Cbl-directed monoubiquitination of CIN85 is involved in regulation of ligand-induced degradation of EGF receptors
Cbl-directed monoubiquitination of CIN85 is involved in regulation of ligand-induced degradation of EGF receptors
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DOI：
10.1073/pnas.192462299
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发表时间：
2002-09-17
影响因子：
11.1
通讯作者：
Dikic, I
中科院分区：
文献类型：
--
作者：
Haglund, K;Shimokawa, N;Dikic, I
向靶蛋白添加泛素或多泛素链分别导致其单泛素化或多泛素化。多泛素化以蛋白质降解为目标，而单泛素化则被认为调节受体内化和内体分选。 CbI 蛋白是主要的泛素连接酶，可促进配体依赖性多泛素化和受体酪氨酸激酶的降解。它们还在与激活的受体的复合物中招募 CIN85-内亲素，从而控制受体的内吞作用。在这里，我们展示了接头蛋白 CIN85 及其同源物 CMS 在表皮生长因子 (EGF) 刺激后被 CbI/CbI-b 单泛素化。 CIN85 的单泛素化需要 CIN85 和 CbI、CbI 的完整环指结构域和 CIN85 羧基末端存在的泛素受体位点之间的直接相互作用。在长时间的 EGF 刺激过程中，CbI-b 和单泛素化 CIN85 存在于与多泛素化 EGF 受体的复合物中，并在溶酶体中一起降解。 CIN85 的主要干扰形式先前已被证明可以延迟 EGF 受体降解，但其单泛素化也受到损害。因此，我们的数据表明，CbI/CbI-b 可以介导货物的多泛素化以及 CIN85 的单泛素化，以控制内体分选和受体酪氨酸激酶的降解。
Addition of ubiquitin or ubiquitin chains to target proteins leads to their mono- or polyubiquitination, respectively. Whereas polyubiquitination targets proteins for degradation, monoubiquitination is thought to regulate receptor internalization and endosomal sorting. CbI proteins are major ubiquitin ligases that promote ligand-dependent polyubiquitination and degradation of receptor tyrosine kinases. They also recruit CIN85-endophilin in the complex with activated receptors, thus controlling receptor endocytosis. Here we show that the adaptor protein CIN85 and its homologue CMS are monoubiquitinated by CbI/CbI-b after epidermal growth factor (EGF) stimulation. Monoubiquitination of CIN85 required direct interactions between CIN85 and CbI, the intact RING finger domain of CbI and a ubiquitin acceptor site present in the carboxyl terminus of CIN85. CbI-b and monoubiquitinated CIN85 are found in the complex with polyubiquitinated EGF receptors during prolonged EGF stimulation and are degraded together in the lysosome. Dominant interfering forms of CIN85, which have been shown previously to delay EGF receptor degradation, were also impaired in their monoubiquitination. Thus, our data demonstrate that CbI/CbI-b can mediate polyubiquitination of cargo as well as monoubiquitination of CIN85 to control endosomal sorting an degradation of receptor tyrosine kinases.