Figure 7
From: Maternal High Estradiol Exposure is Associated with Elevated Thyroxine and Pax8 in Mouse Offspring
MTT assay and gene expression in nthy ori 3–1 cells.
(a) MTT assay. Estradiol at 10−9 to 10−5 M dose-dependently increased cell proliferation (n = 6). Mean ± SE, *P < 0.05 or **P < 0.01 vs. control, student’s t test. (b,c) Gene expression assessed by real-time quantitative PCR in nthy ori 3–1 cells. E2 at 10−7 significantly increased PAX8 mRNA levels (b) while down-regulated DNMT3a (c) in nthy ori 3–1 cells, however, its effect was blocked by pretreatment of estrogen receptor inhibitor ICI182780 (n = 4). Mean ± SE, *P < 0.05 or **P < 0.01 vs. control, #P < 0.05 or ##P < 0.01 vs. E2 (10−7), student’s t test. (d) Immunofluorescence of DNMT3a and PAX8 in nthy ori 3–1 cells. The confocal images showed that DNMT3a and PAX8 were mainly located in the nucleus. When cells were treated with 10−7 M E2, DNMT3a was down-regulated and PAX8 was up-regulated, which were blocked by pretreatment of cells with ICI182780. White scale bar, 50 μm, mean ± SE, **P < 0.01 vs. control, #P < 0.05 vs. E2 (10−7), student’s t test. (e) Schematic view of the possible mechanism involved in the altered thyroid hormone profile of mouse offspring after maternal exposure to high E2 environment. When exposed to high E2 levels during early pregnancy, Pax8/Tpo was up-regulated while Dnmt3a/Mbd1 was down-regulated. The abnormal expression of Dnmt3a and Mbd1 might alter the methylation status of Pax8 CpG islands and increase the expression of Pax8, a transcription factor that binds and activates the promoter of thyroid specific genes such as Tpo, in offspring, so the synthesis/secretion of thyroid hormones increase. Finally, pups displayed altered thyroid hormones companied with abnormal gene expression and changed methylation status.
