The Rho effector ARHGAP18 coordinates a Hippo pathway feedback loop through YAP and Merlin to regulate the cytoskeleton and epithelial cell polarity.

Two major actin regulatory pathways are signal transduction through Rho family GTPases and growth and proliferation signaling through the Hippo pathway. . These two pathways define the actin cytoskeleton, controlling foundational cellular attributes such as morphology and polarity and are hijacked to promote proliferation and motility in aggressive cancers.

In this study, we use human epithelial cells to investigate the interplay between the Hippo and Rho Family signaling pathways, which have predominantly been characterized as independent actin regulatory mechanisms. We identify that the RhoA effector, ARHGAP18, forms a complex with the Hippo pathway transcription factor YAP to address a long-standing enigma in the field. Using super resolution STORM microscopy, we characterize the changes in the actin cytoskeleton, on the single filament level, that arise from CRISPR/CAS9 knockout of ARHGAP18.