Abstract
Background: The human transcription factors (TFs) GATA4, NKX2.5 and TBX5 form part of the core network necessary to build a human heart and are involved in Congenital Heart Diseases (CHDs). The human natriuretic peptide precursor A (NPPA) and α-myosin heavy chain 6 (MYH6) genes are downstream effectors involved in cardiogenesis that have been demonstrated to be in vitro targets of such TFs. Results: To study the interactions between these human TFs and their target enhancers in vivo, we overexpressed them in the whole Drosophila cardiac tube using the UAS/GAL4 system. We observed that all three TFs up-regulate their natural target enhancers in Drosophila and cause developmental defects when overexpressed in eyes and wings. Conclusions: A strong potential of the present model might be the development of combinatorial and mutational assays to study the interactions between human TFs and their natural target promoters, which are not easily undertaken in tissue culture cells because of the variability in transfection efficiency, especially when multiple constructs are used. Thus, this novel system could be used to determine in vivo the genetic nature of the human mutant forms of these TFs, setting up a powerful tool to unravel the molecular genetic mechanisms that lead to CHDs. Developmental Dynamics 241:190–199, 2012. © 2011 Wiley Periodicals, Inc.Key findingsThe mammalian transcription factors GATA4, Nkx2.5 and TBX5 are able to transactivate the Nppa and Myh6 human enhancers in Drosophila embryos.The endogenous Drosophila homologs of GATA4, Nkx2.5 and TBX5 are not transactivated by GATA4, Nkx2.5 or TBX5, ruling out a possible endogenous regulatory circuit.Overexpression in the mesoderm of GATA4, Nkx2.5 or TBX5 is lethal and overexpression in eyes and wings causes reduced organs.
Highlights
The core network of transcription factors (TFs) and the main events that lead to heart formation have been conserved in evolution
Mutations in either NKX2.5 or TBX5 severely reduce the transcription of natriuretic peptide precursor A (NPPA) (Zhu et al, 2000; Ghosh et al, 2001; Hiroi et al, 2001; Fan et al, 2003), whereas the transcription of myosin heavy chain 6 (MYH6) is impaired by TBX5 or GATA4 mutations (Garg et al, 2003; Ching et al, 2005)
We show that the mammalian TFs GATA4, Nkx2.5, and TBX5 are able to up-regulate their natural target enhancers in vivo in Drosophila embryos
Summary
The human transcription factors (TFs) GATA4, NKX2.5 and TBX5 form part of the core network necessary to build a human heart and are involved in Congenital Heart Diseases (CHDs). Conclusions: A strong potential of the present model might be the development of combinatorial and mutational assays to study the interactions between human TFs and their natural target promoters, which are not undertaken in tissue culture cells because of the variability in transfection efficiency, especially when multiple constructs are used. This novel system could be used to determine in vivo the genetic nature of the human mutant forms of these TFs, setting up a powerful tool to unravel the molecular genetic mechanisms that lead to CHDs. Developmental Dynamics 241:190–199, 2012. Overexpression in the mesoderm of GATA4, Nkx2.5 or TBX5 is lethal and overexpression in eyes and wings causes reduced organs
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