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Integrin-dependent activation of MAP kinase: a link to shape-dependent cell proliferation
1Department of Cell Biology and Anatomy, University of Miami School of Medicine, Florida 33101, USA.
Molecular Biology of the Cell
|March 1, 1995
Summary
Extracellular matrix adhesion activates mitogen-activated protein (MAP) kinases, specifically ERK 1 and ERK 2, influencing cell cycle progression. This activation is linked to cell shape changes and cytoskeleton organization, distinct from soluble growth factor signaling.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cell adhesion to the extracellular matrix (ECM) is crucial for cell cycle progression.
- Integrin-dependent cytoskeletal organization and cell shape changes are involved in ECM-mediated cell cycle control.
- Identifying signaling molecules associated with integrin-dependent shape changes is key to understanding this process.
Purpose of the Study:
- To identify kinase activities stimulated by long-term cell adhesion to ECM components.
- To investigate the role of specific kinases in integrin-dependent cell shape changes and cell cycle progression.
- To differentiate the regulation of kinase activity by ECM versus soluble mitogens.
Main Methods:
- G0-synchronized NIH-3T3 cells were adhered to fibronectin-coated dishes.
- Kinase activities were measured using myelin basic protein phosphorylation assays.
- Western blotting with anti-phosphotyrosine and anti-mitogen-activated protein (MAP) kinase antibodies was employed.
- The effect of cytochalasin D on MAP kinase activation was assessed.
- Cell adhesion to vitronectin and type IV collagen was also studied.
Main Results:
- Long-term adhesion to fibronectin stimulated kinase activities, identified as ERK 1 and ERK 2 (42 and 44 kDa).
- MAP kinase activation by fibronectin was gradual, persistent, and associated with cell spreading, unlike rapid, transient activation by platelet-derived growth factor.
- Cytochalasin D inhibited fibronectin-induced MAP kinase activation.
- MAP kinase was also activated by adhesion to vitronectin and type IV collagen, correlating with cell spreading.
Conclusions:
- Fibronectin-stimulated MAP kinase (ERK 1/2) activation is dependent on cytoskeletal organization and cell shape changes.
- The regulation of G1 phase MAP kinase activity by ECM differs from that by soluble mitogens.
- MAP kinase signaling is implicated in ECM-driven, shape-dependent cell cycle progression.