The adenomatous polyposis coli (APC) gene is a tumor suppressor gene, the protein it encodes plays a key regulatory role in the Wnt/β-catenin signaling pathway ^[1]. The APC protein can antagonize the Wnt signaling pathway, assisting in regulating cell migration, adhesion, transcriptional activation, and apoptosis. More than 10% of human tumors have mutations in the APC gene, and most colorectal cancers have mutations in the APC gene ^[2]. Defects in the APC gene lead to the occurrence of familial adenomatous polyposis (FAP), characterized by hundreds to thousands of adenomatous polyps in the rectum. This is an autosomal dominant precancerous disease, which usually develops into malignant tumors ^[1-2]. Disease-related mutations in the APC gene are highly prevalent in a small region known as the mutation cluster region (MCR), which usually leads to the production of truncated proteins ^[3-4]. In mice, either Apc gene deletion or multiple intestinal neoplasia (Min) mutations that result in the production of truncated APC proteins cause phenotypes similar to human familial adenomatous polyposis (FAP) and/or colorectal tumors ^[5-9]. The Apc-KO mouse is a research model constructed by using gene editing technology to knock out the sequence in the mouse Apc gene that contains the mutation cluster region (MCR), and this strain is homozygous lethal. Heterozygous Apc-KO mice can spontaneously develop intestinal adenomas and exhibit significant colorectal cancer disease phenotypes in various aspects such as survival, growth, food intake, and intestinal lesions. Therefore, Apc-KO mice can be used for familial adenomatous polyposis (FAP) and colorectal cancer and other tumors or tumor-related diseases, as well as the study of the regulatory mechanism of the Wnt/β-catenin signaling pathway.

The ALPL gene encodes for the tissue-nonspecific alkaline phosphatase (TNSALP) enzyme, a membrane-bound glycoprotein. This enzyme is expressed in a variety of cellular tissues, most notably in the liver, bone, and kidney, as well as in other areas like teeth and mesenchymal stem cells ^[1]. Its primary function is to act as a hydrolase, removing phosphate groups from molecules. This is a critical function for skeletal and dental mineralization, where it hydrolyzes inorganic pyrophosphate (a mineralization inhibitor) into phosphate, which then combines with calcium to form bone ^[2]. Mutations in the ALPL gene lead to hypophosphatasia (HPP), a rare inherited metabolic disease characterized by defective bone and tooth mineralization, rickets, osteomalacia, and in severe cases, seizures and respiratory complications. The severity of HPP varies, ranging from mild forms with dental issues to life-threatening perinatal forms ^[3]. Variations in the ALPL gene may also be associated with other diseases, such as osteoporosis. Research has found a high frequency of homozygous common ALPL gene variants in adult patients with atypical femoral fractures or with biochemical/clinical signs of hypophosphatasia (HPP). This suggests that variations in the ALPL gene may be linked to an increased risk of these fractures ^[4]. Furthermore, the expression and function of the ALPL gene may be relevant to cancer immunotherapy. Studies have shown that an alkaline phosphatase isoform, known as ALPL-1, is highly expressed in osteosarcoma (OS) ^[5]. The Alpl-KO mouse is a knockout (KO) model in which the exon 3~4 of the Alpl gene (homologous to the human ALPL gene) has been deleted via gene-editing technology. Preliminary validation data indicate that homozygous Alpl-KO mice have a short lifespan, dying within four weeks when given a specialized diet. If they are not provided with this dietary support, no surviving homozygous individuals are obtained. This model can be used to study the pathogenic mechanisms of diseases such as hypophosphatasia (HPP), osteoporosis, and osteosarcoma (OS), and to provide a basis for developing related therapeutic strategies.

The AGXT gene, mapping to chromosome 2q37.3, encodes alanine-glyoxylate aminotransferase (AGT), a pyridoxal 5'-phosphate-dependent homotetrameric enzyme predominantly expressed in hepatic peroxisomes ^[1]. AGT is central to glyoxylate metabolism, catalyzing its transamination to glycine and preventing its oxidation to oxalate ^[1]. Primary Hyperoxaluria Type 1 (PH1), a rare autosomal recessive disorder affecting approximately 1-3 per million individuals, arises from over 175 identified pathogenic mutations in AGXT. These mutations typically result in deficient or mislocalized AGT, leading to marked overproduction of oxalate ^[2]. The ensuing hyperoxaluria causes deposition of calcium oxalate in the kidneys, manifesting as nephrolithiasis and nephrocalcinosis, which can progress to end-stage renal disease ^[3]. In severe cases, systemic oxalosis can occur ^[4]. Agxt-deficient mice serve as critical preclinical models, faithfully mirroring the biochemical and pathological features of PH1 and enabling the evaluation of diverse therapeutic modalities, including enzyme replacement, substrate reduction, and gene therapy. The Agxt-KO mouse is a gene knockout model created using gene-editing techniques to knock out the coding sequence of the Agxt gene (the homolog of the human AGXT gene) in mice. This model is used to research the pathogenic mechanisms of primary hyperoxaluria and develop related therapeutic strategies.

Interferons (IFNs) are potent cytokines that serve as a critical component of the body's first line of defense against viral infections, playing a key role in inflammation and immune control by directly inducing pathogen-inhibiting molecules that suppress viral replication ^[1]. Arthropod-borne viruses (arboviruses) like Dengue virus (DENV), Zika virus (ZIKV), and Yellow Fever virus (YFV) encode proteins that antagonize the IFN response, helping these viruses evade host immunity and maintain sufficient viral loads in the blood (viremia) to sustain the vector-host transmission. Arboviruses pose a significant public health threat, affecting around 3.9 billion people in tropical and subtropical regions. However, most preclinical studies suggest that arboviruses cannot inhibit IFN responses in mice, rendering immunocompetent mice resistant to infection, with low viral loads and limited circulation, thus limiting their use in infection research ^[2-3]. As a result, immunodeficient mouse models with defects in multiple IFN signaling pathways have become essential tools for studying arbovirus pathogenesis and vaccine development ^[2-4]. Studies have demonstrated that wild-type mice of strains like C57BL/6, CD-1, or 129 rarely exhibit clinical symptoms after infection with arboviruses such as ZIKV. However, the virus has been detected in the blood, ovaries, and spleen of ZIKV-infected 129 mice, suggesting that this strain may be more susceptible to arboviruses ^[5-6]. Because the virus can persist in the bloodstream without causing disease or death, the 129 strain can be used to evaluate the teratogenic effects of such viruses. Furthermore, the 129 strain is commonly used in interferon signaling-deficient models related to other viral infections ^[7-8]. The IFNAR1 gene encodes a key component of the type I IFN receptor, while the IFNGR1 gene encodes the ligand-binding chain (α) of the type II (γ) IFN receptor. AG129(IFNα/β/γR-DKO) mice, which are knockout models for both the type I (α/β) IFN receptor (Ifnar1) and the type II (γ) IFN receptor (Ifngr1), lack functional IFNAR1 and IFNGR1 proteins, resulting in deficiencies in α/β/γ interferon receptor signaling and heightened susceptibility to viral infections. Homozygous AG129(IFNα/β/γR-DKO) mice are viable and fertile, and exhibit increased sensitivity to arboviral infections, generating viremia similar to that seen in humans. Compared to IFNα/β/γR KO mice on the C57BL/6 background, the 129-background AG129(IFNα/β/γR-DKO) mice exhibit more pronounced neurological symptoms after infection ^[6,9].

Polycystin-1 (PC1), encoded by the PKD1 gene, is a large transmembrane glycoprotein that orchestrates critical cellular processes—including cell–cell and cell–matrix interactions, calcium signaling, and mechanosensation—in renal tubular epithelial cells. PC1 regulates various aspects of cellular function, including signal transduction, cytoskeletal remodeling, and cell adhesion. It forms a functional complex with Polycystin-2 (PC2), the product of the PKD2 gene, to maintain intracellular calcium homeostasis and facilitate mechanotransduction ^[1]. Disruption of PC1 signaling, due to PKD1 mutations—which account for approximately 85% of autosomal dominant polycystic kidney disease (ADPKD) cases—undermines these regulatory pathways, promoting abnormal cell proliferation and cyst formation ^[2]. Clinically, ADPKD is characterized by the progressive development of multiple fluid-filled cysts, renal enlargement, hypertension, and eventual progression to end-stage kidney disease (ESKD). With a global incidence estimated at 1 in 400 to 1 in 1000 individuals, ADPKD affects nearly 500,000 people in the United States alone and frequently involves extra-renal manifestations, including the heart, liver, pancreas, spleen, and arachnoid membrane ^[3]. Notably, genotypic heterogeneity exists, with PKD1 mutations often associated with an earlier onset and more aggressive disease course ^[2-3]. Traditional systemic Pkd1 knockout models are typically embryonically lethal, precluding long-term pathogenesis studies. In contrast, inducible, kidney-specific conditional knockout models using the Cre-LoxP system recapitulate the clinical features of human ADPKD and permit the investigation of disease progression in adult mice ^[4-5]. Acute-PKD(inducible) mice represent an inducible conditional Pkd1 knockout model generated by crossing Pkd1-floxed mice with kidney-specific, tamoxifen-inducible Cre mice (Cdh16-MerCreMer). Offspring were induced with tamoxifen during lactation to achieve targeted deletion of Pkd1 within renal tubular epithelial cells. Preliminary observations at three weeks post-induction reveal pronounced polycystic kidney disease phenotypes, including the emergence of renal cysts, a marked increase in kidney volume, and elevated serum blood urea nitrogen (BUN) levels. We will continue to monitor this model to assess its late-stage phenotypes and overall disease progression.

The protein encoded by the Angiotensin Converting Enzyme 2 (ACE2) gene belongs to the angiotensin converting enzyme family of dipeptidyl carboxydipeptidases and is homologous to Angiotensin I. ACE2 is expressed in a variety of human organs and has a strong affinity for Angiotensin I (AngⅠ) and Angiotensin II (AngⅡ) receptors. It catalyzes the cleavage of Ang I to angiotensin 1-9 (Ang1-9) and Ang II to angiotensin 1-7 (Ang1-7), which has a vasodilating and antihypertensive effect ^[1], and plays a role in the regulation of blood pressure, fluid balance, inflammation, cell proliferation, hypertrophy, and fibrosis, as well as in the regulation of cardiovascular and renal function and fertility ^[2]. ACE2 is also a common functional receptor for the spike protein of human coronavirus HCoV-NL63 and the severe acute respiratory syndrome coronaviruses SARS-CoV and SARS-CoV-2 ^[3]. This strain is a mouse Ace2 gene knockout model that uses gene editing technology to knock out the homologous gene of human ACE2 in mice. The knockout of the Ace2 gene will result in the absence of ACE2 protein expression, and this model can be used for the study of COVID-19. The homozygous Ace2-KO mice are viable and fertile.

The ABCD1 (ATP-binding cassette subfamily D member 1) gene, located on the X chromosome (Xq28), encodes a peroxisomal transmembrane protein responsible for transporting very long-chain fatty acids (VLCFAs) into peroxisomes for β-oxidation. Widely expressed but particularly prominent in the brain, adrenal glands, and liver, ABCD1 is critical for maintaining lipid homeostasis. Mutations in ABCD1 cause X-linked adrenoleukodystrophy (X-ALD), a neurodegenerative disorder characterized by VLCFA accumulation, demyelination, adrenal insufficiency, and progressive neurological decline. Clinical manifestations vary widely, ranging from asymptomatic carriers to a severe, fatal childhood form. Primarily affecting males (with an estimated incidence of ~1 in 17,000 newborns), X-ALD has been included in newborn screening programs in many U.S. states ^[1-2]. The correlation between specific mutations and symptoms remains unclear, and VLCFA measurement cannot reliably predict disease-specific outcomes such as adrenal insufficiency or neurological decline. Current therapeutic approaches focus on gene repair or mitigating secondary effects like oxidative stress ^[3]. The Abcd1-KO mouse, a gene knockout model generated by deleting exon 2 of the mouse Abcd1 gene (homologous to human ABCD1), serves as a valuable tool for studying the pathogenesis of X-ALD and developing therapeutic interventions.

Progressive Familial Intrahepatic Cholestasis Type 3 (PFIC3) is a rare, life-threatening autosomal recessive hereditary liver disease caused by mutations in the ABCB4 gene (also known as MDR3 in humans and MDR2 in rodents) ^[1-3]. The disease is characterized by early persistent cholestasis, leading to the accumulation of bile acids in the liver and subsequent hepatocellular damage. Clinical manifestations of PFIC3 include jaundice (yellowing of the skin and eyes), pruritus, fatigue, and growth failure. If untreated, it can progress to cirrhosis and liver failure in early childhood ^[4]. The ABCB4 gene encodes Multidrug Resistance Protein 3 (MDR3), a member of the ATP-binding cassette (ABC) transporter family, which is a liver-specific phosphatidylcholine (PC) transporter ^[5]. MDR3 is primarily expressed on the canalicular membrane of hepatocytes (the membrane that forms bile canaliculi). It is involved in the transport of phosphatidylcholine from the hepatocyte membrane to vesicles, which are then secreted into bile, forming PC-cholesterol vesicles and a small number of mixed bile salt micelles ^[6]. Mutations in ABCB4 lead to the loss or dysfunction of MDR3, reducing PC levels in bile, destabilizing micelles, and increasing bile salt concentrations, thereby causing cholestasis and hepatocellular injury ^[7]. Studies have shown that knocking out the Abcb4 gene in mice leads to a phenotype similar to human PFIC3, although the severity and progression of the disease vary across different mouse strains. In the commonly used C57BL/6 background, Abcb4-KO mice exhibit a relatively mild pathological phenotype due to lower bile salt toxicity, and a diet enriched in hydrophobic bile salts is typically required to induce a more human-like PFIC3 phenotype ^[8-10]. In contrast, Abcb4-KO mice in the FVB background naturally exhibit most of the biomarkers and pathological features of human PFIC3, including hepatomegaly, liver fibrosis, and early disease onset with more severe progression ^[10-11]. Cyagen has generated the Abcb4-KO(FVB) mouse model by knocking out the Abcb4 gene in FVB mice. This model lacks the Abcb4 gene and protein expression and exhibits liver enlargement, elevated liver function markers, and increased total bilirubin. Histopathological examination shows hepatocyte necrosis, inflammatory cell infiltration, connective tissue proliferation, bile duct proliferation, and liver fibrosis.

P-glycoprotein (P-gp), also known as multidrug resistance protein 1 (MDR1), is an ATP-binding cassette transporter that acts as a biological barrier by expelling toxins and foreign substances from cells. P-gp is capable of transporting many structurally and functionally different compounds out of cells ^[1]. However, the mechanism of MDR1 also prevents the uptake of many cancer treatment drugs by cells, leading to multidrug resistance (MDR) ^[2]. In normal organisms, MDR1’s distribution in the blood-brain barrier and blood-placenta barrier prevents exogenous drugs and toxins from entering the central nervous system and placenta of the organism, thereby protecting the organism and enabling it to perform normal physiological functions. In pathological conditions, however, the MDR1 in the blood-brain barrier prevents drugs from entering the central nervous system, and in tumor cells, leads to the development of MDR. The evolution of MDR remains one of the major obstacles to controlling or curing cancer ^[3-4]. In humans, the MDR1 protein is encoded by the ABCB1 gene. In mice, two closely located genes, Abcb1a and Abcb1b, encode the MDR1a and MDR1b subtypes of this protein. Mouse MDR1a and MDR1b have 80% homology with human MDR1. MDR1a and MDR1b have the same function as human MDR1 protein in resisting anticancer drugs. Although mouse MDR1a and MDR1b proteins are distributed in different tissues of the body, their overall distribution is consistent with that of human MDR1 protein ^[5-6]. In summary, the distribution and function of mouse MDR1a and MDR1b are consistent with those of human MDR1. This strain is an MDR1 knockout model, in which the human ABCB1 gene’s homologous genes, Abcb1a and Abcb1b, were knocked out in mice using gene editing technology. This model lacks the expression of MDR1 protein and can be used for research in areas such as blood-brain barrier permeability-related diseases and multidrug resistance of anti-tumor drugs.