F8 KO Mice

Catalog Number: C001211

Reproduction: Homozygote × Homozygote

Strain Description

The F8 gene encodes Factor Ⅷ (FⅧ), a large plasma glycoprotein involved in the endogenous pathway of blood coagulation. This gene produces two alternatively spliced transcripts, of which the larger glycoprotein, isoform a, circulates in plasma in the form of a non-covalent complex with von Willebrand factor (vWF). FⅧ serves as a cofactor for Factor Ⅸa and, in the presence of calcium and phospholipids, converts Factor Ⅹ to its activated form Ⅹa. Defects in the F8 gene can lead to Hemophilia A (HA), a common recessive X-linked coagulation disorder, and thrombosis due to FⅧ deficiency.

This strain is constructed by introducing a neomycin resistance gene (Neo) expression element into the mouse F8 gene through gene editing technology, thereby blocking the normal expression of this gene. Homozygous F8 KO mice are fertile, brown in color, and grow normally. The Factor Ⅷ activity of homozygous females and hemizygous males is significantly reduced compared to wild-type mice, and the coagulation time is prolonged, showing a typical Hemophilia A (HA) phenotype. It should be noted that when tail cutting is performed on F8 KO mice, the mouse tail must be cauterized immediately, otherwise the mouse may die within a few hours due to massive blood loss. Therefore, it is recommended to perform tail cutting when the mouse reaches 4 weeks of age. Usually, ear tags are applied to mice at 2 to 3 weeks of age (a small notch is made with scissors for identification). After tail docking for genotyping, the tail wound should be promptly cauterized (using metal forceps heated with an alcohol lamp) to prevent fatal bleeding. Following cauterization, place the mouse in a clean cage to prevent wound infection and add environmental enrichment.

Strain Strategy

The F8 gene is located on mouse chromosome X, and this strain was constructed by embryonic stem (ES) cell technology. Partial exon 16 plus partial intron 16 were replaced with the Neo cassette, resulting in the deletion of the F8 expression.

Validation Data

1. Detection of mRNA expression

Figure 1. F8 mRNA expression in 6-week-old male F8 KO mice and wild-type (WT) mice. RT-qPCR results demonstrate the absence of F8 mRNA expression in the liver of F8 KO mice. 

2. Plasma factor Ⅷ coagulant activity (FⅧ: C)

Figure 2. Determination of Plasma factor Ⅷ coagulant activity in F8 KO mice. Factor Ⅷ coagulant activity (FⅧ: C) in F8 KO mice was 4% of that in wild-type mice, comparable to moderate hemophilia A.

3. Coagulation tetrad test

Figure 3. Coagulation four-item indicators of 8-week-old F8 KO mice and wild-type (WT) mice. The results demonstrate that compared to wild-type mice, F8 KO mice exhibit significantly prolonged activated partial thromboplastin time (APTT), indicating impaired clotting function and prolonged bleeding time, similar to the phenotype of the classical F8 KO disease model ^[1]. Furthermore, there were no significant differences in prothrombin time (PT), thrombin time (TT), and fibrinogen (FIB) levels between F8 KO mice and wild-type mice.

4. Phenotype rescue

Figure 4. hFⅧ^BTX1 and hFⅧ^BTX2 gene delivery*. 18-week-old F8 KO mice do not express FⅧ and only have 2% FⅧ activity, and FⅧ expression and FⅧ activity are significantly increased after the human F8 gene delivery.

*Provided by the customer.

Reference

[1] Bi L, Lawler AM, Antonarakis SE, High KA, Gearhart JD, Kazazian HH Jr. Targeted disruption of the mouse factor Ⅷ gene produces a model of haemophilia A. Nat Genet. 1995 May;10(1):119-21.