The C5 gene encodes a key component of the complement system, primarily produced by hepatocytes in the liver, with macrophages potentially serving as local sources of C5a. As part of the innate immune system, the complement system is activated upon tissue injury or pathogen invasion, playing a crucial role in inflammation, host homeostasis, and defense against pathogens. Complement activation occurs via three main pathways: the classical pathway, the alternative pathway, and the lectin pathway. All three pathways converge to form C3 convertase, which cleaves C3 into C3a and C3b. In addition to promoting opsonization on pathogen surfaces, C3b is also an integral part of C5 convertase (C4b2aC3b or C3bBbC3b). C5 convertase cleaves the C5 precursor protein to produce C5a and C5b. C5a is a potent inflammatory mediator, while C5b initiates the assembly of the membrane attack complex (MAC/C5b-9), which mediates phagocytosis, cell lysis, inflammatory response, immune regulation, and clearance of immune complexes ^[1-2]. Additionally, in cases of inherited C3 deficiency, thrombin can substitute for C3-dependent C5 convertase, indicating an alternative complement activation mechanism linked to the coagulation pathway ^[3]. While the complement system is essential for pathogen elimination and maintaining host homeostasis, its excessive activation can lead to tissue damage and uncontrolled inflammation. Imbalances in complement regulatory proteins are associated with complement-mediated diseases, including age-related macular degeneration (AMD), atypical hemolytic uremic syndrome (aHUS), myasthenia gravis (MG), C3 glomerulopathy, and paroxysmal nocturnal hemoglobinuria. C5 has been identified as a promising therapeutic target in complement-mediated diseases, as inhibiting C5 can block the production of the highly pro-inflammatory C5a and MAC, while preserving the opsonizing functions of C3b and C4b and the immune signaling mediated by C3a ^[4]. Currently, approved C5 inhibitors are predominantly monoclonal antibodies, such as eculizumab, vilobelimab, and crovalimab. The development of a mouse model expressing human C5 is crucial for the preclinical evaluation of the pharmacodynamics and pharmacokinetics of C5 inhibitors. The huC5 mouse model is a humanized model of the Hc gene, with the mouse Hc gene homologous to the human C5 gene. Using gene-editing technology, the mouse Hc gene was replaced with the human C5 gene while retaining the mouse signal peptide; the humanized region also includes the 3’ UTR. In addition, based on the independently developed TurboKnockout fusion BAC recombination technology, Cyagen can also generate mutation models based on this strain and provide customized services.

Retinitis pigmentosa (RP) is a hereditary retinal disease with a global prevalence of approximately 1:5000-1:3000. RP is highly clinically and genetically heterogeneous, with mutations in the rhodopsin (RHO) gene causing approximately 25% of dominant RP ^[1]. The rhodopsin encoded by the RHO gene is closely associated with visual light transduction and GPCR downstream signals. Rhodopsin is essential for the transmission of light signals in the process of vision formation. Most RHO mutations lead to high levels of rhodopsin expression in photoreceptor cells, causing many mutant proteins to be abnormally located and aggregated in cells. This results in the apoptosis of photoreceptor cells, which cannot perform normal light signal transduction functions. Additionally, mutations in the RHO gene are associated with congenital stationary night blindness (CSNB) ^[2-6]. Mutations in the RHO gene can lead to rhodopsin-mediated autosomal dominant retinitis pigmentosa (RHO-adRP). In 25% of autosomal dominant inherited RP (adRP) cases, there are over 150 different RHO gene mutations. Notably, the P23H mutation is one of the most prevalent, accounting for 10% of adRP cases ^[2]. Previous studies have shown that mice carrying the heterozygous human RHO P23H mutation exhibit retinopathy and progressive retinal degeneration similar to the patient's disease process, which could be used for visual signaling and retinitis pigmentosa (RP) studies ^[3]. Current gene therapy targeting the RHO gene to treat retinitis pigmentosa includes ASO, CRISPR, and others. Applying fully humanized animal models will promote the further development of RHO-related potential therapies in clinical trials ^[7-11]. This strain is a mouse Rho gene humanized model, in which the endogenous mouse Rho gene and Rho gene promoter are replaced by the human RHO gene carrying a P23H mutation and RHO gene promoter to express human retinal proteins in mice. Therefore, the abnormal protein encoded by the human gene was expressed in mice, resulting in abnormal retinal appearance and function and visual defects in this model. Based on the self-developed technological innovation of TurboKnockout fusion BAC recombination, Cyagen can also provide customized services for different point mutations to meet the needs of a wide range of R&D personnel regarding the pharmacodynamics of retinitis pigmentosa (RP) and other preclinical needs.

E2f8 is located on chromosome 7 of mice. SgRNA and ssDNA were designed using Nuclease Technology; E2f8 conditional knockout mice were obtained by high-throughput electroporation of fertilized eggs. After sexual maturity, sperm were collected for cryopreservation.