A strategy for the ubiquitous overexpression of human catalase and CuZn superoxide dismutase genes in transgenic mice

In the present study, we generated transgenic mice that overexpress catalase or CuZn superoxide dismutase (CuZnSOD) in all tissues using large genomic DNA fragments. An 80 kb human genomic DNA, containing the 33 kb human CAT gene as well as the 41 kb of 5′ and the 6 kb of 3′ flanking regions, was obtained by screening a human P1 library and was used to produce transgenic mice Tg(CAT). Transgenic mice Tg(SOD1) were produced by a similar strategy using a 64 kb human genomic DNA containing the 10 kb human SOD1 gene and the 27 kb of both 5′ and 3′ flanking regions. Catalase mRNA levels were 2–6- fold higher and catalase activity levels were 2–4- fold higher in the various tissues of the hemizygous Tg(CAT) mice compared with wild type mice. The mRNA levels for CuZnSOD were 2–12- fold higher and the CuZnSOD activity levels were 2–5- fold higher in the hemizygous Tg(SOD1) mice compared with wild type mice. In summary, our study demonstrates that a strategy of using large genomic DNA containing either the entire human CAT or SOD1 gene with large flanking regions gives ubiquitous increased expression of CuZnSOD and catalase. In addition, the expression of catalase closely reflects the tissue specific pattern found in the endogenous gene. These transgenic mice will be useful in studying the role of oxidative stress/damage in aging and age-related pathologies.