Krüppel-like factor 6 (KLF6) is a zinc finger transcription factor involved in differentiation, cell cycle control and proliferation in several cell systems. It is highly expressed in human term placenta, and its mRNA and protein levels increase during human trophoblast cell differentiation. Along this process, KLF6 has a nuclear and cytoplasmatic localization. Pregnancy Specific Glycoproteins (PSGs) are early biochemical markers of trophoblast differentiation and are required for pregnancy protection. They have been considered as target genes of KLF6 regulation, although there is little experimental evidence supporting such a role. Here, we confirmed by immunohistochemistry that KLF6 is expressed on human term placental villi. Immunofluorescence assays revealed that KLF6 is expressed before PSG during in vitro trophoblast cell differentiation. KLF6 over expression led to an increase in PSG mRNA and protein levels. In addition, KLF6 transactivated PSG3 promoter activity in non differentiated cells, and this activation was enhanced when cells were differentiated. Moreover, gel shift assays revealed that KLF6 is linked to the PSG promoter region. Altogether these data provide further evidences that KLF6 is a direct regulator of PSG gene expression during placental differentiation. Supported by CONICET, FONCyT, MinCyT of Córdoba and SECyT-UNC.
