Isotretinoin is converted to active retinoic acid and binds to what receptors?

• A. RXRs
• B. GPCRs
• C. RARs
• D. PPARs

Answer: (C)

Active retinoic acid acts in the nucleus as a ligand for retinoic acid receptors, which are transcription factors that control gene expression by binding to DNA at retinoic acid response elements. Isotretinoin is converted to all-trans retinoic acid, and this molecule binds to RARs, causing a conformational change that recruits coactivators and alters transcription of genes involved in cell differentiation and keratinization. While RXRs often form heterodimers with RARs to regulate transcription, the ligand-binding event for the active metabolite occurs on the RAR component, not the RXR. GPCRs and PPARs are not the primary receptors for this retinoic acid metabolite. So the receptors engaged by isotretinoin-derived retinoic acid are the retinoic acid receptors.