FAM122A is required for mesendodermal and cardiac differentiation of embryonic stem cells [ChIP-seq]

Mesendodermal specification and cardiac differentiation are key issues for developmental biology and heart regeneration medicine. Previously, we demonstrated that FAM122A, a highly conserved house-keeping gene, is an endogenous inhibitor of protein phosphatase 2A (PP2A) and participates in multi facet physiological and pathological processes, however, the in vivo function of FAM122A is largely unknown. In this study, we found that Fam122 deletion results in embryonic lethality with severe defects of cardiovascular developments and significantly attenuates the cardiac functions in conditional cardiac-specific knockout mice. More importantly, Fam122a deficiency impairs mesendodermal specification and cardiac differentiation from mouse embryonic stem cells, but not influences the pluripotent identity. Mechanical investigation shows that the impaired differentiation potential is caused through the dysregulation of histone modification and Wnt and Hippo signaling pathways by modulating PP2A activity. These findings suggest that FAM122A is a novel and critical regulator in mesendodermal specification and cardiac differentiation. This not only significantly extends our understanding the regulatory network of mesendodermal/cardiac differentiation, but also establishes a previously uncharacterized connection between PP2A and mesendodermal specification. Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for the histone modifications H3K4me3, H3K27me3 and H3K27ac in Ctrl and Fam122a KO mESCs at different stage.