Endoglin Regulates Pluripotency and Differentiation in Human Embryonic Stem Cells Through Wnt and TGF-β Signaling...

Although endoglin (ENG) is traditionally recognized as a coreceptor in TGF-β signaling, its role in human pluripotent stem cells (hPSCs) remains unexplored. Here, we report that ENG knockout (ENG^-/-) hPSCs maintain core pluripotency markers yet undergo spontaneous differentiation and exhibit markedly reduced potential to form mesoderm, ectoderm, and endoderm lineages. Contrary to expectations, pharmacological inhibition of TGF-β signaling failed to replicate or rescue this phenotype, implicating pathways beyond TGF-β in governing the ENG^-/- phenotype. Instead, we observed aberrant WNT activation in ENG^-/- cells, which correlated with the emergence of peripherally localized differentiated cells and compromised multilineage commitment. Notably, blocking WNT secretion with IWP2 suppressed spontaneous peripheral differentiated cell formation and partially restored ectodermal and endodermal differentiation. These findings establish a novel regulatory role for ENG in balancing WNT signaling, to preserve hPSCs' developmental potential, thereby illuminating an unrecognized mechanism of stem cell fate control and revealing ENG as a critical mediator of hPSCs' self-renewal and lineage fidelity.