title: TGFbeta Induces Binucleation/Polyploidization in Hepatocytes through a Src-Dependent Cytokinesis Failure.
abstract: In all mammals, the adult liver shows binucleated as well as mononucleated polyploid hepatocytes. The hepatic polyploidization starts after birth with an extensive hepatocyte binucleation and generates hepatocytes of several ploidy classes. While the functional significance of hepatocyte polyploidy is becoming clearer, how it is triggered and maintained needs to be clarified. Aim of this study was to identify a major inducer of hepatocyte binucleation/polyploidization and the cellular and molecular mechanisms involved. We found that, among several cytokines analyzed, known to be involved in early liver development and/or mass control, TGFbeta1 was capable to induce, together with the expected morphological changes, binucleation in hepatocytes in culture. Most importantly, the pharmacological inhibition of TGFbeta signaling in healthy mice during weaning, when the physiological binucleation occurs, induced a significant decrease of hepatocyte binucleation rate, without affecting cell proliferation and hepatic index. The TGFbeta-induced hepatocyte binucleation resulted from a cytokinesis failure, as assessed by video microscopy, and is associated with a delocalization of the cytokinesis regulator RhoA-GTPase from the mid-body of dividing cells. The use of specific chemical inhibitors demonstrated that the observed events are Src-dependent. Finally, the restoration of a fully epithelial phenotype by TGFbeta withdrawal gave rise to a cell progeny capable to maintain the polyploid state. In conclusion, we identified TGFbeta as a major inducer of hepatocyte binucleation both in vitro and in vivo, thus ascribing a novel role to this pleiotropic cytokine. The production of binucleated/tetraploid hepatocytes is due to a cytokinesis failure controlled by the molecular axis TGFbeta/Src/RhoA.
authors.affiliation: Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: De Santis Puzzonia
authors.affiliation: Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy.|L. Spallanzani National Institute for Infectious Diseases, IRCCS, Rome, Italy.
authors.forename: Angela Maria
authors.initials: AM
authors.lastname: Cozzolino
authors.affiliation: L. Spallanzani National Institute for Infectious Diseases, IRCCS, Rome, Italy.
authors.forename: Germana
authors.initials: G
authors.lastname: Grassi
authors.affiliation: Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Bisceglia
authors.affiliation: Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Strippoli
authors.affiliation: Institute of Molecular Biology and Pathology, CNR National Research Council, c/o Department of Biology and Biotechnology, Sapienza University of Rome, Rome, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Guarguaglini
authors.affiliation: Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy.
authors.forename: Franca
authors.initials: F
authors.lastname: Citarella
authors.affiliation: Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy.
authors.forename: Benedetto
authors.initials: B
authors.lastname: Sacchetti
authors.affiliation: Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy.|L. Spallanzani National Institute for Infectious Diseases, IRCCS, Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Tripodi
authors.affiliation: Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy.
authors.forename: Alessandra
authors.identifier: http://orcid.org/0000-0001-9706-848X
authors.initials: A
authors.lastname: Marchetti
authors.affiliation: Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Amicone
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000235:genetics*; D049109:Cell Proliferation; D002478:Cells, Cultured; D048749:Cytokinesis / Q000187:drug effects / Q000502:physiology*; D022781:Hepatocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D011123:Polyploidy; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D016212:Transforming Growth Factor beta; D019061:src-Family Kinases