MybF/F floxed mutant mice possess loxP sites flanking exon 6 of the myeloblastosis oncogene gene. This strain may be useful for studying the proliferation and differentiation of hematopoietic progenitor cells.
E. P. Reddy, Mount Sinai School of Medicine
MybF/F floxed mutant mice possess loxP sites flanking exon 6 of the myeloblastosis oncogene (Myb). MYB is a transcription factor involved in the proliferation and differentiation of hematopoietic progenitor cells. Mice that are homozygous for this allele are viable and fertile. When these mutant mice are bred to mice that express Cre recombinase, resulting offspring will have exon 6 deleted in cre-expressing tissues.
When crossed to B6.Cg-Tg(Lck-cre)548Jxm/J mice (Stock No. 003802) expressing Cre recombinase T lymphocytes, T cells in resulting mybF/F/LckCre mice did not progress from the DN3 stage to the DN4 stage of thymocyte development. Thymic cellularity is decreased to 11% of that seen in controls. Double positive (DP) thymocytes are reduced by 62% compared to littermate controls.
When crossed to B6.Cg-Tg(Mx1-cre)1Cgn/J mice (Stock No. 003556) expressing Cre recombinase in adult bone marrow, resulting mybF/F/MxCre mice have reductions of hematopoietic lineages including neutrophilic, monocytic, B lymphoid, erythroid, and, megakaryocytic cells after polyinosinic-polycytidylic acid (pIpC) administration.
A targeting vector was designed to insert a loxP-flanked neomycin resistance (neo) cassette upstream of exon 6, and a single loxP site downstream of exon 6 of the myeloblastosis oncogene (Myb) gene. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-Kitl+-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were transiently transfected with a pPGKcre-bpA expression plasmid to delete the neo cassette. Resulting ES cells contained multiple gene rearrangments; intact floxed-exon 6, intact floxed-neo cassette, or excision of both exon 6 and the neo cassette. Correctly targeted ES cells, containing only the floxed-exon 6, were injected into C57BL/6 x DBA2 blastocysts and resulting chimeric males were bred with C57BL/6J females. Resulting MybF/F offspring were bred to C57BL/6J mice for at least 10 generations. Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).
|Allele Name||targeted mutation 1, E Premkumar Reddy|
|Allele Type||Targeted (Conditional ready (e.g. floxed), No functional change)|
|Gene Symbol and Name||Myb, myeloblastosis oncogene|
|Strain of Origin||(129X1/SvJ x 129S1/Sv)F1-Kitl+|
|Molecular Note||Exon 6 encoding the high-affinity DNA-binding domain was flanked with loxP sites by homologous recombination of a construct that also contained a PGK-neo and thymidine kinase selection markers. The PGK-neo-thymidine kinase marker was excised by transient transfection of properly targeted ES cells with a cre-expressing plasmid and left exon 6 flanked by loxP sites.|
When maintaining a live colony mice homozygous for the floxed allele may be bred together.
When using the MybF mouse strain in a publication, please cite the originating article(s) and include JAX stock #028881 in your Materials and Methods section.