Membrane Protrusion Formation Mediated by Rho/ROCK Signalling and Modulation of Chloride Flux
Membrane protrusion is an important structural property associated with various cellular functions. The pentaspan membrane protein Prominin-1 (Prom1/CD133) is known to be localised to the protrusions and plays a pivotal role in migration and the determination of cellular morphology; however, the underlying mechanisms have been elusive. Here, we demonstrate that Prom1 is sufficient to trigger membrane protrusion formation. Overexpression of Prom1 in the RPE-1 cells triggers multiple long cholesterol-enriched protrusions, independently from actin and tubulin polymerisation. For this protrusion formation, the five amino acid stretch located at the carboxyl cytosolic region is essential. Moreover, the small GTPase Rho and its effector kinase ROCK are essential for this protrusion formation, and the intersection point of active Rho and Prom1 is where the protrusion formation initiates. Importantly, Prom1 causes the chloride ion efflux induced by calcium ion uptake, and protrusion formation is closely associated with the chloride efflux activity. Altogether, this study has elucidated that Prom1 plays critical roles for the membrane morphology and chloride ion flux.