These R439H Tph2 knockin mice contain a mutation analogous to one found in humans with unipolar major depression.
Marc G Caron, Duke University Medical Center
R439H Tph2 knockin mice contain the amino acid mutation R439H in exon 11 of the tryptophan hydroxylase 2 (Tph2) gene. This substitution creates a loss of function mutation, analogous to the R441H Tph2 mutation found in humans with unipolar major depression. Tph2 encodes an enzyme required for the synthesis of brain serotonin (5-HT), which is dysregulated in mental conditions as diverse as depression, anxiety disorders, bipolar disorder, autism, and schizophrenia. This R441H TPH2 mutation has been identified in individuals from a small cohort of elderly patients with major unipolar depression. Homozygotes are viable and fertile. Tph2 activity and brain 5-HT production are reduced in the frontal cortex (FC) and hippocampus by 40% in heterozygotes and by 80% in homozygotes. These mice exhibit a dose dependent activation of glycogen synthase kinase 3 (GSK3), which is a signaling molecule modulated by many psychiatric therapeutic agents. These mice exhibit behavioral abnormalities such as increased aggression towards other males and increased anxiety responses.
A targeting construct was designed to insert a loxP-flanked neomycin (neo) resistance cassette downstream of exon 9 of the tryptophan hydroxylase 2 (Tph2) gene. A G to A point mutation at position 1449 was introduced in exon 11, corresponding to human amino acid 441, resulting in the a loss of function mutation, R439H, commonly found in humans with unipolar major depression. This targeting construct, designed to replace exons 10 and 11 of the mouse Tph2 gene, was electroporated into 129S6/SvEvTac-derived embryonic stem (ES) cell line. Correctly targeted ES cells were transiently transfected with a Cre expression plasmid to delete the neo cassette and correctly targeted ES cells were injected into blastocysts. The resulting chimeric mice were maintained on a mixed background. 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 Name||targeted mutation 1, Marc G Caron|
|Allele Type||Targeted (Humanized sequence)|
|Allele Synonym(s)||R439H Tph2; Tph2-KI|
|Gene Symbol and Name||Tph2, tryptophan hydroxylase 2|
|Strain of Origin||129S6/SvEvTac|
|Molecular Note||Exon 10 and 11 were replaced with a floxed neo cassette and another copy of exon 10 and 11 with a nucleotide transition of G to A at position 1449 within exon 11. This transition results in an amino acid substitution of a histidine for an arginine at position 439 (R439H). The neo cassette was removed by transient cre-mediated recombination in ES cells. This allele was created to mimic the R441H mutation identified in humans that leads to 80% reduced enzymatic activity in PC12 cells.|
When maintaining a live colony, homozygous mice may be bred together.
When using the R439H Tph2 KI mouse strain in a publication, please cite the originating article(s) and include JAX stock #027307 in your Materials and Methods section.