TRANSCRIPTION FROM THE THYROID HORMONE-DEPENDENT PROMOTER OF THE XENOPUS-LAEVIS THYROID-HORMONE RECEPTOR BETA-A GENE REQUIRES A NOVEL UPSTREAM ELEMENT AND THE INITIATOR, BUT NOT A TATA BOX
Jm. Wong et al., TRANSCRIPTION FROM THE THYROID HORMONE-DEPENDENT PROMOTER OF THE XENOPUS-LAEVIS THYROID-HORMONE RECEPTOR BETA-A GENE REQUIRES A NOVEL UPSTREAM ELEMENT AND THE INITIATOR, BUT NOT A TATA BOX, The Journal of biological chemistry, 273(23), 1998, pp. 14186-14193
The thyroid hormone receptor (TR) beta genes in Xenopus laevis are reg
ulated by thyroid hormone in all organs of an animal during metamorpho
sis. This autoregulation appears to be critical for systematic transfo
rmations of different organs as a tadpole is transformed into a frog.
To understand this autoregulation, we have previously identified a thy
roid hormone response element in the hormone-dependent promoter of the
X. laevis TR beta A gene. We report here the detailed characterizatio
n of the promoter. We have now mapped the transcription start site and
demonstrated the existence of an initiator element at the start site
critical for promoter function. More important, our deletion and mutat
ional experiments revealed a novel upstream DNA element that is locate
d 125 base pairs upstream of the start site and that is essential for
active transcription from the promoter Promoter reconstitution experim
ents showed that this novel element does not function as an enhancer,
but acts as a core promoter element, which, together with the initiato
r, directs accurate transcription from the promoter. Finally, we provi
de evidence for the existence of a protein(s) that specifically recogn
izes this element, Our studies thus demonstrate that the TR beta A pro
moter has a unique organization consisting of an initiator and a novel
upstream promoter element. Such an organization may be important for
the ubiquitous but tissue-dependent temporal regulation of the gene by
thyroid hormone during amphibian metamorphosis.