Retinoic acid is derived from vitamin A found in foods like squash and carrots. It plays an essential role in the development of organs like the heart, lungs, kidneys, brain, spinal cord, limbs, and retina. Too little retinoic acid can cause birth defects like cleft palate. The pathway involves retinol entering a cell and being converted to retinoic acid, which then binds to receptors in the cell nucleus to regulate gene expression.

1. Retinoic Acid Signaling Pathway By: Taylor Johnson Developmental Biology

7. Embryonic Cell Nucleus Alcohol Dehydrogenase Retinaldehyde Dehydrogenase 2

8. Retinol enters the cell.

9. ADH converts the Retinol into Retinaldehyde. Retinol Retinaldehyde

10. RALDH2 converts RALD to Retinoic Acid. Retinoic Acid RALD

11. Retinoic Acid is membrane permeable Cell Membrane

12. CRABP CRABP “grabs” RA as it enters the cell. Embryonic Target Cell

13. CRABP takes RA into the nucleus. RARE DNA binding site Target Cell

14. R X R R A R RARE DNA binding site RA binds to the receptors in the nucleus. Target Cell

15. Non Responding Cell CYP26 In non-responding cells, CYP26 degrades RA. Degraded RA

17. Key

18. Cell Membrane Retinoic Acid Retinol Degraded Retinoic Acid Cytochrome P450

19. Alcohol Dehydrogenase Retinaldehyde Dehydrogenase 2 Retinoid X Receptor Retinoic Acid Receptor

20. Retinaldehyde Cellular Retinoic Acid Binding Protein Retinoic Acid Receptor Enzyme