RACK1 promotes actin-mediated invasion, motility, and cell-to-cell spreading.

is an intracellular bacterium that hijacks the host actin cytoskeleton to invade and disseminate within the colonic epithelium. 's virulence factors induce actin polymerization, leading to bacterial uptake, actin tail formation, actin-mediated motility, and cell-to-cell spreading. Many host factors involved in the -prompted actin rearrangements remain elusive. Here, we studied the role of a host protein receptor for activated C kinase 1 (RACK1) in actin cytoskeleton dynamics and infection. We used time-lapse imaging to demonstrate that RACK1 facilitates -induced actin cytoskeleton remodeling at multiple levels during infection of epithelial cells. Silencing RACK1 expression impaired -induced rapid polymerizing structures, reducing host cell invasion, bacterial motility, and cell-to-cell spreading. In uninfected cells, RACK1 silencing reduced jasplakinolide-mediated filamentous actin aggregate formation and negatively affected actin turnover in fast polymerizing structures, such as membrane ruffles. Our findings provide a role of RACK1 in actin cytoskeleton dynamics and infection.