Cytoskeletal Protein Zyxin Inhibits the Activity of Genes Responsible for Embryonic Stem Cell Status

Zyxin is a cytoskeletal LIM-domain protein that regulates actin cytoskeleton assembly and gene expression. In the present work, we find that zyxin downregulation in Xenopus laevis embryos reduces the expression of numerous genes that regulate cell differentiation, but it enhances that of several genes responsible for embryonic stem cell status, specifically klf4, pou5f3.1, pou5f3.2, pou5f3.3, and vent2.1/2. For pou5f3 family genes (mammalian POU5F1/OCT4 homologs), we show that this effect is the result of mRNA stabilization due to complex formation with the Y-box protein Ybx1. When bound to Ybx1, zyxin interferes with the formation of these complexes, thereby stimulating pou5f3 mRNA degradation. In addition, in zebrafish embryos and human HEK293 cells, zyxin downregulation increases mRNA levels of the pluripotency genes KLF4, NANOG, and POU5F1/OCT4. Our findings indicate that zyxin may play a role as a switch among morphogenetic cell movement, differentiation, and embryonic stem cell status. [Display omitted] •Zyxin inhibits the activity of pou5f3 genes responsible for embryonic stem cell status•Ybx1 binds pou5f3 mRNA, thus increasing its stability•Zyxin directly binds to Ybx1 and holds it in the cytoplasm•Zyxin reduces stability of pou5f3 mRNA by interfering with its binding to Ybx1 Parshina et al. disclose a mechanism by which the cytoskeletal protein zyxin, which has known effects on cell movement and gene expression when it shuttles into the cell nucleus, reduces the mRNA stability of genes, maintaining embryonic stem cell status through its interaction with the mRNA-stabilizing protein Ybx1.