Inhibition of integrin ß1 activity support a naïve-like state in human induced  pluripotent stem cells
Cell states are governed by cell-intrinsic properties and external cues that regulate cell shape and signaling via cell-cell junctions or adhesions. Integrin ß1-mediated adhesion is dispensable in early mouse embryogenesis at pre-implantation but becomes indispensable post-implantation. This implies distinct roles for ß1-integrins in the naïve pre-implantation and primed post-implantation pluripotent stem cells (PSC). These, however, remain poorly understood. We investigated integrin ß1 control of naïve-like and primed human induced PSC (hiPSC) states. We find that integrin ß1 is active in naïve and primed hiPSCs and the degree of activity varies in vitro on different extracellular matrices (ECMs). Integrin ß1 inhibition in primed hiPSCs induces naïve-like colony features, reduces actomyosin contraction and ERK activity and alters gene expression, indicative of more naïve-like features. Reverting the primed state of pluripotency to naïve involves dramatic reorganization of colony morphology, actin and adhesions. Importantly, functional and single-cell transcriptomics analyses demonstrate that integrin ß1 inhibition attenuates colony morphology transitions in cells exiting naïve pluripotency. These data reveal unprecedented integrin-dependent regulation of PSC states and demonstrate how integrin inhibitors may help to fine-tune hiPSC function and properties in vitro. Overall design: Naïve hiPSCs (d0) were capacitated for 2 days (d2) with or without Mab13, and compared to primed hiPSCs (HEL24.3) with or without Mab13.