Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany.
J Hepatol. 2013 Oct;59(4):797-804. doi: 10.1016/j.jhep.2013.05.028. Epub 2013 May 25.
BACKGROUND & AIMS: Gender influences incidence, progression, and therapy of hepatogastrointestinal diseases. The aim of this study was to elucidate the molecular mechanism of gender-specific UDP-glucuronosyltransferases (UGT1A) regulation, representing important hepatogastrointestinal detoxification enzymes for xenobiotics, drugs, and endobiotics.
UGT1A-gene activation was studied by reporter gene experiments and estrogen receptor alpha (ESR1/ERα) co-transfection using KYSE70- and HepG2 cells (male origin), and SW403 cells (female origin). Cell lines, and humanized transgenic UGT1A (htgUGT1A) mice (female/male) were treated with the ERα inhibitor tamoxifen. UGT1A mRNA expression was analyzed by TaqMan PCR, the recruitment of ERα, histone deacetylases (HDAC), and the aryl hydrocarbon receptor (AhR) by chromatin immunoprecipitation (ChIP), and ERα expression in gastrointestinal mouse tissues by Western blot and immunofluorescence.
In KYSE70 cells (male), UGT1A gene expression was induced 5-10 fold, and inhibited in the presence of ERα by 55-77%. In SW403 (female) cells, absent inducibility was restored after tamoxifen treatment. In the jejunum and colon of tgUGT1A mice, UGT1A induction that was exclusively detected in male mice could be restored in female mice after tamoxifen pre-treatment. ChIP assays demonstrated the recruitment of ERα and HDACs to the xenobiotic response elements of UGT1A promoters during gene repression. Western blot showed higher ERα expression in the female jejunum and colon.
We show gender-specific transcriptional control of UGT1A genes in jejunum and colon, which is repressed by ERα and the recruitment of HDCAs to the UGT1A promoter sequence in females. A molecular mechanism controlling gender-specific drug metabolism and its therapeutic reversal is demonstrated.
性别会影响肝胆胃肠疾病的发病、进展和治疗。本研究旨在阐明性别特异性尿苷二磷酸葡萄糖醛酸转移酶（UGT1A）调控的分子机制，UGT1A 是对异生物、药物和内源性物质具有重要解毒作用的肝胆胃肠解毒酶。
采用报告基因实验和 ERα 共转染，研究 UGT1A 基因的激活，转染的细胞株为 KYSE70-和 HepG2 细胞（来源于男性）以及 SW403 细胞（来源于女性）。用 ERα 抑制剂他莫昔芬处理细胞株和人源化 UGT1A 转基因（htgUGT1A）小鼠（雌雄）。采用 TaqMan PCR 分析 UGT1A mRNA 表达，采用染色质免疫沉淀（ChIP）分析 ERα、组蛋白去乙酰化酶（HDAC）和芳香烃受体（AhR）的募集情况，采用 Western blot 和免疫荧光法分析胃肠道小鼠组织中的 ERα 表达情况。
在 KYSE70 细胞（男性）中，UGT1A 基因表达被诱导 5-10 倍，而在存在 ERα 的情况下被抑制 55-77%。在 SW403（女性）细胞中，经他莫昔芬处理后可恢复无诱导能力。在 htgUGT1A 小鼠的空肠和回肠中，仅在雄性小鼠中检测到的 UGT1A 诱导作用，经他莫昔芬预处理后可在雌性小鼠中恢复。ChIP 实验表明，在基因抑制过程中，ERα 和 HDAC 被募集到 UGT1A 启动子的异生物反应元件上。Western blot 显示女性空肠和回肠中的 ERα 表达更高。
本研究表明，空肠和回肠中的 UGT1A 基因存在性别特异性转录调控，女性中 ERα 和 HDAC 被募集到 UGT1A 启动子序列上可抑制其表达。本研究证实了一种控制性别特异性药物代谢及其治疗逆转的分子机制。
