Retinoic Acid Receptors (RARs) are a group of nuclear receptors that play a crucial role in mediating the biological effects of retinoic acid (RA), a form of vitamin A. Nuclear receptors are transcription factors that regulate gene expression by binding to specific DNA sequences called hormone response elements.
RARs are a subfamily of the larger superfamily of nuclear receptors, which includes receptors for thyroid hormones, steroid hormones, and others. They are encoded by three genes in mammals: RARA (RAR alpha), RARB (RAR beta), and RARG (RAR gamma). These receptors are widely expressed in various tissues and cell types throughout the body.
When retinoic acid binds to RARs, the receptor undergoes a conformational change, leading to the recruitment of various co-regulator proteins and subsequent binding to specific DNA sequences in target genes. This binding can either activate or repress the transcription of these genes, depending on the context.
RARs are involved in a wide range of biological processes, including embryonic development, cell differentiation, and immune response. They have been extensively studied in the context of development and are known to play a crucial role in limb formation, organogenesis, and the development of the central nervous system.
Overall, retinoic acid receptors are essential regulators of gene expression, mediating the pleiotropic effects of retinoic acid on development, differentiation, and homeostasis in various tissues and organisms.
