Cd8a-IRES-CreERT2 Mouse

Cd8a (CD8 subunit alpha) encodes the CD8α chain, which assembles with CD8β into the CD8αβ heterodimer that serves as a co-receptor for MHC class I and supports antigen recognition and cytotoxic function of CD8⁺ T cells; CD8α can also form a CD8αα homodimer expressed by intestinal intraepithelial lymphocytes and by a subset of dendritic cells ^[1]. Expression of the mouse Cd8a locus is controlled by multiple enhancers, of which the E8I enhancer mainly drives expression in CD8 single-positive thymocytes, mature CD8⁺ T cells and intraepithelial lymphocytes ^[1]; CD8α-positive conventional dendritic cells type 1 (cDC1) in lymphoid organs constitute the principal cross-presenting population ^[2].

Cd8a-IRES-CreERT2 mice were generated by gene editing, in which the "IRES-CreERT2" cassette was inserted downstream of the stop codon of the endogenous mouse Cd8a gene. In the absence of tamoxifen treatment, the CreERT2 recombinase is mainly localized in the cytoplasm; after tamoxifen treatment, the CreERT2 recombinase enters the nucleus and exerts its recombination function. When Cd8a-IRES-CreERT2 mice are crossed with mice carrying loxP sites, the offspring are expected to undergo Cre recombinase-mediated recombination between loxP sites in Cd8a-positive cells after tamoxifen induction.