Lamella-localized ZBP1 (white) granules do not form if ZBP1 cannot bind actin mRNA (right).
The cell motility connection comes about because localization of the β-actin mRNA to the lamellae is required for cell polarity and motility in fibroblasts. The new results show that this localization depends on ZBP1, a protein associated with cytoplasmic granules that contain the actin mRNA. ZBP1 bound to the mRNA through two COOH-terminal KH domains that were required for granule formation and attachment to the actin cytoskeleton. NH2-terminal regions of ZBP1 were necessary for granule localization in the lamellae.
Dominant–negative ZBP1 constructs that mislocalized actin RNA inhibited fibroblast motility. Since mRNAs for some actin-associated proteins, such as ARP3, also contain...