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

BMC Dev Biol. 2013 Aug 23:13:33. doi: 10.1186/1471-213X-13-33.

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Ear / embryology*
  • Ear / 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*
  • T-Box Domain Proteins / metabolism*

Substances

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