Hydrogel stiffness mediates the PI3K-AKT signaling of mouse bone marrow stromal cells through cellular traction force

Adhesive interface stiffness significantly influences physiological processes by altering cell behaviors and signaling pathways. In particular, phosphoinositide 3-kinase (PI3K)-AKT pathway, one of the most important pathways that cell division, survival, and differentiation, can be affected. However, the detailed mechanism of this interaction remains unclear. In this study, we used gelatin methacrylate (GelMA) hydrogels with varying stiffness to mimic cellular mechanical environments and examine their effects on PI3K-AKT signaling. Cells cultured on stiff hydrogels showed increased spreading, focal adhesion formation, and contractility compared to those on softer hydrogels. Furthermore, mechanotransduction activation on stiff hydrogels upregulated PIP3, PI3K, and phosphorylated AKT (pAKT) expression. Notably, inhibiting myosin II, a key regulator of contractility, reduced PI3K-AKT signaling, suggesting a link between force generation and pathway activation. These findings reveal that how PI3K-AKT signaling can be mediated by cell adhesion interface stiffness through cell contractility, which provides new insights for developing therapies targeting PI3K-AKT-associated diseases.