Retinoic Acid Receptors (RARs) are a group of nuclear receptors that play a crucial role in various biological processes, including embryonic development, cell differentiation, and cell proliferation. RARs belong to the steroid hormone receptor superfamily and act as ligand-dependent transcription factors. The primary ligand for RARs is retinoic acid, a derivative of vitamin A.
RARs consist of three isoforms: RARα, RARβ, and RARγ, which share a high degree of structural similarity. These receptors are primarily located in the nucleus, where they bind to specific DNA sequences called retinoic acid response elements (RAREs) within target genes. Upon ligand binding, RARs form heterodimers with Retinoid X Receptors (RXRs) and recruit coactivator or corepressor proteins, influencing gene expression.
Due to their regulatory role, RARs are crucial during embryonic development, particularly in organogenesis, morphogenesis, and tissue differentiation. They are involved in determining the anterior-posterior axis of vertebrate embryos and regulate the expression of genes responsible for limb development, craniofacial formation, and neural patterning. RARs also play a vital role in maintaining epithelial cell differentiation and preventing the proliferation of undifferentiated cells.
The dysregulation of RARs has been associated with several diseases, including cancer. Aberrant RAR signaling can disrupt normal cell differentiation, leading to uncontrolled cell growth and tumor formation. Thus, RARs have become an important target for pharmacological intervention, with retinoids and synthetic derivatives being used as potential therapeutic agents for cancer treatment and other disorders involving RAR dysfunctions.
