B6N.Cg-Mapkapk2^tm2.1Yaff/J

Stock number: 032450
Product name: MK2^FL
Research areas: Apoptosis Research, Cancer Research, Cell Biology Research, Neurobiology Research, Research Tools

Description

MK2^FL is a floxed allele with loxP sites flanking exon 2 of the MAP kinase-activated protein kinase 2 gene (Mapkapk2). Cre recombinase-mediated removal of the floxed sequence creates a knock-out allele. MK2^FL mice may be useful in studying the p38 MAP kinase/MK2 pathway, other checkpoint control pathways, DNA damage response, DNA repair, cell cycle arrest, apoptosis and inflammation-driven tumorigenesis, as well as with other cancer models to study sensitization of tumors to DNA-damaging chemotherapeutics in vivo.

Detailed description

MAP kinase-activated protein kinase 2 (MK2) is a kinase regulated through direct phosphorylation by p38 MAP kinase. The p38MAPK/MK2 pathway is a DNA damage responsive, cell-cycle checkpoint pathway that is mediated by the stress-activated protein kinase p38 mitogen-activated protein kinase (MAPK) and its substrate MAPKAP kinase-2 (MK2).

MK2^FL is a floxed allele with loxP sites flanking Mapkapk2 exon 2. Exposure to Cre recombinase results in the knock-out allele (MK2^D) with no expression of both known MK2 isoforms (46 KDa and 42 KDa). In the absence of Cre recombinase, mice homozygous for the floxed allele (MK2^FL/FL) are viable and fertile with normal fertility, and no gross phenotypic or behavioral abnormalities.

Specifically, when MK2^FL are bred to CMV-Cre mice (Tg(CMV-cre)1Cgn; see Stock No. 006054), the resulting global MK2 knock-out mice (MK2^D/D) show total loss of MK2 expression (both known MK2 isoforms) in multiple tissues by western blot, RT-PCR and immunohistochemistry.

To study the effect of MK2 on tumor incidence in a DSS-induced colitis protocol, MK2^FL were bred to Villin-Cre mice (Tg(Vil-cre)20Syr) or to LysM-Cre mice (Lyz2^tm1(cre)Ifo; Stock No. 004781) to generate intestinal epithelia knock-out mice (IEC MK2 KO; mixed C57BL/6N;129SvJ) or myeloid lineage knock-out mice (LysM MK2 KO ; N5 onto C57BL/6N), respectively. Compared to similarly-treated controls, the IEC MK2 KO mice exhibited enhanced tumor incidence whereas the LysM MK2 KO mice developed significantly smaller tumors. [Suarez-Lopez et al. 2018 PNAS 115:E4236 (PMID:29666270)]

MK2^FL is a "traditional" floxed allele (loxP sites in same orientation) designed to eliminate Mapkapk2 exon 2 permanently upon exposure to Cre recombinase. Additionally, The Jackson Laboratory Repository has the MK2 "Cre-inducible/reversible" mouse line with inward-facing loxP sites flanking Mapkapk2 exon 2 (MK2^CV; Stock No. 024176). Those MK2^CV mice allow exon 2 to reversibly switch from the MK2-expressing orientation (MK2^+CV) to the MK2-null orientation (MK2^-CV) and back as long as Cre recombinase is active in the cell - which can generate MK2^+/- chimeric cell populations.

MK2^CV mice may be bred to β-actin-Cre driver mice to generate the "whole-body MK2 knock-out" animals. Those "whole-body MK2 knock-out" mice and the global MK2 knock-out mice (MK2^D/D) both show complete loss of both MK2 isoforms and behave similarly in DSS-induced colitis and LPS challenge protocols. [Suarez-Lopez et al. 2018 PNAS 115:E4236 (PMID:29666270)]

Development

The MK2^FL floxed allele was created by Dr. Michael B. Yaffe (Massachusetts Institute of Technology). A targeting vector was designed to insert a loxP site upstream of exon 2, and a second loxP site followed by a frt-flanked PGK-neo cassette just downstream of exon 2 of the MAP kinase-activated protein kinase 2 locus (Mapkapk2) on chromosome 1. The construct was electroporated into 129/B6 hybrid embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. Chimeric mice were bred with FLPe-expressing mice (N1 on C57BL/6NTac and then N4 onto C57BL/6J) for germline transmission and deletion of the PGK-neo cassette. The donating investigator reports the resulting MK2^FL colony was bred once to a non-germline Cre recombinase strain (C57BL/6J.Tie2-Cre), and then the MK2^FL colony was maintained by backcrossing MK2^FL males to C57BL/6NTac females for ten generations (the FLPe- and Cre-expressing alleles were removed). After this, MK2^FL males (black coat color) were sent to The Jackson Laboratory Repository in 2018. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6NJ oocytes (Stock No. 005304).
Of note, the donating investigator reports that the Y chromosome may not have been fixed to the C57BL/6N background during backcrossing.

Allele

Symbol: Mapkapk2^tm2.1Yaff
Name: targeted mutation 2.1, Michael Yaffe
MGI accession ID: MGI:6203066
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Synonyms: MK2^FL
Marker symbol: Mapkapk2
Marker name: MAP kinase-activated protein kinase 2
Marker synonyms: MAPKAP kinase 2; MAPKAP-K2; MK2; MK-2; Rps6kc1
Chromosome: 1
Strain of origin: (C57BL/6 x 129S4/SvJae)F1
Molecular note: Exon 2 was floxed and the 5' loxP site is in reverse complement sequence to the 3' loxP site. Flp-mediated recombination removed the selection cassette inserted downstream of the loxP site inserted into intron 2.