... in the postnatal testis regulate their cellular fates by differential responsiveness to the differentiation signal provided by retinoic acid. Spermatogonia Retinoic acid Testis Spermatogenesis CYP26 Prospermatogonia Morphogens induce cellular differentiation based on their concentrations across...

...Ariel B. Rydeen; Joshua S. Waxman Normal heart development requires appropriate levels of retinoic acid (RA) signaling. RA levels in embryos are dampened by Cyp26 enzymes, which metabolize RA into easily degraded derivatives. Loss of Cyp26 function in humans is associated with numerous...

... controlled by regulated synthesis through the action of specific retinol and retinaldehyde dehydrogenases and by degradation via specific cytochrome P450s (CYP26s). Recent studies indicate that RA action involves an interplay between diffusion (morphogen-like) gradients and the establishment of signalling...

... responsiveness can be shaped by mechanisms other than the simple diffusion of RA from a localized posterior source. Here, we show that the cytochrome p450 enzymes of the Cyp26 class, which metabolize RA into polar derivatives,function redundantly to shape RA-dependent gene-expression domains during hindbrain...

... and Cyp26 generate shifting boundaries of RA activity, such that r3-r4 receives a short pulse of RA and r5-r8 receives a long pulse of RA. These two pulses of RA activity function to establish expression of Hoxb1 and vHnf1 on opposite sides of the r4/r5 boundary. * Author for correspondence (e...

..., retinoic acid (RA), Fgf and Wnt signals in the promotion of posterior fates in the ectoderm. We analyze expression and function of cyp26/P450RAI , a gene that encodes retinoic acid 4-hydroxylase, as a tool for investigating these events. Cyp26 is first expressed in the presumptive anterior neural ectoderm...