Laminin 411 mediates endothelial specification via multiple signaling axes that converge on β-catenin.

The extracellular matrix (ECM) provides essential cues to promote endothelial specification during tissue development in vivo; correspondingly, ECM is considered essential for endothelial differentiation outside of the body. However, systematic studies to assess the precise contribution of individual ECM proteins to endothelial differentiation have not been conducted. Further, the multi-component nature of differentiation protocols makes it challenging to study the underlying mechanisms by which the ECM contributes to cell fate. In this study, we determined that Laminin 411 alone increases endothelial differentiation of induced pluripotent stem cells over collagen I or Matrigel. The effect of ECM was shown to be independent of vascular endothelial growth factor (VEGF) binding capacity. We also show that ECM-guided endothelial differentiation is dependent on activation of focal adhesion kinase (FAK), integrin-linked kinase (ILK), Notch, and β-catenin pathways. Our results indicate that ECM contributes to endothelial differentiation through multiple avenues, which converge at the expression of active β-catenin.
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