Integrins are cell surface receptors that interact with the extracellular matrix and mediate intracellular signals in response to the extracellular matrix including cellular shape, mobility, and progression through the cell cycle. Integrins do not themselves possess a kinase domain or enzymatic activity but rely on association with other signaling molecules to transmit signals. Interactions between the extracellular matrix and the actin cytoskeleton commonly take place at focal adhesions on the cell surface that contain localized concentrations of integrins, signaling molecules, and cytoskeletal elements. Talin forms a direct interaction with the integrin cytoplasmic domain, and interacts with cytoskeletal elements (actin) and signaling factors. Paxillin and CAS also localize in focal adhesions and may serve as a scaffold for other integrin signaling components like FAK and src. Interaction of FAK, CAS and src may be required for integrin regulation of cell cycle progression. The CrkL adaptor protein may regulate downstream integrin signaling. Growth factor signaling pathways and the caveolin receptor exhibit important cross talk with integrin receptors in cellular responses like activation of map kinase, proliferation and motility.

Contributor: Glenn Croston, PhD.

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