B6(Cg)-Isr(HSA19;APOE_i3*)2Dkn/J

Stock number: 038623
Product name: APOE-TOMM40VL
Strain synonyms: B6(Cg)-Tc(HSA19*)VLDkn/J
Research areas: Metabolism Research, Neurobiology Research, Research Tools

Description

Humanized transchromosomal TOMM40VL mice are a knock-in/knock-out model in which the mouse genomic region from Tomm40 (translocase of outer mitochondrial membrane 40) to Apoe (apolipoprotein E) is exchanged for a modified human TOMM40 to APOEε3. Mice carry the TOMM40 523 polyT genetic variant where T=30 deoxythymidine residues creating the very long (VL) allele. These mice may serve as base models into which additional alterations can be introduced to explore more fully the complex cis-regulatory controls in the human 19q13.32 region associated with cardiovascular risk, altered levels of inflammatory markers, altered lipid metabolism, late onset Alzheimer's Disease (LOAD) risk and age-at-onset (AAO) risk.

Of note, the TOMM40S (short allele) is distributed as Stock No. 038624.

Detailed description

The human 19q13.32 region (TOMM40-APOE-APOC1) genomic region is associated with multiple phenotypes including cardiovascular risk, altered levels of inflammatory markers, altered lipid metabolism, late onset Alzheimer's Disease (LOAD) risk and age-at-onset (AAO) risk. The humanized transchromosomal TOMM40VL mice are knock in/ knock out model in which the mouse genomic region (approx. 20 kbp) from Tomm40 (translocase of outer mitochondrial membrane 40) to Apoe (apolipoprotein E) including promoter and regulatory regions are exchanged for a modified human TOMM40 to APOEε4 (including promoter, regulatory and intergenic regions). The human APOEε4 sequence is converted to APOEε3 and the LOAD-associated TOMM40 523 polyT (T=15) genetic variant (S – short allele) is modified to include 30 deoxythymidine residues creating the very long (VL) allele. mRNA levels of human APOE in spleen are higher in VL/VL mice than in S/S mice, similarly hTOMM40 levels in liver are higher in VL/VL mice than in S/S mice until 18 months of age when the reverse is observed. Mice homozygous for TOMM40VL are viable and fertile with no obvious anatomical or behavior issues. These mice may serve as base models into which additional alterations can be introduced to explore more fully the complex cis-regulatory controls.

Of note, the TOMM40S (short allele) is distributed as Stock No. 038624.

Development

The transchromosomal (Tc) TOMM40VL strain is created in a multi-step process by exchanging approx. 20 kb on mouse chromosome 7 stretching from and including Tomm40 (translocase of outer mitochondrial membrane 40) to Apoe (apolipoprotein E) from BAC RP24-136M6 with an acceptor cassette containing PGK-hygromycin and HSV-TK flanked by loxP/lox2272 sites from C57BL/6N-derived C2(Nagy) embryonic stem cells (ES). The 5' loxP site is located downstream of Pvrl2 and the 3' lox2272 site is located downstream of the last Apoe exon (including the enhancer segment). ES cells carrying the acceptor cassette were electroporated with the exchange vectors and a plasmid carrying Cre recombinase to insert 23.77 kbp from human BAC (RP11-84C16) containing TOMM40 to APOE and the flanking sequences (including promoter and regulatory regions) followed by an FRT-flanked PGK-neo cassette and a loxP site on chr19 : 45,393,394-45,417,163 (HSA19). The modified BAC carries the 523 polyT short allele (S) on an APOEε3 backbone. APOEε4 is converted to APOEε3 by exchanging the APOEε4 arginine (CGC) at SNP rs429358 with the APOEε3 cysteine (TGC). The TOMM40 523 polyT site is modified by homologous recombination from 15 deoxythymidine residues to 30 deoxythymidine residues creating the very long (VL) allele. Correctly targeted ES cells were injected into blastocysts. The resulting chimeric animals were crossed to C57BL/6J females and maintained on the C57BL/6J background (see SNP note below). The neo cassette was removed by an unspecified Flp recombinase. Upon arrival, mice were bred to C57BL/6J (Stock No. 000664) to establish the colony.

In 2024, 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 rederived living colony at The Jackson Laboratory Repository. One of the 43 markers throughout the genome wa segregating with an unknown source on Chromosome 2. Also, 3 of the 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: Isr(HSA19;APOE_i3*)2Dkn
Name: interspecies replacement, human Chr 19, William Gottschalk 2
MGI accession ID: MGI:7539492
Generation method: Targeted
Attributes: Inserted expressed sequence; Humanized sequence
Synonyms: APOE-TOMM40VL; Tc(HSA19*)VLDkn
Marker symbol: Isr(HSA19;APOE_i3*)2Dkn
Marker name: interspecies replacement, human Chr 19, William Gottschalk 2
Marker synonyms: Tc(HSA19*)VLDkn
Chromosome: 7
Strain of origin: C57BL/6NTac
Molecular note: The allele is created in a multi-step process by exchanging approx. 20 kb on mouse chromosome 7 stretching from and including Tomm40 to Apoe from BAC RP24-136M6 with an acceptor cassette containing PGK-hygromycin and HSV-TK flanked by loxP/lox2272 sites from C57BL/6N-derived C2(Nagy) embryonic stem cells (ES). The 5' loxP site is located downstream of Pvrl2 and the 3' lox2272 site is located downstream of the last Apoe exon (including the enhancer segment). ES cells carrying the acceptor cassette were electroporated with the exchange vectors and a plasmid carrying Cre recombinase to insert 23.77 kbp from human BAC (RP11-84C16) containing TOMM40 to APOE and the flanking sequences (including promoter and regulatory regions) followed by an FRT-flanked PGK-neo cassette and a loxP site on chr19 : 45,393,394-45,417,163 (HSA19). The modified BAC carries the 523 polyT short allele (S) on an APOE epsilon 3 backbone. APOE epsilon4 is converted to APOE epsilon3 by exchanging the APOE epsilon4 arginine (CGC) at SNP rs429358 with the APOE epsilon3 cysteine (TGC). The TOMM40 523 polyT site is modified by homologous recombination from 15 deoxythymidine residues to 30 deoxythymidine residues creating the very long (VL) allele.