STOCK Pik3r1^tm1Lca/J

Stock number: 012871
Research areas: Cancer Research, Cell Biology Research, Diabetes and Obesity Research, Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

These p85α^loxP mice harbor loxP sites flanking exon 7 (the first common exon for the three encoded isoforms [p85α, p55α, and p50α]) of the phosphatidylinositol 3-kinase, regulatory subunit, polypeptide 1 (p85 alpha) locus. These mutant mice may be useful in generating conditional mutations for studying class IA phosphoinositide 3-kinases (PI3Ks) in cell growth, cell proliferation cell survival signaling, insulin signaling and tumor angiogenesis, as well as genomic aberrations that promote tumorigenesis/cancer through upregulation of the PI3K/AKT signaling axis.

Detailed description

Mice homozygous for this p85α^loxP allele are viable and fertile, with loxP sites flanking exon 7 of the targeted gene. The Pik3r1 locus encodes three proteins (p85α, p55α, and p50α) that arise from alternative transcription initiation sites; and exon 7 is the first common exon for all three isoforms. When bred to mice that express Cre recombinase, the resulting offspring will have exon 7 deleted in the cre-expressing tissue(s); splicing of upstream exons (exon 6, 1b, or 1c) directly into the downstream exon 8 results in a frameshift mutation that introduces an immediate stop codon. Such a deletion should prevent the translation of the SH2 and p110-binding domains, eliminating the ability to form a functional protein from any of the three transcription initiation sites. These mutant mice may be useful in generating conditional mutations for studying class IA phosphoinositide 3-kinases (PI3Ks) in cell growth, cell proliferation cell survival signaling, insulin signaling and tumor angiogenesis, as well as genomic aberrations that promote tumorigenesis/cancer through upregulation of the PI3K/AKT signaling axis.

When these p85α^loxP mice are bred with p85β mutant mice (Stock No. 012872) and Tie2-Cre transgenic mice (Stock No. 004128), the resulting multiple mutant mice may be used to study vascular integrity during development and tumor neovascularization/angiogenesis.

When these p85α^loxP mice are bred with p85β mutant mice (Stock No. 012872) and MCK-Cre transgenic mice (Stock Nos. 006405 or 006475), the resulting multiple mutant mice may be used to study protection from cardiac hypertrophy.

Development

The Pik3r1 locus encodes three proteins (p85α, p55α, and p50α) that arise from alternative transcription initiation sites; and all three transcripts share the last nine exons (exons 7-15). A targeting vector was designed to insert an frt-flanked PGK-neo cassette and a loxP site upstream of exon 7, and a second loxP site downstream of exon 7 of the targeted locus. The donating investigator reports that the construct was electroporated into 129S6/SvEvTac-derived TC-1 embryonic stem (ES) cells, and chimeric mice were bred with C57BL/6NCrl mice to generate the colony. At some point, mutant mice were bred with Flp recombinase-expressing mice (Rosa26-FLP on undisclosed genetic background; see Stock No. 003946) to remove the frt-flanked neo cassette. The resulting p85α^loxP mice (with single frt site remaining upstream of the floxed exon 7) were bred together to remove the Rosa26-FLP allele. p85α^loxP mice on a mixed genetic background (C57BL/6, 129Sv, FVB/N, and maybe others) were sent to The Jackson Laboratory Repository (see additional information below). Upon arrival, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation to establish the p85α^loxP colony.

Prior to arrival at The Jackson Laboratory Repository, p85α^loxP mice were also bred with Cre recombinase-expressing mice, conditional EGFP-expressing mice, and Pik3r2 mutant mice (Stock No. 012872); this results in the mixed genetic background (C57BL/6, 129Sv, FVB/N, and maybe others). The donating investigator reports that the mice did not harbor Cre recombinase when they were sent to The Jackson Laboratory Repository. Colony managers here at The Jackson Laboratory Repository will assay the mice (and selectively breed away any unwanted mutant alleles, if necessary) to maintain the p85α^loxP colony.

Allele

Symbol: Pik3r1^tm1Lca
Name: targeted mutation 1, Lewis C Cantley
MGI accession ID: MGI:3607981
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Marker symbol: Pik3r1
Marker name: phosphoinositide-3-kinase regulatory subunit 1
Chromosome: 13
Strain of origin: 129S6/SvEvTac
Molecular note: A targeting vector was designed such that exon 7 is flanked by loxP sequences. Upon cre-mediated deletion of the exon, splicing of upstream exons 6, 1b or 1c directly into exon 8 results in a frameshift mutation producing an immediate stop codon. As a result the p85alpha isoform is truncated and p55alpha and p50alpha are essentially abolished. Flp mediated recombination removed the neo cassette. Western blot demonstrates the floxed allele is expressed just like the wild-type.