B6.Cg-Ppm1d^tm2.1Ble/J

Stock number: 038173
Product name: Ppm1d^T476-fl
Research areas: Cancer Research, Research Tools

Description

Ppm1d^T476-fl incorporates a conditionally expressed C-terminal truncating mutation of the protein phosphatase 1D magnesium-dependent, delta isoform (Ppm1d) mouse gene. Cre recombinase-mediated excision of the floxed endogenous exon 6 enables expression of the truncating threonine 476 (T476*) form of the exon that is analogous to the somatic modifications commonly observed in humans. This strain is useful in studies of the DNA damage response (DDR) and cancer.

Detailed description

Ppm1d (protein phosphatase 1D magnesium-dependent, delta isoform) encodes a serine/threonine phosphatase that is transcriptionally activated by TRP53, and negatively regulates the DNA damage response (DDR) and p53 signaling. It is commonly mutated in clonal hematopoiesis and myeloid neoplasms, particularly in patients exposed to cytotoxic agents. It is an important regulator of genotoxic stress in hematopoietic stem cells.

Ppm1d^T476-fl mice incorporate a conditionally expressed C-terminal truncating mutation of the mouse Ppm1d gene. Cre recombinase-mediated excision of the floxed endogenous exon 6 enables expression of the truncating threonine 476 (T476*) form of the exon that is analogous to the somatic modifications commonly observed in humans.

When crossed with hematopoietic-specific Vav-Cre mice (PMID 12434335) or polyinosinic:polyscytidylic acid (plpC)-inducible Mx-Cre mice (Stock No. 002527), no significant difference in peripheral blood or bone marrow composition is observed. Protein levels of the truncated protein have not been assessed by the donating laboratory. In competitive bone marrow transplantation assays, cells from Ppm1d^fl/fl;Vav-Cre  show an advantage compared to wild type bone marrow, particularly after exposure to genotoxic stress.

Development

A loxP-exon 6-3xPA-loxP-exon 6 T476* cassette was used to replace exon 6 of the mouse Ppm1d gene via homologous recombination in C57BL/6J x 129S6-derived embryonic stem cells. An FRT-flanked neomycin cassette was excised through crosses with 129S4/SvJaeSor-Gt(ROSA)26Sor^tm1(FLP1)Dym mice (Stock No. 003946) that had been backcrossed to C57BL/6J for 13 generations. The donating laboratory reported that the resultant mice were backcrossed to a progressed C57BL/6J background through genome scanning (see SNP note below).

Upon arrival at The Jackson Laboratory, sperm was cryopreserved. Cryorecovery/live colony development will involve C57BL/6J (Stock No. 000664).

In 2023, a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the mice sent to The Jackson Laboratory Repository. All 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6N;C57BL/6J genetic background.

Allele

Symbol: Ppm1d^tm2.1Ble
Name: targeted mutation 2.1, Benjamin Ebert
MGI accession ID: MGI:7461273
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed)
Synonyms: Ppm1d^T476-fl; Ppm1d^T476*-fl
Marker symbol: Ppm1d
Marker name: protein phosphatase 1D magnesium-dependent, delta isoform
Marker synonyms: IDDGIP; JDVS; PP2C-DELTA; Wip1
Chromosome: 11
Strain of origin: C57BL/6J x 129S6/SvEvTac
Molecular note: A loxP site was inserted into intron 5 and a second loxP site, three copies of SV40 poly(A) signal sequences, an FRT site flanked neomycin resistance gene cassette, followed by a third loxP site, the 3' end of intron 5 and a modified copy of exon 6 were inserted into the 3' UTR of the endogenous exon 6. The modification involves changing threonine codon 476 (ACT) to a stop codon (TGA) (p.T476*) and inserting sequence TTAATTAA downstream for stop codons in the other two reading frames. The neo cassette was removed through subsequent Flp-mediated recombination. Cre recombinase-mediated excision of the floxed endogenous exon 6 enables expression of the modified exon that is analogous to the somatic modifications commonly observed in humans.