B6.Cg-Grn^tm1.2Blrl Hprt1^tm1(GRN)Blrl/J

Stock number: 036240
Product name: Grn^- GRN^Tg
Research areas: Neurobiology Research, Research Tools

Description

Humanized Grn^-/- GRN^Tg mice are carry a knock-out allele of Grn (progranulin) and express human GRN from the X-linked Hprt1 locus. In these mice, the lipofuscinosis phenotype characteristic of neuronal ceroid lipofuscinosis (NCL) is rescued. These mice may be useful for studying gene regulation and gene therapy related to frontotemporal dementia and neuronal ceroid lipofuscinosis.

Detailed description

Progranulin (Grn) is a glycopeptide secreted by many cell types and is processed into growth modulating peptides called granulins. Granulin proteins function in wound healing, inflammation, embryogenesis and tumor growth. Loss-of -function mutations in progranulin are associated with neurodegenerative syndrome familial frontotemporal dementia (FTD) and neuronal ceroid lipofuscinosis (NCL).

The Grn^- (knock-out) allele has exons 3 and 4 removed disrupting expression of Grn. The GRN^Tg allele expresses human GRN from the X-linked Hprt1 locus. Homozygous Grn^-/- males develop age-dependent neuropathological abnormalities associated with NCL including excessive deposition of the aging pigment lipofuscin, astrogliosis and microgliosis. When combined with the GRN^Tg allele expressing human, GRN, Grn^-/- GRN^Tg mice have lipofuscin deposition at similar levels as wild-type, thus rescuing the excessive deposition of lipofuscin found in the Grn null phenotype. Mice homozygous for the Grn null allele and hemizygous for human GRN are viable and fertile. These mice may be useful for studying gene regulation and gene therapy related to frontotemporal dementia and neuronal ceroid lipofuscinosis.

Development

The Grn KO targeting construct contained a loxP site upstream of exon 3, a second loxP site downstream of exon 4 followed by an FRT-flanked cassette composed of a splice acceptor-IRES-βgeo (containing a neo/beta-galactosidase fusion protein)- stop codon - polyA sequence inserted into the Grn locus on chromosome 11. The construct was electroporated into 129S1/SvImJ-derived mEMS128 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts. Chimeric males were crossed to C57BL/6J females. Heterozygous targeted mice were then crossed to mice carrying the Flp recombinase gene under the control of the human β-actin promotor (B6.Cg-Tg(ACTFLPe)9205Dym/J, Stock No. 005703). A heterozygous Flp-recombined animal was subsequently crossed to a C57BL/6 congenic mouse carrying the Cre recombinase gene under the control of the human β-actin promoter (B6.FVB-Tmem163^{Tg(ACTB-cre)2Mrt}/EmsJ, Stock No.033984)). Heterozygous Flp- and Cre-recombined mice were backcrossed to C57BL/6 mice for more than 7 generations.

GRN^Tg was created using bacterial artificial chromosome RP11-1145H1, carrying a 170 kb insert from human chromosome 17. The BAC includes the entire GRN coding sequence (8 kb) plus approximately 8 kb of upstream sequence. the original BAC was modified to remove other genes prior to making the mice. The 35 kb construct including Hprt1 homologous recombination targeting arms was inserted into the Hprt1 locus on the X chromosome. The construct was electroporated into C57BL/6-derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts. Chimeric males were crossed to C57BL/6J females. The colony was maintained on the C57BL/6 background. Heterozygous GRN^Tg females were then crossed to Grn^-/- males to create Grn^-/- GRN^Tg mice. Upon arrival, mice were bred to C57BL/6J for at least 1 generation to establish the colony.

Allele

Symbol: Grn^tm1.2Blrl
Name: targeted mutation 1.2, Blair R Leavitt
MGI accession ID: MGI:6149575
Generation method: Targeted
Attributes: Null/Knockout
Synonyms: Grn^-
Marker symbol: Grn
Marker name: granulin
Marker synonyms: acrogranulin; CLN11; epithelin; FTD2; GEP; GP88; PC cell-derived growth factor; PCDGF; PEPI; Pgrn; progranulin
Chromosome: 11
Strain of origin: 129S1/SvImJ
Molecular note: Parental line mouse Grn^tm1Blrl consisting of a loxP site inserted upstream of exon 3 and a cassette containing (5' to 3') a loxP site, FRT site, splice acceptor, IRES, beta-geo cassette, stop codon, polyadenylation sequence, and FRT site inserted downstream of exon 4 was crossed with Flp-deleter to remove the cassette leaving loxP flanked exons 3 and 4. The mice was further crossed with cre-deleter to remove exon 3 and 4, resulting in constitutively null mice.

Allele

Symbol: Hprt1^tm1(GRN)Blrl
Name: targeted mutation 1, Blair R Leavitt
MGI accession ID: MGI:6512847
Generation method: Targeted
Attributes: Inserted expressed sequence; Humanized sequence
Synonyms: GRN^Tg
Marker symbol: Hprt1
Marker name: hypoxanthine phosphoribosyltransferase 1
Marker synonyms: HGPRT; Hgprtase; Hprt
Chromosome: X
Strain of origin: C57BL/6
Molecular note: The targeting construct is created using bacterial artificial chromosome RP11-1145H1, carrying a 170 kb insert from human chromosome 17. The BAC includes the entire GRN coding sequence (8 kb) plus approximately 8 kb of upstream sequence. The 35 kb construct including Hprt homologous recombination targeting arms was inserted into the Hprt locus.