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Regular fragmentation of hydrogen peroxide-treated fibronectin
1Department of Pathology, University of Helsinki, Finland.
The Journal of Biological Chemistry
|March 15, 1989
Summary
Hydrogen peroxide at low concentrations generates specific fibronectin fragments through oxygen radical reactions. This controlled degradation of fibronectin suggests a potential in vivo mechanism for its breakdown.
Area of Science:
- Biochemistry
- Molecular Biology
- Oxidative Stress Research
Background:
- Fibronectin (Fn) is a crucial extracellular matrix protein involved in cell adhesion and migration.
- Oxidative stress, mediated by reactive oxygen species like hydrogen peroxide (H2O2), can alter protein structure and function.
- Understanding the specific effects of oxidative damage on fibronectin is important for comprehending cellular processes and disease mechanisms.
Purpose of the Study:
- To investigate the fragmentation patterns of fibronectin induced by hydrogen peroxide.
- To elucidate the mechanism of fibronectin degradation by reactive oxygen species.
- To characterize the generated fibronectin fragments and their origins within the protein structure.
Main Methods:
- Incubation of plasma and fibroblast fibronectin with varying concentrations of hydrogen peroxide.
- Analysis of fibronectin degradation products using SDS-PAGE and immunoblotting.
- Inhibition studies using radical scavengers (deferoxamine, DTPA, thiourea) and Chelex pretreatment.
- Characterization of fragment origins using monoclonal antibodies against different fibronectin domains.
Main Results:
- Low concentrations of H2O2 (less than 0.5 mM) generated Mr 350,000 and 170,000 fragments from fibronectin.
- Complete degradation required a 200-300-fold higher H2O2 concentration.
- Degradation was inhibited by radical scavengers, suggesting a Fenton-type reaction producing hydroxyl radicals (.OH).
- The Mr 170,000 fragment originated from the NH2-terminal part of fibronectin subunits.
- Reduced Mr 350,000 fragments yielded monomers and Mr 95,000/85,000 fragments, indicating disulfide bonding in the intact protein.
Conclusions:
- Oxygen radical action can induce defined and reproducible fragmentation of fibronectin.
- The NH2-terminal region of fibronectin is particularly susceptible to radical-induced cleavage.
- The susceptibility of fibronectin to radical degradation suggests this process may occur in vivo.