The HRas oncogene (HRAS), also known as the Harvey Rat Sarcoma Viral Oncogene Homolog (HRAS), is a member of the Ras oncogene family, which also includes KRAS and NRAS. All members of this family are associated with the development of mammalian sarcoma retroviruses ^[1]. HRAS encodes the H-Ras protein, a small GTPase responsible for transmitting signals from cell surface receptors to the nucleus, regulating cell proliferation, survival, and differentiation. HRAS is primarily expressed in various tissues, including the brain, heart, and skeletal muscle, and is involved in controlling the cellular response to growth factors. As a member of the small GTPase family, HRAS acts as a molecular switch, cycling between active and inactive states to influence key cellular processes. Mutations in the HRAS gene can lead to abnormal signal transduction, commonly found in tumors of stratified epithelial tissues, such as bladder cancer, thyroid cancer, and head and neck squamous cell carcinoma. Additionally, HRAS is associated with Costello syndrome, a genetic disorder characterized by developmental delays and an increased risk of tumors ^[2-3]. Early studies have shown that genotoxic carcinogens shorten the latency period and increase the incidence of malignant tumors in rasH2 mice, which carry the human HRAS (c-Ha-ras) oncogene, compared to non-transgenic mice. Therefore, rasH2 mice are ideal animal models for rapid carcinogenicity testing ^[4-5]. Further research has shown that F1 hybrid mice (CB6F1 background rasH2 mice) obtained by mating male C57BL/6J mice carrying the human prototype c-Ha-ras gene with female BALB/c mice are significantly more sensitive to both mutagenic and non-mutagenic carcinogens than control mice ^[5]. These mice are highly sensitive to the carcinogenicity of both genotoxic and non-genotoxic compounds while showing no response to non-carcinogens ^[6]. Between 12 to 18 months of age, rasH2 mice primarily develop spontaneous alveolar adenomas/bronchial adenomas/adenocarcinomas, splenic hemangiomas/hemangiosarcomas, and a smaller number of skin and gastric papillomas and lymphomas ^[4]. In the 1990s, this mouse model was officially approved by the FDA for carcinogenicity evaluations in drug safety assessments, reducing the standard two-year carcinogenicity test in common rodents to six months. BALB/c;B6J-Rosa26-hHRAS mice are obtained by crossing Rosa26-hHRAS mice on a C57BL/6JCya background (Catalog No.: I001213) with BALB/cAnCya mice. This hybrid strain exhibits higher sensitivity to both genotoxic and non-genotoxic human carcinogens. BALB/c;B6J-Rosa26-hHRAS mice can be used for rapid in vivo testing of the carcinogenicity of genotoxic and non-genotoxic compounds, studying the impact of HRAS oncogene point mutations on tumorigenesis and development, and developing tumor prevention or suppression therapies.

The Transferrin receptor (TFRC) gene encodes Transferrin Receptor 1 (TFR1), a protein that is expressed at low levels in most normal cells but shows increased expression in highly proliferative cells, such as basal epidermal cells, intestinal epithelium, and certain activated immune cells. Brain capillary endothelial cells, which constitute the blood-brain barrier (BBB), also express this receptor at high levels ^[1]. TFR1 plays a critical role in maintaining iron metabolism and homeostasis by facilitating receptor-mediated endocytosis of iron-bound transferrin (Tf) via Tf cycling, thereby promoting iron uptake ^[2]. Cellular iron deficiency can lead to apoptosis, while cellular transformation requires substantial iron to sustain proliferation, with iron overload contributing to tumor progression. The high expression of TFR1 in many tumors makes it a potential tumor marker, offering a target for therapies to inhibit tumor growth and metastasis ^[1]. Moreover, TFR1 is implicated in anemia and iron metabolism disorders. Studies have shown that elevated TFR1 expression in cardiomyocytes is associated with exacerbated inflammation in myocarditis patients ^[3]. The tau protein, a microtubule-associated protein encoded by MAPT, is primarily localized to neuronal axons and plays a critical role in microtubule stability and assembly. By binding to microtubules, the tau protein helps to maintain neuronal cell shape. Mutations in MAPT can promote tau aggregation, leading to pathological tau protein accumulation and death of glutamatergic cortical neurons ^[4]. Additionally, certain MAPT mutations can affect pre-mRNA exon splicing, altering the ratio of 3R to 4R tau protein isoforms and increasing the relative production of 4R-tau protein, which is more prone to fibril formation ^[5]. The B6-hTFRC/htau mice are a model expressing human TFRC protein and tau protein, generated by crossing B6-hTFRC(CDS) mice (Catalog No.: C001584) with B6-htau mice (Catalog No.: C001410). These mice can be used for research on neurodegenerative diseases and iron metabolism disorders, as well as for the development and preclinical evaluation of TFRC/MAPT-targeted therapeutic agents.

Lipoprotein A (LPA) is a type of particle similar to low-density lipoprotein (LDL) that is considered one of the risk factors for cardiovascular disease (CVD), such as atherosclerosis, coronary heart disease, stroke, etc ^[1]. LP(a) is similar in size and lipid content to LDL (low-density lipoprotein) and also contains the lipoprotein ApoB-100. However, unlike LDL, LP(a) additionally contains a variable-length lipoprotein called Apo(a), which covalently binds to ApoB-100 through a single disulfide bond. LP(a) plays an important role in systemic lipid transport, guiding inflammatory cells into blood vessel walls and leading to smooth muscle cell proliferation. Furthermore, it is involved in wound healing and tissue repair, interacting with the components of blood vessel walls and the extracellular matrix ^[2]. However, LP(a) can also cause arterial narrowing by adhering to the arterial wall, accelerating the formation of blood clots, and thereby triggering a series of pathological changes related to coronary heart disease, cardiovascular disease, atherosclerosis, thrombus formation, and stroke ^[3]. The plasma concentration of LP(a) is closely related to genetic factors and is primarily regulated by the LPA gene. Therefore, the LPA gene is an important potential target for cardiovascular disease treatment. The LPA gene encodes a serine protease that inhibits the activity of tissue-type plasminogen activator I. Fragments of this protein, generated through protein hydrolysis, can adhere to atherosclerotic lesions in arteries, promoting blood clot formation. The LPA gene is expressed in both humans and non-human primates but is not expressed in mice. Constructing mouse models expressing the human LPA gene is of significant importance for developing lipid-lowering drugs, which can drive the development of novel therapies for cardiovascular diseases. Currently, various novel therapies targeting the transcription rate of the LPA gene are under development, including small interfering RNA (siRNA) and antisense oligonucleotides (ASO) ^[4]. Proprotein convertase subtilisin/kexin 9 (PCSK9) is a serine protease primarily produced in the liver but expressed in other tissues, including the intestine, heart, and neurons. The N-terminal domain of the PCSK9 protein is responsible for protein localization and stability, while the C-terminal domain is responsible for protein enzymatic activity ^[5]. The Low-density lipoprotein receptor (LDLR) is a receptor that is responsible for clearing low-density lipoprotein cholesterol (LDL-C) from the blood. PCSK9 cleaves the intracellular domain of LDLR on the cell surface, causing it to detach from the cell membrane and be transported to the lysosome for degradation, promoting LDLR degradation, and increasing plasma LDL-C. Overexpression or gain-of-function mutations of the PCSK9 gene can lead to LDL-C accumulation by reducing LDLR levels. This can cause hypercholesterolemia, which increases the risk of cardiovascular diseases, such as atherosclerosis and coronary heart disease, and neurodegenerative diseases, such as Alzheimer's disease ^[6]. PCSK9 has emerged as a key target for the development of lipid-lowering drugs. Several PCSK9-targeted antibodies or small nucleic acid drugs have been approved for marketing worldwide, including evolocumab from Amgen, alirocumab from Sanofi and Regeneron, and inclisiran from Novartis. These drugs primarily work by inhibiting PCSK9 activity or preventing PCSK9 protein from binding to LDLR, lowering LDL-C levels in the blood to treat hypercholesterolemia ^[7-8]. In addition, PCSK9 can promote tumor growth and development by regulating cell proliferation, migration, and invasion. It can also regulate the expression of inflammatory factors that contribute to inflammation. Therefore, targeting the expression of PCSK9 has been investigated in tumor immunotherapy and autoimmune disease therapy ^[9-10]. The B6-hLPA (CKI)/Alb-cre/hPCSK9 mouse model is generated by crossing B6-hLPA (CKI) mice (Catalog No.: C001521, a mouse strain with conditional expression of the human LPA gene), Alb-Cre mice (liver-specific Cre-expressing mice), and B6-hPCSK9 mice (Catalog No.: C001617). This model harbors two cardiovascular disease risk factors, namely Lp (a) (lipoprotein (a)) and PCSK9, making it suitable for research on hyperlipidemia, stroke, coronary heart disease, and other atherosclerotic cardiovascular diseases (ASCVD).

TNF-like ligand 1A (TL1A), also known as TNF superfamily member 15 (TNFSF15), is a member of the tumor necrosis factor (TNF) family encoded by the TNFSF15 gene in humans. TL1A acts as a ligand for death receptor 3 (DR3) and decoy receptor 3 (DcR3), providing a stimulatory signal for downstream pathways. It regulates the proliferation, activation, and apoptosis of effector cells, as well as cytokine and chemokine production. TL1A is expressed in various immune cells, including monocytes, macrophages, dendritic cells, and T cells, as well as in non-immune cells such as synovial fibroblasts and endothelial cells. It plays a crucial role in modulating immune responses by promoting the differentiation and survival of T cells, particularly Th17 cells involved in inflammatory processes ^[1]. TL1A enhances IL-2 responses in anti-CD3/CD28-stimulated T cells and synergizes with IL-12 and IL-18 to augment IFN-γ release in human T and NK cells, biasing T cell differentiation toward a Th1 phenotype ^[2]. Dysregulation of TL1A expression is implicated in autoimmune diseases, including inflammatory bowel disease (IBD), rheumatoid arthritis (RA), primary biliary cholangitis (PBC), systemic lupus erythematosus (SLE), and ankylosing spondylitis (AS) ^[1]. TL1A has emerged as a promising therapeutic target, with ongoing research focused on developing monoclonal antibodies and other biologics to neutralize TL1A and reduce inflammation in autoimmune disorders. Clinical trial results suggest that TL1A inhibition can be used in the treatment of various autoimmune diseases, particularly IBD ^[3-5]. The Cryopyrin protein, encoded by the NOD-like receptor family pyrin domain-containing 3 (NLRP3) gene, is a core component of the inflammasome in the innate immune system. As a member of the NOD-like receptor (NLR) family, NLRP3 is predominantly expressed in leukocytes and chondrocytes. It participates in the host defense against damage and infection by recognizing pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) to activate immune responses ^[6]. In its inactive monomeric state, NLRP3 senses intracellular damage signals, such as abnormal protein aggregates and lipid accumulation. Upon activation, NLRP3 oligomerizes, adopting an active conformation and assembling into inflammasome complexes, subsequently activating Caspase-1 to drive the maturation and secretion of pro-inflammatory cytokines, including IL-1β and IL-18 ^[6-7]. Activated NLRP3 not only induces the release of inflammatory cytokines but also triggers lytic cell pyroptosis. The intracellular components released during pyroptosis can further amplify inflammatory signals, forming a positive feedback loop of autoinflammation. Moreover, IL-1β can exacerbate the inflammatory cascade by stimulating the production of inflammatory markers such as IL-6 and high-sensitivity C-reactive protein (hsCRP) ^[8-9]. Given NLRP3's upstream position relative to IL-1β/IL-18 and other inflammatory factors, targeting its activity can effectively block the self-reinforcing mechanism of chronic inflammation, providing a significant therapeutic strategy for inflammation-related diseases ^[10]. The potential therapeutic areas include Alzheimer’s disease, Parkinson’s disease (via neuroinflammation modulation), inflammatory bowel disease, metabolic dysfunction-associated steatohepatitis (MASH), gout, and obesity-related metabolic inflammation ^[11-12]. B6-hTL1A/hNLRP3 mice are TL1A and NLRP3 double humanized mouse models obtained by mating TL1A humanized mouse models (Catalog No. C001603) with NLRP3 humanized mouse models (Catalog No. C001616). B6-hTL1A/hNLRP3 mice express human TL1A and NLRP3 genomic sequences under the control of mouse promoters. This model is capable of reproducing human TL1A and NLRP3 and is a valuable tool for studying autoimmune diseases and inflammation-related diseases. In addition, this model also provides a powerful preclinical research platform for evaluating the efficacy and mechanism of therapeutic drugs targeting TL1A and NLRP3.

The Transferrin receptor (TFRC) gene encodes Transferrin Receptor 1 (TFR1), a protein that is expressed at low levels in most normal cells but shows increased expression in highly proliferative cells, such as basal epidermal cells, intestinal epithelium, and certain activated immune cells. Brain capillary endothelial cells, which constitute the blood-brain barrier (BBB), also express this receptor at high levels ^[1]. TFR1 plays a critical role in maintaining iron metabolism and homeostasis by facilitating receptor-mediated endocytosis of iron-bound transferrin (Tf) via Tf cycling, thereby promoting iron uptake ^[2]. Cellular iron deficiency can lead to apoptosis, while cellular transformation requires substantial iron to sustain proliferation, with iron overload contributing to tumor progression. The high expression of TFR1 in many tumors makes it a potential tumor marker, offering a target for therapies to inhibit tumor growth and metastasis ^[1]. Moreover, TFR1 is implicated in anemia and iron metabolism disorders. Studies have shown that elevated TFR1 expression in cardiomyocytes is associated with exacerbated inflammation in myocarditis patients ^[3]. As a target for antibody-mediated cancer therapy, TFR1 can be leveraged through two approaches: one involves the use of antibodies conjugated to anti-cancer drugs, which are indirectly internalized via receptor-mediated endocytosis; the other employs antibodies that directly disrupt receptor function or induce Fc effector functions such as antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), or complement-dependent cytotoxicity (CDC). Various clinical drugs targeting TFR1 are currently under development, including antisense oligonucleotides (ASOs), antibody-drug conjugates (ADCs), and antibody-oligonucleotide conjugates, applicable to diseases such as cancer, anemia, and neurodegenerative disorders. Research indicates that enhancing antibody transport across the blood-brain barrier via TFR1, by forming specific bispecific antibodies with anti-β-amyloid antibodies, can improve therapeutic outcomes in Alzheimer's patients ^[4-5]. As research progresses, TFR1 is expected to become an effective clinical target for multiple diseases and a synergistic target for drug delivery across the blood-brain barrier (BBB). The tau protein, a microtubule-associated protein encoded by MAPT, is primarily localized to neuronal axons and plays a critical role in microtubule stability and assembly. By binding to microtubules, the tau protein helps to maintain neuronal cell shape. Mutations in MAPT can promote tau aggregation, leading to pathological tau protein accumulation and death of glutamatergic cortical neurons ^[6]. Additionally, certain MAPT mutations can affect pre-mRNA exon splicing, altering the ratio of 3R to 4R tau protein isoforms and increasing the relative production of 4R-tau protein, which is more prone to fibril formation ^[7-8]. The B6-huTFRC/htau mouse is a dual-gene humanized model obtained by mating B6-huTFRC mice (catalog number: C001860) with B6-htau mice (catalog number: C001410). This model can be used for research on neurodegenerative diseases and iron metabolism diseases, as well as pre-clinical studies of TFRC/MAPT-targeted therapeutic drugs.