Human pregnancy-specific glycoproteins (PSGs) are encoded by 11 highly similar and
transcriptionally active genes, essential for the maintenance of gestation. High levels of
PSG biosynthesis are restricted to the placenta syncytiotrophoblast (STB), and only
very low levels are found in other cell types, such as the choriocarcinoma Jeg3 cell
line. PSGs are early biochemical markers of trophoblast differentiation. Krüppel-like factor-
6 (KLF6) plays a crucial role in the regulation of genes involved in differentiation,
angiogenesis, cell cycle control and proliferation in several cell systems. Although it is
highly expressed in human term placenta tissue, little is known about its role in regulating
placenta specific genes. Objectives: In order to get further insight into PSG genes transcriptional
regulation, we have investigated the roles of KLF6 and Small Nuclear RING
Finger co-activator (SNURF) in trophoblast PSG expression. Methods: Western blot, immunofluorescence,
transfection assays and qRT-PCR were used to explore the expression
of these regulatory factors and their impact on PSG genes transcription. Results: KLF6
protein and transcript levels increase during in- vitro differentiation of cytotrophoblast
isolated from third trimester placenta as well as in choriocarcinoma Jeg3 cell line.
Overexpression of KLF6 increases trophoblastic PSG mRNA expression. PSG promoter
constructs are activated by KLF6 and this effect is enhanced by the co-expression of the
co-activator SNURF, which is expressed in trophoblastic cells. Conclusion: Our data provide
evidence that KLF6 and SNURF may cooperate in regulating PSG-genes expression
during trophoblast differentiation.
Supported by CONICET, FONCyT and SECyT-UNC.
