The deubiquitinating inhibitor EerI induces tumor cell apoptosis

去泛素化抑制剂EerI诱导肿瘤细胞凋亡

• 批准号: 7593555
• 负责人: Yihong Ye
• 金额: $ 29.8万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7593555
• 关键词: ATP phosphohydrolase; Affect; Apoptosis; Cancerous; Cell Cycle; Cell Proliferation; Cell division; Cells; Complex; Cytosol; Deubiquitinating Enzyme; Deubiquitination; Endoplasmic Reticulum; Enzymes; Eukaryota; Eukaryotic Cell; Goals; Homeostasis; Human; Life; Lymphoma; MJD1 protein; Malignant Neoplasms; Mediating; Names; Patients; Polyubiquitin; Polyubiquitination; Primary Neoplasm; Process; Proteasome Binding; Proteins; Reaction; Reagent; Reporting; Role; System; Testing; Tumor Cell Line; Ubiquitin; cell growth; eeyarestatin I; inhibitor/antagonist; leukemia; multicatalytic endopeptidase complex; neoplastic cell; novel; novel therapeutics; polypeptide; protein degradation; protein misfolding; tumor

Elimination of misfolded proteins from the endoplasmic reticulum (ER) by ER-associated degradation (ERAD) involves substrate retrotranslocation from the ER lumen into the cytosol for degradation by the proteasome. For many substrates, retrotranslocation requires the action of ubiquitinating enzymes, which polyubiquitinate substrates emerging from the ER lumen, and of the p97-Ufd1-Npl4 ATPase complex, which dislocates polyubiquitinated substrates into the cytosol. Polypeptides extracted by p97 are eventually transferred to the proteasome for destruction. Eeyarestatin I (EerI) was recently identified as a potent inhibitor of retrotranslocation, but the mechanism of its action is unclear. Here we report that EerI blocks p97-associated deubiquitination (PAD) essential for the degradation of misfolded ER proteins. We further identify ataxin-3 (atx3), a p97-associated deubiquitinating enzyme previously implicated in ERAD, as one of the targets affected by EerI. In the absence of PAD, substrates carrying unprocessed polyubiquitin chains reach the proteasome, but remain bound by the proteasome without being degraded. Our analyses establish a role for a novel deubiquitinating process in proteasome dependent protein turnover. EerI, as the first deubiquitination inhibitor that acts on living cells, may offer novel therapeutics for certain types of human cancer. Indeed, we find that EerI can effectively induce apoptosis in both tumor cell lines and primary tumor cells isolated from patients.

通过 ER 相关降解 (ERAD) 消除内质网 (ER) 中错误折叠的蛋白质涉及底物从 ER 腔逆向转位到胞质溶胶中，以便被蛋白酶体降解。对于许多底物，逆转位需要泛素化酶和 p97-Ufd1-Npl4 ATP 酶复合物的作用，泛素化酶对 ER 腔中出现的底物进行多泛素化，而 p97-Ufd1-Npl4 ATP 酶复合物将多泛素化底物移位到胞质溶胶中。 p97提取的多肽最终被转移到蛋白酶体中进行破坏。 Eeyarestatin I (EerI) 最近被鉴定为一种有效的逆转录转位抑制剂，但其作用机制尚不清楚。在这里，我们报告 EerI 阻断 p97 相关的去泛素化 (PAD)，这对错误折叠的 ER 蛋白的降解至关重要。我们进一步确定了 ataxin-3 (atx3)，一种先前与 ERAD 相关的 p97 相关去泛素化酶，是受 EerI 影响的靶标之一。在没有 PAD 的情况下，携带未加工的多聚泛素链的底物到达蛋白酶体，但仍被蛋白酶体结合而不被降解。我们的分析确定了一种新型去泛素化过程在蛋白酶体依赖性蛋白质周转中的作用。 EerI 作为第一个作用于活细胞的去泛素化抑制剂，可能为某些类型的人类癌症提供新的治疗方法。事实上，我们发现 EerI 可以有效诱导肿瘤细胞系和从患者分离的原代肿瘤细胞凋亡。