title: Gain of function of Tbx1 affects pharyngeal and heart development in the mouse.
abstract: Mammalian development is highly sensitive to Tbx1 gene dosage reduction. Gene function insights can also be learned from increased or ectopic expression. The authors generated a novel mouse transgenic line, named COET, which expresses Tbx1 upon Cre-mediated recombination. The authors crossed this transgenic line with Tbx1(Cre) animals to activate expression in the Tbx1-expression domain. Compound mutant COET;Tbx1(Cre/+) animals died after birth and showed heart enlargement. At E18.5, compound mutants showed ventricular septal defects and thymic abnormalities. The authors crossed compound mutants into a Tbx1 null background to understand whether this phenotype is caused by gene overdosage. Results showed that gene dosage reduction at the endogenous locus could not rescue heart and thymic defects, although the transgene rescued the loss of function phenotype. Thus, the transgenic phenotype appears to be due to gain of function. Resultant data demonstrate that Tbx1 expression must be tightly regulated to be compatible with normal embryonic development.
authors.forename: Francesca
authors.initials: F
authors.lastname: Vitelli
authors.forename: Tuong
authors.initials: T
authors.lastname: Huynh
authors.forename: Antonio
authors.initials: A
authors.lastname: Baldini
mesh_terms: D000818:Animals; D002645:Chickens; D003433:Crosses, Genetic; D018628:Gene Dosage / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006321:Heart / Q000196:embryology*; D006330:Heart Defects, Congenital / Q000196:embryology / Q000235:genetics; D019426:Integrases / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D010614:Pharynx / Q000196:embryology*; D020825:T-Box Domain Proteins / Q000096:biosynthesis* / Q000235:genetics; D013950:Thymus Gland / Q000002:abnormalities / Q000196:embryology
chemical_list: D020825:T-Box Domain Proteins; C491573:Tbx1 protein, mouse; C045073:Cre recombinase; D019426:Integrases