Cullin-4B E3 ubiquitin ligase mediates Apaf-1 ubiquitination to regulate caspase-9 activity
Cullin-4B E3 ubiquitin ligase mediates Apaf-1 ubiquitination to regulate caspase-9 activity
复制标题
DOI：
10.1371/journal.pone.0219782
复制
发表时间：
2019-07
期刊：
影响因子：
3.7
通讯作者：
E. Ohta;M. Itoh;M. Ueda;Yoko Hida;Miao-xing Wang;M. Hayakawa-Ogura;Shimo Li;Emika Nishida;Kazunori Ohta;Tana;S. Islam;Kiyomi Nakagawa;Tomomi Sunayama;Huayue Chen;So Hirata;Masashi Endo;Yoya Ohno;Toshiyuki Nakagawa
中科院分区：
文献类型：
--
作者：
E. Ohta;M. Itoh;M. Ueda;Yoko Hida;Miao-xing Wang;M. Hayakawa-Ogura;Shimo Li;Emika Nishida;Kazunori Ohta;Tana;S. Islam;Kiyomi Nakagawa;Tomomi Sunayama;Huayue Chen;So Hirata;Masashi Endo;Yoya Ohno;Toshiyuki Nakagawa
凋亡蛋白酶激活因子1(APAF-1)是凋亡体的一种成分，调节caspase-9的活性。除细胞凋亡外，APAF-1在S期检查点中发挥重要作用；因此，APAF-1在化疗耐药的恶性黑色素瘤中的表达受损，APAF-1的核易位代表了非小细胞肺癌患者良好的预后。相比之下，亨廷顿病患者大脑中APAF-1蛋白水平升高。目前对APAF-1蛋白的调控尚不完全清楚。在这项研究中，我们证明了依托泊苷触发了APAF-1与Cullin-4B的相互作用，导致APAF-1泛素化增强。泛素化的APAF-1在健康细胞中被降解，与p62结合并在胞浆中形成聚集体。这种泛素化的APAF-1和p62的复合体在MG132处理稳定表达bclxl的HEK293T细胞后诱导caspase-9激活。这些结果表明，泛素化的APAF-1可能在蛋白酶体损伤的条件下激活caspase-9。
Apoptotic protease-activating factor 1 (Apaf-1) is a component of apoptosome, which regulates caspase-9 activity. In addition to apoptosis, Apaf-1 plays critical roles in the intra-S-phase checkpoint; therefore, impaired expression of Apaf-1 has been demonstrated in chemotherapy-resistant malignant melanoma and nuclear translocation of Apaf-1 has represented a favorable prognosis of patients with non-small cell lung cancer. In contrast, increased levels of Apaf-1 protein are observed in the brain in Huntington’s disease. The regulation of Apaf-1 protein is not yet fully understood. In this study, we show that etoposide triggers the interaction of Apaf-1 with Cullin-4B, resulting in enhanced Apaf-1 ubiquitination. Ubiquitinated Apaf-1, which was degraded in healthy cells, binds p62 and forms aggregates in the cytosol. This complex of ubiquitinated Apaf-1 and p62 induces caspase-9 activation following MG132 treatment of HEK293T cells that stably express bcl-xl. These results show that ubiquitinated Apaf-1 may activate caspase-9 under conditions of proteasome impairment.