B6;129-Dbh^tm2(Th)Rpa Th^tm1Rpa/J

Stock number: 009688
Research areas: Developmental Biology Research, Neurobiology Research, Research Tools

Description

Dopamine-deficient (DA-deficient, DA^-/-, or DD) mice are homozygous for the TH mutant allele and heterozygous for the DBH-TH mutant allele (Th^-/-;Dbh^Th/+). While no expression from the TH mutant allele is observed in any tissues (resulting in deficiency of both dopamine (DA) and norepinephrine (NE)), the DBH-TH mutant allele contains the TH coding sequence under the control of the endogenous DBH promoter region and restores TH expression in noradrenergic neurons. These DD mice may be useful in studying dopaminergic neurobiology (including neurotransmitters, addiction, feeding, learning and memory, catecholamines, and Parkinsonian phenotypes).

Detailed description

Mice heterozygous for both targeted mutations are viable and fertile. Dopamine-deficient (DA-deficient, DA^-/-, or DD) mice are homozygous for the TH mutant allele and heterozygous for the DBH-TH mutant allele (Th^-/-; Dbh^Th/+). While no expression from the TH mutant allele is observed in any tissues (resulting in deficiency of both dopamine (DA) and norepinephrine (NE)), the DBH-TH mutant allele contains the TH coding sequence under the control of the endogenous DBH promoter region and restores TH expression in noradrenergic neurons. DD mice become hypoactive and hypophagic around two weeks of age and usually die before four weeks of age. Treatment with L-DOPA, the product of TH enzymatic activity, rescues size, feeding, and life span. These DD mice may be useful in studying dopaminergic neurobiology (including neurotransmitters, addiction, feeding, learning and memory, catecholamines, and Parkinsonian phenotypes).

NOTE: Th^-/-; Dbh^Th/+ mice congenic on a C57BL/6 genetic background may exhibit declining birth rates and increased mortality (Hnasko et al 2007 J Neurosci 27:12484-8).

Development

To generate the TH knockout allele , the pTH4 targeting vector was designed to replace the proximal promoter and first two exons of the Th locus with a PGK-neomycin resistance cassette. The construct was electroporated into 129S7/SvEvBrd-Hprt1⁺ derived AB1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and the resulting heterozygous mice were maintained on a C57BL/6/129S hybrid background.


To generate the DBH-TH mutant allele (Dbh^Th), the pDBH-TH vector was designed to insert the entire mouse Th coding region (including 1 kb sequence after the polyA site) and a neo cassette between exons 1 and 2 of the Dbh locus. The construct was electroporated into unspecified embryonic stem (ES) cells and heterozygous animals were obtained.


Next, mice heterozygous for the TH mutant allele (Th^-/+) were bred with mice heterozygous for the DBH-TH mutant allele (Dbh^Th/+). The donating investigator reports that double mutant mice were subsequently backcrossed to C57BL/6J mice for several (9-14) generations prior to arrival at The Jackson Laboratory. Upon arrival, mutant mice were bred with C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.

A 27 SNP (single nucleotide polymorphism) panel analysis performed by The Jackson Laboratory revealed the mice to be ~85% C57BL/6 genetic background; 4 of 27 markers were segregating for C57BL/6 or 129S allele-type markers (on chromosomes 2, 3, 8 and 11). These data suggest that, prior to arrival at the Jackson Laboratory, the mice were not backcrossed to C57BL/6 for as many generations as originally reported.

Allele

Symbol: Th^tm1Rpa
Name: targeted mutation 1, Richard D Palmiter
MGI accession ID: MGI:1860450
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Th
Marker name: tyrosine hydroxylase
Chromosome: 7
Strain of origin: 129S7/SvEvBrd-Hprt1⁺
Molecular note: A neomycin selection cassette replaced the proximal promoter and exons 1 and 2.

Allele

Symbol: Dbh^tm2(Th)Rpa
Name: targeted mutation 2, Richard D Palmiter
MGI accession ID: MGI:1928960
Generation method: Targeted
Marker symbol: Dbh
Marker name: dopamine beta hydroxylase
Chromosome: 2
Strain of origin: Not Specified
Expressed genes: Th,tyrosine hydroxylase,mouse, laboratory
Molecular note: The entire Th coding region, including 1kb sequence after the polyadenylation site and a neomycin resistance cassette, was inserted between exons 1 and 2 of the Dbh gene.