The ITGAV gene encodes the Integrin subunit α V (also known as αv or CD51), a transmembrane glycoprotein that is a member of the integrin superfamily. The encoded preproprotein is proteolytically processed into light and heavy chains that form the αv subunit, which then heterodimerizes with various β subunits (specifically β1, β3, β5, β6, or β8) to create functional receptors, with the αv β3 heterodimer being famously known as the vitronectin receptor ^[1]. αv integrins function as essential cell surface adhesion and signaling receptors that mediate interactions with the extracellular matrix (ECM) ligands, often recognizing the Arg-Gly-Asp (RGD) sequence, playing a crucial role in cell adhesion, migration, proliferation, angiogenesis, and the activation of latent growth factors like TGF-β1 ^[2]. While generally expressed at low levels in most healthy tissues, ITGAV is notably found on various cell types, including endothelial cells, macrophages, osteoclasts, synovial fibroblasts, and mesenchymal stromal cells, and its expression is often highly upregulated in various pathological conditions, including several cancers (e.g., hepatocellular, prostate, colorectal, esophageal, and head and neck squamous cell carcinoma), where its overexpression is frequently associated with poor prognosis and metastasis; additionally, ITGAV is implicated in autoimmune diseases such as rheumatoid arthritis (RA) and is exploited by various viral infections (e.g., West Nile virus, Adenovirus) ^[3]. B6-hITGAV mouse is a humanized model generated using gene editing technology, in which the sequence from partial exon 1 to partial intron 1 of mouse Itgav is replaced with ITGAV chimeric CDS-WPRE-BGH pA cassette. The murine signal peptide was preserved. This model can be used for studying the pathological mechanisms and therapeutic approaches of various cancers, autoimmune diseases such as rheumatoid arthritis (RA), and various viral infections, as well as for the development of ITGAV-targeted drugs.

Cluster of differentiation 3 (CD3) is a multimeric protein complex that is essential for T cell activation and antigen recognition. It consists of five different polypeptide chains (γ, δ, ε, ζ, and η) that are noncovalently associated with the T cell receptor (TCR). The TCR is responsible for recognizing antigens presented by antigen-presenting cells (APCs), while CD3 transduces the activation signal into the T cell and activates helper T-cells and cytotoxic T-cells ^[1-2]. The CD3-TCR complex is expressed on the surface of all mature T cells, and its assembly is required for T cell development and function. CD3 plays a crucial role in stabilizing the TCR and facilitating its interaction with antigens. It also recruits signaling molecules to the TCR, which initiates a cascade of events that leads to T cell activation. CD3 is a highly specific T cell marker, and its expression is increased upon T cell activation. This makes it a valuable tool for identifying and characterizing T cells in tissues and blood samples. CD3 staining is also used to diagnose T-cell lymphomas and leukemias. Due to its essential role in T cell activation, CD3 is a promising target for immunosuppressive therapy. Several anti-CD3 monoclonal antibodies have been developed and are being tested in clinical trials for the treatment of autoimmune diseases, such as type 1 diabetes and rheumatoid arthritis ^[3]. The BALB/c-hCD3 mice are a CD3 humanized model obtained by replacing the mouse CD3 coding gene with the human CD3 gene using embryonic stem (ES) cell targeting technology. This model can be used to study T cell activation and antigen recognition mechanisms and for the development of CD3-targeted drugs in immunosuppressive therapies for autoimmune diseases.

Interleukin 17A (IL-17A) is a signature cytokine of the T helper 17 (Th17) subset of CD4+ T cells and one of the six members (IL-17A~IL-17F) of the IL-17 family. IL-17A is primarily produced by Th17 cells and can also be produced by other immune cells under certain conditions, including CD8+ T cells, γδT cells, natural killer T (NKT) cells, monocytes, neutrophils, and microglia ^[1]. IL-17A mediates downstream pathways that induce the production of inflammatory molecules, chemokines, antimicrobial peptides, and remodeling proteins, which have important effects on host defense, cell transport, immune regulation, and tissue repair, especially in inducing innate immune defense. In healthy skin, commensal microorganisms induce the production of IL-17A to provide antifungal protection. When the skin barrier is damaged, IL-17A promotes epithelial cell proliferation and can clear pathogenic factors, promoting tissue repair and wound healing ^[2]. IL-17A usually protects the body when it is acutely injured, but when a wound requires long-term healing and becomes a chronic injury, the role of IL-17A may transform into wound erosion or excessive proliferation, ultimately leading to loss of function ^[3]. IL-17A plays a key role in various infectious diseases, inflammations, autoimmune diseases, and cancers. Its high expression level is associated with chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, and multiple sclerosis. Lung injury caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is largely the result of the promotion of inflammatory reactions by cytokines such as IL-17A. Dysregulation of IL-17 signaling promotes pathogenic inflammation. IL-17A has a pathogenic role in mediating the important inflammatory pathway of psoriasis. The IL-23/Th17/IL-17A pathway is a key link in its pathogenesis, and inhibiting the expression of IL-17A can effectively alleviate psoriasis ^[4]. IL-17A is also associated with the course of ankylosing spondylitis (AS), and IL-17A inhibitors can effectively treat AS ^[5]. In addition, studies have shown that IL-17A is involved in the pathogenesis of neurodegenerative diseases in the central nervous system, and its expression level is related to the severity and progression of the disease ^[3]. B6-hIL-17A mice are humanized mouse models that express human IL-17A protein. They were constructed by using gene editing technology to replace the sequence encoding the endogenous extracellular domain of the mouse Il17a gene with the corresponding sequence from the human IL17A gene while retaining the mouse signal peptide. This strain can be used for mechanism research and preclinical evaluation of therapeutic drugs for various chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, and multiple sclerosis. The homozygotes are viable and fertile.

Cluster of differentiation 3 (CD3) is a multimeric protein complex that is essential for T cell activation and antigen recognition. It consists of five different polypeptide chains (γ, δ, ε, ζ, and η) that are noncovalently associated with the T cell receptor (TCR). The TCR is responsible for recognizing antigens presented by antigen-presenting cells (APCs), while CD3 transduces the activation signal into the T cell and activates helper T-cells and cytotoxic T-cells ^[1-2]. The CD3-TCR complex is expressed on the surface of all mature T cells, and its assembly is required for T cell development and function. CD3 plays a crucial role in stabilizing the TCR and facilitating its interaction with antigens. It also recruits signaling molecules to the TCR, which initiates a cascade of events that leads to T cell activation. CD3 is a highly specific T cell marker, and its expression is increased upon T cell activation. This makes it a valuable tool for identifying and characterizing T cells in tissues and blood samples. CD3 staining is also used to diagnose T-cell lymphomas and leukemias. Due to its essential role in T cell activation, CD3 is a promising target for immunosuppressive therapy. Several anti-CD3 monoclonal antibodies have been developed and are being tested in clinical trials for the treatment of autoimmune diseases, such as type 1 diabetes and rheumatoid arthritis ^[3]. The BALB/c-hCD3 (line2) mice are a CD3 humanized model obtained by replacing the mouse CD3 coding gene with the human CD3 gene using embryonic stem (ES) cell targeting technology. This model can be used to study T cell activation and antigen recognition mechanisms and for the development of CD3-targeted drugs in immunosuppressive therapies for autoimmune diseases.

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 contains the lipoprotein ApoB-100. However, unlike LDL, LP(a) 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]. This strain was a conditional mouse model expressing the human LPA gene, where the ‘loxP-Stop-loxP-hLPA’ sequence was inserted into the intron 1 of the ROSA26 safe harbor locus. When this model is bred with tool mice expressing Cre recombinase, sequence recombination occurs in the Cre-positive cells and tissues of the offspring mice. After the Cre-recombinase-mediated deletion of the stop element (LSL), specific expression of the human LPA gene can be achieved. The B6-hLPA(CKI) mice can be used for research related to atherosclerosis, and thrombotic cardiovascular diseases, as well as the development, screening, and preclinical evaluation of human LPA gene-targeted drugs.

Calcitonin-related polypeptide alpha (CALCA) is a protein-encoded gene, also known as CALC1, CGRP, or CGRP-α. Multiple genetic factors and epigenetic modifications regulate CALCA gene expression, and it forms peptide hormones calcitonin (CT), α-isoform of calcitonin gene-related peptide (CGRP), and katacalcin through tissue-specific RNA alternative splicing and non-active precursor protein cleavage in transcription and translation. Calcitonin is synthesized and secreted by thyroid parafollicular cells, mainly involved in regulating calcium levels and phosphorus metabolism in bones and kidneys. It can reduce the concentration of calcium and phosphorus in the plasma and inhibit the absorption of calcium and phosphorus. CGRP mainly acts as a vasodilator and antimicrobial peptide, which can cause dilatation of coronary arteries, cerebral vessels, and systemic vessels, and help to regulate blood pressure. CGRP is also widely distributed in the pain pathways of the peripheral and central nervous system (CNS) of the human body, and its receptors are also expressed in the pain pathways. CGRP participates in the transmission of pain signals from the periphery to the CNS and plays a key role in pain regulation, which is related to the pathogenesis of a variety of pain diseases and related syndromes, including somatic pain, visceral pain, neuropathic pain, inflammatory pain, and migraine. Katacalcin mainly exists as a peptide that can effectively lower plasma calcium, and its effect of lowering serum calcium levels is almost the same as that of calcitonin. CALCA gene polymorphism is associated with a variety of diseases, including reflex sympathetic dystrophy syndrome, complex regional pain syndrome, ischemic stroke, Parkinson's disease, ovarian cancer, bone mineral density, migraine, schizophrenia, bipolar disorder, and primary hypertension ^[1-5]. CALCA is a potential target for new therapies for a variety of diseases. Currently, various CALCA antagonists are being developed for the treatment of migraine and primary hypertension, and research on targeting CALCA for diseases such as Alzheimer's disease and Parkinson's disease is also ongoing ^[6-7]. This strain is a humanized mouse model of the Calca gene. Using gene editing technology, the base sequence of the mouse Calca gene from the start codon to the 3’UTR region was replaced by the corresponding sequence in the human CALCA gene, while the 5’UTR region of the mouse Calca gene was retained. Homozygous B6-hCALCA mice are viable and fertile and can be used to study the mechanisms of various physiological and pathological processes such as blood pressure regulation, cell proliferation, cell apoptosis, vascular biology, physiological bone marrow production, inflammation, tumor growth, and research on CALCA-targeted migraine drugs and therapies.

The interleukin-2 receptor alpha subunit, encoded by the IL2RA gene and also known as CD25, is a critical determinant of IL-2 signaling, a pathway fundamental to T cell biology. While CD25 alone exhibits low affinity for IL-2, its assembly with the IL-2 receptor beta and gamma chains forms the high-affinity receptor complex essential for robust cellular responses to this pleiotropic cytokine ^[1]. Expressed prominently on activated T lymphocytes, including effector and regulatory T cells, CD25 is pivotal for diverse processes such as T cell proliferation, differentiation, and the maintenance of immune tolerance, largely mediated through its indispensable role in regulatory T cell development and function ^[2]. Consequently, perturbations in IL2RA expression or genetic variants within the locus are strongly associated with susceptibility to a range of severe autoimmune disorders, including multiple sclerosis, type 1 diabetes, and rheumatoid arthritis, highlighting its central involvement in immune homeostasis breakdown ^[3]. Furthermore, aberrant CD25 expression has been observed in certain malignancies, suggesting roles beyond adaptive immunity ^[4]. The demonstrable impact of IL2RA on immune regulation and disease pathogenesis underscores its significance as a key molecule in immunology and a compelling target for therapeutic intervention. The B6-hIL2RA mouse is a humanized model constructed by replacing the sequence of the mouse Il2ra endogenous extracellular domain in situ with the corresponding extracellular domain from the human IL2RA. The murine signal peptide and transmembrane-cytoplasmic region were preserved. The B6-hIL2RA mice can be used for the study of the pathogenesis of autoimmune diseases such as multiple sclerosis, type 1 diabetes, and rheumatoid arthritis, and certain malignancies, as well as for IL2RA-targeted drug development.