University of California Irvine (UCI) researchers discovered how embryonic cells may regulate levels of retinoic acid, a derivative of vitamin A that is used to treat certain types of leukemia and acne.
The investigators used zebrafish embryos genetically engineered to be unable to make enough retinoic acid and become fluorescent in response to retinoic acid when illuminated with an ultraviolet light. The UCI scientists implanted tiny retinoic acid-soaked beads, which gradually released retinoic acid into the embryos, and then tracked how the retinoic acid moved within the embryos.
The scientists found that if the level becomes too high, an enzyme called Cyp26a1 degrades the excess, bringing the concentration back to normal. When levels drop too low, proteins called fibroblast growth factors (Fgfs) stop the retinoic acid from degrading as rapidly.
“Those two things work together to keep the whole system adjusted to the right level,” says Thomas Schilling, Ph.D., associate professor of developmental and cell biology. “Retinoic acid induces its own degradation, and Fgfs, also present in the embryo, have the opposite effect by inhibiting retinoic acid degradation.”
The study is published this week in PLoS Biology.