Retinoic acid

Retinoic acid is a metabolite of vitamin A that plays important roles in cell growth, differentiation, and organogenesis. Retinoic acid is a natural agonist of RAR nuclear receptors, with IC₅₀s of 14 nM for RARα/β/γ. Retinoic acid bind to PPARβ/δ with K_d of 17 nM. Retinoic acid acts as an inhibitor of transcription factor Nrf2 through activation of retinoic acid receptor alpha. IC50 & Target:IC50: 14 nM (RARα/β/γ)^[5]
Kd: 17 nM (PPARβ/δ), 103 nM (PPARα), 178 nM (PPARγ)^[2] In Vitro: Retinoic acid (All-trans-retinoic acid, ATRA) is a highly potent derivative of vitamin A that is required for virtually all essential physiological processes and functions because of its involvement in transcriptional regulation of over 530 different genes. Retinoic acid exerts its actions by serving as an activating ligand of nuclear retinoic acid receptors (RARα-γ), which form heterodimers with retinoid X receptors (RXRα-γ)^[1].
Retinoic acid (RA) bound to PPARα and PPARγ with a low affinity demonstrated by K_d values of 100-200 nM. In contrast, Retinoic acid associates with PPARβ/δ with a K_d of 17 nM, revealing both high affinity and isotype selectivity^[2].
Undifferentiated P19 cells express the Retinoic acid (RA) receptors RARα, RARβ, RARγ, and PPARβ/δ, as well as the Retinoic acid -binding proteins CRABP-II and FABP5. Induction of differentiation by treatment of cells with Retinoic acid results in transient up-regulation of CRABP-II and down-regulation of FABP5 that are observed at the level of both the respective proteins and mRNAs. Following the initial decrease, the level of both FABP5 protein and mRNA increases to attain a 2-2.5-fold higher level in mature neurons as compared with undifferentiated P19 cells. Induction of differentiation does not markedly affect the levels of either RARα or PPARβ/δ. The level of RARγ mRNA decreases by about 5-fold by day 4 and remained low in mature neurons^[3].
Retinoic acid (RA) is a morphogen derived from retinol (vitamin A) that plays important roles in cell growth, differentiation, and organogenesis. The Retinoic acid interacts with retinoic acid receptor (RAR) and retinoic acid X receptor (RXR) which then regulate the target gene expression^[4].