This miR-17~92Δ17,18 knock-out strain is useful in studies of the miR-17 (Mir19a & Mir19b-1), and miR-18 (Mir18) seed families, the Mirc1 microRNA cluster, Feingold syndrome, tumorigenesis and tumor progression.
Andrea Ventura, Memorial Sloan Kettering Cancer Center
The polycistronic Mirc1, microRNA cluster, or miR-17~92, consists of 6 members: Mir17, microRNA 17; Mir18, microRNA 18; Mir19a, microRNA 19a; Mir20a, microRNA 20a; Mir19b-1, microRNA 19b-1; and Mir92-1, microRNA 92-1. The region of nucleotides 2–7 from the mature miRNA 5´-end is called the miRNA seed sequence, which is essential for target recognition and binding to mRNA. The same seed sequence is often shared amongst miRNAs within the same family.
These miR-17~92Δ17,18 mice have the miR-17 and miR-18 seed families (Mir17 & Mir20a and Mir18) knocked out of the Mirc1, microRNA cluster.
No Mir17, Mir20a, or Mir18 miRNAs are detected by RT-qPCR and small RNA sequencing analysis of tail tissue from homozygotes. Mice that are homozygous for the targeted mutation are viable and fertile on the mixed B6;129 background. miR-17~92Δ17,18 mice exhibit a more severe phenotype than miR-17~92Δ17 mice. Mendelian frequency for homozygotes on the C57BL/6J background is lower than expected (3%). More than half of homozygotes on the C57BL/6J background (N7 on the C57BL/6 background) exhibit vertebral fusion and transformation, and 21% exhibit carpal bone fusion. Heterozygotes and homozygotes are smaller in size than wildtype controls, and on the C57BL/6 background (N7) exhibit shortened fifth mesophalanx bones. Homeotic transformations of one or more vertebrae are fully penetrant in homozygotes. Pre-B-cell number is reduced in homozygotes on the B6;129 background, while ossification is delayed in homozygotes on the B6 background. The severity of the phenotype (including perinatal lethality) in homozygotes increases when the mice are backcrossed to C57BL/6.
This strain is part of a miR-17~92 (Mirc1, microRNA cluster 1, including Mir17 through Mir92-1) allelic series:
(Stock No. 027317), (Stock No. 027318),
(Stock No. 027319), (Stock No. 027320), (Stock No. 027321), (Stock No. 027322).
A targeting vector containing a FRT site flanked neo selection cassette was utilized in the construction of this mutant. PCR-mediated mutagenesis was employed to delete
pre-miRNA sequences for Mir17, Mir20a and Mir18 from the targeting vector.
The construct was electroporated into (C57BL/6 x 129S4/SvJae)F1 derived V6.5 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric animals were tested for germline transmission. Heterozygotes were then bred to beta-Actin-Flpe mice, carrying the Tg(ACTFLPe)9205Dym transgene, on the C57BL/6 background, to excise the FRT flanked NEO cassette. The mice were then backcrossed to C57BL/6J for 10 generations. Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony.
|Allele Name||targeted mutation 3.1, Andrea Ventura|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||miR-17~92 delta17,18|
|Gene Symbol and Name||Mirc1, microRNA cluster 1, including Mir17 through Mir92-1|
|Strain of Origin||(C57BL/6 x 129S4/SvJae)F1|
|Molecular Note||The Mir17, Mir18 and Mir20a genes were replaced by an FRT-flanked neomycin cassette. Flp-mediated recombination removed the FRT-flanked neo cassette.|
When maintaining a live colony, these mice can be bred as homozygotes. The severity of the phenotype (including perinatal lethality) in homozygotes increases when the mice are backcrossed to C57BL/6.
When using the B6.Cg-Mirc1tm3.1Aven/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #027321 in your Materials and Methods section.