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Transcription Activation by Nuclear Receptors
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Transcription Activation by Nuclear Receptors
• Retinoid X receptor (RXR) and Retinoic Acid receptor (RAR) are nuclear
receptors that bind either all trans-retinoic (tRA) or 9-cis-retinoic acid (9cis-RA). In the absence of ligand, corepressors, such as Nuclear
Receptor Corepressor (NCoR), Silencing Mediator of Retinoid and
Thyroid Hormone Receptor (SMRT), and Histone Deacetylase-1 (HDAC1) associate with the RAR:RXR heterodimer complex and repress
transcription. The histone deacetylase activity of the complex helps
maintain tight association between the deacetylated histones and
chromatin that results in this repression.
sigma-aldrich.com/cellsignaling
Transcription Activation by Nuclear Receptors
sigma-aldrich.com/cellsignaling
Transcription Activation by Nuclear Receptors
• When tRA or 9-cis-RA binds to the RAR:RXR complex, a conformational
change in the receptors causes the dissociation of the corepressors and
subsequent recruitment and binding of coactivators such as Steroid
Receptor Coactivator-1 (SRC-1), Glucocorticoid Receptor Interacting
Protein-1 (GRIP-1), CREB Binding Protein (CBP) and CBP-Associated
Factor (PCAF). This receptor:coactivator complex activates histone
acetyltransferase (HAT). Acetylated histones dissociate from the
chromatin and allow for the basal transcription machinery complex to
bind to DNA and activate transcription of target genes.
sigma-aldrich.com/cellsignaling