A hCXCR1 transgenic mouse model containing a conditional color-switching system for imaging of hCXCL8/IL-8 functions in vivo.

To address the functions of human CXCL8 (hCXCL8)/IL-8 through hCXCR1 in vivo, we have developed a humanized, transgenic mouse for hCXCR1. This mouse line is versatile and allows for a variety of functional analyses using bioimaging, including Cre/loxP-mediated, tissue-specific hCXCR1 expression in a spatiotemporal manner; a color-switching mechanism, which uses spectrum-complementary, genetically encoded green and red fluorescence markers to label the hCXCR1-expressing cells [enhanced GFP (eGFP)] against the background [monomeric red fluorescent protein (mRFP)]; a bioluminescent marker, which is present in the hCXCR1-expressing cells; and an exogenous cell surface marker (eGFP moiety) in the hCXCR1-expressing cells, which facilitates identification, isolation, and targeting of these cells. The established, transgenic founder line RCLG3A (TG(+)) expresses only mRFP and does so ubiquitously. When the RCLG3A mice are crossed with the tamoxifen-inducible, whole-tissue Cre mice (ROSA26-Cre/Esr(+/-)), administration of tamoxifen induces whole-body hCXCR1 expression and color-switching. When RCLG3A mice are crossed with thymocyte-specific Cre mice (Lck-Cre(+/+)), the hCXCR1 expression and color-switching are restricted in a lineage-specific manner. This mouse line can be used to understand the functions of hCXCL-8 in vivo. In addition, our approach and vectors can be used to establish other tissue-specific, transgenic mice in conjunction with multifunctional cell markers, which facilitate cell imaging, tracing, and manipulation in vivo.