B6.Cg-Mirc1^tm2.1Aven/J

Stock number: 027319

Description

This miR-17~92^Δ19 knock-out strain is useful in studies related to the Mir19a and Mir19b-1 seed family, the Mirc1 microRNA cluster, and Myc-driven tumorigenesis and tumor progression.

Detailed description

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-17~92^Δ19 mice have the miR-19 single seed family (Mir19a and Mir19b-1) knocked out of the Mirc1, microRNA cluster.

No Mir19a or Mir19b-1 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, and slightly smaller than wildtype controls. Mendelian frequency for homozygotes on the C57BL/6J background is lower than expected (5%). 20% of homozygotes on the C57BL/6J background (N7 on the C57BL/6 background) exhibit vertebral fusion. 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).

Development

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 Mir19a and Mir19b-1 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

Symbol: Mirc1^tm2.1Aven
Name: targeted mutation 2.1, Andrea Ventura
MGI accession ID: MGI:5648458
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Mirc1
Marker name: microRNA cluster 1, including Mir17 through Mir92-1
Chromosome: 14
Strain of origin: (C57BL/6 x 129S4/SvJae)F1
Molecular note: The Mir19a and Mir19b-1 genes were replaced by an FRT-flanked neomycin cassette. Flp-mediated recombination removed the FRT-flanked neo cassette.