Fang Hai-Lin, Shenoy Sarita, Duanmu Zhengbo, Kocarek Thomas A, Runge-Morris Melissa
Institute of Environmental Health Sciences, Wayne State University, 2727 Second Avenue, Room 4000, Detroit, MI 48201, USA.
Drug Metab Dispos. 2003 Nov;31(11):1378-81. doi: 10.1124/dmd.31.11.1378.
The purpose of the current study was to establish the role of the glucocorticoid receptor (GR) and androgen receptor (AR) transcription factors in the transactivation of rat aryl sulfotransferase (SULT1A1) gene transcription and to identify the functional hormone-responsive element(s) in the SULT1A1 gene. A cis-acting inverted repeat with three intervening bases (IR3) was identified in the 5'-flanking of the SULT1A1 gene that mediates the transactivation of SULT1A1 gene transcription by both the GR and AR. CV-1 cells were cotransfected with SULT1A1-luciferase reporter plasmids and either wild-type or mutant GR or AR expression constructs. In cotransfectants expressing the wild-type GR, treatment with triamcinolone acetonide produced an approximately 4- to 6-fold induction of luciferase activity in IR3-containing SULT1A1 reporter plasmids. IR3-containing SULT1A1 reporter constructs were also activated by treatment with the synthetic androgen R1881 in cells cotransfected with wild-type but not mutant AR. In primary cultured rat hepatocytes, androgen-inducible expression of IR3-containing SULT1A1 reporter plasmids required cotransfection with AR expression plasmid. Targeted disruption of the SULT1A1 IR3 by mutation of a conserved GT sequence in the 3' half-site of the element ablated GR and AR responsiveness. These results indicate that a proximal IR3 element in the 5'-flanking region of the rat SULT1A1 gene is sufficient for the transactivation of SULT1A1 gene transcription by the GR and AR, and that relative to the GR, functional AR activity is reduced in primary cultured rat hepatocytes.
本研究的目的是确定糖皮质激素受体（GR）和雄激素受体（AR）转录因子在大鼠芳基磺基转移酶（SULT1A1）基因转录反式激活中的作用，并鉴定SULT1A1基因中的功能性激素反应元件。在SULT1A1基因的5'侧翼区域鉴定出一个具有三个间隔碱基的顺式作用反向重复序列（IR3），它介导GR和AR对SULT1A1基因转录的反式激活。将SULT1A1-荧光素酶报告质粒与野生型或突变型GR或AR表达构建体共转染CV-1细胞。在表达野生型GR的共转染细胞中，用曲安奈德处理可使含IR3的SULT1A1报告质粒中的荧光素酶活性诱导约4至6倍。在与野生型而非突变型AR共转染的细胞中，含IR3的SULT1A1报告构建体也可被合成雄激素R1881激活。在原代培养的大鼠肝细胞中，含IR3的SULT1A1报告质粒的雄激素诱导表达需要与AR表达质粒共转染。通过突变该元件3'半位点中的保守GT序列对SULT1A1 IR3进行靶向破坏，消除了GR和AR的反应性。这些结果表明，大鼠SULT1A1基因5'侧翼区域的近端IR3元件足以实现GR和AR对SULT1A1基因转录的反式激活，并且相对于GR，原代培养的大鼠肝细胞中功能性AR活性降低。
