B6.129P2(Cg)-Ago4^tm1.1Peco/J

Stock number: 021335
Research areas: Apoptosis Research, Cell Biology Research, Reproductive Biology Research, Research Tools

Description

This strain may be useful for studying the regulation of meiotic entry and meiotic sex chromosome inactivation in germ cells by small RNA pathways.

Detailed description

These AGO4-/- mice lack exons 3-17 of the argonaute RISC catalytic subunit 4 (Ago4) gene. This gene encodes one of the four Argonaute genes which are essential for processing of small RNAs in multiple RNA interference pathways. Ago4 is mainly expressed in the testis, specifically localized to the XY body during meiotic prophase I. Homozygous females and heterozygous males are viable and fertile, while homozygous males are subfertile. Males exhibit severely reduced fertility associated with premature entry of male germ cells into meiosis, and silencing defects in the XY body during meiosis. They have reduced testis size, lower sperm counts, and exhibit an increase in apoptotic cells within the prophase I layers of the seminiferous epithelium.

Development

A targeting vector was designed to insert a loxP site upstream of exon 3, and a frt-flanked neomycin resistance (neo) cassette, followed by a second loxP site, downstream of exon 17 of the argonaute RISC catalytic subunit 4 (Ago4) gene. The construct was electroporated into 129P2-derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and resulting chimeric mice were bred together. Offspring were bred with B6.129S4-Gt(ROSA)26Sor/RainJ mice (Stock No. 009086) to delete the neo cassette, and progeny were crossed to remove the Flp-expressing transgene, resulting in a colony homozygous for the floxed-AGO4 allele. Floxed-AGO4 offspring were bred with FVB/N-Tg(ACTB-cre)2Mrt/J transgenic mice (Stock No. 003376) to delete the floxed exons. These AGO4-/- mice were bred to C57BL/6J mice for at least 7 generations. Upon arrival, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Ago4^tm1.1Peco
Name: targeted mutation 1.1, Paula E Cohen
MGI accession ID: MGI:5438526
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Ago4
Marker name: argonaute RISC catalytic subunit 4
Chromosome: 4
Strain of origin: 129P2/OlaHsd
Molecular note: A loxP site was inserted in intron 2 and an FRT flanked pgk-neo cassette and loxP site were inserted into intron 17 via homologous recombination. Recombinase mediated recombination removed exons 3-17 and the neo cassette.