April 10, 2014

When you host a party at your home, do you hire a caterer to bring in food or do you cook the food right there in your kitchen? One of these options leaves a lot more wiggle room for last-minute changes—a few extra guests, a gluten allergy, a pregnant lady with a disgust for wobbly desserts. A cell recognizes this distinction too. When making certain proteins, a cell will synthesize proteins where and when they’re needed. Today’s image is from Natasha Gutierrez, who recently published a study describing the role of β-actin mRNA and monomer synthesis in adherens junction assembly.

The actin cytoskeleton is made of actin filaments and countless actin-regulating proteins that guide the ever-changing dynamics of the cytoskeleton. Actin filament polymerization is regulated by localized synthesis of β-actin monomers from β-actin mRNA. A recent paper by Gutierrez and colleagues shows that the assembly of adherens junctions (AJs), epithelial cell-cell adhesion structures, requires localized β-actin monomer synthesis, the β-actin 3’ UTR and β-actin mRNA zipcode sequence at cell-cell contact sites. Additionally, active RhoA, which targets zipcode-mediated β-actin mRNA localization, is localized to cell-cell contact sites. In the unpublished images above, mammalian cells were treated with increasing levels (top to bottom) of a Rho inhibitor. The ability to form AJs, seen as the colocalization of actin filaments (left, green in merged) and E-cadherin (middle, red in merged) at cell-cell contact sites, decreased with increasing levels of the Rho inhibitor.

Gutierrez, N., Eromobor, I., Petrie, R., Vedula, P., Cruz, L., & Rodriguez, A. (2014). The B-actin mRNA zipcode regulates epithelial adherens junction assembly but not maintenance RNA DOI: 10.1261/rna.043208.113