The ERRα orphan nuclear receptor controls morphogenetic movements during zebrafish gastrulation

Gastrulation is a process involving cellular commitment and movements whereby the three fundamental germ layers are established in vertebrates embryos. Estrogen Receptor-Related (ERR) α is a nuclear receptor displaying high sequence identity to the Estrogen Receptors (ERs). However, ERRα is unable to bind and to be regulated by estrogens or any natural ligand to date. Whereas recent studies have suggested roles for ERRα in bone and adipose tissue metabolism in the mouse, little is known about its roles during embryonic development. In zebrafish embryos, ERRα is expressed from the beginning of gastrulation at the margin of the blastoderm that represents the presumptive mesendoderm. Using loss of function (morpholinos or a dominant-negative version of the protein) and gain of function (mRNA injection) strategies, we show here that ERRα is involved in epiboly and convergent-extension (CE) processes in the zebrafish. Altogether, these results propose ERRα as a new regulator of morphogenetic movement during gastrulation, independently of cell fate determination.