B6.129P2(Cg)-Pitx2^tm1.1Dmm/J

Stock number: 018054
Research areas: Cell Biology Research, Developmental Biology Research, Internal/Organ Research, Neurobiology Research, Research Tools

Description

In this mutant strain, an IRES Tau-lacZ cassette abolishes expression of all three PITX2 isoforms. TaulacZ is expressed in neurons projecting from the mammillary tract of the hypothalamus.

Detailed description

In this mutant strain an IRES Tau-lacZ cassette replaces exon 4 of the paired-like homeodomain transcription factor 2 (Pitx2) gene, abolishing expression of all three PITX2 isoforms. PITX2 is a transcription factor expressed in the developing mammillary and retromammillary regions of the hypothalamus. PITX2 is involved in memory processing by regulating neural axonal migration. Heterozygous Pitx2^tlz/+ mice are viable and fertile, while homozygous Pitx2^tlz/tlz mice exhibit embryonic lethality. Pitx2^tlz/+ embryos show lacZ staining in the eye, pituitary, teeth, heart, craniofacial regions, and neural tube. The brains of heterozygous embryos show lacZ staining the hypothalamus and midbrain. Pitx2^tlz/tlz embryos exhibit defects of the heart, abdominal viscera, and distal turning. They have improperly bundled and disorganized axonal fibers in the primary mammillary tract which are still able to project caudally.

Development

A targeting construct was designed to replace exon 4 of the paired-like homeodomain transcription factor 2 (Pitx2) gene with (from 5' to 3') a stop codon, an internal ribosome entry site (IRES), bovine Tau-β-galactosidase (lacZ) fusion protein, and a floxed-neomycin (neo) resistance cassette. This construct was electroporated into 129P2/OlaHsd-derived E14Tg2A embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J x DBA/2J recipient blastocysts and chimeric males were bred with C57BL/6J females. Their offspring were bred to EIIa-cre mice to remove the floxed-neo. The resulting mice were backcrossed to C57BL/6J mice for at least 8 generations. Upon arrival at The Jackson Laboratory Repository, mutant mice were bred with C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Pitx2^tm1.1Dmm
Name: targeted mutation 1.1, Donna M Martin
MGI accession ID: MGI:5308807
Generation method: Targeted
Attributes: Reporter; Null/Knockout
Marker symbol: Pitx2
Marker name: paired-like homeodomain transcription factor 2
Chromosome: 3
Strain of origin: 129P2/OlaHsd
Expressed genes: lacZ,beta-galactosidase,E. coli
Site of expression: TaulacZ is expressed in neurons projecting from the mammillary tract of the hypothalamus.
Molecular note: Exon 4 was replaced with a splice acceptor, stop codon, IRES, bovine MAPT fused to lacZ (tau-lacZ) and floxed neo cassette. Cre-mediated recombination removed the neo cassette. Immunofluorescence confirmed the absence of protein expression.