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Characterization of the signaling pathways regulating alpha2beta1 integrin-mediated events by a pharmacological
1UMR 144, CNRS, Subcellular Structure and Cellular Dynamics, Institut Curie Research Division, Paris, France.
Abstract:
In certain instances of developing and adult organism, epithelial cells can change morphology and transform into mesenchymal-like type in order to move through the extracellular matrix. However, because of the multiplicity and complexity of signaling pathways that contribute to these processes, their molecular dissection has remained difficult. By using a pharmacological approach on the rat bladder carcinoma cell line NBT-II dispersion system, we have identified distinct signaling events for adhesion and motility in response to collagen, both activities depending on alpha2beta1 integrin. Treatment of cells with PKC inhibitors markedly impaired initial attachment on collagen without affecting the capacity of cells to move, suggesting that PKC activity is required for initial adhesion strength during cell translocation. Both adhesion and motility were diminished by tyrosine kinase inhibitors herbimycin and tyrphostin whereas tyrosine phosphatase inhibitors amplified cell scattering. The collagen-induced dispersion was insensitive to genistein which we previously showed to abrogate growth factor-induced scattering, thus demonstrating inducer specificity. Finally. Ras inhibitors and expression of a dominant negative form of Ras (N17Ras) while affecting initial cell attachment, did not prevent cell migration, and instead favored the dissociated state on collagen. The specific signaling pathways identified for adhesion and motility should help to understand the sequential processes associated with cell migration.
Insights
This study identifies distinct signaling pathways for epithelial cell adhesion and motility on collagen. Protein kinase C (PKC) and tyrosine kinases are crucial for cell attachment and migration during epithelial-mesenchymal transition.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Epithelial cells can undergo epithelial-mesenchymal transition (EMT) to become motile, a process crucial for development and disease.
- The complex signaling pathways governing EMT, particularly cell adhesion and motility, are not fully understood.
- Dissecting these pathways is challenging due to their multiplicity and intricate interactions.
Purpose of the Study:
- To identify distinct molecular signaling events regulating cell adhesion and motility in response to collagen.
- To elucidate the roles of specific signaling molecules, including protein kinase C (PKC), tyrosine kinases, and Ras, in collagen-induced cell migration.
- To differentiate the signaling requirements for initial cell attachment versus sustained cell movement.
Main Methods:
- Utilized a pharmacological approach on the NBT-II rat bladder carcinoma cell line dispersion system.
- Investigated the effects of specific inhibitors (PKC inhibitors, tyrosine kinase inhibitors, tyrosine phosphatase inhibitors, Ras inhibitors) and dominant-negative Ras expression.
- Assessed cell attachment, motility, and scattering in response to collagen, with a focus on alpha2beta1 integrin-dependent activities.
Main Results:
- PKC activity is essential for initial cell attachment to collagen but not for subsequent cell movement.
- Tyrosine kinase inhibitors diminished both adhesion and motility, while tyrosine phosphatase inhibitors enhanced cell scattering.
- Ras inhibition and dominant-negative Ras affected initial attachment but promoted cell dissociation and migration, indicating pathway specificity.
Conclusions:
- Distinct signaling pathways govern cell adhesion and motility during collagen-induced cell migration.
- PKC and tyrosine kinases play critical roles in the initial stages of cell attachment and translocation.
- Understanding these specific pathways provides insights into the sequential processes of cell migration and EMT.