Generation of a p21 Reporter Mouse and Its Use to Identify and Eliminate p21(high) Cells In Vivo

P21 and p16 have been identified as inducers of senescence. Many transgenic mouse models have been developed to target cells expressing high levels of p16(Ink4a) (p16(high)) and investigate their potential contribution to tissue dysfunction in aging, obesity, and other pathological conditions. However, the specific roles of p21 in various senescence-driven processes remain unclear. To gain a deeper understanding of p21, we built a p21-3MR mouse model containing a p21 promoter-driven module that allowed us to target cells with high p21(Chip) expression (p21(high)). Using this transgenic mouse, we monitored, imaged, and eliminated p21(high) cells in vivo. We also applied this system to chemically induced weakness and found that the clearance of p21(high) cells improved doxorubicin (DOXO)-induced multi-organ toxicity in mice. By recognizing p21 transcriptional activation spatially and temporally, the p21-3MR mouse model can be a valuable and powerful tool for studying p21(high) cells to further understand senescence biology.