EXPRESSION OF G-PROTEINS IN HUMAN PLACENTAE FROM MOLAR PREGNANCIES

Hydatidiform mole is a conceptus, usually devoid of an intact fetus, w ith variable proliferation of trophoblast and altered placental protei n synthesis, including high human chorionic gonadotropin (hCG) and low human placental lactogen (hPL) production. Little is known about the control of the production of these tyro placental proteins in molar pr egnancies. Regulatory guanine 5'triphosphate (GTP)-binding proteins (G proteins) play key roles in the endocrine control of peptide producti on by the placenta. The present authors recently demonstrated that Gi2 , Gi3 Go, and Gs alpha-subunits were expressed in normal human placent a throughout pregnancy. This study analysed the expression of placenta l G protein alpha-subunits in molar pregnancies. Western and Northern blot analyses were performed on membrane protein and total mRNA prepar ations of human placentae, respectively, from hydatidiform mole (n = 5 ) and normal pregnancies (n = 4). The levels of hPL and beta-hCG mRNAs were 60 and 237 per cent respectively, of those from normal placentae . The autoradiographs for G proteins and their mRNAs showed decreased expression in molar placentae in comparison with normal tissues. Speci fically, Gai2, Gai3, Gao, and Gas levels reached 39, 4, 42, and 89 per cent, respectively, of those from normal placentae. In parallel with the protein levels, their mRNAs expression were 8, 3, 54 and 65 per ce nt of normal values for Gai2, Gai3, Gao, and Gas, respectively. The re sults demonstrate important changes in placental G protein expression in hydatidiform moles suggesting alterations in the signal transductio n machinery within the molar trophoblast. (C) 1996 W. B. Saunders Comp any Ltd