B6(Cg)-Asxl2^tm1.1Oaw/J

Stock number: 030338
Product name: Asxl2^fl
Research areas: Cancer Research, Cell Biology Research, Developmental Biology Research, Hematological Research, Immunology, Inflammation and Autoimmunity Research, Neurobiology Research, Research Tools

Description

The Asxl2^fl floxed allele has loxP sites flanking exon 11 of the aadditional sex combs like 2 (Drosophila) gene. Removal of the floxed sequence creates a knock-out allele. These mice may be useful in studying hematopoiesis and transcriptional effects associated with leukemia.

Detailed description

ASXL2 is a critical regulator of hematopoiesis (required for normal hematopoietic stem cell self-renewal) and serves as a haploinsufficient tumor suppressor. Somatic mutations in this transcription factor are associated with acute myeloid leukemia (AML) patients bearing the RUNX1-RUNX1T1 (AML1-ETO) fusion oncoprotein. ASXL2 is also involved in transcriptional regulation mediated by ligand-bound nuclear hormone receptors.

The Asxl2^fl allele has loxP sites flanking Asxl2 exon 11. Mice homozygous for this floxed allele are viable and fertile with no reported gross physical or behavioral abnormalities. When bred to mice that express Cre recombinase, the resulting offspring will have the floxed region deleted in cre-expressing tissues; creating the Asxl2 knock-out allele.

For example, when Asxl2^fl are bred to germline Cre-expressing mice, the resulting global null homozygous mice may be expected to exhibit a phenotype similar to other published ASXL2 knock-out alleles - near complete perinatal lethality and developmental defects in heart and bone, as well as abnormalities in skeletal, lipid and glucose homeostasis. Of note, the donating investigator has not attempted to create this global knock-out to date (March 2017).
In addition, breeding Asxl2^fl to Mx1-cre transgenic mice (Stock No. 003556) results in mice that allow deletion of Asxl2 in postnatal tissues via administration of IFN-α, interferon beta or synthetic double-stranded RNA (such as polyI:C). Specifically, after four week treatment of polyI:C, ASXL2 protein expression was fully eliminated and ASXL2-deficiency was not associated with altered Asxl1 expression at the protein or mRNA level.

Development

The Asxl2^fl (floxed exon 11) allele was created by Dr. Omar Abdel-Wahab (Memorial Sloan Kettering Cancer Center). First, a targeting vector was designed to insert a frt-loxP-neo cassette-frt-loxP upstream of exon 11, and a loxP downstream of exon 11 of the additional sex combs like 2 (Drosophila) gene (Asxl2) on chromosome 12. The targeting vector was electroporated into C57BL/6-derived embryonic stem cells (derived from iTL IC1, mostly C57BL/6N but found to have some C57BL/6J). Chimeric animals were bred to C57BL/6N Flp-deleter mice for germline deletion of the neo cassette. The resulting mice with the Asxl2^fl allele were mated to C57BL/6N inbred mice for one generation (and the Flp-expressing allele was removed). Next, Asxl2^fl mice were bred to C57BL/6J-congenic, tissue-specific Cre recombinase strains for at least one generation (i.e., Stock Nos. 003556 and/or 008610). Offspring were bred together and mice were made homozygous for Asxl2^fl (and the Cre recombinase alleles were removed). In 2017, Asxl2^fl homozygous males with black coat color were sent to The Jackson Laboratory Repository. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).
Of note, it is not known if the Y chromosome has been fixed to the C57BL/6 background.

Allele

Symbol: Asxl2^tm1.1Oaw
Name: targeted mutation 1.1, Omar Abdel-Wahab
MGI accession ID: MGI:5829437
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Synonyms: Asxl2^fl
Marker symbol: Asxl2
Marker name: additional sex combs like 2, transcriptional regulator
Marker synonyms: 4930556B16Rik; ASXH2; mKIAA1685; SHAPNS
Chromosome: 12
Strain of origin: C57BL/6NTac
Molecular note: The targeting vector is designed to insert an FRT-loxP-neomycin cassette-FRT-loxP upstream of exon 11, and a loxP downstream of exon 11. Flp-mediated recombination removed the FRT-flanked neo cassette leaving exon 11 floxed.