Qiu C, Liu X, Wang J, Zhao Y, Fu Q
Department of Orthopaedics, Shengjing Hospital of China Medical University, No. 36 San Hao Street, Shenyang, 110004, China.
Osteoporos Int. 2014 Apr;25(4):1357-67. doi: 10.1007/s00198-013-2613-1. Epub 2014 Feb 7.
The expression of α2-Heremans-Schmid-glycoprotein (AHSG) was estrogen responsive in oophorectomized (OVX) osteopenic rats and HepG2 cells. Estrogen receptor α (ERα) interacted with the c-Jun/c-Fos heterodimer and indirectly associated with the -1488/-1482 activator protein-1 (AP-1) motif of the AHSG promoter. Estrogen increased c-Jun/c-Fos expression via the mitogen-activated protein kinase (MAPK) pathway.
AHSG is a hepatic secretory protein implicated in the regulation of bone homeostasis. Serum AHSG in women has been reported to decrease after menopause and increase with estrogen therapy. The detailed regulatory mechanism of estrogen on AHSG is unclear.
A postmenopausal osteoporosis model was generated in OVX rats. Skeletal parameters were determined by automatic biochemical analysis and dual X-ray absorptiometry. The expression of AHSG was evaluated by ELISA, real-time PCR, and Western blot. The 1.5-kb 5'-promoter region of AHSG was analyzed by serial truncation and luciferase assays. The putative -1488/-1482 AP-1 responsive element was identified by electrophoresis mobility shift assay (EMSA). Chromatin immunoprecipitation (ChIP), re-ChIP, and co-immunoprecipitation (Co-IP) were used to characterize the interaction of ERα and AP-1 at the -1488/-1482 AP-1 binding site. The MAPK pathway was evaluated using a specific inhibitor and active transfection.
The expression of AHSG was estrogen responsive in both OVX rats and estradiol (E2)/ERα-treated HepG2 cells. E2/ERα most prominently increased luciferase activity of a construct with a putative -1488/-1482 AP-1 binding element. ERα interacted with the c-Jun/c-Fos heterodimer and indirectly associated with the -1488/-1482 AP-1 motif of the AHSG promoter. c-Jun/c-Fos expression was increased via the MAPK pathway by E2/ERα.
Estrogen activated the transcription of AHSG through an indirect binding of ERα to the -1488/-1482 AP-1 binding element, with the c-Jun/c-Fos heterodimers.
α2-赫雷曼斯-施密德糖蛋白（AHSG）的表达在去卵巢（OVX）骨质疏松大鼠和HepG2细胞中对雌激素有反应。雌激素受体α（ERα）与c-Jun/c-Fos异二聚体相互作用，并间接与AHSG启动子的-1488 / -1482激活蛋白-1（AP-1）基序相关联。雌激素通过丝裂原活化蛋白激酶（MAPK）途径增加c-Jun/c-Fos的表达。
AHSG是一种肝脏分泌蛋白，参与骨稳态的调节。据报道，女性绝经后血清AHSG水平下降，雌激素治疗后升高。雌激素对AHSG的详细调节机制尚不清楚。
在OVX大鼠中建立绝经后骨质疏松模型。通过自动生化分析和双能X线吸收法测定骨骼参数。通过ELISA、实时PCR和蛋白质印迹法评估AHSG的表达。通过连续截短和荧光素酶测定分析AHSG的1.5kb 5'-启动子区域。通过电泳迁移率变动分析（EMSA）鉴定推定的-1488 / -1482 AP-1反应元件。采用染色质免疫沉淀（ChIP）、再免疫沉淀（re-ChIP）和共免疫沉淀（Co-IP）来表征ERα和AP-1在-1488 / -1482 AP-1结合位点的相互作用。使用特异性抑制剂和活性转染评估MAPK途径。
AHSG的表达在OVX大鼠和雌二醇（E2）/ ERα处理的HepG2细胞中对雌激素均有反应。E2 / ERα最显著地增加了具有推定的-1488 / -1482 AP-1结合元件的构建体的荧光素酶活性。ERα与c-Jun/c-Fos异二聚体相互作用，并间接与AHSG启动子的-1488 / -1482 AP-1基序相关联。E2 / ERα通过MAPK途径增加c-Jun/c-Fos的表达。
雌激素通过ERα与-1488 / -1482 AP-1结合元件的间接结合以及c-Jun/c-Fos异二聚体激活AHSG的转录。
