KSHVmediated regulation of proline metabolism

项目总结/摘要 代谢重编程已被公认为癌症标志的一部分。尤其是， 脯氨酸代谢对肿瘤转移至关重要，如吡咯啉-5-羧酸还原酶 P5 CR是一种关键的线粒体脯氨酸生物合成酶，在多种细胞中高度过表达。 转移的肿瘤和促进肿瘤细胞生长。这表明脯氨酸的合成 是癌症治疗的一个有吸引力的靶点。卡波济肉瘤相关疱疹病毒 （KSHV）是口腔疱疹病毒之一，引起卡波西肉瘤和胸腔积液淋巴瘤。 该研究旨在探讨KSHV介导的KSHV-1蛋白表达的分子机制。 脯氨酸代谢的调节。我们已经证明KSHV K1糖蛋白在细胞内 基于C-末端酪氨酸免疫受体中生长转化的信号转导 激活基序（ITAM）依赖的方式。令人惊讶的是，我们发现（目标1）， 未磷酸化的K1以非ITAM依赖的方式直接与线粒体P5 CR相互作用 这种相互作用激活了它的酶活性，增加了细胞内脯氨酸的合成。 此外，KSHV基因筛选鉴定出ORF 75，一种酶缺陷型病毒谷氨酰胺 酰胺转移酶（vGAT）通过与宿主GAT之一PFAS结合而发挥底物募集剂的作用 （磷酸核糖甲酰甘氨脒合成酶）和vGAT/PFAS酶复合物脱酰胺 细胞内核酸传感器，逃避宿主先天免疫反应。而且我们的 蛋白质组范围的脱酰胺筛选发现（目的2），vGAT/PFAS复合物有效地 诱导KSHV裂解复制过程中P5 C合酶（P5 CS）的脱酰胺。基于这些，我们 假设KSHV利用两种基因产物对脯氨酸代谢进行新病毒调节 解除脯氨酸合成途径的调节：K1激活ITAM中P5 CR的酶活性， vGAT与宿主PFAS协同诱导P5 CS脱酰胺， 其最终协同作用以增强脯氨酸合成和细胞生长转化（目的3）。的 拟议的研究将提供一种新的致癌策略的KSHV的理解，以诱导 脯氨酸代谢的病毒诱导的发病机制。

Project Summary/Abstract Metabolic reprograming has been readily recognized as part of the hallmarks of cancer. Particularly, proline metabolism is critically important for tumor metastasis, as pyrroline-5-carboxylate reductase (P5CR), a key mitochondrial proline biosynthesis enzyme, is highly overexpressed in various metastasized tumors and to promote tumor cell growth. This suggests that the proline synthesis pathway is an attractive target for cancer treatment. Kaposi’s sarcoma-associated herpesvirus (KSHV) is one of oral herpesviruses and causes Kaposi’s sarcoma and pleural effusion lymphoma. The proposed research is directed toward investigating the molecular mechanism of KSHV-mediated regulation of proline metabolism. We have shown that KSHV K1 glycoprotein elicits intracellular signal transduction for growth transformation in a C-terminal immunoreceptor tyrosine-based activation motif (ITAM)-dependent manner. Surprisingly, we discovered (Aim 1) that the unphosphorylated K1 directly interacted with mitochondrial P5CR in an ITAM-independent manner and this interaction activated its enzymatic activity, increasing intracellular proline synthesis. Furthermore, KSHV gene screening identified that ORF75, an enzyme-deficient viral glutamine amidotransferase (vGAT), functions as a substrate recruiter by binding one of host GATs, PFAS (phosphoribosylformylglycinamidine synthetase), and vGAT/PFAS enzyme complex deamidates intracellular nucleic acid sensors, evading host innate immune response. Furthermore, our proteome-wide deamidation screen discovered (Aim 2) that the vGAT/PFAS complex effectively induced the deamidation of P5C synthase (P5CS) during KSHV lytic replication. Based on these, we hypothesize a novel viral regulation of proline metabolism where KSHV utilizes two gene products to deregulate proline synthesis pathway: K1 activates the enzymatic activity of P5CR in an ITAM- independent manner and vGAT collaborates with host PFAS to induce the deamidation of P5CS, which ultimately synergizes to enhance proline synthesis and cell growth transformation (Aim 3). The proposed studies will provide an understanding of a novel oncogenic strategy of KSHV to induce proline metabolism for virus-induced pathogenesis.