B6.Cg-Cfh^tm1.1Song/J

Stock number: 040651
Product name: FH^R (FH^W1206R)
Research areas: Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

FH^R knock-in mice have a W1206R mutation in the complement component factor h (Cfh) gene. These mice are useful for studying alternative pathway complement activity as these mice develop complement-mediated systemic thrombotic angiopathy leading to renal failure, stroke, and retinopathy.

Detailed description

FH^R knock-in mice have a tryptophan to arginine mutation at amino acid 1206 (W1206R) of the complement component factor h (Cfh) gene. Cfh encodes a serum glycoprotein that is involved in the regulation of the alternative pathway of the complement system of innate immunity. The complement pathway plays an essential role in the migration of cells during development and in innate and adaptive immune responses that help the body clear foreign material by recognizing pathogens and neutralizing them. In cells and in circulation, CFH inhibits the activation of C3 to C3a and C3b and inactivates existing C3b. This inhibits the formation of the membrane attack complex and lysis of the target cell, both of which contribute to tissue injury and pathogen recognition and elimination. Cfh is associated with age-related macular degeneration (AMD).

Western blot analysis of plasma from homozygous FH^R/R shows higher FH protein levels (115%) than the normal protein levels in wild-type mice. FH^R/R mice are smaller and thinner than homozygous wildtype (FH^W/W) and heterozygous (FH^W/R) littermates from 4 to 18 weeks of age. 30% of FH^R/R mice exhibit severe neurological abnormalities, including hindlimb paralysis and circular movement with most of these mice showing ischemic brain injury and the presence of thrombi and/or intracerebral hemorrhage in the brain. Also, 48% of FH^R/R mice die by 30 weeks of age due to severe thrombocytopenia involving multiple organs, including liver, lung, spleen, and kidney and anemia that is evident at 4 and 8 weeks of age, which leads to renal failure, stroke, and retinopathy. These mice have a normal white blood cell count, low hemoglobin (Hb) levels, and an increased reticulocyte count.

Heterozygous mice are viable and fertile. Homozygous mice are viable but exhibit high mortality; around 58.5% of homozygous FH^R/R mice die by 16 weeks of age. The donating investigator suggests breeding heterozygous mice together.

Development

The FH^R targeting vector contains a T to A single nucleotide mutation in exon 22 of the complement component factor h (Cfh) gene, resulting in a tryptophan to arginine mutation at amino acid 1206 (W1206R) that corresponds to the human W1183R variant found in families with atypical hemolytic uremic syndrome. An FRT-flanked neomycin resistance (neo) cassette was inserted upstream of exon 22. The construct was electroporated into B6.Cg-Thy1^a-derived Bruce 4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting chimeric mice were bred to C57BL/6J (Stock No. 000664) mice and then to ACTB:FLPe mice (Stock No. 005703) to remove the neo cassette. Mice lacking the neo cassette were maintained on the C57BL/6J genetic background by the donating investigator. Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes.

Allele

Symbol: Cfh^tm1.1Song
Name: targeted mutation 1.1, Wen-Chao Song
MGI accession ID: MGI:6314797
Generation method: Targeted
Attributes: Humanized sequence
Synonyms: FH^R; FH^W1206R
Marker symbol: Cfh
Marker name: complement component factor h
Marker synonyms: AHUS1; AMBP1; AMBP-1; ARMD4; ARMS1; CFHL3; FH; FHL1; HF; HF1; HF2; HUS; Mud-1; Sas1; Sas-1
Chromosome: 1
Strain of origin: B6.Cg-Thy1^a
Molecular note: A T to A single nucleotide mutation was introduced by site-directed mutagenesis resulting in a tryptophan (W) to arginine (R) mutation at amino acid 1206. An FRT-flanked neomycin selection cassette was inserted upstream of exon 22 and was removed via Flp-mediated recombination. The W1206R change in mouse corresponds to the W1183R mutation found in families with atypical hemolytic uremic syndrome. Western blot analysis of plasma indicates that protein levels are higher (115%) than the normal protein levels in wild-type mice.