Different insulin-like growth factor binding species in human placenta and decidua.
Previous studies demonstrated that human decidua secretes a 34K insulin-like growth factor binding protein (34K IGF-BP) earlier designated placental protein 12, whereas placenta contains IGF receptors and IGF mRNA. We studied binding of [125I]IGF-I to paired placental and decidual tissues using competitive binding, gel filtration, RIA, and cross-linking techniques, and compared the binding characteristics of these two tissues which are located in close proximity in vivo. The effect of decidual cytosols on [125I]IGF-I binding to placental membranes also was studied. Consistent with previous data the dominating binding species in placental membranes were IGF receptors. In contrast, the binding of [125I]IGF-I to decidual membranes was mainly due to binding species with mol wts of 34K and 39K. The 34K IGF-BP was more readily detected in decidual cytosols than in decidual membranes and little was detected in placental cytosols. Purified 34K IGF-BP as well as decidual cytosols inhibited [125I]IGF-I binding to placental receptors. The inhibitory effect of decidual cytosol on IGF receptor binding was linearly correlated to the decidual content of 34K IGF-BP. The results suggest that the decidual 34K IGF-BP might act as a local modulator of the IGF action at the interface between the decidua and the placenta.
Pekonen
F
F
Minerva Institute for Medical Research, Kauniainen, Finland.
Suikkari
A M
AM
Mäkinen
T
T
Rutanen
E M
EM
D001345:Autoradiography; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000378:metabolism*; D002850:Chromatography, Gel; D003432:Cross-Linking Reagents; D003600:Cytosol / Q000378:metabolism; D003656:Decidua / Q000378:metabolism*; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011863:Radioimmunoassay; D011972:Receptor, Insulin / Q000378:metabolism*; D017451:Receptors, Somatomedin; D012995:Solubility; D013002:Somatomedins / Q000378:metabolism*
D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D007328:Insulin; D018969:Insulin-Like Growth Factor Binding Proteins; D017451:Receptors, Somatomedin; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D011972:Receptor, Insulin