Caspase-8 Inhibition Prevents the Cleavage and Degradation of E3 Ligase Substrate Receptor Cereblon and Potentiates Its Biological Function.
Caspase-8 Inhibition Prevents the Cleavage and Degradation of E3 Ligase Substrate Receptor Cereblon and Potentiates Its Biological Function.
复制标题
Caspase-8 抑制可防止 E3 连接酶底物受体 cereblon 的裂解和降解，并增强其生物学功能
DOI：
10.3389/fcell.2020.605989
复制
发表时间：
2020
影响因子：
5.5
通讯作者：
Xu G
中科院分区：
文献类型：
--
作者：
Zhou L;Yu W;Jayabalan DS;Niesvizky R;Jaffrey SR;Huang X;Xu G
cereblon（CRBN）是cullin 4 - RING E3连接酶（CRL4）的一种底物受体，介导组成型底物以及免疫调节药物诱导的新底物（包括MEIS2、c - Jun、CLC1、IKZF1/3、CK1α和SALL4）的泛素化和降解。据报道，CRBN自身可通过泛素 - 蛋白酶体系统被与其相关的或其他cullin - RING E3连接酶降解，从而影响其生物学功能。然而，尚不清楚caspases是否可调节CRBN的稳定性及其生物学功能。在本研究中，利用模型细胞系，我们发现使用肿瘤坏死因子相关凋亡诱导配体（TRAIL）激活死亡受体可导致CRBN蛋白水平降低。通过对caspase - 8（CASP - 8）进行药理学抑制和激活，我们揭示了CASP - 8在细胞系中调节CRBN的切割。位点定位实验表明，在CASP - 8激活时，CRBN在Asp9之后被切割，导致稳定性降低。以骨髓瘤作为模型系统，我们进一步揭示，抑制CASP - 8或使其基因缺失可通过阻碍CRBN切割增强来那度胺（Len）的抗骨髓瘤活性，导致IKZF1和IKZF3蛋白水平降低以及骨髓瘤细胞系和患者原发性骨髓瘤细胞的活力降低。本研究发现E3连接酶的底物受体的稳定性可被CASP - 8调节，并提示施用CASP - 8抑制剂可提高基于来那度胺的联合疗法在骨髓瘤中的整体疗效。
Cereblon (CRBN), a substrate receptor of cullin 4-RING E3 ligase (CRL4), mediates the ubiquitination and degradation of constitutive substrates and immunomodulatory drug-induced neo-substrates including MEIS2, c-Jun, CLC1, IKZF1/3, CK1α, and SALL4. It has been reported that CRBN itself could be degraded through the ubiquitin-proteasome system by its associated or other cullin-RING E3 ligases, thus influencing its biological functions. However, it is unknown whether the CRBN stability and its biological function could be modulated by caspases. In this study, using model cell lines, we found that activation of the death receptor using tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) leads to the decreased CRBN protein level. Through pharmacological inhibition and activation of caspase-8 (CASP-8), we disclosed that CASP-8 regulates CRBN cleavage in cell lines. Site mapping experiments revealed that CRBN is cleaved after Asp9 upon CASP-8 activation, resulting in the reduced stability. Using myeloma as a model system, we further revealed that either inhibition or genetic depletion of CASP-8 enhances the anti-myeloma activity of lenalidomide (Len) by impairing CRBN cleavage, leading to the attenuated IKZF1 and IKZF3 protein levels and the reduced viability of myeloma cell lines and primary myeloma cells from patients. The present study discovered that the stability of the substrate receptor of an E3 ligase can be modulated by CASP-8 and suggested that administration of CASP-8 inhibitors enhances the overall effectiveness of Len-based combination therapy in myeloma.