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Fibronectin harbors anticell adhesive activity
1Department of Patho-Physiology, Faculty of Pharmaceutical Sciences, Science University of Tokyo, Japan.
Abstract:
Effect of fibronectin (FN) fragment derived from the carboxyl-terminal heparin-binding (Hep 2) domain on cell adhesion was studied. A 30-kDa Hep 2 fragment showed no significant effect on adhesion of Mardin Darbyn caine kidney (MDCK) cells to FN substrate, whereas after exposure to urea, the Hep 2 fragment suppressed the MDCK cell adhesion to FN in an incompetitive fashion. This anti-cell adhesive Hep 2 fragment preferentially inhibited the RGD (Arg-Gly-Asp)-dependent cell adhesion to FN. No significant binding of the Hep 2 fragment with FN was detected. Additionally, data of flow cytometry showed the presence of specific binding site for the Hep 2 fragment on MDCK cell surface. These results indicate that the Hep 2 domain of FN has a cryptic molecular region having the anti-cell adhesive activity that is probably transduced by a putative cell surface receptor.
Insights
A fibronectin (FN) fragment from the Hep 2 domain suppressed cell adhesion after urea exposure, suggesting a cryptic anti-adhesion site. This site likely interacts with a cell surface receptor, not FN itself.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Fibronectin (FN) is a crucial extracellular matrix protein involved in cell adhesion.
- The carboxyl-terminal heparin-binding (Hep 2) domain of FN plays a role in mediating cell interactions.
- Understanding the specific functions of FN domains is key to deciphering cell-matrix communication.
Purpose of the Study:
- To investigate the effect of a fibronectin (FN) Hep 2 domain fragment on cell adhesion.
- To determine if urea treatment alters the Hep 2 fragment's interaction with cell adhesion pathways.
- To identify the mechanism by which the Hep 2 fragment influences cell adhesion.
Main Methods:
- Utilized a 30-kDa Hep 2 fragment derived from fibronectin.
- Assessed Madin-Darby Canine Kidney (MDCK) cell adhesion to FN substrates.
- Employed urea treatment to modulate fragment activity.
- Performed competitive inhibition assays and flow cytometry to analyze binding interactions.
Main Results:
- The Hep 2 fragment alone did not significantly affect MDCK cell adhesion to FN.
- Urea-treated Hep 2 fragment suppressed MDCK cell adhesion to FN in an incompetitive manner.
- The suppression was specific to RGD (Arg-Gly-Asp)-dependent cell adhesion.
- No direct binding of the Hep 2 fragment to FN was observed; however, specific binding sites on MDCK cells were detected.
Conclusions:
- The Hep 2 domain of fibronectin contains a cryptic molecular region with anti-cell adhesive activity.
- This anti-adhesive activity is revealed or enhanced by urea treatment.
- The mechanism involves interaction with a putative cell surface receptor, not direct binding to FN.
- This finding sheds light on novel regulatory mechanisms of cell adhesion mediated by fibronectin.