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Interaction of basic fibroblast growth factor (FGF-2) with nonresponsive HeLa cells
L Gannoun-Zaki1, I Pieri, J Badet
1Laboratoire C.R.R.E.T., INSERM CJF 9014, Université Paris XII, Créteil, France.
Experimental Cell Research
|August 1, 1994
Summary
Basic fibroblast growth factor (bFGF) binding and internalization were studied in HeLa cells. Heparan sulfate proteoglycans mediate bFGF binding and internalization in non-proliferating HeLa cells, suggesting roles beyond cell growth.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Basic fibroblast growth factor (bFGF), also known as FGF-2, is a potent mitogen involved in cell proliferation, differentiation, and survival.
- While bFGF is known to bind to high-affinity receptors, its interaction with cell surface molecules, particularly heparan sulfate proteoglycans, is crucial for its biological activities.
- Human HeLa adenocarcinoma cells are generally considered non-responsive to bFGF's proliferative effects, making them a unique model to study alternative bFGF functions.
Purpose of the Study:
- To investigate the binding characteristics of bFGF to nonresponsive human HeLa cells.
- To elucidate the role of heparan sulfate proteoglycans in bFGF binding and internalization in HeLa cells.
- To explore potential mechanisms of bFGF internalization in HeLa cells independent of canonical high-affinity receptor signaling.
Main Methods:
- Binding assays using radiolabeled bFGF (125I-bFGF) were performed on HeLa cells and Chinese hamster lung fibroblasts (CCL 39).
- Heparinase II treatment was employed to assess the contribution of heparan sulfate to bFGF binding.
- Cross-linking experiments and internalization studies were conducted to analyze bFGF-cell interactions and uptake.
Main Results:
- HeLa cells exhibited bFGF binding to a single family of low-affinity sites, similar in quantity to responsive CCL 39 cells.
- Heparinase II treatment significantly reduced bFGF binding in both cell types, confirming the involvement of heparan sulfate.
- bFGF was internalized in HeLa cells via heparitinase-sensitive binding sites, independent of high-affinity receptors observed in CCL 39 cells.
Conclusions:
- Heparan sulfate proteoglycans play a critical role in mediating bFGF binding and internalization in nonresponsive HeLa cells.
- The internalization of bFGF in HeLa cells occurs through heparitinase-sensitive sites, suggesting mechanisms distinct from canonical FGF receptor signaling.
- These findings indicate that bFGF may possess functions beyond cell proliferation, mediated through interactions with cell surface heparan sulfates.