B6.129S1(C)-Nkx2-5^tm4Rph/J

Stock number: 024662
Product name: Nkx2-5^GFP
Strain synonyms: Nkx2-5^-
Research areas: Cardiovascular Research, Developmental Biology Research, Internal/Organ Research, Research Tools

Description

Nkx2-5^gfp mice have a GFP inserted into the first coding exon of the Nkx2-5 gene, causing a frameshift. These mice may be useful for studying for congenital heart defects using echocardiography, electrocardiography, and anatomical dissection.

Detailed description

Nkx2-5^gfp mice have a green fluorescent protein inserted into the first coding region of the NK2 homeobox 5 (Nkx2-5). The insertion causes a frameshift downstream of the GFP and the allele is null for NKX2-5 function. NKX2-5 is a transcription factor involved in formation and development of the heart and other structures including pharyngeal arch arteries and spleen. Mutations of NKX2-5 have been implicated in familial cases of atrial septal defect (ASD) with severe atrioventricular conduction block. Heterozygous Nkx2-5^gfp mice are viable and fertile, while homozygous mice are not viable due to developmental arrest at the heart tube stage. Homozygous Nkx2-5^gfp embryos display abnormal heart morphology at E8.5 and E9.5 causing arrest at a rudimentary unlooped heart tube stage. They show arrested chamber development, diminished deployment of heart progenitor cells and other abnormalities. Heterozygous mice exhibit atrial septal defects (at a low prevalence), atrial septal aneurysms, and patent foramen ovale arising from a decrease in the length of the septum primum flap valve. The prevalence of atrial defects is strain-dependent. A proportion of heterozygotes die during fetal stages, likely due to ventricular septal defects and other cardiac abnormalities. In live heterozygotes, numerous conduction abnormalities were found including prolonged PR interval due to diminished AV node function, although this does not progress beyond first-degree AV block. Defects in the His bundle and intraventricular propagation, and Purkinje fibre differentiation, have also been noted.

Development

A targeting vector was designed to insert a green fluorescent protein, followed by a loxP-flanked neomycin resistance cassette, into the first coding region of the NK2 homeobox 5 (Nkx2-5). The construct was electroporated into 129S1/Sv-Oca2⁺ Tyr⁺ Kitl⁺-derived W9.5 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and the resulting chimeric mice were bred to C57BL/6J mice. These mice were then bred to B6.C-Tg(CMV-cre)1Cgn/J mice (Stock No. 006054) to delete the neo cassette. Offspring were bred to remove the cre-expressing transgene, and resulting mice were bred to C57BL/6J mice for at least 11 generations. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Nkx2-5^tm4Rph
Name: targeted mutation 4, Richard P Harvey
MGI accession ID: MGI:3655239
Generation method: Targeted
Attributes: Reporter; Null/Knockout
Marker symbol: Nkx2-5
Marker name: NK2 homeobox 5
Chromosome: 17
Strain of origin: 129S1/Sv-Oca2⁺ Tyr⁺ Kitl⁺
Expressed genes: GFP,Green Fluorescent Protein,
Site of expression: GFP is expressed in cells involved in formation and development of the heart and other structures including pharyngeal arch arteries and spleen.
Molecular note: Sequence encoding enhanced GFP was inserted at codon 35 of the endogenous locus via homologous recombination.