TGF-β2 gene and protein expression in maternal and fetal tissues at various stages of murine development

The transforming growth factor beta family of peptides have diverse actions on the reproductive tracts of primates and rodents. In this study we report the expression of high levels of mRNA of one member of this superfamily, TGF-beta 2, in the pregnant mouse uterus. Using Northern blot analysis and in situ hybridization techniques, we have examined the pattern of expression of TGF-beta 1, TGF-beta 2 and colony-stimulating factor (CSF-1) in mouse maternal and fetal tissue at specific days of gestation. We report here that TGF-beta 2 is synthesized primarily in maternal decidual and uterine epithelial tissues. We observed a shift in the major site of synthesis from decidua to uterus between days 8.5 and 10.5 of gestation. These data demonstrate that the expression of TGF-beta 2 is differentially regulated in the decidua and uterine epithelial cells at various times during gestation. Small amounts of TGF-beta 2 mRNAs were detected in the fetus, and none was detected in placenta, yolk sac, or amniotic membrane. The uterus is likely the major site of synthesis of the TGF-beta 2 found in mouse amniotic fluid. TGF-beta 1 mRNAs are expressed in the uterus at markedly lower levels when compared to TGF-beta 2 mRNAs in both the decidua and uterus. Our results suggest that there is a unique regulation of TGF-beta 2 during pregnancy which may depend on pregnancy hormone(s) and differentiates it from the other mammalian isoforms of the TGF-beta s. TGF-beta 2 may play an important, albeit unknown, role at the maternal/fetal interface.