Identification of a Novel Mouse Brachyury (T) Allele Causing a Short Tail Mutation in Mice

Abstract

Mutations in T-box genes are associated with numerous disease states in humans. The objective of this paper was to characterize the T(shao), a specific T-box mutation, in mice. T(shao), a short-tailed mutant mouse strain in a B6 background, was obtained by ethylnitrosourea mutagenesis. Microsatellite genomic scans mapped the location of the mutation. RT-PCR was used to amplify the identified region and the product was sequenced. DNA of the region was sequenced and scanned for mutations. Tails of T(shao) mice were mostly curly with tail length ranging from less than 1 cm (tail bud) to half of the normal length. T(shao) presented single dominance gene inheritance, and homozygous mutant mice died approximately at E10. Scans of the F2 generation mapped the mutant gene to chromosome 17, near D17Mit143. The Brachyury (T) gene was identified as a potential candidate gene in this location. To confirm this, RT-PCR was performed on RNA from intercrossed 8.5-day embryos, and products were sequenced. A 67-nucleotide deletion in exon 2 of the mutant T gene was identified. Further sequencing of the genomic DNA from this region identified a T to A transversion at the 67th nucleotide of exon 2. The T(shao) mutation is a result of a deletion in exon 2 causing the early termination and loss of function of protein encoded by the T gene, manifesting as a short tail phenotype.

Multiple mutant T alleles cause haploinsufficiency of Brachyury and short tails in Manx cats

“…Short-tailed phenotypes in mouse (Wu et al 2010) and dog (Haworth et al 2001; Hytonen et al 2009; Indrebo et al2008) have been associated with naturally occurring T mutants and induced by disrupting Brachyury expression in model organisms such as zebrafish (Schulte-Merker et al 1994) and Xenopus (Conlon et al 1996). Complete absence of the tail is a phenotype found virtually only in the Manx cat.…”

“…Across species, both missense and frameshift mutations have been found to cause short-tail phenotypes (Haworth et al 2001; Schulte-Merker et al 1994; Wu et al 2010). These mutations occur in the T-box domain (e.g., mouse and dog) and downstream (e.g., mouse and cat) with little evidence of a relationship between genotype and loss of functional activity or phenotype (Hytonen et al 2009; Wu et al 2010).…”

“…These mutations occur in the T-box domain (e.g., mouse and dog) and downstream (e.g., mouse and cat) with little evidence of a relationship between genotype and loss of functional activity or phenotype (Hytonen et al 2009; Wu et al 2010). This is not entirely surprising as mutations in T both within and outside of the T-box domain have been demonstrated to abrogate the ability of Brachyury to activate transcription (Haworth et al 2001; Kispert et al 1995).…”

“…However, mice heterozygous for mutations of the canonical T-box gene, T , which encodes the transcription factor Brachyury, a key regulator of notochord differentiation in all vertebrates, have tail length variation. To date, eight different T alleles that cause a short-tailed phenotype in mice have been described (Wu et al 2010). These alleles include both point mutations and frameshifts that result in truncation of either the amino or carboxy terminal end of Brachyury.…”

Insights into regeneration from the genome, transcriptome and metagenome analysis ofEisenia fetida

“…4A). Brachyury, literally meaning short-tail after the heritable shortened tail of mice that carry a mutation in this transcription factor 42,43 , is expressed in the mesoderm and is required for the specification of posterior structures in fruit flies 44 , sea urchins 45 , nematodes 46 , zebrafish 47 , frogs 48 , chicken 49 and humans, suggesting a conserved role across evolution 50,51 . In the hydra and newt, it has been shown to be induced in regenerating tissues 52,53 .…”