KSHVmediated regulation of proline metabolism

项目摘要/摘要 新陈代谢再编程很容易被认为是癌症的特征之一。尤其是， 脯氨酸代谢与吡咯酸-5-羧酸还原酶一样，在肿瘤转移中起着至关重要的作用 (P5CR)是线粒体中一种关键的脯氨酸生物合成酶，在多种组织中都有高表达。 促进肿瘤转移，促进肿瘤细胞生长。这表明，脯氨酸的合成 PATH是治疗癌症的一个有吸引力的靶点。卡波西肉瘤相关疱疹病毒 KSHV是一种口腔疱疹病毒，可引起卡波西氏肉瘤和胸腔积液淋巴瘤。 这项研究旨在研究KSHV介导的分子机制。 脯氨酸代谢的调节。我们已经证明KSHV K1糖蛋白可以引起细胞内 基于酪氨酸的C末端免疫受体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) 非磷酸化K1以不依赖ITAM的方式与线粒体P5CR直接相互作用 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基因筛选证实，ORF75是一种酶缺陷型病毒谷氨酰胺 氨基转移酶(VGAT)通过与宿主GATs之一PFAS结合而发挥底物招募功能 和vGAT/PFAS酶复合体脱胺 细胞内的核酸传感器，逃避宿主的先天免疫反应。此外，我们的 蛋白质组范围的脱酰胺筛选发现(目标2)vGAT/PFAS复合体有效 诱导KSHV裂解复制过程中P5C合成酶(P5CS)的脱酰胺。基于这些，我们 假设KSHV利用两个基因产物对Pro代谢进行新的病毒调控 解除对Pro合成途径的调控：K1激活ITAM中P5CR的酶活性 独立方式和vGAT与宿主PFAS合作诱导P5CS的脱酰胺化， 最终发挥协同作用，促进脯氨酸合成和细胞生长转化(目标3)。这个 拟议的研究将提供对KSHV一种新的致癌策略的理解，以诱导 病毒诱导的致病机制中的脯氨酸代谢。

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.