In vivo protein transduction: Biologically active intact pep-1-superoxide dismutase fusion protein efficiently protects against ischemic insult

Reactive oxygen species (ROS) are implicated in reperfusion injury after transient focal cerebral ischemia. The antioxidant enzyme Cu,Zn-superoxide dismutase (SOD) is one of the major means by which cells counteract the deleterious effects of ROS after ischemia. Recently, we reported that denatured Tat-SOD fusion protein is transduced into cells and skin tissue. Moreover, PEP-1 peptide, which has 21 amino acid residues, is a known carrier peptide that delivers full-length native proteins in vitro and in vivo. In the present study, we investigated the protective effects of PEP-1-SOD fusion protein after ischemic insult. A human SOD gene was fused with PEP-1 peptide in a bacterial expression vector to produce a genetic in-frame PEP-1-SOD fusion protein. The expressed and purified fusion proteins were efficiently transduced both in vitro and in vivo with a native protein structure. Immunohistochemical analysis revealed that PEP-1-SOD injected intraperitoneally (i.p.) into mice can have access into brain neurons. When i.p.-injected into gerbils, PEP-1-SOD fusion proteins prevented neuronal cell death in the hippocampus caused by transient forebrain ischemia. These results suggest that the biologically active intact forms of PEP-1-SOD provide a more efficient strategy for therapeutic delivery in various human diseases related to this antioxidant enzyme or to ROS, including stroke.