Six6flox mice were generated from a Six6 European Conditional Mouse Mutagenesis Program(EUCOMM) KO first construct. Because the Six6 gene has only two exons and thus only one intron, an artificial intron was inserted into exon 1 to contain the flippase recombinase target(FRT)–flanked selection cassette followed by the 5' loxPsite. The intron was derived from the Ifitm2 gene and remains in the final Six6 exon 1 in the floxed mouse, where it contains the remaining single FRT element and the 5' loxP site. The plasmid was introduced by electroporation into male C57BL/6J mouse embryonic stem cells, selected by using G418 (selection against vector insertion was diphtheria toxin A on the backbone of the plasmid), and screened for homologously recombined cells by PCR. A homologously recombined clone of mouse embryonic C57BL/6J stem cells was then injected into albino C57BL/6J blastocysts to produce chimeric mice. These were screened for percentage chimerism and correct recombination. The highest percentage male chimeric mice were bred to C57BL/6J females to create heterozygous Six6flox mice. Once confirmed as correctly floxed for Six6, they were crossed with a FLPase mouse (B6;SJL-Tg(ACTFLPe)9205Dym/J - RRID:IMSR_JAX:003800) to remove the selection cassette, leaving only one FRT site and the 5' loxP site in the artificial intron and the 3' loxP site in the original intron between exons 1 and 2 to create the Six6flox conditional KO allele. LoxP sites flanked most of exon 1 of the Six6 gene. Floxed homozygous mice evidenced no previously described phenotypes, indicating that the artificial intron was correctly spliced.
Conditional phenotype: Yes, various when crossed with specific Cre alleles.
Pandolfi EC, Tonsfeldt KJ, Hoffmann HM, Mellon PL. Deletion of the Homeodomain Protein Six6 From GnRH Neurons Decreases GnRH Gene Expression, Resulting in Infertility. Endocrinology. 2019 Sep 1;160(9):2151-2164. doi: 10.1210/en.2019-00113. (Medline PMID: 31211355)
Pandolfi EC, Breuer JA, Nguyen Huu VA, Talluri T, Nguyen D, Lee JS, Hu R, Bharti K, Skowronska-Krawczyk D, Gorman MR, Mellon PL, Hoffmann HM. The Homeodomain Transcription Factors Vax1 and Six6 Are Required for SCN Development and Function. Mol Neurobiol. 2020 Feb;57(2):1217-1232. doi: 10.1007/s12035-019-01781-9. Epub 2019 Nov 9. (Medline PMID: 31705443)
|Viability and Fertility:||Female||Male||Comments|
|Homozygotes are viable:||Yes||Yes|
|Homozygotes are fertile:||Yes||Yes|
|Heterozygotes are fertile:||Yes||Yes|
|Age Reproductive Decline:||7 to 9 months||10 to 12 months|
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.
The donor or their institution limits the distribution to non-profit institutions only.