Retinoic Acid Receptors

Retinoids, a class of hydrophobic compounds including retinol (vitamin A), retinoic acid (RA) and a series of natural and synthetic derivatives, exhibit a vast array of profound and diverse effects on vertebrate development from early embryogenesis to maturity. Several families of serum, cytoplasmic and nuclear proteins are involved in the metabolism and biological actions of retinoids. Some of these proteins mediate direct effects of retinoids on gene expression while others are involved in their transport, storage and metabolism. The effects of retinoids on transcription are mediated by a number of nuclear binding proteins of two types: retinoic acid receptors (RARs) and retinoid X receptors (RXRs). RXR serves as an auxiliary factor required by RAR and other nuclear receptors for target gene regulation. These ligand-inducible transcription factors belong to the nuclear receptor superfamily, which also includes receptors for thyroid hormone, vitamin D 3 and steroid hormones. Detailed studies of RAR and RXR function have revealed the existence of a vast elaborate web of gene regulation. This chapter will aim to analyse the diverse and complex pathways of retinoic acid responses. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.