Exon 2 of the Lin28b (lin-28 homolog B (C. elegans)) gene, encoding the functional cold shock domain, was flanked by loxP sites in this conditional mutation strain. Cre-mediated excision of the floxed segment creates a knockout allele.
George Q. Daley, Children's Hospital Boston
Lin28b (lin-28 homolog B (C. elegans)) is highly expressed during normal embryogenesis and is upregulated in some cancers to potently and selectively block the maturation of let-7 (Mirlet7) tumor suppressor microRNA's.
Exon 2 of the gene, encoding the functional cold shock domain, was flanked by loxP sites in this conditional mutation strain. Cre-mediated excision of the floxed segment creates a knockout allele.
Male (but not female) knockout mice created through crosses with germline-specific Ddx4-cre mice (e.g. Stock No. 006954) show postnatal dwarfism and reduced organ weights.
Skeletal muscle-directed knockouts of Lin28b, created through crosses with Myf5 (myogenic factor 5)-cre mice, produce males with phenotypic dwarfism that recapitulates that of the germline deletion. Muscle-specific loss of LIN28B leads to insulin resistance and impaired glucose uptake.
Exon 2, encoding the functional cold shock domain, was flanked by loxP sites and an FRT-flanked PGK-neomycin cassette was introduced to intron 2. The mutation was created in (C57BL/6 x 129S4/SvJae)F1-derived v6.5 embryonic stem (ES) cells. Chimeric males were bred to BALB/c females. The neomycin cassette was excised via a Flp recombinase. This strain was backcrossed to C57BL/6 for 6 generations by the donating lab (see SNP note below).
A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 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 rederived living colony at The Jackson Laboratory Repository. Eight of the 27 markers throughout the genome were segregating suggested an incomplete backcross. Also, 2 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic.
|Allele Name||targeted mutation 1.2, George Q Daley|
|Allele Type||Targeted (Conditional ready (e.g. floxed), No functional change)|
|Gene Symbol and Name||Lin28b, lin-28 homolog B (C. elegans)|
|Strain of Origin||(C57BL/6 x 129S4/SvJae)F1|
|Molecular Note||A loxP site was inserted upstream of exon 2. An FRT-flanked neomycin resistance cassette with a 5' loxP site was inserted downstream of exon 2. FLP-mediated recombination removed the neomycin cassette.|
Homozygous and heterozygous floxed mice are viable and fertile.
When using the STOCK Lin28btm1.2Gqda/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #023914 in your Materials and Methods section.