PP2A: B56E is required for Wnt/β-catenin signaling during embryonic development

The Wnt/β-catenin pathway plays important roles during embryonic development and growth control. The B56 regulatory subunit of protein phosphatase 2A (PP2A) has been implicated as a regulator of this pathway. However, this has not been investigated by loss-of-function analyses. Here we report loss-of-function analysis of PP2A:B56E during early Xenopus embryogenesis. We provide direct evidence that PP2A:B56E is required for Wnt/β-catenin signaling upstream of Dishevelled and downstream of the Wnt ligand. We show that maternal PP2A:B56E function is required for dorsal development, and PP2A:B56E function is required later for the expression of the Wnt target gene engrailed, for subsequent midbrain-hindbrain boundary formation, and for closure of the neural tube. These data demonstrate a positive role for PP2A:B56E in the Wnt pathway.