P. Mccaffery et al., Dorsal and ventral retinal territories defined by retinoic acid synthesis,break-down and nuclear receptor expression, MECH DEVEL, 82(1-2), 1999, pp. 119-130
Determination of the dorso-ventral dimension of the vertebrate retina is kn
own to involve retinoic acid (RA), in that high RA activates expression of
a ventral retinaldehyde dehydrogenase and low RA of a dorsal dehydrogenase.
Here we show that in the early eye vesicle of the mouse embryo, expression
of the dorsal dehydrogenase is preceded by, and transiently overlaps with,
the RA-degrading oxidase CYP26. subsequently in the embryonic retina, CYP2
6 forms a narrow horizontal boundary between the dorsal and ventral dehydro
genases, creating a trough between very high ventral and moderately high do
rsal RA levels. Most of the RA receptors are expressed uniformly throughout
the retina except for the RA sensitive RAR beta, which is down-regulated i
n the CYP26 stripe. The orphan receptor COUP-TFII, which modulates RA respo
nses, colocalizes with the dorsal dehydrogenase. The organization of the em
bryonic vertebrate retina into dorsal and ventral territories divided by a
horizontal boundary has parallels to the division of the Drosophila eye dis
c into dorsal, equatorial and ventral zones, indicating that the similariti
es in eye morphogenesis extend beyond single molecules to topographical pat
terns. (C) 1999 Elsevier Science ireland Ltd. All rights reserved.