Abstract
How different integrins that bind to the same type of extracellular matrix protein mediate specific functions is unclear. We report the functional analysis of β1- and αv-class integrins expressed in pan-integrin-null fibroblasts seeded on fibronectin. Reconstitution with β1-class integrins promotes myosin-II-independent formation of small peripheral adhesions and cell protrusions, whereas expression of αv-class integrins induces the formation of large focal adhesions. Co-expression of both integrin classes leads to full myosin activation and traction-force development on stiff fibronectin-coated substrates, with αv-class integrins accumulating in adhesion areas exposed to high traction forces. Quantitative proteomics linked αv-class integrins to a GEF-H1-RhoA pathway coupled to the formin mDia1 but not myosin II, and α5β1 integrins to a RhoA-Rock-myosin II pathway. Our study assigns specific functions to distinct fibronectin-binding integrins, demonstrating that α5β1integrins accomplish force generation, whereas αv-class integrins mediate the structural adaptations to forces, which cooperatively enable cells to sense the rigidity of fibronectin-based microenvironments.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Carrier Proteins / metabolism
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Cell Adhesion
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Cell Line
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Cell Movement
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Cellular Microenvironment*
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Extracellular Matrix / metabolism
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Extracellular Matrix Proteins / metabolism
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Fibroblasts
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Fibronectins / metabolism*
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Focal Adhesions / metabolism
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Formins
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Guanine Nucleotide Exchange Factors / genetics
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Guanine Nucleotide Exchange Factors / metabolism
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Integrin alpha5beta1 / metabolism
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Integrin alphaV / metabolism*
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Integrin beta1 / metabolism*
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Male
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Mice
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Mice, Transgenic
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Myosin Type II / metabolism*
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Protein Binding
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Protein Serine-Threonine Kinases / metabolism
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism
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RNA Interference
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RNA, Small Interfering
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Rho Guanine Nucleotide Exchange Factors
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rho-Associated Kinases / metabolism
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rhoA GTP-Binding Protein / metabolism
Substances
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Arhgef2 protein, mouse
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Carrier Proteins
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Diap1 protein, mouse
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Extracellular Matrix Proteins
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Fibronectins
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Formins
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Guanine Nucleotide Exchange Factors
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Integrin alpha5beta1
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Integrin alphaV
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Integrin beta1
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Proto-Oncogene Proteins
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RNA, Small Interfering
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Rho Guanine Nucleotide Exchange Factors
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integrin-linked kinase
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Protein Serine-Threonine Kinases
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rho-Associated Kinases
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Myosin Type II
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rhoA GTP-Binding Protein