DNA damage response and DNA repair triggered by genotoxic phenylpropanoids in the diet

苯丙素或苯丙烯（PP）是天然存在的草药和香料成分，如罗勒、肉豆蔻、茴香和菖蒲。它们是苯的化学衍生物，具有不饱和的c3侧链，含有末端双键（烯丙基PP）或内部双键（1-丙烯PP）。这些化合物以结构依赖的方式进行代谢激活：1-丙烯PP通过细胞色素P450酶（CPY）和烯丙基PP通过CYP和硫转移酶（SULT）。主要的靶器官是肝脏，已知PP在肝脏中具有遗传毒性和致癌性。然而，DNA损伤反应如何对pp诱导的DNA加合物提供保护以及哪些DNA修复途径参与DNA加合物的去除在很大程度上是未知的。此外，DNA修复缺陷如何影响细胞存活和基因组完整性尚不清楚。本研究的目的是了解PP-DNA加合物引发的DNA损伤反应，并揭示参与DNA修复的机制。为此，将研究与食品相关的烯丙基PP甲基丁香酚和1-丙烯基PP ß-Asaron。将使用具有代谢能力的肝细胞系以及具有DNA修复特异性缺陷的原代肝细胞。由于我们的初步研究结果，我们将重点关注全球基因组和转录偶联核苷酸切除修复（GG-NER和TC-NER分别）。这些模型应该解决以下问题：1)当烯丙基和1-丙烯PP形成DNA加合物时，细胞中会触发哪种类型的DNA损伤反应？这种反应是如何调节的？2 . GG-NER和TC-NER对于pp诱导的DNA加合物的去除有何相关性，dG-N2-和da - n6加合物是否存在差异；pp诱导的DNA损伤在细胞毒性和致裂性方面的生物学后果是什么？这些终点分别如何受到GG-NER和TC-NER缺陷的影响。

Phenylpropanoids or Phenylpropenes (PP) are naturally occurring ingredients of herbs and spices such as basil, nutmeg, anise and calamus. They are chemical derivatives of benzol with an unsaturated C3-side chain, which contains either a terminal double bond (allylic PP) or an internal double bond (1-propenylic PP). These compounds undergo metabolic activation in a structure-dependent manner: 1-propenylic PP via Cytochrome P450 enzymes (CPY) and allylic PP via CYP and Sulfotransferases (SULT). The major target organ represents the liver, where PP are known to act genotoxic and carcinogenic. However, it is largely unknown how the DNA damage response confers protection against PP-induced DNA adducts and which DNA repair pathways are involved in DNA adduct removal. Furthermore, it is unclear how defects in DNA repair will affect cell survival and genome integrity.The objective of this study is to understand the DNA damage response triggered by PP-DNA adducts and to reveal the engaged DNA repair mechanism. To this end, the allylic PP Methyleugenol and the 1-propenylic PP ß-Asaron will be studied, which are both relevant in food. Metabolic competent liver cell lines as well as primary liver cells with specific defects in DNA repair will be used. Due to the results obtained in our preliminary studies, we will focus on global-genomic and transcription-coupled nucleotide excision repair (GG-NER and TC-NER, respectively). The followings issues should be addressed with these models: 1.) Which type of DNA damage response in triggered in cells upon DNA adduct formation by allylic and 1-propenylic PP and how is this regulated, 2.) What is the relevance of GG-NER and TC-NER for the removal of PP-induced DNA adducts and are there differences concerning dG-N2- and dA-N6-adducts, and 3.) What are the biological consequences of PP-induced DNA damage with regard to cytotoxicity and clastogenicity, and how are these endpoints influenced by defects in GG-NER and TC-NER, respectively.