Analysis of messenger ribonucleic acid and protein for the ligands and receptors of the platelet-derived growth factor signaling pathway in the placenta, extraembryonic membranes, and uterus during the latter half of murine gestation.

Previous investigation of ligand and receptor messenger RNA (mRNA) expression implicated the platelet-derived growth factor (PDGF) pathway as a participant in the maintenance of pregnancy and fetal development during the first half of murine gestation. We extended these studies using Northern and in situ RNA hybridization and immunohistochemical detection of protein to evaluate the expression kinetics and cell-specific localization of PDGF-A, PDGF-B, PDGF alpha-receptor, and PDGF beta-receptor in mouse placenta, extraembryonic membranes, and uterus during the second half of gestation (days 9.5-18.5). Northern blotting experiments reveal that mRNAs for the PDGF signaling components exhibit unique time-dependent and tissue-specific expression in the placenta and uterus, being progressively and coordinately up-regulated as gestation proceeds. Cell-specific localization of mRNA and protein by in situ hybridization and immunohistochemistry demonstrates widespread expression in multiple cell types of the placenta, gravid uterus, and extraembryonic membranes. Abundant PDGF protein and mRNA expression is exhibited in the nucleated fetal erythroid progenitor cells that originate in the extraembryonic membranes and circulate throughout the developing conceptus. Our data together with those of previous studies demonstrate that PDGF ligands and receptors are globally expressed in many cell types within fetal and maternal tissues during murine gestation and, thus, imply a potential role for PDGF in fetal development and maternal-fetal interactions.