FIG. 3.

A factor regulating primary trophoblast differentiation also regulates HERV-W env mRNA and protein expression. (A) After 24 h of culture, the primary cytotrophoblasts were incubated for 48 h in the presence of 0.1 mM 8-bromo-cAMP. At 72 h, the cells were fixed and immunostained with anti-desmoplakin monoclonal antibody (green fluorescence). Nuclei were labeled with DAPI (blue fluorescence). Large syncytia were observed in the control and with the cAMP treatment. (B) HERV-W and hCGβ mRNA expression after 72 h of cytotrophoblast culture. mRNA data are expressed as the level of each marker mRNA normalized by Po mRNA levels. Three culture dishes were pooled for each determination, and transcripts were assayed in duplicate. (C) Levels of hCG (expressed in milli-international units per milliliter) secreted at the indicated time into the culture medium of control cells or cells treated with 0.1 mM 8-bromo-cAMP. (D) Western blot analysis of HERV-W Env expression in cell lysates of cells treated with cAMP or left untreated (detection by the anti-SU polyclonal antibody). **, P < 0.01; ***, P < 0.001.