PP2A:B56ε is required for eye induction and eye field separation

Eye induction and eye field separation are the earliest events during vertebrate eye development. Both of these processes occur much earlier than the formation of optic vesicles. The insulin-like growth factor (IGF) pathway appears to be essential for eye induction, yet it remains unclear how IGF downstream pathways are involved in eye induction. As a consequence of eye induction, a single eye anlage is specified in the anterior neural plate. Subsequently, this single eye anlage is divided into two symmetric eye fields in response to Sonic Hedgehog (Shh) secreted from the prechordal mesoderm. Here, we report that B56ε regulatory subunit of protein phosphatase 2A (PP2A) is involved in Xenopus eye induction and subsequent eye field separation. We provide evidence that B56ε is required for the IGF/PI3K/Akt pathway and that interfering with the PI3K/Akt pathway inhibits eye induction. In addition, we show that B56ε regulates the Hedgehog (Hh) pathway during eye field separation. Thus, B56ε is involved in multiple signaling pathways and plays critical roles during early development.