DHA通过Nrf2信号通路影响泛素—蛋白酶体系统促进高危型HPV E6/E7病毒蛋白降解的机制研究

Persistent infection and constitutive E6/E7 expression of high risk human papillomavirus (hrHPV) is tightly linked to the development of nongenital and genital malignancies. We have recently reported for the first time that cellular ubiquitin–proteasome system (UPS) activation by docosahexaenoic acid (DHA)-induced reactive oxygen species (ROS), leads to proteasome-mediated degradation of E6/E7 viral proteins and the induction of cell death in hrHPV-infected cells, highlighting a novel biological function of DHA in controlling UPS and hrHPV key proteins. Yet, the molecular mechanism underlying the increases in UPS activity mediated by ROS in DHA-treated cells infected with hrHPV remains unclear. As nuclear factor E2-related factor 2 (Nrf2) signaling plays a pivotal role in response to ROS and has been shown to enhance cellular UPS activity, we here attempt to determine whether DHA is capable of up-regulating Nrf2 signaling via promoting ROS overproduction, thereby inducing UPS activation, E6/E7 viral protein destabilization and the subsequent cell death . The results of this study will help to further elucidate the mechanism by which DHA mediates Nrf2 signaling as well as hrHPV E6/E7 expression, and provide solid evidence for the use of DHA as a mechanistically unique natural agent for the chemoprevention and treatment of hrHPV-associated diseases.

高危型人乳头瘤病毒（hrHPV）的致病性与病毒早期蛋白E6/E7过表达关系甚密。我们前期研究发现，人体必需的二十二碳六烯酸（DHA）在hrHPV感染细胞内可通过上调活性氧（ROS）促进依赖于泛素—蛋白酶体系统（UPS）的E6/E7降解，但DHA是如何通过对ROS的影响来激发UPS及后续E6/E7降解的具体机制却并不明确。核因子E2相关因子2（Nrf2）信号通路能被ROS激活，进而上调UPS活性。鉴于此，本项目将检测Nrf2信号通路及UPS活性变化情况，明确DHA能否通过上调ROS激活Nrf2信号通路，并由此通路介导增加UPS活性及E6/E7的降解，探索Nrf2通路在DHA诱导hrHPV感染细胞死亡过程中的作用。研究结果不仅有助于理解必需脂肪酸在HPV感染细胞内所扮演的角色，还将为应用DHA治疗hrHPV相关性疾病提供理论依据。

高危型人乳头瘤病毒（hrHPV）的致病性与病毒早期蛋白E6/E7过表达关系甚密。我们前期发现，人体必需的二十二碳六烯酸（DHA）在hrHPV感染细胞内可通过上调活性氧（ROS）促进依赖于泛素—蛋白酶体系统（UPS）的E6/E7降解，但DHA是如何通过对ROS的影响来激发UPS及后续E6/E7降解的具体机制却并不明确。在本研究中我们证实：（1）DHA可激活核因子E2相关因子2（Nrf2）信号通路；（2）ROS抑制剂可有效逆转DHA对Nrf2信号通路活化作用；（3）基因沉默Nrf2后，DHA对UPS的活化及下调E6/E7病毒蛋白表达作用受到抑制。以上结果提示，DHA可通过上调ROS激活Nrf2信号通路，并由此通路介导增加UPS活性及E6/E7的降解。本研究阐明了必需脂肪酸在HPV感染细胞内所扮演的角色，并为应用DHA治疗hrHPV相关性疾病提供了理论依据。