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

Buenos Aires

Congreso; IFPA 2019 - VIII SLIMP; 2019

IFPA - SLIMP

Objectives: KLF6 is a ubiquitous transcription factor with an N-terminalacidic transactivation domain and a C-terminal zinc finger DNA-bindingdomain. klf6-/- mice die at day E12.5 showing impaired placenta development.We have demonstrated that KLF6 expression is early upregulatedduring syncytialization and is required for cell fusion in human primaryvillous cytotrophoblast as well as in the BeWo trophoblast-derived cellline. The aim of the present study was to analyze the mechanisms involvedin KLF6-dependent human trophoblast cell fusion.Methods: BeWo cells were transduced with lenti-virus particles togenerate stable cell lines for the full-length KLF6 protein, a deletionmutant lacking its acidic domain (KLF6Dac), or the empty vector.These cell lines were treated or not with 30 mM forskolin and cellfusion was analysed by immunofluorescence after 72 h. Transcript andprotein levels were measured by qRT-PCR and western blot, respectively.Cell proliferation was evaluated by BrdU labelling and cellcounting assays.Results: KLF6 overexpression induces the formation of syncytium-likestructures, indeed the fusion index of KLF6-BeWo cells is significantlyhigher than that observed in the empty vector-BeWo cells. Forskolininducedcell fusion is further increased in KLF6-BeWo cells. In addition, bhCG,syncytin-1 and p21 expression are higher in KLF6-BeWo cells treatedor not with forskolin compared to the corresponding control conditions.Cell proliferation is reduced in KLF6-overexpressing cells. On the otherhand, cell differentiation is not induced and forskolin effect is impaired inthe KLF6Dac-BeWo cell line.Conclusion: Present results reveal that KLF6 overexpression triggers cellcellfusion, increases b-hCG and syncytin-1 expression, and downregulatescell proliferation. These findings suggest that KLF6 is a master regulator ofcell differentiation into the syncytial pathway and that its N-terminalacidic transactivation domain is required for this function.