Expression of human pregnancy specific beta 1 glycoprotein (PSG) genes during placental development

Using gene-specific oligonucleotide probes, the expression of four pregnancy specific beta 1 glycoprotein (PSG) genes termed A, B, C-D and E (Streydio et al., 1988 and in press) and of some of their splice variants Ci, C and D were analysed during human placental development. Except for a stronger hybridization signal obtained at 9 weeks of gestation, which might be correlated to the development of the placenta, the relative amounts of the different PSG mRNAs showed little variation throughout pregnancy as revealed by Northern blots performed at 6, 13, 18 and 40 weeks of gestation. The expression of the different PSG genes does not seem to be developmentally regulated, in contrast to placental lactogen, used as a control, the expression of which is clearly correlated with the age of gestation. PSG D, A, E transcripts seem equally abundant, while PSG B expression was much lower. Moreover, the proportion of the PSG C-D variants resulting from alternative splicing remained constant during gestation.