The concerted action of SEPT9 and EPLIN modulates the adhesion and migration of human fibroblasts

Abstract

Septins are cytoskeletal proteins that participate in cell adhesion, migration and polarity establishment. The septin subunit SEPT9 directly interacts with the single LIM domain of EPLIN, an actin bundling protein. Using a human SEPT9 KO fibroblast cell line we show that cell adhesion and migration are regulated by the interplay between both proteins. The low motility of SEPT9-depleted cells could be partly rescued by increased levels of EPLIN. The normal organization of actin-related filopodia and stress fibers was directly dependent on the expression level of SEPT9 and EPLIN. Increased levels of SEPT9 and EPLIN enhanced the size of focal adhesions in cell protrusions, correlating with a stabilization of actin bundles, whereas decreased levels have the opposite effect. Our work thus establishes the interaction between SEPT9 and Eplin as important link between the septin and the actin cytoskeleton that influences cell adhesion and motility.