Inhibition of FAK Signaling by Integrin a6B1 Supports Human Pluripotent Stem Cell Self‐Renewal

A newly identified pathway in hPSCs contributes to a better understanding of how laminin-521 maintains pluripotency and self‐renewal. In hPSCs, α6β1 is the dominant integrin of which laminin-521 is a strong inducer. Here the authors describe a signaling pathway in hPSCs linking self‐renewal and expression of pluripotency transcription factors to integrin α6β1 and inactivation of focal adhesion kinase (FAK). Disruption of this pathway results in hPSC differentiation. During differentiation, integrin α6 levels diminish and FAK is phosphorylated and activated. Integrin α6 functions in the inactivation of integrin B1 and FAK signaling and prevention of hPSC differentiation. hPSCs remodel the extracellular microenvironment and deposit laminin α5, the primary ligand of integrin α6β1. The knockdown of laminin α5 resulted in a reduction of integrin α6 expression, phosphorylation of FAK and decreased Oct4. In conclusion, hPSCs promote the expression of integrin α6β1, and nuclear localization and inactivation of FAK to supports stem cell self‐renewal.