KRÜPPEL-LIKE FACTOR 6 TRANSCRIPTION FACTOR IS REQUIRED FOR HUMAN TROPHOBLAST FUSION

RACCA AC; RIDANO ME; CAMOLOTTO SA; GENTI-RAIMONDI S; PANZETTA-DUTARI GM

Mar del Plata, Buenos Aires

Congreso; VI Latin American Symposium on Maternal-Fetal Interaction and Placenta (SLIMP) and the V Latin American Symposium on Reproductive Immunology (LASRI); 2015

The fusion of trophoblast cells into a highly specialized multinucleatedsyncytiotrophoblast layer is a key process of human placenta development.Defects in this process are associated with pathologies like preeclampsiaand intrauterine growth restriction. Krüppel-Like Factor 6(KLF6) is a member of the Sp/KLF family mostly implicated in humancarcinogenesis, cell cycle regulation, and in some differentiation processes.We have previously demonstrated its expression throughout the in-vitrosyncytialization process.Objective: The aim of this work was to address KLF6 contribution tosyncytiotrophoblast formation by gain- and loss-of function studies.Methods and Results: KLF6 knockdown, through small interfering RNAexperiments, resulted in an evident hindrance in cell-cell fusion, revealedby immunofluorescence microscopy in human primary villous cytotrophoblastfrom term placentas as well as in the human placental-derivedBeWo cell line. Moreover, KLF6 silencing led to a decrease in the expressionof the fusogenic protein Syncytin-1 and the cell cycle regulator p21Cip1/Waf1, measured by quantitative RT-PCR and western blot assays. In contrast,transcript levels of genes that encode for proteins involved in STB formationlike Syncytin-1, Syncytin-2, Connexin-43, and Zonula Occludens-1 increased when KLF6 was overexpressed in the non-fusing placentalderivedJEG-3 cells. Furthermore, KLF6 overexpression increased Syncytin-2 and Connexin-43 mRNAs even in villous cytotrophoblasts undergoing invitro syncytialization. Interestingly, the expression of two trophoblastbiochemical differentiation markers, bhCG and PSG3, was not reducedafter KLF6 silencing in the differentiating trophoblast cells.Conclusions: The present results support the notion that KLF6 is a relevantparticipant in cytotrophoblast fusion. In addition, they provide furtherevidence to sustain that trophoblast fusion is not a pre-requisite forbiochemical differentiation.