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Suppression of cell spreading by v-Crk requires Ras-MEK-MAP kinase signaling
1Department of Molecular Pathogenesis, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
Abstract:
We investigated the attachment and spreading of v-Crk-transformed cells, v-Crk3Y1, on fibronectin. Transformation by v-Crk virtually suppressed the spreading, but not the attachment, of cells on fibronectin. This suppression of cell spreading was not correlated with the suppression of integrin alpha5 and beta1 expression. However, the spreading of v-Crk3Y1 on fibronectin was dramatically restored by either expression of dominant-negative Ras or treatment with manumycin A, a Ras farnesyltransferase inhibitor. Moreover, both expression of dominant-negative MEK1 and treatment of cells with U0126, a MEK1 inhibitor, restored the cell spreading of v-Crk3Y1. In contrast, neither treatment with LY294002, a PI3K inhibitor, nor expression of dominant-negative C3G showed no effect on cell spreading on fibronectin. Taken together, our results suggest that, among multiple signaling pathways activated by v-Crk, the Ras-MEK1-MAP kinase cascade plays a pivotal role in the suppression of cell spreading on fibronectin, but C3G and the PI3 kinase do not.
Insights
v-Crk transformation suppresses cell spreading on fibronectin by activating the Ras-MEK1-MAP kinase pathway. Inhibiting Ras or MEK1 restores cell spreading, indicating their crucial role in this process.
Area of Science:
- Cell Biology
- Molecular Biology
- Signal Transduction
Background:
- Cell transformation by v-Crk significantly impacts cell adhesion and spreading.
- Fibronectin is a key extracellular matrix protein involved in cell adhesion and migration.
Purpose of the Study:
- To investigate the role of v-Crk transformation in cell spreading on fibronectin.
- To identify the specific signaling pathways involved in the suppression of cell spreading.
Main Methods:
- Studied attachment and spreading of v-Crk-transformed cells (v-Crk3Y1) on fibronectin.
- Assessed the effects of dominant-negative Ras, manumycin A (Ras farnesyltransferase inhibitor), dominant-negative MEK1, U0126 (MEK1 inhibitor), LY294002 (PI3K inhibitor), and dominant-negative C3G on cell spreading.
- Examined integrin alpha5 and beta1 expression levels.
Main Results:
- v-Crk transformation suppressed cell spreading on fibronectin but not attachment.
- Suppression of spreading was not linked to integrin alpha5/beta1 expression.
- Cell spreading was restored by dominant-negative Ras, manumycin A, dominant-negative MEK1, and U0126.
- PI3K inhibition (LY294002) and dominant-negative C3G had no effect on cell spreading.
Conclusions:
- The Ras-MEK1-MAP kinase cascade is pivotal in v-Crk-mediated suppression of cell spreading on fibronectin.
- C3G and PI3 kinase pathways are not involved in this specific suppression mechanism.