Characterization of ER-localized Activity of HHV-8 Interleukin-6

描述(申请人提供)：人类疱疹病毒8型(HHV-8)在病因学上与卡波西肉瘤、多中心性Castleman病和原发渗出性淋巴瘤(PEL)有关。该病毒编码白介素6的同源物(病毒IL-6，VIL-6)，这种病毒细胞因子与HHV-8相关肿瘤的发生和发病有关。VIL-6是PEL细胞生长和存活所必需的，已知它定位于这些细胞的内质网(ER)，在那里它有能力介导其促生长和存活的作用。VIL-6在潜伏感染的PEL细胞中介导这些活动的机制尚不清楚。然而，我们最近发现了VIL-6的一个新的相互作用伙伴，维生素K环氧化物还原酶复合体亚基1变异体2(VKORC1v2)，它也定位于ER，并通过与VIL-6相互作用的机制促进PEL细胞的生长和存活。在酵母双杂交筛选和随后的共沉淀实验中，VKORC1v2还被证明与硫氧还蛋白样蛋白1(TMX1)相互作用，TMX1是一种ER定位的蛋白，参与二硫键的还原。VKORC1v2与TMX1的内质网定位和相互作用表明，这些蛋白可能在VIL-6的折叠和/或调节内质网应激反应中发挥作用。最近的研究也表明，IL-6信号转导蛋白gp130对于PEL细胞的生长和维持是必需的，尽管vIL-6在这一过程中起着特殊的作用 进程尚未确定。这份F31申请建议在分子水平上进一步表征VIL-6：VKORC1v2的相互作用，确定VKORC1v2和TMX1与VIL-6活性的关系，并阐明VIL-6：gp130信号对PEL细胞生长和存活的贡献和机制。通过了解VIL-6在病毒生物学和致病机制中的分子机制，可能会发现和开发新的靶点，用于治疗PEL和其他HHV-8相关疾病。

DESCRIPTION (provided by applicant): Human herpesvirus 8 (HHV-8) has been etiologically linked to Kaposi sarcoma, multicentric Castleman's disease, and primary effusion lymphoma (PEL). The virus encodes a homolog of interluekin-6 (viral IL-6, vIL-6), and this viral cytokine has been implicated in development and pathogenesis of HHV-8 associated neoplasias. vIL-6 is required for PEL cell growth and survival, and it is known to localize to the endoplasmic reticulum (ER) of these cells where it is competent to mediate its pro-growth and survival effects. The mechanism by which vIL-6 mediates these activities in latently infected PEL cells is unclear. However, we have recently identified a novel interaction partner of vIL-6, vitamin K epoxide reductase complex subunit 1 variant 2 (VKORC1v2), which also localizes to the ER and functions to promote PEL cell growth and survival by a mechanism involving its interaction with vIL-6. In a yeast two-hybrid screen and subsequently by co-precipitation assay, VKORC1v2 was also shown to interact with thioredoxin-like protein 1 (TMX1), an ER-localized protein known to participate in the reduction of disulfide bonds. ER localization and interaction of VKORC1v2 with TMX1 suggest that these proteins may play a role in the folding of vIL-6 and/or in regulating the ER stress response. Recent studies have also indicated that the IL-6 signal transducer, gp130, is required for the growth and maintenance of PEL cells although the specific role of vIL-6 in this process has not been determined. This F31 application proposes to further characterize the vIL-6:VKORC1v2 interaction at the molecular level, to determine the connection of VKORC1v2 and TMX1 with vIL-6 activity, and to elucidate the contribution and mechanism of vIL-6:gp130 signaling to PEL cell growth and viability. By understanding the molecular mechanisms of vIL-6 effects in virus biology and pathogenesis, new targets may be identified and exploited for therapeutic benefit to treat PEL and other HHV-8 associated diseases.