Fah KO Mice

Catalog Number: C001273

Strain Name: C57BL/6JCya-Fahem1/Cya

Genetic Background: C57BL/6JCya

Reproduction: Heterozygote x WT

 

Strain Description

The FAH gene encodes the fumarylacetoacetate hydrolase (FAH) protein, a key enzyme in the tyrosine catabolism pathway. FAH is expressed in many tissues throughout the body but is most abundant in the liver and kidneys. Mutations in the FAH gene can lead to a deficiency in FAH activity, which results in the accumulation of fumarylacetoacetate (FAA) and other toxic metabolites in the body. This can lead to a variety of health problems, including hereditary tyrosinemia type 1 (HT1) [1-2]. HT1 is a rare autosomal recessive genetic disorder that is characterized by a deficiency in FAH activity. Symptoms of HT1 typically appear in early infancy and can include vomiting, diarrhea, jaundice, and failure to thrive. If left untreated, HT1 can lead to severe liver and kidney damage, as well as intellectual disability.

This model is a Fah gene knockout (Fah KO) mouse. The Fah gene in the mouse, which is homologous to the human FAH gene, has been knocked out using gene editing technology. Heterozygous Fah KO mice are viable and fertile. These mice can exhibit the typical characteristics of hereditary tyrosinemia type 1 (HT1), that is, the metabolic disorder of tyrosine in the body, leading to the accumulation of fumarate acetoacetate (FAA), which in turn causes hepatocyte damage. Homozygous Fah KO mice will die shortly after birth, manifesting as liver and kidney dysfunction, hypoglycemia, and significant changes in liver mRNA expression, and nitisinone (NTBC) is required to maintain their survival [3]. In addition, FRG mice (Fah KO/Rag2 KO/Il2rg KO) constructed by crossing Fah KO mice with Rag2 KO mice and Il2rg KO mice can be used for the study of human hepatocyte regeneration, thus creating mice "with a human liver" [4], which is of great significance for research on liver biology, stem cells, infectious diseases, metabolism, and gene therapy.

 

Strain Strategy


Figure 1. Gene editing strategy of Fah KO mice. The Fah gene is located on mouse chromosome 7, and exons 2-10 of this gene were knocked out using gene editing techniques.

 

Application

  • Research on tyrosinemia type 1 (HT1).
  • Research on liver stem cell and hepatic gene therapy.
  • Research on liver repopulation.

 

Validation Data

1. Nitisinone (NTBC) treatment conditions exploratory experiments

a. Growth curves


Figure 1. Changes in body weight of Fah KO mice (Homo) and wild-type (WT) mice after the termination of NTBC treatment (Fah KO mice: homozygous, 6-week-old, 1 male and 1 female, n = 2; WT: 6-week-old, 1 male and 2 females, n = 3). NTBC at a concentration of 7.5 mg/L was added to the drinking water of pregnant female mice in the late pregnancy stage and their offspring. After the offspring were born, the NTBC treatment lasted from postnatal day 0 (P0) until the mice were 6 weeks old. After 6 weeks, the NTBC treatment was terminated and the body weight of the mice was monitored (D0-D13). The results showed that compared with WT mice, Fah KO mice showed a significant decrease in body weight after the termination of NTBC treatment.

 

b. Tyrosine (Tyr) levels


Figure 2. Tyrosine levels in the plasma of Fah KO mice (Homo) and wild-type (WT) mice after the termination of NTBC treatment (Fah KO mice: homozygous, 6-week-old, 1 male and 1 female, n = 2; WT: 6-week-old, 1 male and 1 female, n = 2). NTBC at a concentration of 7.5 mg/L was added to the drinking water of pregnant female mice in the late pregnancy stage and their offspring. After the offspring were born, the NTBC treatment lasted from postnatal day 0 (P0) until the mice were 6 weeks old. After 6 weeks, the NTBC treatment was terminated. The plasma of the mice was collected on day 13 after the drug withdrawal to detect tyrosine levels (one of the Fah KO mice died on day 9 after the drug withdrawal, and the blood was collected on the day of death). The results showed that compared with WT mice, Fah KO mice showed extremely high plasma tyrosine levels after the termination of NTBC treatment.

 

c. Liver & Kidney Pathological Observations


Figure 3. H&E staining of the liver and kidney of Fah KO mice (Homo) and wild-type (WT) mice after the termination of NTBC treatment. The liver and kidney tissues of the mice were collected on postnatal day 51 (P51) and postnatal day 55 (P55) for H&E staining.

① The results of liver H&E staining showed that there were no obvious abnormalities in the control group. In homozygous Fah KO mice, severe hepatocyte hyaline degeneration occurred, with an increase in vacuoles in hepatocytes and unclear boundaries of hepatocytes.

② The results of kidney H&E staining showed that there were no obvious abnormalities in the control group. In homozygous Fah KO mice, severe tubular edema occurred in the renal tubules (as indicated by the red arrows).



References
[1]Morrow G, Angileri F, Tanguay RM. Molecular Aspects of the FAH Mutations Involved in HT1 Disease. Adv Exp Med Biol. 2017;959:25-48.
[2]Frequent mutation reversioninversely correlates with clinical severity in a genetic liver disease, hereditary tyrosinemia.
[3]Grompe M, Lindstedt S, al-Dhalimy M, Kennaway NG, Papaconstantinou J, Torres-Ramos CA, Ou CN, Finegold M. Pharmacological correction of neonatal lethal hepatic dysfunction in a murine model of hereditary tyrosinaemia type I. Nat Genet. 1995 Aug;10(4):453-60.
[4]Grompe M. Fah Knockout Animals as Models for Therapeutic Liver Repopulation. Adv Exp Med Biol. 2017;959:215-230.