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Open Access Methodology article

Conditional and constitutive expression of a Tbx1-GFP fusion protein in mice

Laina Freyer1, Sonja Nowotschin13, Melinda K Pirity14, Antonio Baldini5 and Bernice E Morrow12*

Author affiliations

1 Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Avenue, Bronx, NY 10461, USA

2 Departments of Ob/Gyn and Pediatrics, Albert Einstein College of Medicine, 1301 Morris Park Avenue, Bronx, NY 10461, USA

3 Present address: Department of Developmental Biology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA

4 Present address: Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Temesvari krt 62, H-6726, Szeged, Hungary

5 Institute of Genetics and Biophysics, Via Pietro Castellino 111, 80131, Napoli, Italy

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Citation and License

BMC Developmental Biology 2013, 13:33  doi:10.1186/1471-213X-13-33

Published: 23 August 2013

Abstract

Background

Velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS) is caused by a 1.5-3 Mb microdeletion of chromosome 22q11.2, frequently referred to as 22q11.2 deletion syndrome (22q11DS). This region includes TBX1, a T-box transcription factor gene that contributes to the etiology of 22q11DS. The requirement for TBX1 in mammalian development is dosage-sensitive, such that loss-of-function (LOF) and gain-of-function (GOF) of TBX1 in both mice and humans results in disease relevant congenital malformations.

Results

To further gain insight into the role of Tbx1 in development, we have targeted the Rosa26 locus to generate a new GOF mouse model in which a Tbx1-GFP fusion protein is expressed conditionally using the Cre/LoxP system. Tbx1-GFP expression is driven by the endogenous Rosa26 promoter resulting in ectopic and persistent expression. Tbx1 is pivotal for proper ear and heart development; ectopic activation of Tbx1-GFP in the otic vesicle by Pax2-Cre and Foxg1-Cre represses neurogenesis and produces morphological defects of the inner ear. Overexpression of a single copy of Tbx1-GFP using Tbx1Cre/+ was viable, while overexpression of both copies resulted in neonatal lethality with cardiac outflow tract defects. We have partially rescued inner ear and heart anomalies in Tbx1Cre/- null embryos by expression of Tbx1-GFP.

Conclusions

We have generated a new mouse model to conditionally overexpress a GFP-tagged Tbx1 protein in vivo. This provides a useful tool to investigate in vivo direct downstream targets and protein binding partners of Tbx1.

Keywords:
VCFS/DGS; Tbx1; Rosa26; Mouse model; Gain-of-function