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The Lif gene codes for the cytokine leukemia inhibitory factor (LIF), which is implicated in many biological processes including inflammation, implantation, differentiation of leukemic cells, hematopoietic differentiation and neuronal cell differentiation. These Lif-floxed mice have lox sites flanking exon 2 of the Lif gene.
Homozygous floxed mice are viable and fertile with no overt phenotype. When bred to mice that express tissue-specific Cre recombinase, offspring will have exon 2 deleted, resulting in complete loss of protein in the cre-expressing cells. When these Lif-floxed mice are bred to an Hprt1-Cre mouse line, leading to global deletion of LIF protein, the resulting Lif knock-out (KO) mice demonstrate reduced body weight, bone defects, and shortened tails as well as impaired fertility in female knock-outs. Lif-floxed mice may be useful for studying the role of LIF in immunity, inflammation and implantation.
Conditional phenotype: Cre-mediated deletions may lead to variable phenotypes depending on the Cre used.
The Lif-floxed targeting vector was designed to insert loxP sites flanking exon 2 of the leukemia inhibitory factor (Lif) gene. The construct also contained an FRT-flanked neomycin cassette. The final targeting construct was electroporated into (129S6/SvEvTac x C57BL/6NCr)F1-derived G4 embryonic stem (ES) cells and correctly targeted ES cells were aggregated with morula stage recipient embryos. Chimeric male mice were bred to CD1 females. Resulting progeny were bred to B6.Cg-Tg(ACTFLPe)9205Dym/J (JAX Stock No. 005703) mice to remove the neomycin cassette. The resulting Lif-floxed mice, with neomycin cassette removed and floxed exon 2 intact, were then backcrossed to C57BL/6J background for 8 generations by the donating laboratory (see SNP note below). 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.
In 2025, a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the males sent to The Jackson Laboratory Repository. Of the 43 markers throughout the genome, one on Chromosome 9 (~101.0 Mb) was segregating with an unknown source and one on Chromosome 11 (~21.0 Mb) was segregating with 129 allele-type. Of note, the Lif locus is on Chromosome 11 ~4.2 Mb.
Disclaimer: If MMRRC Strain Genetic Quality Control (GQC; based on MiniMUGA genotyping and analysis) has been completed for this strain, the information might differ from the genetic background information provided by the submitter. MiniMUGA genetic analysis is done on a strain’s tissue samples taken when archived by or ordered from the assigned MMRRC Center.
Limited quantities of breeder mice (up to 2 males and 2 females or 4 mice) per investigator per month are available from a live colony, usually available to ship in under 12 weeks. Larger quantities may be available, please contact the distributing center directly at csmmrrc@jax.org for more details.
Cryopreserved material may be available upon request, please inquire to csmmrrc@jax.org for more information.
A Commercial License Agreement from the Donor is required for for-profit entities to use this strain. For more information, please contact Technology Transfer Office.
A Commercial License Agreement from the Donor is required for for-profit entities to use this strain. For more information, please contact Technology Transfer Office
Distribution of this strain requires submission of the MMRRC Conditions of Use (COU). A link to the COU web form will be provided via email after an order has been placed; the form should be completed then or the email forwarded to your institutional official for completion.
Additional charges may apply for any special requests. Shipping costs are in addition to the basic distribution/resuscitation fees. Information on shipping costs and any additional charges will be provided by the supplying MMRRC facility.
1 The distribution fee covers the expense of rederiving mice from a live mouse; you will receive the resulting litter. The litter will contain at minimum one mutant carrier; the actual number of animals and the gender and genotype ratios will vary. (Typically, multiple breeder pairs can be established from the recovered litter.) Prior to shipment, the MMRRC will provide information about the animals recovered. If you anticipate or find that you need to request specific genotypes, genders or quantities of mice in excess of what is likely from a resuscitated litter, you may discuss available options and pricing with the supplying MMRRC facility.
2 An aliquot contains a sufficient number of embryos (in one or more vials or straws and based on the transfer success rate of the MMRRC facility) to transfer into one to three recipients. The MMRRC makes no guarantee concerning embryo transfer success experienced in the recipient investigator's laboratory. Neither gender nor genotype ratios are guaranteed.
3 An aliquot is one straw or vial with sufficient sperm to recover at least one litter of mice, as per provided protocols, when performed at the MMRRC facility. The MMRRC makes no guarantee concerning the success of these procedures when performed outside the MMRRC facilities.
4 The distribution fee covers the expense of resuscitating mice from the cryo-archive; you will receive the resulting litter. The litter will contain at minimum one mutant carrier; the actual number of animals and the gender and genotype ratios will vary. (Typically, multiple breeder pairs can be established from the recovered litter.) Prior to shipment, the MMRRC will provide information about the animals recovered. If you anticipate or find that you need to request specific genotypes, genders or quantities of mice in excess of what is likely from a resuscitated litter, you may discuss available options and pricing with the supplying MMRRC facility.
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