Differential expression of retinoic acid-inducible (Stra) genes during mouse placentation

Several retinoid binding proteins and nuclear receptors are specifically ex pressed in murine placenta. However, little is known about molecular events and target genes regulated by retinoids during placentation. Here, we repo rt that several retinoic acid-inducible (Stra) genes, originally isolated b y a differential screening procedure, exhibit specific expression patterns in mouse placental tissues. Three Stra genes, including the ephrinB1 recept or tyrosine kinase ligand, are prominently expressed in the regions of exch anges between maternal and embryonic circulations, i.e. the yolk sac and/or the labyrinthine zone of the mature placenta. The Meis2 homeobox gene appe ars to be specifically expressed in maternally-derived cell populations. Th ree other Stra gents, including the AP-2-related gene AP-2 gamma, are diffe rentially expressed in the trophoblastic cell lineage. Thus, retinoids may regulate various signaling pathways in specific placental cell-types. (C) 2 000 Elsevier Science Ireland Ltd. All rights reserved.