Eichenlaub-Ritter Ursula, Winterscheidt Ulrike, Vogt Edgar, Shen Ying, Tinneberg Hans-Rudolf, Sorensen Ralph
University of Bielefeld, Faculty of Biology, Institute of Gene Technology/Microbiology, D-33501 Bielefeld, Germany.
Biol Reprod. 2007 May;76(5):784-93. doi: 10.1095/biolreprod.106.055111. Epub 2007 Jan 17.
2-Methoxyestradiol (2-ME) is a metabolite of 17beta-estradiol and a natural component of follicular fluid. Local concentrations of 2-ME may be increased by exposure to environmental pollutants that activate the expression of enzymes in the metabolic pathway from 17beta-estradiol to 2-ME. It has been suspected that this may have adverse effects on spindle formation in maturing oocytes, which would affect embryo quality. To study the dose-response patterns, we exposed denuded mouse oocytes to 2-ME during in vitro maturation. Meiotic progression, spindle morphology, centrosome integrity, and chromosome congression were examined by immunofluorescence and noninvasive polarizing microscopy (PolScope). Chromosomal constituents were assessed after spreading and C-banding. 2-ME sustained MAD2L1 expression at the centromeres and increased the number of meiosis I-blocked oocytes in a dose-dependent manner. 2-ME also caused dramatic dose-dependent increases in the hyperploidy of metaphase II oocytes. Some of these meiosis II oocytes contained anaphase I-like chromosomes, which suggests that high concentrations of the catecholestradiol interfere with the physical separation of chromosomes. Noninvasive PolScope analysis and tubulin immunofluorescence revealed that perturbations in spindle organization, which resulted in severe disturbances of the chromosome alignment at the spindle equator (congression failure), were caused by 2-ME at meiosis I and II. Pericentrin-positive centrosomes failed to align at the spindle poles, and multipolar spindles and prominent arrays of cytoplasmic microtubule asters were induced in 2-ME-exposed metaphase II oocytes. In conclusion, a micromolar level of 2-ME is aneugenic for mammalian oocytes. Therefore, exposure to 2-ME and conditions that increase the intrinsic local concentration of 2-ME in the ovary may affect fertility and increase risks for chromosomal aberrations in the oocyte and embryo.
2-甲氧基雌二醇（2-ME）是17β-雌二醇的代谢产物，也是卵泡液的天然成分。接触能激活从17β-雌二醇到2-ME代谢途径中酶表达的环境污染物，可能会使局部2-ME浓度升高。人们怀疑这可能会对成熟卵母细胞的纺锤体形成产生不利影响，进而影响胚胎质量。为了研究剂量反应模式，我们在体外成熟过程中将去除卵丘细胞的小鼠卵母细胞暴露于2-ME中。通过免疫荧光和非侵入性偏振显微镜（PolScope）检查减数分裂进程、纺锤体形态、中心体完整性和染色体排列。在染色体铺展和C显带后评估染色体组成。2-ME使着丝粒处的MAD2L1表达持续存在，并以剂量依赖的方式增加减数分裂I期阻滞的卵母细胞数量。2-ME还导致中期II期卵母细胞超倍体率呈显著的剂量依赖性增加。这些减数分裂II期卵母细胞中的一些含有后期I样染色体，这表明高浓度的儿茶酚雌二醇会干扰染色体的物理分离。非侵入性PolScope分析和微管蛋白免疫荧光显示，2-ME在减数分裂I期和II期导致纺锤体组织紊乱，进而导致染色体在纺锤体赤道处的排列严重紊乱（排列失败）。在暴露于2-ME的中期II期卵母细胞中，围绕中心粒蛋白的中心体未能在纺锤体极排列，并且诱导产生了多极纺锤体和显著的细胞质微管星状体阵列。总之，微摩尔水平的2-ME对哺乳动物卵母细胞具有致染色体非整倍性作用。因此，接触2-ME以及卵巢中增加2-ME内在局部浓度的情况可能会影响生育能力，并增加卵母细胞和胚胎中染色体畸变的风险。
