First published online December 12, 2006
Development 134, 102e (2007)
© The Company of Biologists Limited
Degrading uniformity in hindbrain patterning
Retinoic acid (RA) plays an essential role in establishing
anterior-posterior patterning in the hindbrain, where a spatio-temporal
gradient of RA is believed to generate domains of RA-responsive gene
expression. Given this, it is puzzling that a uniform concentration of
exogenous RA can rescue RA-depleted embryos. Cecilia Moens and co-workers now
resolve this puzzle by showing that Cyp26 enzymes (which degrade RA) generate
the RA-response gene expression patterns required for zebrafish hindbrain
development (see p.
177). The researchers first documented dynamic spatio-temporal
expression domains for the three zebrafish cyp26 genes - cyp26a1, cyp26b1 and
cyp26c1 - in the developing hindbrain. They then showed that, in embryos
depleted of all three enzymes, the entire hindbrain expresses RA-responsive
genes that are normally restricted to the posterior hindbrain. Finally, they
report that cyp26 genes are responsible for the ability of exogenous RA to
rescue embryos depleted of endogenous RA. Given these results, the researchers
propose a `gradient-free' model for hindbrain patterning in which Cyp26
activity establishes sequential RA-responsiveness boundaries.
Related articles in Development:
- Cyp26 enzymes generate the retinoic acid response pattern necessary for hindbrain development
- Rafael E. Hernandez, Aaron P. Putzke, Jonathan P. Myers, Lilyana Margaretha, and Cecilia B. Moens
Development 2007 134: 177-187.
[Abstract]
[Full Text]
