RESUMO
Epithelial cell-cell contact stimulates actin cytoskeleton remodeling to down-regulate branched filament polymerization-driven lamellar protrusion and subsequently to assemble linear actin filaments required for E-cadherin anchoring during adherens junction complex assembly. In this manuscript, we demonstrate that de novo protein synthesis, the ß-actin 3' UTR, and the ß-actin mRNA zipcode are required for epithelial adherens junction complex assembly but not maintenance. Specifically, we demonstrate that perturbing cell-cell contact-localized ß-actin monomer synthesis causes epithelial adherens junction assembly defects. Consequently, inhibiting ß-actin mRNA zipcode/ZBP1 interactions with ß-actin mRNA zipcode antisense oligonucleotides, to intentionally delocalize ß-actin monomer synthesis, is sufficient to perturb adherens junction assembly following epithelial cell-cell contact. Additionally, we demonstrate active RhoA, the signal required to drive zipcode-mediated ß-actin mRNA targeting, is localized at epithelial cell-cell contact sites in a ß-actin mRNA zipcode-dependent manner. Moreover, chemically inhibiting Src kinase activity prevents the local stimulation of ß-actin monomer synthesis at cell-cell contact sites while inhibiting epithelial adherens junction assembly. Together, these data demonstrate that epithelial cell-cell contact stimulates ß-actin mRNA zipcode-mediated monomer synthesis to spatially regulate actin filament remodeling, thereby controlling adherens junction assembly to modulate cell and tissue adhesion.
