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Osteopontin-induced modifications of cellular functions
D T Denhardt1, C A Lopez, E E Rollo
1Department of Biological Sciences, Rutgers University, Piscataway, New Jersey 08855, USA.
Annals of the New York Academy of Sciences
|April 21, 1995
Summary
Osteopontin (OPN) is a protein that aids cell attachment and signaling. Recombinant OPN affects intracellular calcium, protein phosphorylation, and gene expression, while also protecting cells from damage and immune attack.
Area of Science:
- Biochemistry
- Cell Biology
- Immunology
Background:
- Osteopontin (OPN) is a multifunctional protein involved in cell adhesion and signaling.
- The alpha v beta 3 integrin is a key receptor for OPN's cell signaling functions.
- Understanding OPN's actions is crucial for various biological processes.
Purpose of the Study:
- To investigate the effects of recombinant Osteopontin (OPN) on mammalian cells.
- To characterize the cell signaling pathways initiated by OPN.
- To explore OPN's influence on cellular responses to stress and immune surveillance.
Main Methods:
- Production of recombinant OPN in E. coli and human cells.
- Analysis of intracellular calcium ion levels.
- Assessment of protein tyrosine phosphorylation, including pp60src and focal adhesion components.
- Evaluation of gene expression changes, specifically nitric oxide synthase induction.
- Measurement of cellular peroxide levels and cell survival under hypoxia.
- Investigation of OPN's effect on macrophage-mediated tumor cell killing.
Main Results:
- Recombinant OPN triggers signal transduction cascades involving intracellular calcium and tyrosine phosphorylation.
- OPN suppresses the induction of nitric oxide synthase by inflammatory mediators.
- OPN reduces cellular peroxide levels and enhances cell survival during hypoxia.
- OPN inhibits the killing of tumor cells by activated macrophages.
Conclusions:
- Osteopontin (OPN) exhibits diverse biological activities, including modulation of signal transduction, gene expression, and cellular protection.
- OPN's functions extend to influencing immune responses against tumor cells.
- Recombinant OPN produced in different systems retains significant biological activity, highlighting its therapeutic potential.