Erk signaling suppresses embryonic stem cell self-renewal to specify endoderm

Area of Science:

• Stem cell biology
• Developmental biology
• Cell signaling

Background:

• Fibroblast growth factor (FGF) signaling, mediated by Erk activation, is implicated in embryonic stem cell (ESC) self-renewal, neural induction, and differentiation into somatic lineages.
• The precise role of Erk signaling in ESC pluripotency maintenance and lineage specification requires further elucidation.

Purpose of the Study:

• To investigate the specific functions of Erk signaling in ESC self-renewal and differentiation towards different lineages.
• To differentiate the roles of Erk in neural versus endodermal differentiation pathways.

Main Methods:

• Utilized pharmacological inhibition of Erk signaling pathways.
• Employed genetic loss-of-function approaches to study Erk's role.
• Examined ESC differentiation in various in vitro settings.

Main Results:

• Erk signaling is crucial for endodermal differentiation but dispensable for neural differentiation.
• Neural differentiation proceeds normally even with complete inhibition of Erk phosphorylation.
• Erk activation in ESCs inhibits the pluripotent/epiblast network, leading to derepression of primitive endoderm (PrE) gene expression.
• Early Erk activation primes for PrE formation, while sustained activity drives PrE differentiation.

Conclusions:

• Erk signaling acts by suppressing pluripotent gene expression, thereby facilitating endodermal differentiation.
• The findings delineate a specific role for Erk in promoting endodermal fate over pluripotency and neural development.