Zhu Y S, Pfaff D W
Laboratory of Neurobiology and Behavior, Rockefeller University, New York, NY 10021, USA.
Brain Res Mol Brain Res. 1998 Mar 30;55(1):115-25. doi: 10.1016/s0169-328x(97)00369-0.
Ap-1 proteins such as Fos and Jun are nuclear transcription factors that have been postulated to function as third messengers in signal transduction pathways to regulate target gene expression. Using electrophoretic mobility shift assays (EMSA), we have studied estrogen (E) effects on regulation of AP-1 DNA binding activity in the rat hypothalamus and pituitary. AP-1 binding is defined herein as the specific association with a consensus AP-1 site during EMSA. Specific AP-1 binding activity was observed in nuclear extracts from the hypothalamus and pituitary of ovariectomized (OVX) female and castrated (CAS) male rats. Treatment with E increased the levels of AP-1 binding activity in the pituitary and uterus, whereas E decreased the levels of AP-1 binding in the hypothalamus, of OVX females. These effects were observed within 60 min and maintained for at least 72 h after a single dose of estrogen. Estrogen-induced changes in AP-1 binding were much more prominent in OVX females than in CAS males. Treatment with progesterone in OVX females had no significant effects on AP-1 binding activity in either pituitary or hypothalamus. Analysis of AP-1 binding activity in both hypothalamus and pituitary by supershift, immunodepletion and shift-Western blot indicated that part of the AP-1 binding was due to the presence of Fos and Jun proteins. However, Western blot analysis shows that the levels of Fos and Jun proteins in the hypothalamic nuclear extracts were not altered by E treatment. We conclude that E produced tissue and sex-differentiated alterations in AP-1 DNA binding activity in the hypothalamus and pituitary of female rats, which may be related to differential estrogenic actions on gene regulation.
诸如Fos和Jun之类的Ap-1蛋白是核转录因子，据推测它们在信号转导途径中作为第三信使发挥作用，以调节靶基因的表达。我们使用电泳迁移率变动分析（EMSA）研究了雌激素（E）对大鼠下丘脑和垂体中AP-1 DNA结合活性调节的影响。本文中AP-1结合定义为在EMSA期间与共有AP-1位点的特异性结合。在去卵巢（OVX）雌性大鼠和去势（CAS）雄性大鼠的下丘脑和垂体的核提取物中观察到特异性AP-1结合活性。用E处理可增加垂体和子宫中AP-1结合活性的水平，而E可降低OVX雌性大鼠下丘脑的AP-1结合水平。在单次给予雌激素后60分钟内观察到这些效应，并至少维持72小时。雌激素诱导的AP-1结合变化在OVX雌性大鼠中比在CAS雄性大鼠中更为明显。在OVX雌性大鼠中用孕酮处理对垂体或下丘脑的AP-1结合活性没有显著影响。通过超迁移、免疫去除和迁移-蛋白质印迹法分析下丘脑和垂体中的AP-1结合活性表明，部分AP-1结合是由于Fos和Jun蛋白的存在。然而，蛋白质印迹分析表明，下丘脑核提取物中Fos和Jun蛋白的水平不受E处理的影响。我们得出结论，E在雌性大鼠的下丘脑和垂体中产生了AP-1 DNA结合活性的组织和性别差异变化，这可能与雌激素对基因调节的不同作用有关。
