FVB.129S6-Gt(ROSA)26Sor^{tm3(Pik3ca*E545K)Egan}/J

Stock number: 040558
Product name: R26-Pik3ca^E545K
Research areas: Cancer Research, Research Tools

Description

This R26-Pik3ca^E545K strain carries a floxed transcriptional stop cassette upstream of the E545K mutant allele of Pik3ca within the Gt(ROSA)26Sor locus. When crossed with an MMTV-Cre strain, progeny develop mammary tumors as well as lymphoid and skin malignancies. The R26-Pik3ca^E545K mice enable conditional, Cre recombinase-dependent expression of the mutant form of murine Pik3ca^E545K from the ubiquitous Gt(ROSA)26Sor promoter. When crossed with cell/tissue-specific Cre-expressing mice or injected with adenoviruses expressing Cre recombinase (Ad-Cre), this model is useful in studying highly activated tumor formation and progression.

Detailed description

Pik3ca (phosphatidylinositol 3-kinase, catalytic, alpha polypeptide; also called PI3K) encodes the p110alpha catalytic subunit of phosphatidylinositol 3-kinase. In this strain, an E545K mutant form of murine Pik3ca was targeted to the Gt(ROSA)26Sor locus behind a floxed PGK-Neo stop cassette. The R26-Pik3ca^E545K allele, upon Cre-mediated recombination, expresses the missense mutant form of Pik3ca^E545K frequently found in various cancers. In cancers, PIK3CA dominant gain-of-function mutations occur mostly at one of two hotspots: E542 or E545 in the helical domain and H1047 in the kinase domain. In breast cancer, PIK3CA^E545K mutants are mostly found in slow-growing luminal A breast tumors, whereas PIK3CA^H1047R mutations are common in both luminal A and luminal B. When crossed with cell/tissue-specific Cre-expressing mice or adenoviruses expressing Cre recombinase (Ad-Cre) are injected, the mutant protein product of Pik3ca^E545K is expressed in cells expressing Cre and their descendants. The heterozygous and homozygous mice are viable and fertile. There are no exceptional features before Cre recombination. The R26-Pik3ca^E545K mice may be useful in studying a highly activated allele (PIK3CA^E545K) in tumorigenesis and progression.

Of note, in addition to these mice, The Jackson Laboratory Repository has R26-Pik3ca^H1047R mice (Stock No. 016977) and R26-Pik3ca^E545K-H1047R mice (Stock No. 040532).

Development

Shuttle vectors containing either E545K mutant Pik3ca cDNA were subcloned into the pROSA26PA gene targeting vector. pR26-Pik3ca plasmids were linearized with and electroporated into 129S6/SvEvTac derived mouse W4 embryonic stem cells (ESCs). Correctly targeted clones were identified by PCR and tested for Cre-inducible Pik3ca^E545K transgene expression and used for morula aggregation and transferred into pseudo-pregnant female mice. The resulting male chimaeras were bred with FVB/NJ females for germline transmission. The founder mice were backcrossed further with FVB mice for at least 10 generations. The resulting mice were maintained on an FVB/NJ background in the donating laboratory. Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize FVB/NJ oocyte (Stock No. 001800).

Allele

Symbol: Gt(ROSA)26Sor^{tm3(Pik3ca*E545K)Egan}
Name: targeted mutation 3, Sean E Egan
MGI accession ID: MGI:7493251
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Inserted expressed sequence
Marker symbol: Gt(ROSA)26Sor
Marker name: gene trap ROSA 26, Philippe Soriano
Marker synonyms: beta geo; Gtrgeo26; Gtrosa26; R26; ROSA26; SETD5-AS1; Thumpd3as1
Chromosome: 6
Strain of origin: 129S6/SvEvTac
Molecular note: The following sequences were inserted into intron 1: splice acceptor site, a STOP cassette (loxP site flanked neomycin resistance gene cassette), Pik3ca cDNA sequence where glutamic acid codon 545 (GAA) was changed to lysine (p.E545K), and bovine GH poly(A) signal sequences.