Essner J J, Breuer J J, Essner R D, Fahrenkrug S C, Hackett P B
Department of Genetics and Cell Biology, University of Minnesota, St. Paul 55108-1095, USA.
Differentiation. 1997 Dec;62(3):107-17. doi: 10.1046/j.1432-0436.1997.6230107.x.
Nuclear receptors are a large family of ligand dependent transcription factors which participate in many diverse processes during development. In this report, we describe the cloning of the zebrafish thyroid hormone receptor alpha 1 (TR alpha 1) gene, the cellular counterpart of the viral oncogene v-erbA. TR alpha 1 is expressed during oogenesis and maternally supplied to the embryo. TR alpha 1 is expressed again after the mid blastula transition. By examining the effects of increased expression of TR alpha 1 on expression of a reporter gene which responds to both TR alpha 1 and retinoic acid receptors (RARs), we show that the zebrafish TR alpha 1 can act as a repressor during early zebrafish development before thyroid hormone is present in the embryo. In addition, our data suggest that TR alpha 1 can repress retinoic acid (RA)-signaling during early development. We propose that TR alpha 1 functions during early development as a transcriptional repressor, similar to the constitutive repressor activity of its viral counterpart v-erbA, which regulates anterior-posterior (A/P) patterning by repressing RA-signaling.
核受体是一大类依赖配体的转录因子家族，它们在发育过程中参与许多不同的过程。在本报告中，我们描述了斑马鱼甲状腺激素受体α1（TRα1）基因的克隆，它是病毒癌基因v-erbA在细胞中的对应物。TRα1在卵子发生过程中表达，并由母体提供给胚胎。在囊胚中期转变后，TRα1再次表达。通过检测TRα1表达增加对一个同时响应TRα1和视黄酸受体（RARs）的报告基因表达的影响，我们发现斑马鱼TRα1在胚胎中甲状腺激素出现之前的早期斑马鱼发育过程中可作为一种阻遏物。此外，我们的数据表明TRα1在早期发育过程中可抑制视黄酸（RA）信号传导。我们提出TRα1在早期发育过程中作为转录阻遏物发挥作用，类似于其病毒对应物v-erbA的组成型阻遏物活性，v-erbA通过抑制RA信号传导来调节前后（A/P）模式形成。
