LAUSR

Oxygen (O2) homeostasis is essential to the metazoan life. O2‐sensing or hypoxia‐regulated molecular pathways are intimately involved in a wide range of critical cellular functions and cell survival from embryogenesis to adulthood. In this report, we have designed an innovative hypoxia sensor (O2CreER) based on the O2‐dependent degradation domain of the hypoxia‐inducible factor‐1α and Cre recombinase. We have further generated a hypoxia‐sensing mouse model, R26‐O2CreER, by targeted insertion of the O2CreER‐coding cassette in the ROSA26 locus. Using the ROSAmTmG mouse strain as a reporter, we have found that this novel hypoxia‐sensing mouse model can specifically identify hypoxic cells under the pathological condition of hind‐limb ischemia in adult mice. This model can also label embryonic cells including vibrissal follicle cells in E13.5–E15.5 embryos. This novel mouse model offers a valuable genetic tool for the study of hypoxia and O2 sensing in mammalian systems under both physiological and pathological conditions.