B6N.129-Mmp28^tm1Mani/J

Stock number: 035491
Product name: Mmp28^KO
Strain synonyms: epilysin-null

Research areas: Immunology, Inflammation and Autoimmunity Research, Internal/Organ Research

Description

Epilysin knock-out mice lack exons 4-8 of the Mmp28 locus. Knock-out mice exhibit increased macrophage infiltration of the lungs and faster bacterial clearance after exposure to Pseudomonas aeruginosa, reduced cigarette smoke-induced emphysema, and reduced bleomycin-induced pulmonary fibrosis. These mice may be useful in studying chemotaxis, immunology, and pulmonary pathophysiology.

Detailed description

The Mmp28 gene encodes the matrix metalloproteinase, epilysin, an effector enzyme expressed by bone marrow-derived macrophages and Clara cells involved in inflammatory responses and innate immune function.

The epilysin knock-out allele (also called Mmp28^KO) has a PGK-neo cassette replacing exons 4-8 of the Mmp28 gene. No Mmp28 mRNA is detected in homozygous alveolar macrophages (by RT-PCR). Homozygous knock-out mice exhibit increased macrophage infiltration of the lungs when tested 4 hours after exposure to Pseudomonas aeruginosa. These mice also exhibit faster macrophage-dependent clearance of the bacteria, reduced pulmonary neutrophilia, and reduced levels of the chemokines KC and MIP-2 in the lungs (Manicone et al., 2009).

When exposed to cigarette smoke for 3 or 6 months, Mmp28^KO mice exhibit reduced inflammatory responses including reduced neutrophil recruitment and chemokine expression, resulting in significantly lower incidence of emphysema (Manicone et al., 2017). Otherwise, homozygous mice are viable and fertile with no reported reproductive deficiency or overt phenotypes.

Mice heterozygous for the Mmp28^KO allele are also viable and fertile with normal breeding, and have no gross physical or behavioral abnormalities.

Development

The epilysin knock-out allele (also called Mmp28^KO) was created in the laboratory of Dr. William C. Parks (Washington University in St. Louis). First, a targeting vector was designed to replace exons 4-8 of the matrix metallopeptidase 28 (epilysin) locus (Mmp28) on chromosome 11 with a PGK-neo cassette. The construct was electroporated into 129X1/SvJ-derived RW4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric mice were bred with C57BL/6NTac for germline transmission. The resulting Mmp28^KO colony was then backcrossed to C57BL/6NTac mice for at least 10 generations prior to sending males to The Jackson Laboratory Repository in 2020. 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).

Allele

Symbol: Mmp28^tm1Mani
Name: targeted mutation 1, Anne M Manicone
MGI accession ID: MGI:3836773
Generation method: Targeted
Attributes: Null/Knockout
Synonyms: Epilysin^-
Marker symbol: Mmp28
Marker name: matrix metallopeptidase 28 (epilysin)
Marker synonyms: epilysin; MM28; MMP-25; MMP-28
Chromosome: 11
Strain of origin: 129X1/SvJ
Molecular note: Exons 4-7 and the coding portion of exon 8 were replaced with a neomycin selection cassette. This mutation was predicted to be a null allele because the remaining exons 1-3 only encode the proregion of the protein product. Protein product was absent in the airways of homozygote mice as determined by immunofluorescence staining.