The Xenoestrogen Bisphenol A Inhibits Postembryonic Vertebrate Development by Antagonizing Gene Regulation by Thyroid Hormone

The xenoestrogen bisphenol A inhibits postembryonic vertebrate development by antagonizing gene regulation by thyroid hormone.

Bisphenol A (BPA), a chemical widely used to manufacture plastics, is estrogenic and capable of disrupting sex differentiation. However, recent in vitro studies have shown that BPA can also antagonize T(3) activation of the T(3) receptor. The difficulty in studying uterus-enclosed mammalian embryos has hampered the analysis on the direct effects of BPA during vertebrate development. This study ...

Regulation of gene expression by thyroid hormone.

The thyroid hormones (3,5,3',5'-tetraiodo-L-thyronine [L-T4]' and 3,5,3'triiodo-L-thyronine [L-T3]) have marked effects on the growth, development, and metabolic function of virtually all organ systems and tissues ofhuman beings and other higher organisms (1-3). L-T4 was one of the first hormones to be isolated and its structure determined (4-6). Several decades later L-T3 was identified in the...

Negative Regulation of the Thyrotropin Gene by Thyroid Hormone

Thyroid hormone (T3 and T4) is secreted from the thyroid gland, and is known to reduce the level of serum thyrotropin (thyroid-stimulating hormone, TSH) in the pituitary gland (Sarapura et al., 2002; Shupnik et al., 1989) (Fig. 1A). This is a typical example of negative feedback between the pituitary and endocrine organs, and is a key component of thyroid hormone homeostasis. TSH is one of the ...

Regulation of Gene Transcription by the Thyroid Hormone Receptors

Regulation of thyroid hormone-induced development in vivo by thyroid hormone transporters and cytosolic binding proteins.

Differential tissue sensitivity/responsivity to hormones can explain developmental asynchrony among hormone-dependent events despite equivalent exposure of each tissue to circulating hormone levels. A dramatic vertebrate example is during frog metamorphosis, where transformation of the hind limb, brain, intestine, liver, and tail are completely dependent on thyroid hormone (TH) but occurs async...