Dorsal-ventral patterning defects in the eye of BF-1-deficient mice associated with a restricted loss of shh expression

Brain factor 1 (BF-1) is a winged-helix transcription factor with restricte d expression in the anterior optic vesicle and in the telencephalic neuroep ithelium of the neural tube. We have previously found that targeted disrupt ion of the BF-1 gene results in hypoplasia of the cerebral hemispheres, whi ch is more severe in structures derived from the ventral telencephalon. Her e we show that the loss of BF-1 leads to multiple developmental anomalies o f the eyes. The most ventral structure arising from the optic vesicle, the optic stalk, is missing and is replaced by an expanded retina. Ventral clos ure of the optic cup and choroid fissure does not occur. These dorsal-ventr al patterning defects are not limited to the BF-1-expressing (anterior) cel ls, but also involve the cells of the posterior optic vesicle. Sonic hedgeh og (shh) expression within the ventral telencephalic neuroepithelium is spe cifically lost in the BF-1(-/-) mutant. Taken together, these findings sugg est that shh produced at this site plays a role in patterning the developin g eye. This localized deficit in shh expression may also contribute to the prominence of the ventral defects in the telencephalon of the BF-1(-/-) mut ant. (C) 1999 Academic Press.