Gene Activation by Thyroid Hormone Receptor In Vitro and Purification of the TRAP Coactivator Complex
Thyroid hormone receptors (TRs) are capable of both activating and repressing transcription from genes bearing TR-binding elements (TREs). In general, TRs function as activators in the presence of thyroid hormone (T3) and repressors in the absence of T3 (1). The ability of TRs to regulate transcription has been linked to their ability to recruit distinct types of transcriptional coregulatory factors, termed coactivators and corepressors, to target gene promoters (2,3). Remarkably, yeast 2-hybrid and conventional expression library screens have identified numerous TR-binding coregulatory factors (reviewed in refs. 2 and 3). The best characterized TR coactivators include members the p160/SRC family (2-4). While the precise mechanism of action of the p160/ SRC proteins is still being defined, their ability to associate with histone acetyltransferases (HATs) such as the CREB-binding protein (CBP) and p300, and the presence of intrinsic HAT activity in some family members indicates a functional role in chromatin modification (2-4).
KeywordsCellulose Glycerol Urea EDTA Fractionation
- 2.Glass, C. K. and Rosenfeld, M. G. (2000) The coregulator exchange in transcriptional functions of nuclear receptors. Genes & Dev. 14, 121–141.Google Scholar
- 6.Fondell, J. D., Guermah, M., Malik, S., and Roeder, R. G. (1999) Thyroid hormone receptor-associated proteins and general positive cofactors mediate thyroid hormone receptor function in the absence of the TATA box-binding protein-associated factors of TFIID. Proc. Natl. Acad. Sci. USA 96, 1959–1964.PubMedCrossRefGoogle Scholar
- 12.Chiang, C.-M. and Roeder, R. G. (1993) Expression and purification of general transcription factors by FLAG-tagging and peptide elution. Peptide Res. 6, 62–64.Google Scholar
- 15.Sawadogo, M. and Roeder, R. G. (1985) Factors involved in specific transcription by human RNA polymerase II: analysis by a rapid and quantitative in vitro assay. Proc. Natl. Acad. Sci. USA 85, 6460–6464.Google Scholar
- 20.Zhang, J. and Fondell, J. D. (1999) Identification of mouse TRAP100: a transcriptional coregulatory factor for thyroid hormone and vitamin D receptors. Mol. Endocrinol. 13, 947–955.Google Scholar