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

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.

• Authors: Laina Freyer, Sonja Nowotschin, Melinda K Pirity, Antonio Baldini, Bernice E Morrow
• Journal: BMC developmental biology (BMC Dev Biol) Vol. 13 Pg. 33 (Aug 23 2013) ISSN: 1471-213X [Electronic] England
• PMID: 23971992 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Gt(ROSA)26Sor non-coding RNA, mouse
• RNA, Untranslated
• Recombinant Fusion Proteins
• T-Box Domain Proteins
• Tbx1 protein, mouse
• Green Fluorescent Proteins

Topics

• Animals
• Ear (embryology, pathology)
• Embryo, Mammalian
• Gene Dosage
• Green Fluorescent Proteins (metabolism)
• Heart (embryology)
• Mice
• Models, Animal
• RNA, Untranslated (genetics)
• Recombinant Fusion Proteins (metabolism)
• T-Box Domain Proteins (genetics, metabolism)