Actin stress in cell reprogramming

Mechanical signaling plays many roles in cell physiology, including stem cell differentiation and reprogramming. To better understand the roles of mechanical forces in stem cells, we created genetically coded probes for actin that enables the direct measurement of forces in actin in living cells. This is the first force probe created for oligomeric proteins. We reprogrammed HEK-293 and Madin-Darby canine kidney cells into stem-like cells by culturing them on a soft substrate without using transcription factors. The mechanical properties of the microenvironment, and thus the local forces, promote cell reprogramming. Surprisingly, the cells showed close association of stemness to high tension in actin. Given the universal presence of actin in animal cells, the actin force probes have broad applications in biology.