The TFflox floxed allele has loxP sites flanking exon 1 of the coagulation factor III gene (F3; tissue factor [TF], thromboplastin or CD142). Removal of the floxed sequence creates a null allele. These mice may be useful in studying deficiency of the primary activator of the blood coagulation cascade.
Nigel Mackman, University of North Carolina at Chapel Hill
The coagulation factor III gene (F3; tissue factor [TF], thromboplastin or CD142) encodes a cell surface glycoprotein that is the primary activator of the blood coagulation cascade.
The TFflox allele has loxP sites flanking exon 1 of the coagulation factor III gene. Mice homozygous for the floxed allele are viable and fertile with no reported abnormalities.
When bred to mice that express Cre recombinase, the resulting offspring will have TF RNA (and functional TF protein expression) deleted in cre-expressing tissues.
For example, when bred to germline Cre-expressing mice (EIIa-Cre; Stock No. 003724), the resulting TF global knockout homozygotes die in utero.
TFflox mice allow studying cell/tissue-specific TF deficiency in myeloid cells (LysM-Cre ; Stock No. 004781), megakaryocytes and platelets (Pf4-iCre; Stock No. 008535), vascular smooth muscle (SM22-Cre; see Stock No. 017491) and hepatocytes (Alb-Cre; Stock No. 003574).
In addition, breeding TFflox mice to Tie2-Cre transgenic mice (Stock No. 008863) results in offspring with TF deficiency in both endothelial cells and hematopoietic cells. Such mice may also be useful in studying sickle cell anemia in the Townes model (Stock No. 013071).
The TFflox floxed allele was created by Dr. Nigel Mackman (while at The Scripps Research Institute, now at University of North Carolina at Chapel Hill). First, a targeting vector was designed to have a loxP site upstream of exon 1, and a second loxP site followed by an frt-flanked neo cassette just downstream of exon 1 of the coagulation factor III gene (F3; tissue factor [TF], thromboplastin or CD142) on chromosome 3.
The construct was electroporated into 129S6/SvEv-derived CMTI-1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric males were bred with C57BL/6J females for germline transmission and to establish the TFfloxneo colony.
TFfloxneo mice were bred with ACTB-Flpe-transgenic mice (on an undisclosed genetic background) for germline deletion of the neo cassette.
The resulting TFflox mice were bred with C57BL/6J wildtype mice for ~3-4 generations (and the Flp-expressing transgene was removed) prior to sending males to The Jackson Laboratory Repository in 2016.
Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).
Of note, it is not known if the Y chromosome has been fixed to the C57BL/6J background during backcrossing.
|Allele Name||targeted mutation 1, Nigel Mackman|
|Allele Type||Targeted (Conditional ready (e.g. floxed), No functional change)|
|Gene Symbol and Name||F3, coagulation factor III|
|Strain of Origin||129S6/SvEvTac|
|Molecular Note||A loxP site was inserted upstream of exon 1 and an frt-flanked neo cassette with a 5' loxP site was inserted downstream of exon 1. Germ line, flp-mediated reombination was used to remove the neo cassette leaving exon 1 floxed.|
When maintaining a live colony, heterozygous mice may be bred together, to wildtype mice from the colony or to C57BL/6J inbred mice (Stock No. 000664). Alternatively, homozygous mice may be bred together.
When using the TFflox mouse strain in a publication, please cite the originating article(s) and include JAX stock #028721 in your Materials and Methods section.