PSX, A NOVEL MURINE HOMEOBOX GENE EXPRESSED IN PLACENTA

To identify homeobox genes involved in mouse embryo development, we ha ve screened a mouse cDNA library prepared from the 13.5-day-old entire conceptus for homeobox-containing sequences using a polymerase chain reaction (PCR) cloning strategy. We identified a mouse homeobox gene t hat might be the prototype of a new class. The full-length cDNA, desig nated Psx (placenta specific-homeobox), encodes a protein of 247 amino acids. The expression patterns of the Psx during embryonic developmen t and in adult tissues were studied by Northern blot analysis. The Psx transcript was first detected at embryonic day 8.5 of conceptus and p ersisted until birth. Psx mRNA is expressed in extraembryonic tissues, mainly in placenta, but not in fetus, pups and adult tissues tested, suggesting that Psx plays an important role in placenta. Psx is a new member of the murine homeobox genes which are expressed in extraembryo nic tissues such as placenta and amnion. (C) 1998 Elsevier Science B.V .