TGFbeta Induces Binucleation/Polyploidization in Hepatocytes through a Src-Dependent Cytokinesis Failure

• Published in: PloS one Vol. 11; no. 11; p. e0167158
• Main Authors: De Santis Puzzonia, Marco, Cozzolino, Angela Maria, Grassi, Germana, Bisceglia, Francesca, Strippoli, Raffaele, Guarguaglini, Giulia, Citarella, Franca, Sacchetti, Benedetto, Tripodi, Marco, Marchetti, Alessandra, Amicone, Laura
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 28.11.2016; Public Library of Science (PLoS)
• Subjects: Analysis; Animals; Biology and Life Sciences; Cell culture; Cell cycle; Cell Nucleus - drug effects; Cell Nucleus - genetics; Cell Proliferation; Cells, Cultured; Cytokines; Cytokinesis; Cytokinesis - drug effects; Cytokinesis - physiology; Failure; Fibroblasts; Gene expression; Growth factors; Guanosine triphosphatases; Health aspects; Hematology; Hepatocytes; Hepatocytes - cytology; Hepatocytes - drug effects; Hepatocytes - metabolism; Hepatology; Infectious diseases; Insulin; Kinases; Liver; Liver - cytology; Liver - drug effects; Liver - metabolism; Liver diseases; Mammals; Medicine and Health Sciences; Mice; Mice, Inbred C57BL; Microscopy; Molecular biology; Molecular modelling; Pharmacology; Phenotypes; Ploidy; Polyploidy; Progeny; Research and Analysis Methods; Restoration; RhoA protein; Rodents; Signaling; src-Family Kinases - genetics; src-Family Kinases - metabolism; Transforming Growth Factor beta - pharmacology; Transforming growth factors; Weaning; United Kingdom > UK; United States > US; Italy
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0167158

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.