Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea.
Mol Biomed. 2024 Nov 13;5(1):58. doi: 10.1186/s43556-024-00224-9.
X-linked inhibitor of apoptosis-associated factor 1 (XAF1) is a stress-inducible pro-apoptotic protein that is commonly inactivated in multiple human cancers. Nevertheless, the molecular basis for its tumor suppression function remains largely uncharacterized. Here we report that XAF1 antagonizes the oncogenic activity of tripartite motif containing 28 (TRIM28) ubiquitin E3 ligase through zinc finger protein 313 (ZNF313)-induced ubiquitination and proteasomal degradation. XAF1 exerts apoptosis-promoting effect more strongly in TRIM28 versus XAF1 tumor cells and suppresses tumor cell growth, migration, invasion, and epithelial-to-mesenchymal transition and xenograft tumor growth in a highly TRIM28-dependent fashion. Mechanistically, XAF1 interacts directly with the RING domains of TRIM28 and ZNF313 through the ZF6 and ZF7 domain, respectively, thereby facilitating ZNF313 interaction with and ubiquitination of TRIM28. A mutant XAF1 lacking either ZF6 or ZF7 domain exhibits no activity to promote TRIM28 ubiquitination. By destabilizing TRIM28, XAF1 blocks TRIM28-driven ubiquitination of p53 and RLIM, p53-HDAC1 interaction, and TWIST1 stabilization. Intriguingly, TRIM28 destabilizes XAF1 through K48-linked polyubiquitination and proteasomal degradation to protect tumor cells from apoptotic stress, indicating its role as an intrinsic antagonist against XAF1 and the antagonistic interplay of XAF1 and TRIM28. XAF1 expression is inversely correlated with TRIM28 expression in cancer cell lines and tumor tissues and more tightly associated with the survival of TRIM28-high versus TRIM28-low patients. Together, this study uncovers a novel mechanism by which XAF1 suppresses tumor malignancy and an important role for XAF1-TRIM28 interplay in governing stress response, illuminating the mechanistic consequence of its alteration during tumorigenic process.
X 连锁凋亡抑制因子相关因子 1（XAF1）是一种应激诱导的促凋亡蛋白，通常在多种人类癌症中失活。然而，其肿瘤抑制功能的分子基础在很大程度上仍未得到阐明。在这里，我们报告 XAF1 通过锌指蛋白 313（ZNF313）诱导的泛素化和蛋白酶体降解来拮抗三肽基含 28（TRIM28）泛素 E3 连接酶的致癌活性。XAF1 在 TRIM28 相对于 XAF1 肿瘤细胞中更强烈地发挥促凋亡作用，并以高度依赖 TRIM28 的方式抑制肿瘤细胞生长、迁移、侵袭和上皮间质转化以及异种移植肿瘤生长。在机制上，XAF1 通过分别的 ZF6 和 ZF7 结构域直接与 TRIM28 的 RING 结构域相互作用，从而促进 ZNF313 与 TRIM28 的相互作用和泛素化。缺失 ZF6 或 ZF7 结构域的突变 XAF1 没有促进 TRIM28 泛素化的活性。通过破坏 TRIM28，XAF1 阻断了 TRIM28 驱动的 p53 和 RLIM 的泛素化、p53-HDAC1 相互作用和 TWIST1 稳定。有趣的是，TRIM28 通过 K48 连接的多泛素化和蛋白酶体降解来破坏 XAF1，以保护肿瘤细胞免受凋亡应激，表明其作为 XAF1 的内在拮抗剂和 XAF1 和 TRIM28 的拮抗相互作用的作用。XAF1 的表达与癌症细胞系和肿瘤组织中的 TRIM28 表达呈负相关，并且与 TRIM28 高表达患者的生存更为紧密相关，而与 TRIM28 低表达患者的生存无关。总之，本研究揭示了 XAF1 抑制肿瘤恶性的新机制，以及 XAF1-TRIM28 相互作用在调节应激反应中的重要作用，阐明了其在肿瘤发生过程中改变的机制后果。
