Transcriptional Regulaton of Pro-Inflammatory Genes by Gambogic Acid

描述（由申请人提供）：本R21申请是针对标题为“免疫调节机制”的RFA（#AT-07-005）提交的。“我们提出的研究的主要目标是了解一种重要的补充药物--具有悠久药用历史的藤黄酸（GA）的分子作用机制。GA是一种聚异戊二烯化的氧杂蒽酮，?-不饱和羰基，从藤黄中分离，从藤黄莫雷拉和藤黄的树脂中分离。许多具有这种活性碳中心的植物都具有有趣的药理学特性。在这方面，具有抗肿瘤活性的GA被认为具有迄今为止尚未测试的抗炎活性。由于存在的？，？- GA是一种有效的迈克尔受体，可以与蛋白质（包括转录因子）中的游离巯基共价相互作用。我们的初步研究结果表明，GA对细菌脂多糖（LPS）诱导的核因子-？B（NF-？B）。NF-？B是负责炎症驱动的疾病进展的主要转录因子。我们将扩展这些研究，以阐明潜在的分子机制的免疫调节炎症GA的转录的两个NF-？B靶向促炎基因环氧合酶（考克斯）-2和TNF-α。具体的假设进行测试是，GA下调转录的考克斯-2和TNF？通过形成共价迈克尔加合物与蛋白质成分的NF-？B级联。该假设将使用LPS刺激的小鼠骨髓衍生的巨噬细胞进行测试，并在C57/BL 6小鼠中的体内炎症模型中进行验证，具体目的有两个：1）检查GA对考克斯-2和TNF？转录调节的影响，阐明NF-？B的活化和功能。研究将集中在减轻炎症GA通过转录调控的考克斯-2和TNF？并且将涉及使用基于酶的报告和染色质免疫沉淀分析。此外，GA与NF-？B途径将通过在质谱和生化功能研究中使用生物素化-GA来评估。我们的长期目标是加强对补充和替代医学中使用的植物药在炎症免疫调节中作用的分子机制的理解。 公共卫生：藤黄，从藤黄莫雷拉和G。原产于亚洲、澳大利亚、南部非洲和波利尼西亚的属于Clusiaceae（Guttiferae）家族的汉布里（hanburyi）富含聚异戊二烯化的氧杂蒽酮、藤黄酸（GA）。有一个悠久的历史药用藤黄提取物对许多疾病。有趣的是，GA的抗肿瘤活性已经得到很好的证明，并且被认为部分是由于与GA相关的抗炎活性而产生的。然而，GA的抗炎活性尚未被测试。我们建议研究NF-？GA在体外和体内炎症模型中促炎基因的B依赖性表达。

DESCRIPTION (provided by applicant): This R21 application is submitted in response to an RFA (#AT-07-005) entitled "Mechanisms of Immune Modulation." The primary objective of our proposed studies is to understand the molecular mechanism of action of an important complementary medicine, gambogic acid (GA) that has a long history of medicinal use. GA is a polyprenylated xanthone, with an ?, ?-unsaturated carbonyl group, isolated from gamboges, the resin from Garcinia morella and Garcinia hanburyi. Many botanicals with such a reactive carbon center are known to possess interesting pharmacological properties. In this regard, GA, which possesses anti-tumor activity, is thought to possess anti-inflammatory activities that have so far remained untested. Due to the presence of the ?,?-unsaturated carbonyl group, GA is a potent Michael acceptor that can covalently interact with free thiol groups in proteins, including transcription factors. Our preliminary results demonstrate an inhibitory effect of GA on the bacterial lipopolysaccharide (LPS)-induced activation of nuclear factor-?B (NF-?B). NF-?B is a major transcription factor responsible for inflammation-driven disease progression. We will extend these studies to elucidate the underlying molecular mechanism of immune modulation of inflammation by GA with a specific focus on the transcription of two NF-?B target pro-inflammatory genes, cyclooxygenase (COX)-2 and tumor necrosis factor (TNF)-?. The specific hypothesis to be tested is that GA down-regulates the transcription of COX-2 and TNF? via the formation of covalent Michael adducts with protein components of the NF-?B cascade. The hypothesis will be tested using LPS-stimulated murine bone marrow-derived macrophages and validated in an in-vivo inflammation model, in C57/BL6 mice, in two Specific Aims: 1) To examine the effect of GA on the transcriptional regulation of COX-2 and TNF?, and 2) To elucidate the molecular mechanism of attenuation of NF-?B activation and function by GA. Studies will be focused on attenuation of inflammation by GA via the transcriptional regulation of COX-2 and TNF? and will involve the use of luciferase-based reporter and chromatin immunoprecipitation assays. Furthermore, the interaction of GA with protein components of the NF-?B pathway will be assessed by using biotinylated-GA in mass spectrometric and biochemical functional studies. Our long-term objective is to enhance the understanding of the molecular mechanism of action of botanicals used in complementary and alternative medicine for their role in immune regulation of inflammation. PUBLIC HEALTH REVELANCE: Gamboges, the resin from Garcinia morella and G. hanburyi that belong to the family Clusiaceae (Guttiferae), which are native to Asia, Australia, Southern Africa, and Polynesia, are rich in a polyprenylated xanthone, gambogic acid (GA). There is a long history of medicinal use of Garcinia extracts against many ailments. Interestingly, the anti-tumor activity of GA has been well demonstrated and is thought to arise partly due to the anti-inflammatory activity associated with GA. However, the anti-inflammatory activity of GA has not been tested. We propose to study the molecular basis of the down-regulation of NF-?B-dependent expression of pro-inflammatory genes by GA in in vitro and in vivo models of inflammation.