These mutant mice carry a targeted mutation of Th (tyrosine hydroxylase) and exhibit an embryonic lethal phenotype. Homozygous embryos exhibit abnormal heart development with dilated atria, thin atrial walls, ventricular hypoplasia, blood congestion and reduced levels of norepinephrine, epinephrine and dopamine. This mutant mouse strain may be useful in studies of catecholamine biosynthesis and heart development
Dona Chikaraishi, Duke University Medical Center
Mice that are heterozygous for the targeted mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. A small amount of gene product (protein) is detected by Western blot analysis of heads of homozygotes embryonic day 14.5 in age. Homozygous mice have an embryonic lethal phenotype, begin to die at embryonic day 11.5 and fail to develop past embryonic day 14.5. Homozygous embryos exhibit abnormal heart development with dilated atria, thin atrial walls, ventricular hypoplasia and blood congestion, dying with symptoms of congestive heart failure. Catecholamine containing cells are not detected by glyoxylic acid-induced histofluorescence analysis of embryos. Administration of L-Dopa or +/- isoproterenol to pregnant heterozygous females rescues approximately 90% of the homozygous pups, which then survive up to 3 weeks after birth. Homozygous pups can also be rescued by exposuring the pregnant dam to high oxygen (33-60%). Norepinephrine, epinephrine and dopamine levels in heart, skin, adrenal gland and brain tissues are significantly reduced in homozygous mutants. Heterozygotes also have reduced levels of catecholamine. This mutant mouse strain may be useful in studies of catecholamine biosynthesis and heart development.
A targeting vector containing neomycin resistance and herpes simplex virus thymidine kinase genes was used to disrupt exons 6, 7 and 8, which encode part of the catalytic domain. The construct was electroporated into 129S2/SvPas derived D3 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting chimeric animals were crossed to C57BL/6J mice, and then crossed to CD-1 (ICR) outbred mice for nine generations.
|Allele Name||targeted mutation 1, Suzanne Roffler-Tarlov|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||Th-; TH-null|
|Gene Symbol and Name||Th, tyrosine hydroxylase|
|Strain of Origin||129S2/SvPas|
|Molecular Note||A neomycin selection cassette was used to replace sequence from exons 6, 7, and 8. The deleted region encompassed 268 nucleotides encoding a portion of the catalytic domain. Low levels of a peptide, slightly smaller than normal, were detected by Western blot analysis of extracts obtained from homozygous mutant fetuses. The mutant peptide could not be detected by immunohistochemical analysis of fetal adrenals or in fetal or postnatal brains.|
|Mutations Made By|| |
Suzanne Roffler-Tarlov, Tufts University School of Medicine
When maintaining a live colony, these mice can be bred as heterozygotes. Homozygotes have an embryonic lethal phenotype and die between embryonic days 12.5-14.5.
When using the STOCK Thtm1Srt/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #008779 in your Materials and Methods section.