The expression of insulin-like growth factor (IGF) and IGF-binding protein (IGFBP) genes in the human placenta and membranes: evidence for IGF-IGFBP interactions at the feto-maternal interface.

Abstract

The placenta synthesizes insulin-like growth factors (IGFs) and their binding proteins (IGFBPs), which are believed to regulate its growth and development in an autocrine/paracrine manner. To delineate the cellular sites of expression of IGP and IGFBP messenger ribonucleic acids (mRNAs) in human placenta throughout pregnancy, we used in situ hybridization histochemistry with 35S-labeled IGF and IGFBP complementary RNA probes on human placentas and fetal membranes of gestational ages 6 weeks to term (40 weeks). In placental regions where trophoblasts (fetal) or decidua (maternal) coexist (e.g. basal plate), the identity was delineated by their cytokeratin or vimentin immunoreactivity, respectively. Except for IGF-II, mRNAs encoding peptides of the IGF system were expressed in a similar spatial pattern and relative abundance throughout gestation. Both IGF mRNAs showed similar tissue distribution, but the IGF-II mRNA was more abundant than IGF-I mRNA at all gestational ages. IGF-II mRNA was expressed in the ...