title: Tbx2 and Tbx3 regulate the dynamics of cell proliferation during heart remodeling.
abstract: BACKGROUND
  The heart forms from a linear tube that is subject to complex remodeling during embryonic development. Hallmarks of this remodeling are the looping of the heart tube and the regionalization into chamber and non-chamber myocardium. Cardiomyocytes in the future chamber myocardium acquire different cellular and physiological characteristics through activation of a chamber-specific genetic program, which is in part mediated by T-box genes.
  
  
  RESULTS
  We characterize two new zebrafish T-box transcription factors, tbx3b and tbx2a, and analyze their role during the development of the atrioventricular canal. Loss- and gain-of-function analyses demonstrate that tbx3b and tbx2a are necessary to repress the chamber-genetic program in the non-chamber myocardium. We also show that tbx3b and tbx2a are required to control cell proliferation in the atrioventricular canal and that misregulation of cell proliferation in the heart tube influences looping. Furthermore, we characterize the heart phenotype of a novel Tbx3 mutation in mice and show that both the control of cell proliferation and the repression of chamber-specific genetic program in the non-chamber myocardium are conserved roles of Tbx3 in this species.
  
  
  CONCLUSIONS
  Taken together, our results uncover an evolutionarily conserved role of Tbx2/3 transcription factors during remodeling of the heart myocardium and highlight the importance of controlling cell proliferation as a driving force of morphogenesis.
authors: Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America.
authors: Inês
authors: I
authors: Ribeiro
authors: Yasuhiko
authors: Y
authors: Kawakami
authors: Dirk
authors: D
authors: Büscher
authors: Angel
authors: A
authors: Raya
authors: Joaquín
authors: J
authors: Rodríguez-León
authors: Masanobu
authors: M
authors: Morita
authors: Concepción
authors: C
authors: Rodríguez Esteban
authors: Juan Carlos
authors: JC
authors: Izpisúa Belmonte
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D015027:Zebrafish
chemical_list: D014157:Transcription Factors