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A GTPase controls cell-substrate adhesion in Xenopus XTC fibroblasts
1Department of Pharmacology, University of California, San Francisco 94143-0450.
The Journal of Cell Biology
|September 1, 1992
Summary
Researchers explored how GTPases regulate cell-substrate adhesion in Xenopus fibroblasts. Activating GTPases increased adhesion, while inhibiting them decreased it, suggesting a cytoplasmic GTPase controls this process.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cell-substrate adhesion is vital for tissue development and maintenance.
- The molecular mechanisms regulating cell adhesion are not fully understood.
- GTPases are known regulators of cell morphology and cytoskeletal dynamics.
Purpose of the Study:
- To investigate the role of GTPases in controlling cell-substrate adhesion.
- To elucidate the signaling pathways involved in regulating cell adhesion.
Main Methods:
- Injection of guanine nucleotide analogs (GTPγS, GDPβS) into Xenopus XTC fibroblasts.
- Treatment with GRGDSP peptide to inhibit integrin binding.
- Assessment of cell morphology changes (ruffling, spreading, rounding).
- Treatment with phorbol ester (12-O-tetradecanoylphorbol-13-acetate) to activate protein kinase C.
Main Results:
- GTPase activation (GTPγS) increased cell spreading and adhesion, while GDPβS decreased it.
- GTPase activation did not affect cell rounding induced by trypsin, indicating contractility is unaffected.
- GRGDSP treatment showed that GTPase-activated cells resisted rounding longer than controls.
- Phorbol ester treatment had opposite effects to GTPase activation, suggesting distinct pathways.
Conclusions:
- A cytoplasmic GTPase plays a significant role in regulating cell-substrate adhesion.
- At least two distinct signaling pathways control cell-substrate adhesion in these cells: one involving GTPases and another involving protein kinase C.