Spermidine/spermine-N1-acetyltransferase ablation protects against liver and kidney ischemia-reperfusion injury in mice

Expression of spermine/spermidine-N1-acetyltransferase (SSAT), the rate-limiting enzyme of polyamine backconversion cascade, increases after ischemia-reperfusion injuries (IRI). We hypothesized that SSAT plays an important role in the mediation of IRI. To test our hypothesis, wild-type (SSAT-wt) and SSAT-deficient (SSAT-ko) mice were subjected to liver or kidney IRI by ligation of hepatic or renal arteries. The liver and kidney content of putrescine (Put), a downstream by-product of SSAT activity, increased in SSAT-wt animals but not in SSAT-ko animals after IRI, indicating that polyamine backconversion is not functional in SSAT-deficient mice. When subjected to hepatic IRI, SSAT-ko mice were significantly protected against liver damage compared with SSAT-wt mice. Similarly, SSAT-ko animals subjected to renal IRI showed significantly greater protection against damage to kidney tubules than SSAT-wt mice. These studies indicate that SSAT-deficient animals are protected against IRI and suggest that SSAT is an important mediator of the tissue damage in IRI.