【作者】 杨超毅；

【导师】 吴乔；

【作者基本信息】 厦门大学 ， 细胞生物学， 2006， 硕士

【摘要】 雌激素受体(estrogen receptor,ER)是核受体超家族(nucleus receptor,NR)成员之一。作为一种激素受体,ER能够被其配体雌激素中的主要成分雌二醇(steroid hormone 17?-estradiol,E2 )激活。ER广泛地分布在雌性或雄性生殖系统、乳腺、中枢神经系统的部分区域里。同时,ER还参与细胞增殖、分化、凋亡等各种重要的生理调控过程。ER可以分成ERα和ERβ两个亚型,它们都由4个不同的功能域组成,每个功能域都发挥不同的作用。这4个功能域分别是:转录激活区(A/B)、配体结合区(LBD)、铰链区(Hinge)和DNA结合区(DBD)。本文中,我们通过构建ERα的不同缺失突变体(ER△LBD、ER△DBD和ER△Hinge)来研究不同功能域在细胞增殖、亚细胞定位和E2刺激对ERα亚细胞定位的影响。结果表明,ERα呈核多浆少的分布、ER△LBD为核定位、ER△DBD为核多浆少分布、ER△Hinge主要分布在浆,核中有很少量。进一步分析表明,E2诱导的ERα入核是入核序列(NLS)依赖性。此外,我们还发现,ERα能够增强293Τ细胞增殖,且这种促增殖效应依赖于ERα在细胞核与胞浆的正常转运。视黄素X受体(retinoid X receptor, RXR)属于类固醇/甲状腺激素受体超家族成员,其配体视黄素(retinoids)是天然的或人工合成的维生素A衍生物。视黄素通过RXRs的介导在细胞生长、分化和凋亡过程中发挥重要的作用。RXRα能够与ERα结合形成异源二聚体,但RXRα在协助ERα转运过程中的作用未见报导。我们的研究表明,RXRα能够协助突变体ER△DBD和ER△Hinge出核,并且当E2处理细胞后,出核的ER△DBD又重新回到核中,而出核的ER△Hinge不受影响。结果提示,ERα不同功能域在与RXRα、E2作用时发挥不同的功能。总之,通过研究,我们确定了ERα不同功能域在其亚细胞定位、促细胞增殖中的作用,并且发现RXRα能够协助ER△DBD和ER△Hinge出核。这为我们进一步研究ERα和E2的作用机理以及更有效地防治乳腺癌提供了一些研究思路。更多还原

【Abstract】 Estrogen receptor (ER), known as a hormone receptor, is one of the members of nucleus receptor (NR). ER has been shown to be activated in response to its ligand: steroid hormone 17?-estradiol (E2). As a mediator of estrogen action, the ER is involved in many important physiological processes, such as in spermary, ovary and neurocyte. At the same time, ER also participates in cell proliferation, differentiation and apoptosis.There are two kinds of ER, ERαand ERβ, which have four different functional regions. They are transcriptional activity domain, ligand binding domain, hinge domain and DNA binding domain. In this study, we constructed three different ERαmutants (ER△LBD、ER△DBD and ER△Hinge) to study the influence of ERαin cell proliferation and ERαsubcellular localization in response to E2. The results showed that in the 293T cell ERαlocalized more in the nucleus than in the cytoplasm. The ER△LBD localized in the cytoplasm, the ER△DBD was the same as ERα, and the ER△Hinge almost localized in the cytoplasm. We also found that the nuclear import of ERα, induced by E2, was nuclear location signal-dependent (NLS-dependent). Moreover, we showed that ERαcould increase proliferation of 293T cells and such increase depended on the ERαcapability of shuttling between the nucleus and the cytoplasm.Retinoic X receptors (RXRs) belongs to the steroid hormone receptor superfamily. RXRs have three different subspecies, RXRα、RXRβand RXRγ, which ligands are natural or synthetic vitamin A derivatives. RXRs play an important role in regulating a broad range of biological processes, including cell proliferation, differentiation and apoptosis.RXRαmay form heterodimer with ERα. However, its function in assistance of ERαtranslocation is still largely unknown. In our study, we indicated that RXRαhad an ability to assist ER△DBD and ER△Hinge translocation from the nucleus to the cytoplasm, and after treatment of E2, the ER△DBD returned to the nucleus while the ER△Hinge still localized in the cytoplasm. These results demonstrate that the different domains of ERαmay exert different functions when it interacts with RXRαin response to E2 treatment.To sum up, we demonstrate effects of different functional region of ERαin its subcellular localization and cellular proliferation. Our data reveal that RXRαcan assist the ER△DBD and ER△Hinge export from the nucleus. These findings will be helpful for further research on the functional mechanisms of ERαand E2 and prevention of breast cancer.更多还原