Equipe d'Accueil 4483, Faculté de Médecine/Pôle Recherche, UDSL, Université Lille-Nord de France, Place de Verdun, 59045, Lille Cedex, France.
Alcohol Alcohol. 2013 Jul-Aug;48(4):415-25. doi: 10.1093/alcalc/agt028. Epub 2013 Apr 4.
In response to acute ethanol consumption, tryptophan 2,3-dioxygenase (TDO) induces the kynurenine pathway (KP) through a glucocorticoid-mediated mechanism, which could lead to a dramatic accumulation of neurotoxic metabolites in association with serotonin depletion. As a result, interindividual variability in ethanol-induced behavioural disorders, such as black-outs and violent impulsive behaviours (BOVIBs) following binge drinking, could be partly explained by genetic polymorphisms affecting the KP. The aim of this study was to identify polymorphisms on the promoter of the TDO2 gene that could affect expression and/or activity of TDO through glucocorticoid induction.
Polymorphisms were screened using a PCR-sequencing strategy applied to 31 alcohol-dependent patients and 49 unrelated healthy volunteers, and functionally analysed with bioinformatic prediction tools and gene reporter assays in HepG2 and A549 cell lines.
We identified 12 polymorphisms in the human TDO2 promoter region, 2 of them corresponding to previously unknown single-nucleotide polymorphisms (SNPs) and 3 of them located in putative glucocorticoid-responsive elements (GREs). Gene reporter assays using HepG2 and A549 cell lines confirmed the presence of several functional GREs in the promoter region of TDO2 and revealed that some of the identified polymorphisms affect the promoter activity under glucocorticoid receptor over-expression and dexamethasone exposure conditions.
Correlational studies in larger samples could help to determine whether these polymorphisms are responsible for variations of expression and/or activity of TDO, in particular under conditions where release of glucocorticoids is increased, such as acute ethanol intake. If confirmed, such results would be of major interest in explaining part of the interindividual variability observed in behavioural responses to acute ethanol consumption.
在急性乙醇摄入的情况下，色氨酸 2,3-双加氧酶（TDO）通过糖皮质激素介导的机制诱导犬尿氨酸途径（KP），这可能导致与 5-羟色胺耗竭相关的神经毒性代谢物的大量积累。因此，个体间在急性乙醇摄入引起的行为障碍方面的差异，如狂欢饮酒后的昏迷和暴力冲动行为（BOVIBs），可能部分可以通过影响 KP 的遗传多态性来解释。本研究旨在鉴定 TDO2 基因启动子上的多态性，这些多态性可能通过糖皮质激素诱导影响 TDO 的表达和/或活性。
采用 PCR-测序策略对 31 名酒精依赖患者和 49 名无关健康志愿者进行筛查，并应用生物信息学预测工具和 HepG2 和 A549 细胞系中的基因报告基因进行功能分析。
我们在人类 TDO2 启动子区域鉴定出 12 个多态性，其中 2 个对应于先前未知的单核苷酸多态性（SNP），3 个位于推定的糖皮质激素反应元件（GRE）中。使用 HepG2 和 A549 细胞系的基因报告基因实验证实了 TDO2 启动子区域存在多个功能 GRE，并且发现鉴定出的一些多态性影响糖皮质激素受体过表达和地塞米松暴露条件下的启动子活性。
在更大的样本中进行相关性研究可以帮助确定这些多态性是否负责 TDO 的表达和/或活性的变化，特别是在糖皮质激素释放增加的情况下，如急性乙醇摄入。如果得到证实，这些结果将对解释个体间在急性乙醇摄入引起的行为反应方面的差异具有重要意义。
