STOCK Tmprss2^{tm1.1(cre/ERT2)Ychen}/J

Stock number: 040657
Product name: Tmprss2-CreER^T2
Strain synonyms: Tmprss2-CreERT2-IRES-nlsEGFP
Research areas: Cancer Research, Cell Biology Research, Research Tools, Virology Research

Description

Tmprss2-CreER^T2 knock-in/knock-out mice express a CreER fusion protein and IRES-nlsGFP driven by the Tmprss2 endogenous promoter, while abolishing endogenous Tmprss2 expression. When these mice are bred with mice containing a loxP-flanked sequence of interest, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the floxed sequences in the Tmprss2-expressing cells of the offspring. These mice may be useful for studying the role of TMPRSS2 in certain cancers, such as prostate and colon, but also in viral cell entry.

Detailed description

Tmprss2 (transmembrane protease, serine 2) codes for a cell surface serine protease that is expressed in many epithelial tissues, including prostate, bladder, stomach, intestines, and lung. Both SARS-CoV and SARS-CoV-2 (COVID-19) use angiotensin-converting enzyme 2 (ACE2) and TMPRSS2 to facilitate entry to lung epithelial cells. In the prostate, TMPRSS2 is highly expressed in luminal epithelial cells. In ~50% of prostate cancers, there are oncogenic genomic fusions between non-coding exon 1 of TMPRSS2 and several ETS family members (ERG, ETV1, ETV4, ETV5) to drive aberrant overexpression. These Tmprss2-CreER^T2 knock-in/knock-out (KI/KO) mice express a CreER fusion protein and an IRES-nlsGFP protein driven by the Tmprss2 endogenous promoter, while abolishing endogenous Tmprss2 expression.

Homozygous mice are viable and fertile with no overt phenotype. Restricted to the cytoplasm, Cre-ERT can only gain access to the nuclear compartment after exposure to tamoxifen. When Tmprss2-CreER^T2 mice are bred with mice containing loxP-flanked sequences, tamoxifen-inducible Cre-mediated recombination will result in deletion of the floxed sequences in the cre-expressing cells of the offspring. The donating investigator notes that the nuclear GFP signal is dim at baseline levels and is not useful for direct lineage tracing.

The donating laboratory confirmed expression and recombination efficiency by crossing the Tmprss2-CreER^T2 mice to a RCL-EYFP reporter mouse line (Stock No. 007903). After 2 weeks of tamoxifen treatment, the resulting Tmprss2-CreER^T2; RCL-EYFP/EYFP mice demonstrated robust YFP labelling in the epithelial cells of the stomach, colon, esophagus, bladder and prostate, as well as other analyzed tissues, similar to mouse Tmprss2 expression patterns. These Tmprss2-CreER^T2 mice may be useful for studying the role of TMPRSS2 in certain cancers, such as prostrate and colony, but also in viral entry into cells.

Development

The Tmprss2-CreER^T2 knock-in/knock-out (KI/KO) targeting vector was designed to replace exon 2 of the transmembrane protease, serine 2 (Tmprss2) gene with a cre/ERT2 fusion protein and IRES-nlsGFP. Specifically, this vector includes (from 5' to 3') an adenovirus splice acceptor (SA) site, an FRT-flanked PGK-neomycin cassette, followed by a cre/ERT2 fusion gene (Cre recombinase fused to a human estrogen receptor ligand binding domain), an internal ribosome entry site (IRES) and nuclear localization signal-tagged green fluorescent protein (nls-GFP) sequence. The construct was electroporated into albino C57BL/6J-derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts and the resulting chimeric mice were bred to albino C57BL/6J (Stock No. 000058) mice to confirm germline transmission. Heterozygous Tmprss2-CreER^T2 KI/KO mice were then bred to a FLPe-recombinase mouse line (Stock No. 003800) to remove the FRT-flanked neomycin cassette. Tmprss2-CreER^T2 KI/KO mice were then crossed to an Ai3(RCL-EYFP) reporter line (Stock No. 007903). The donor males provided to The Jackson Laboratory were homozygous for both the Tmprss2-CreER^T2 KI/KO allele and for the Ai3(RCL-EYFP) allele. To remove the Ai3(RCL-EYFP) allele, these mice were backcrossed to C57BL/6J (Stock No. 000664) mice for 1-2 generations at The Jackson Laboratory.

Allele

Symbol: Tmprss2^{tm1.1(cre/ERT2)Ychen}
Name: targeted mutation 1.1, Yu Chen
MGI accession ID: MGI:5911389
Generation method: Targeted
Attributes: Recombinase-expressing; Reporter; Inducible
Synonyms: Tmprss2-CreER^T2
Marker symbol: Tmprss2
Marker name: transmembrane protease, serine 2
Marker synonyms: D16Ertd61e; epitheliasin; PRSS10
Chromosome: 16
Strain of origin: C57BL/6J
Molecular note: The targeting construct replaced exon 2 with an FRT-flanked neomycin resistance cassette, an inducible cre recombinase gene (cre/ERT2), and IRES-nlsGFP. Flp-mediated recombination removed the selection cassette.