Characterising the role of CR1 and CR2 in a humanised mouse model

The complement cascade is being increasingly implicated in development and disease. To understand these various roles, mouse models have been used and are proving to be an excellent tool. While they have helped to elucidate many roles of central cascade components, they do not adequately model complement regulators. Complement Receptors 1 (CR1) and 2 (CR2) have been implicated in modifying disease states, such as Alzheimer’s disease and Systemic Lupus Erythematosus, but they are not well replicated in mice. This leaves a gap in knowledge about how these receptors are functioning. To overcome this, a mouse model was engineered to replace endogenous murine Cr2 with the human complement receptors, CR1 and CR2. This model will be an asset to the complement research community, but there is need for characterizing the expression of CR1. This project aims to establish and validate this model. CR1 has an array of allotypes in human populations, and using traditional recombination methods (FLP-FRT and Cre recombination) two of the most common alleles are replicated within this mouse, along with creating a CR1 knockout allele. To validate the model a variety of techniques were used to ensure the correct targeting of the genomic construct into the murine Cr2 locus. Once integration was confirmed, the allelic series was established. Expression patterns in blood-derived cells were probed at an RNA level, with the different isoforms of CR1 being identified at a protein level. These models accurately produce viable protein products. These findings ensure that an accurate mouse model will be available to the complement research community