3D microenvironment alters cancer cell RhoA activity and is affected by emerin

During cancer metastasis, cancer cells migrate across the extracellular matrix (ECM) and into the bloodstream. These cells sense and integrate various physical microenvironments in the ECM, such as substrate shape and stiffness, thereby adopting specific migration mechanisms. RhoA, a small GTPase, plays a pivotal role in mechanotransduction. However, the relationship between the cytoskeleton and the nucleus during confined cell migration remains poorly understood, particularly the interaction between RhoA and the nucleus. In this study, we investigated the dynamics of RhoA in cell migration by preparing microchannels of different widths. We observed that confinement led to a regional distribution of RhoA within the cell, with the most intense activation at the rear of the nucleus. By manipulating nuclear stability, we discovered that the nuclear membrane protein emerin significantly stabilizes RhoA activation in these regions. Moreover, knocking down emerin enhanced the polarity of intracellular myosin II distribution during confined migration and altered nuclear stiffness. Through mechanistic analysis, we propose that emerin-induced changes in myosin and nuclear stiffness play a crucial role in the restricted cell migration. Our findings reveal that RhoA is regionally distributed during cell migration in restricted microchannels, showing enhanced activation with increasing degrees of confinement, and is importantly regulated by emerin.