显性阴性形式阻止了稳态置于内在化并独立于配体结合而激活Notch信号，并且Deltex进一步增强了这种效果。 NEDD4将Deltex命名为依赖于缺口的方式。 NEDD4通过促进Notch的内在化和Notch和Deltex的降解来拮抗Notch信号传导。 NEDD4的这些功能对于保护未刺激的细胞免于零星信号的激活可能很重要。