E2F4 Is Required for Early Eye Patterning

Increasingly, studies reveal novel functions for cell cycle proteins during development. Here, we investigated the role of E2F4 in eye development. E2F4-deficient mouse embryos exhibit severe early eye patterning defects, which are evident from embryonic day 11.5 and characterized by aberrant shape of the optic cup, coloboma as well as abnormal eye pigmentation. Loss of E2F4 is associated with proximal-distal patterning defects in the optic vesicle. These defects are characterized by the expansion of optic stalk marker gene expression to the optic cup and reduced expression of ventral optic cup markers. These defects are associated with a split of <i>Shh</i> expression domain at the ventral midline of the forebrain and expansion of the Shh activity into the ventral optic cup. Despite these patterning defects, early neuronal differentiation and <i>Shh</i> expression in the retina are not affected by E2F4 deletion. Overall, the results of our studies show a novel role of E2F4 in the early eye development.