CPEB1 regulates beta-catenin mRNA translation and cell migration in astrocytes.

A crucial step in directed cell migration is the recruitment of cytoskeletal regulatory and signaling proteins to the leading edge of the cell. One protein localized to the leading edge of a migrating astrocyte is beta-catenin. Using an in vitro wound-healing assay, we show that the localization of beta-catenin to the leading edge is dependent upon new protein synthesis at the time of wounding. We examined the mRNA encoding beta-catenin for potential regulatory elements and identified a conserved cytoplasmic polyadenylation element in the 3'-untranslated region (UTR). We now show that the CPE-binding protein (CPEB1) is expressed in astrocytes and that translation of beta-catenin mRNA is regulated by CPEB1. Further, expression of a mutant CPEB1 protein in astrocytes not only blocks beta-catenin protein localization, it also inhibits cell migration. These findings demonstrate a role for CPEB1-mediated protein synthesis in the localization of beta-catenin protein to the leading edge of migrating astrocytes and in regulating directed cell motility.