STOCK Kmt2a^{tm2(MLLT3)Thr}/KsyJ

Stock number: 009079
Product name: Mll-AF9
Research areas: Cancer Research, Developmental Biology Research, Hematological Research, Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

Beginning around six months of age, these Mll-AF9 knock-in mice recapitulate the acute myeloid leukemia (AML) phenotype associated with the t(9;11)(p22;q23) translocation in humans and may be useful for studying hematopoietic development, cancer, and acute myeloid leukemia.

Detailed description

These Mll-AF9 knock-in mice are on a mixed genetic background (C57BL/6, 129P and possibly other contributions). It should be noted that their phenotype could vary from that originally published. We may modify the strain description if necessary as published results become available. The published phenotype is described below:

The Mll-AF9 knock-in allele encodes a MLL-AF9 fusion protein that mimics the t(9;11)(p22;q23) translocation identified in acute myeloid leukemia (AML) patients. While homozygous mice are not viable, heterozygotes are viable and fertile but females are poor mothers and may not survive pregnancy. Expression of the MLL-AF9 fusion protein results in development of leukemia beginning around six months of age; almost all of which are AMLs. Detectable proliferation of myeloid cells is observed in bone marrow by as little as six days after birth, and this early accumulation of myeloid precursors likely confers a greater chance of acquiring secondary mutations that cooperate in the appearance of overt cancer. These Mll-AF9 knock-in mice may be useful for studying hematopoietic development, cancer, and AML. As of 2014, our Mll-AF9 knock-in colony exhibits several coat colors including black, agouti and tan.

Development

These Mll-AF9 knock-in mice were generated in the laboratory of Dr. Terence H Rabbitts (Medical Research Council Laboratory of Molecular Biology, Cambridge UK and currently Leeds Institute of Molecular Medicine, Leeds UK). A targeting vector was used for in-frame fusion of a 3'-terminal human AF9 cDNA sequence (nucleotide 1634 to the translation terminus of the MLLT3 locus) and an SV40 poly(A) signal into the BamHI site of exon 8 (corresponding to nucleotide 3987) of the targeted gene. This also inserted a MC1-neo-poly(A) cassette immediately downstream of the fusion segment. The targeting construct was electroporated into 129P2/OlaHsd-derived E14 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and chimeric males were bred with C57BL/6 and/or wildtype siblings and/or outbred MF1 females. Mll-AF9 knock-in mice were subsequently bred with C57BL/6 mice for an unknown number of generations and then sent to the laboratory of Dr. John H Kersey (Masonic Cancer Center, University of Minnesota). There, the mutant males were bred with C57BL/6NCrl females for four generations, and next maintained by breeding mutant males with wildtype female siblings for approximately 20 generations prior to arrival at The Jackson Laboratory. The donating investigator reports both agouti and black coat colors (see SNP note below). In 2010, agouti males and black males were sent to The Jackson Laboratory Repository. Upon arrival, sperm was frozen. An aliquot of the frozen sperm was used to fertilize oocytes from C57BL/6NJ (Stock No. 005304). Until 2012, The Jackson Laboratory Repository colony was maintained by breeding heterozygous males with wildtype females from the colony or C57BL/6NJ females. Beginning in 2012, in an attempt to improve breeding performance, The Jackson Laboratory Repository will maintain the live colony by breeding heterozygous males with wildtype females from the colony or B6129PF1/J females (Stock No. 100492).

In 2011, a 32 SNP (single nucleotide polymorphism) panel analysis, with 27 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 living colony rederived using C57BL/6NJ at The Jackson Laboratory Repository. At least 3 markers are segregating, suggesting an incomplete backcross. Also, 3 of 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 genetic background.

Allele

Symbol: Kmt2a^{tm2(MLLT3)Thr}
Name: targeted mutation 2, Terence H Rabbitts
MGI accession ID: MGI:2671905
Generation method: Targeted
Attributes: Inserted expressed sequence; Humanized sequence
Marker symbol: Kmt2a
Marker name: lysine (K)-specific methyltransferase 2A
Chromosome: 9
Strain of origin: 129P2/OlaHsd
Expressed genes: MLLT3,MLLT3, super elongation complex subunit,human
Molecular note: Sequence encoding a 3' portion of human MLLT3 extending from nucleotide 1634 to the translation terminus replaced a 3' portion of murine Kmt2a exon 8. A downstream neo cassette was also included in the targeting vector for selection. The resultant fusion product putatively recapitulates the KMT2A(MLL)/MLLT3 protein produced in patients with the acute myeloid leukamia (AML) associated transloaction T(9;11)(p22;q23).