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Targeting SOD by gene and protein engineering and inhibition of free radical injury
M Inoue1, N Watanabe, T Utsumi
1Department of Biochemistry, Kumamoto University Medical School, Japan.
Abstract:
Although oxygen toxicity of tissues can be decreased by a variety of antioxidants and some enzymes, such as SOD and catalase, their protective effect on tissue injury in various diseases are fairly small predominantly because of their unfavorable in vivo behavior. To minimize oxidative stress in various diseases, such as ischemic myocardial injury, circulatory disturbance and corneal inflammation, we synthesized three types of SOD derivatives by gene and protein engineering technique. One type of SOD (SM-SOD covalently linked with hydrophobic anions) circulates bound to albumin with a half life of 6 h and accumulates in tissues whose local pH is decreased. The other type of SOD (AC-SOD covalently linked with long chain fatty acids via the epsilon-amino group of lysyl residues) anchors onto membrane/lipid bilayers of various cells. The last type of SOD (HB-SOD synthesized by constructing a fusion gene coding human CuZn-type SOD and a C-terminal heparin-binding domain) binds to heparin-like proteoglycans on vascular endothelial cell surface. Intravenous administration of either SM-SOD or HB-SOD markedly inhibited postischemic reflow arrhythmias in the rat. When the left anterior descending artery was occluded permanently, about 65% of animals died within 30 min predominantly due to irreversible ventricular fibrillation; the motality of animals decreased to 15% by administering SM-SOD either before or after occlusion. Topically administered AC-SOD bound to the corneal epithelial cell surface and polymorphonuclear leukocytes and efficiently dismutated superoxide radicals at their cell surface. Thus, endotoxin-induced keratitis was inhibited markedly by topical instillation of AC-SOD.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Engineered superoxide dismutase (SOD) derivatives show improved in vivo behavior for treating oxidative stress. These novel SOD variants effectively protected against tissue injury in models of ischemia and inflammation.
Area of Science:
- Biochemistry
- Molecular Biology
- Biotechnology
Background:
- Oxidative stress contributes to tissue injury in various diseases.
- Existing antioxidants and enzymes like superoxide dismutase (SOD) have limited efficacy due to poor in vivo behavior.
- Novel strategies are needed to enhance the protective effects of SOD in vivo.
Purpose of the Study:
- To engineer novel SOD derivatives with improved pharmacokinetic and tissue-targeting properties.
- To evaluate the efficacy of these engineered SOD derivatives in preclinical models of oxidative stress-related diseases.
Main Methods:
- Gene and protein engineering techniques were used to synthesize three types of SOD derivatives: SM-SOD, AC-SOD, and HB-SOD.
- SM-SOD was designed to bind albumin and accumulate in low-pH tissues.
- AC-SOD was modified with fatty acids to anchor onto cell membranes.
- HB-SOD was fused with a heparin-binding domain to target vascular endothelial cells.
Main Results:
- SM-SOD and HB-SOD significantly inhibited post-ischemic reflow arrhythmias in rats, reducing mortality from 65% to 15% in a myocardial infarction model.
- AC-SOD effectively targeted corneal epithelial cells and leukocytes, significantly inhibiting endotoxin-induced keratitis upon topical administration.
Conclusions:
- Engineered SOD derivatives demonstrate enhanced in vivo behavior and potent protective effects against oxidative tissue injury.
- SM-SOD, AC-SOD, and HB-SOD represent promising therapeutic strategies for conditions involving ischemia, inflammation, and oxidative stress.