Identification of a new gene family specifically expressed in chicken embryonic stem cells and early embryo

Chicken embryonic stem (CES) cells are pluripotent cells derived from chick en early blastoderm. In order to identify new genes specifically expressed in these pluripotent cells, we have used a gene trap strategy and cloned a novel gene family called cENS for chicken Embryonic Normal Stem cell gene. The cENS genes expression decreases after induction of CES cells differenti ation in culture and is restricted in vivo to the very early embryo. We hav e characterized three different cENS genes. One, cENS-1, is composed of an open reading frame inserted between two terminal direct repeats which are t he common point of the tENS genes. cENS-1 encodes a protein identical to cE RNI, a recently described protein, cENS-2 is a truncated form of cENS-1. cE NS-3 presents two adjacent open reading frames coding respectively for env and pol related proteins. The presence of conserved direct repeats, of retr ovirus related genes and the absence of introns argue in favor of a retrovi ral origin of the cENS genes. In the c ENS we identified a promoter region whose activity is strong in CES cells and decreases after induced different iation showing a highly specific transcriptional activity specific of undif ferentiated chicken embryonic stem cells. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.