KRÜPPEL-LIKE TRANSCRIPTION FACTOR 6 (KLF6) OVEREXPRESSION INDUCES CELL CYCLE ARREST AND FUSION OF BEWO CELLS

MIRANDA, AL; KOURDOVA, LUCILLE T; RACCA, A.C.; ROJAS, MARIA L.; CRUZ DEL PUERTO, MARIANO; GENTI-RAIMONDI, S.; PANZETTA-DUTARI, G.M.

Congreso; IFPA 2019; 2019

ObjectiveKLF6 is a ubiquitous transcription factor with an N-terminal acidic transactivation domain and a C‐terminal zinc finger DNA-binding domain. klf6-/- mice die at day E12.5 showing impaired placenta development. We have demonstrated that KLF6 expression is early upregulated during syncytialization and is required for cell fusion in human primary villous cytotrophoblast as well as in the BeWo trophoblast-derived cell line. The aim of the present study was to analyze the mechanisms involved in KLF6-dependent human trophoblast cell fusion.MethodsBeWo cells were transduced with lenti-virus particles to generate stable cell lines for the full-length KLF6 protein, a deletion mutant lacking its acidic domain (KLF6∆ac), or the empty vector. These cell lines were treated or not with 30 µM forskolin and cell fusion was analysed by immunofluorescence after 72 h. Transcript and protein levels were measured by qRT-PCR and western blot, respectively. Cell proliferation was evaluated by BrdU labelling and cell counting assays. ResultsKLF6 overexpression induces the formation of syncytium-like structures, indeed the fusion index of KLF6-BeWo cells is significantly higher than that observed in the empty vector-BeWo cells. Forskolin-induced cell fusion is further increased in KLF6-BeWo cells. In addition, β-hCG, syncytin-1 and p21 expression are higher in KLF6-BeWo cells treated or not with forskolin compared to the corresponding control conditions. Cell proliferation is reduced in KLF6-overexpressing cells. On the other hand, cell differentiation is not induced and forskolin effect is impaired in the KLF6∆ac-BeWo cell line.ConclusionsPresent results reveal that KLF6 overexpression triggers cell-cell fusion, increases β-hCG and syncytin-1 expression, and downregulates cell proliferation. These findings suggest that KLF6 is a master regulator of cell differentiation into the syncytial pathway and that its N-terminal acidic transactivation domain is required for this function.