B6.Cg-Tg(FCGRT)32Dcr Alb^em12Mvw Fcgrt^tm1Dcr/MvwJ

Stock number: 025201
Research areas: Immunology, Inflammation and Autoimmunity Research, Metabolism Research, Research Tools

Description

This TALEN-mediated deletion in Alb results in the absence of any albumin protein in the blood. When combined with the knockout allele of the FcRn a-chain and a transgene expressing a human FcRn a-chain (FCGRT) under control of the human FcRn promoter, this albumin-deficient model may be useful for studying human serum albumin pharmacokinetics.

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Detailed description

Mice homozygous for the Alb^em12Mvw allele lack albumin protein in their blood. FcRn-/- hFcRn (32) Tg mice harbor a knockout allele of the Fc receptor, IgG, alpha chain transporter (Fcgrt^tm1Dcr) and express a human FcRn a-chain (FCGRT) transgene under control of the human FcRn promoter. Mouse IgG levels are low due to the species-specific activity of human FcRn. Mice do not exhibit any gross abnormal phenotype. This albumin-deficient model may be useful for studying the biology and pathobiology of serum albumin as well as evaluating human albumin pharmacokinetics.

C57BL/6J-Alb^em8Mvw/MvwJ (Stock No. 025200) was generated as a control for this strain.

Development

A targeting scheme was designed using a TALEN-mediated Non-Homologous End Joining (NHEJ) repair pathway to knock out the mouse albumin gene in B6.Cg-Fcgrt^tm1Dcr Tg(FCGRT)32Dcr/DcrJ ((Stock No. 014565)). TALEN mRNAs were introduced into mutant zygotes, and the resulting founder mouse (#6074) was crossed to a B6.Cg-Fcgrt^tm1Dcr Tg(FCGRT)32Dcr/DcrJ mouse in order to characterize the mutation, a 2-base deletion resulting in early termination of the translated protein. N1 Heterozygous offspring were filial-crossed to establish the colony as homozygotes.

Allele

Symbol: Alb^em12Mvw
Name: endonuclease-mediated mutation 12, Michael Wiles
MGI accession ID: MGI:5494605
Generation method: Endonuclease-mediated
Attributes: Null/Knockout
Marker symbol: Alb
Marker name: albumin
Chromosome: 5
Strain of origin: B6.Cg-Fcgrt^tm1Dcr Tg(FCGRT)32Dcr/DcrJ
Molecular note: Exon 4 was targeted by introduction of TALEN mRNA into fertilized B6.Cg-Fcgrt^tm1Dcr Tg(FCGRT)32Dcr/DcrJ oocytes and the resulting founder screened and found to have a 2 base pair deletion beginning at Chromosome 5 base 90,464,113 (GRCm38.p2) which is predicted to result in a frame shift then a premature stop codon 5 amino acids downstream of the encoded frame shift. By ELISA, heterozgyotes have a decrease in serum albumin of approximately 30 percent and homozygotes have no detectable serum albumin.

Allele

Symbol: Fcgrt^tm1Dcr
Name: targeted mutation 1, Derry C Roopenian
MGI accession ID: MGI:3511510
Generation method: Targeted
Attributes: Null/Knockout
Synonyms: FcRn^-
Marker symbol: Fcgrt
Marker name: Fc receptor, IgG, alpha chain transporter
Chromosome: 7
Strain of origin: 129X1/SvJ
Molecular note: Sequence from exon 1 and part of exon2 was replaced with a PGK-neo cassette. Quantitative PCR of liver cDNA indicated the absence of mRNA. Western blot analysis of neonatal intestinal extracts failed to reveal protein product.

Allele

Symbol: Tg(FCGRT)32Dcr
Name: transgene insertion 32, Derry C Roopenian
MGI accession ID: MGI:4944199
Generation method: Transgenic
Attributes: Inserted expressed sequence; Humanized sequence
Synonyms: hFcRn(32) vhFcRn (32) Tg hFcRn (32) Tg; Tg32
Marker symbol: Tg(FCGRT)32Dcr
Marker name: transgene insertion 32, Derry C Roopenian
Chromosome: 2
Strain of origin: C57BL/6J
Expressed genes: FCGRT,Fc fragment of IgG receptor and transporter,human
Site of expression: The transgene expresses human FCGRT from the native human promoter, and displays a physiological human FCGRT expression pattern (Latvala et al., 2017).
Molecular note: A 34Kb fragment of a BAC containing the entire human FCGRT , Fc fragment of IgG, receptor, transporter, alpha, gene (approximately 11kb) and approximately 10kb of flanking sequence was sublconed into a SuperCos vector. The resulting cosmid was microinjected into fertilized C57BL/6J mouse eggs. Founder line 32 was established. Transgene insertion occurred on Chr 2.